The effect of land use configurations on concentration, spatial distribution, and ecological risk of heavy metals in coastal sediments of northern part along the Persian Gulf

Enhancing water quality monitoring through the integration of deep learning neural networks and fuzzy method

The escalating growth of the global population has led to degraded water quality, particularly in seawater environments. Water quality monitoring is crucial to understanding the dynamic changes and implementing effective management strategies. In this study, water samples from the southwestern regions of Iran were spatially analyzed in a GIS environment using geostatistical methods. Subsequently, a water quality map was generated employing large and small fuzzy membership functions. Additionally, advanced prediction models using neural networks were employed to forecast future water pollution trends. Fuzzy method results indicated higher pollution levels in the northern regions of the study area compared to the southern parts. Furthermore, the water quality prediction models demonstrated that the LSTM model exhibited superior predictive performance (R2 = 0.93, RMSE = 0.007). The findings also underscore the impact of urbanization, power plant construction (2010 to 2020), and inadequate urban wastewater management on water pollution in the studied region.

The hidden threat of heavy metal leaching in urban runoff: Investigating the long-term consequences of land use changes on human health risk exposure

This study evaluated the potential effects of long-term land use and climate change on the quality of surface runoff and the health risks associated with it. The land use change projection 2030 was derived from the main changes in land use from 2009 to 2019, and rainfall data was obtained from the Long Ashton Research Station Weather Generator (LARS-WG) model. The Long-Term Hydrological Impact Assessment (L-THIA) model was then utilized to calculate the rate of runoff heavy metal (HM) pollutant loading from the urban catchment. It was found that areas with heavy development posed a significantly greater public health risk associated with runoff, with higher risks observed in high-development and traffic areas compared to industrial, residential, and commercial areas. Additionally, exposure to Lead (Pb), Mercury (Hg), and Arsenic (As) was found to contribute significantly to overall non-carcinogenic health risks for possible consumers of runoff. Carcinogenic risk values of As, Cadmium (Cd), and Pb were also observed to increase, particularly in high-development and traffic areas, by 2030. This investigation offers important insight into the health risks posed by metals present in surface runoff in urban catchment areas under different land use and climate change scenarios.

Risk assessment of heavy metals and total petroleum hydrocarbons (TPHs) in coastal sediments of commercial and industrial areas of Hormozgan province, Iran

The significant increase in the pollution of heavy metals and organic pollutants, their stable nature, and their high toxicity are gradually becoming a global crisis. In a recent study, a comprehensive assessment of the spatial distribution of heavy metals and total petroleum hydrocarbons (TPHs), as well as an assessment of their ecological risks in the sediments of 32 stations located in commercial and industrial areas (Mainly focusing on petrochemical and power industries, desalination plants and transit Ports) of Hormozgan province (East and West of Jask, Bandar Abbas, Qeshm, and Bandar Lengeh) was performed during 2021-2022. The sediment samples were digested with HNO3, HCl and HF solvents. The concentration of heavy metals was determined with furnace and flame systems of atomic absorption spectrometer. The concentration of heavy metals showed significant spatial changes between stations. The ecological assessment indices between the regions indicated that the stations located in Shahid Bahonar Port, Suru Beach, and Khor gorsouzuan had a higher intensity of pollution than other places and significant risks of pollution, especially in terms of Cr and Ni. The average contamination degree (CD) (14.89), modified contamination degree (MCD) (2.48), pollution load index (PLI) (2.32), and potential ecological risk index (PERI) (100.30) showed the sediments in the area of Shahid Bahonar Port, Suru beach and Khor gorsouzuan, experience significant to high levels of pollution, especially Cr and Ni. Using contamination factor (CF) and Geoaccumulation index (Igeo), Cr was considered the most dangerous metal in the studied areas. Based on the global classification of marine sediment quality for the concentrations of TPHs, the sediments of the studied stations were classified as non-polluted to low pollution. In all regions, indices of the PELq (General toxicity) and CF (Contamination factor) were much lower than 0.1 and 1 respectively, showing the absence of adverse biological effects caused by TPHs in sediments. It is necessary to consider comprehensive and impressive strategies to control and reduce pollution of heavy metals, especially in the areas of Shahid Bahonar Port, Suru Beach, and Khor gorsouzuan, so that the sources of this pollution are required to be identified and managed.

Pollution sources and risk assessment of potentially toxic elements in soils of multiple land use types in the arid zone of Northwest China based on Monte Carlo simulation

The concentration of potentially toxic elements (PTEs) in soils of different land-use types varies depending on climatic conditions and human. Topsoil samples were collected in Northwest China to investigate PTE pollution and risk in different land uses, and thereby estimate the risk of various pollution sources. The results showed that human activity had an impact on PTE concentrations in the study area across all land use types, with farmland, grassland, woodland, and the gobi at moderate pollution levels and the desert at light pollution levels. Different PTE sources pose different risks depending on the land-use type. Apart from deserts, children are exposed to carcinogenic risk from a variety of sources. A mixed natural and agricultural source was the main source of public health risk in the study area, contributing 38.7% and 39.0% of the non-carcinogenic and 40.7% and 35.5% of the carcinogenic risks, respectively. Monte Carlo simulations showed children were at a higher health risk from PTEs than adult s under all land uses, which ranked in severity as farmland > woodland > grassland > gobi > desert. As and Ni has a higher probability of posing both a non-carcinogenic and a carcinogenic risk to children. Sensitivity analysis showed that the contribution of parameters to the assessment model of PTEs exhibited the following contribution pattern: concentration > average body weight > ingestion rate > other parameters. The PTEs affecting the risk assessment model were not common among different land use types, where the importance distribution pattern of each parameter was basically the same in woodland, grassland, and farmland, and Ni contributed the most to carcinogenic risk. However, Cr contributed the most to the carcinogenic risk in the desert and gobi.

Pollution, spatial distribution, and health risks assessment of nutrient concentration in surface water resources of Maroon-Jarahi Basin in southwestern Iran

Nowadays, the introduction of nutrients caused by human activities is considered an environmental issue and a significant problem in river basins and coastal ecosystems. In this study, the concentration of nutrients (NO 3 - andPO 4 3 - ) in the surface water sources of the Maroon-Jarahi watershed in the southwest of Iran was determined, and the pollution status and health risk assessment were done. The average concentration of nitrate and phosphate in Ludab, Maroon, Zard, Allah, Jarahi rivers, and Shadegan wetland were obtained at 2.25-0.59, 4.59-1.84, 4.07-2.02, 5.40-2.81, 11.51-4.67, 21.63 and 6.20 (mg/l), respectively. A comparison of the results with the World Health Organization (WHO) limit showed that nitrate was lower than in all stations, but phosphate was higher than the limit in some stations of the Maroon, Allah, Jarahi rivers, and Shadegan wetland. Calculation of linear regression analysis showed significant positive relationships between nitrate and phosphate in all surface water sources (except Ludab) and based on the N/P ratio, nitrogen was estimated as the limiting factor in phytoplankton growth (N/P < 16). The evaluation of the status of the Nutrient pollution index (NPI) was observed as: Shadegan > Jarahi > Allah > Maroon > Zard > Ludab that the Jarahi River and Shadegan wetland were in the medium pollution class (1 < NPI ≤ 3) and other waterbodies were in the non-polluted to low pollution state (NPI < 1). Calculation of the chronic daily intake (CDI) showed that water body nutrients cause more non-carcinogenic health risks through the oral route than dermal exposure, and according to HI, children's health is more at risk than adults. Findings showed that surface water resources especially downstream of the Maroon-Jarahi watershed are at eutrophication risk, and to control the nearby human activities and as a result increase the nutrients in these water resources, measures should be taken.

Lactational Exposure of Human Infants to Metal (loid)s: A Comparison of Industrial and Urban Inhabitants in North of the Persian Gulf

In this study, postnatal metal (loid)s (MLs) exposure was compared between the petrochemical and gas area of Asaluyeh (PGA) and urban area of Kaki (UA) in Bushehr province, Iran. Two hundred human breast milk (BM) samples from the industrial and urban areas were analyzed for MLs using Inductivity Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Boron (B), copper (Cu), iron (Fe), and nickel (Ni) were found at the highest levels in both study areas. Adjusted multiple linear regression models revealed that the mean concentration of total MLs in BM samples collected from the PGA was statistically significantly greater than that of the UA (655.85 vs. 338.17 µg/L). Also, the mean concentrations of all detected MLs in BM samples collected from the PGA were statistically significantly higher than those collected from the UA. The hazard index (HI) of combined MLs in the PGA and UA illustrated non-cancer risk for infants. Lead (Pb) and chromium (Cr) in the PGA and Cr in the UA showed the risk of cancer. So it can be concluded that nursing infants from an industrial area are most at risk for MLs exposure during entire lactation course than those from an urban area.

A novel ratiometric electrochemical aptasensor based on M-shaped functional DNA complexes for simultaneous detection of trace lead and mercury ions in series aquatic edible vegetables

Simultaneous quantification of multiple heavy metal ions (HMIs) is essential due to enhanced toxicity induced by synergistic effects. The currently available detection methods suffer from drawbacks such as costly devices, poor anti-interference, and specificity. In this work, a ratiometric electrochemical aptasensor for simultaneous detection of trace lead (Pb2+) and mercury ions (Hg2+) was developed. Here, a metal-organic framework, UiO-66-CNTs, with inherent and stable electrochemical signal was used for loading complementary strands (CSs) and internal reference. Guanine-rich and thymine-rich oligonucleotides, labelled with carbon dots (CDs), acted as aptamers (Apts) and hybridized with CSs to form M-shaped DNA complexes. Pb2+ and Hg2+ could be recognized and captured by Apts to form Pb2+-G-quadruplex and T-Hg2+-T complexes, leading to the destruction of M-shaped DNA complexes and changes in CDs' signal. The current ratios, ICDs/IUiO-66-CNTs, were applied to quantify Pb2+ and Hg2+. Benefiting from the anti-interference ability of the ratiometric strategy and the specificity of Apts, the proposed method enabled detection Pb2+ and Hg2+ through simple instrumentation, with detection limits of 2.0 ng mL-1 and 0.5 ng mL-1. Moreover, it was applied to assess Pb2+ and Hg2+ contamination in series of aquatic edible vegetables. The experimental results were consistent with inductively coupled plasma-mass spectrometry (ICP-MS), demonstrating its potential in practical applications.

Accumulation, sources, and health risks of phthalic acid esters (PAEs) in road dust from heavily industrialized, urban and rural areas in southern Iran

In this research, a total of 51 road dust samples were collected from three districts (Asaluyeh, Bushehr, and Goshoui) in the south of Iran from April to June 2022 and analyzed for the concentration of 7 phthalic acid esters (PAEs) compounds. Asaluyeh was considered as an industrial area (near gas and petrochemical industries), Bushehr as an urban area, and Goshoui as a rural area (far from pollution sources). The PAEs concentration of the street dust samples was determined using a mass detection gas chromatography (GC/MS). The mean ± SD levels of ƩPAEs in samples from industrial, urban, and rural sources were 56.9 ± 11.5, 18.3 ± 9.64, and 5.68 ± 1.85 μg/g, respectively. The mean concentration levels of ƩPAEs was significantly (P < 0.05) higher in samples from the industrial area than urban and rural areas. The mean levels of di(2-Ethylhexyl) phthalate (DEHP) in industrial, urban, and rural areas were 20.3 ± 8.76, 4.59 ± 1.71, and 2.35 ± 0.98 μg/g, respectively. The results of the PCA analysis indicate that the likely major sources of PAEs in the road dust in the studied areas are the application of various plasticizers in industry, solvents, chemical fertilizers, waste disposal, wastewater (e.g., agricultural, domestic, and industrial), and the use of plastic films and plastic-based irrigation pipes in greenhouses. As well as, it was found that the non-cancer risk of exposure to dust-bound PAEs was higher for children than for adults. These values were <1 for both age groups (children and adults) and the exposure of inhabitants to PAEs in road dust did not pose a notable non-cancer risk. The cancer risk from exposure to DEHP in road dust was below the standard range of 10-6 in all three areas. Further studies that consider different routes of exposure to these contaminants are needed for an accurate risk assessment. Moreover, since higher PAEs level was found in industrial area, decision-makers should adopt strict strategies to control the discharging of pollution from industries to the environment and human societies.

Assessment of land use effect, mapping of human health risks and chemometric analysis of potential toxic elements in topsoils of Aran-o-Bidgol, Iran

This study examines topsoil contamination in Aran-o-Bidgol urban region of central Iran, with a focus on potentially toxic elements (PTEs). A total of 135 topsoil samples in different land types were characterized, ranging from areas with agricultural farms, desert, industrial and residential activity, and brick kilns. The average concentrations of Cd, Pb, Cu, Ni, Cr, Co, Fe, Zn, and Mn were 0.72, 11.41, 14.82, 29.87, 51.13, 106.69, 8741.87, 48.59, and 346.42 mg kg-1, respectively, which all exceed the local background levels. The results reveal that land use significantly affected PTE concentrations. Cr, Co, Mn, and Fe concentrations in soils of residential and brick kiln areas were especially high. In contrast, concentrations of Cu, Ni, and Zn were higher in agricultural and residential areas. Risk assessment analysis showed that the sum of toxic units for PTEs for brick kilns (1.72), residential (1.82), and agricultural (1.79) areas exceeded those of other land types and that Ni and Cr contributed the most to the high toxic risk index values. Both carcinogenic and non-carcinogenic risk indices of PTEs in soils were within an acceptable limit, except for the cancer risk of Ni (3.52E-04) and Cr (3.00E-04) among children. The spatial hazard index and carcinogenic health risk of PTEs showed that samples from the southwestern parts of the study area might pose significant health problems to adults and children. This study demonstrates how combining different techniques can help spatially characterize PTE accumulation and protect populations at risk.

The multi-media environmental behavior of heavy metals around tailings under the influence of precipitation

Precipitation can lead to significant leaching of heavy metals from abandoned tailings，resulting in a decline in the quality of the surrounding environment. This study aimed to simulate and quantify the migration patterns and fate of heavy metals in tailings caused by precipitation in various environmental media (tailings, air, water, soil, and sediments) using leaching tests, source apportionment, and a fugacity model. Results revealed that the average contents of Cd, Cu, As, Pb, Zn, and Cr in the un-weathered tailings were 3.43, 495.56, 160.70, 138.94, 536.57, and 69.52 mg/kg, respectively. The ecological risk factors in the tailings as well as in sediments and soils, were in the following order: Cd >Cu >As >Pb >Zn >Cr. A fugacity model based on the mass-balance methods was established, achieving a good agreement between simulation and measured values. The total amounts of Cd, Cu, As, Pb, and Zn leached from abandoned tailings over the 30-year evaluation period were estimated to be 1.09, 62.44, 0.16, 0.94, and 102.12 t, respectively. Soil and sediments are important reservoirs for heavy metals. The sum of the As, Cd, Cu, Pb, and Zn storage capacities in the soil and sediment accounted for 77.28%, 75.63%, 73.94%, 69.39%, and 57.80% of the total storage capacity, respectively. This study could provide the means for the establishment of a targeted pollution control plan, a guide for restoration projects, and will aid in controlling pollution risk and improving the surrounding environment.

Static and dynamic source identification of trace elements in river and soil environments under anthropogenic activities in the Haraz plain, Northern Iran

Unsustainable human activities have disrupted the natural cycle of trace elements, causing the accumulation of chemical pollutants and making it challenging to determine their sources due to interwoven natural and human-induced processes. A novel approach was introduced for identifying the sources and for quantifying the contribution of trace elements discharge from rivers to soils. We integrated fingerprinting techniques, soil and sediment geochemical data, geographically weighted regression model (GWR) and soil quality indices. The FingerPro package and the state-of-the-art tracer selection techniques including the conservative index (CI) and consensus ranking (CR) were used to quantify the relative contribution of different upland sub-watersheds in trace element discharge soil. Our analysis revealed that off-site sources (upland watersheds) and in-site sources (land use) both play an important role in transferring trace elements to the Haraz plain (northern Iran). The unmixing model's results suggest that the Haraz sub-watersheds exhibit a higher contribution to trace elements transfer in the Haraz plain, and therefore, require greater attention in terms of implementing soil and water conservation strategies. However, it is noteworthy that the Babolroud (adjacent to Haraz) exhibited a better performance of the model. A spatial correlation between certain heavy metals, such as As and Cu, and rice cultivation existed. Additionally, we found a significant spatial correlation between Pb and residential areas, particularly in the Amol region. Our result highlights the importance of using advanced spatial statistical techniques, such as GWR, to identify subtle but critical associations between environmental variables and sources of pollution. The methodology used comprehensively identifies dynamic trace element sourcing at the watershed scale, allowing for pollutant source identification and practical strategies for soil and water quality control. Tracer selection techniques (CI and CR) based on conservatives and consensus improve unmixing model accuracy and flexibility for precise fingerprinting.

Heavy metals concentration in zooplankton (copepods) in the western Bay of Bengal

Along the coastline, urbanisation and industrialization pose significant challenges to marine habitats and biodiversity. Most wastewater that reaches the marine environment contains toxic metals, which, as they are non-biodegradable, accumulate in the biota and enter the marine food chain. This study presents the concentration of nine heavy metals (Fe, Zn, Cu, Co, Cr, Mn, Ni, Pb, and Cd) in zooplankton (copepods) during the Spring Intermonsoon/Pre-Monsoon (April 2019) in the western Bay of Bengal (BoB). Higher Fe concentrations were found in copepods both nearshore (42,352 µg/g) and offshore (9835 µg/g). However, the relative amounts of heavy metals in copepods from 16 locations (eight nearshore and eight offshore) varied in the order of Fe > Zn > Cu > Co > Cr > Mn > Ni > Pb > Cd. The copepods in the nearshore locations had higher concentrations of heavy metals than those offshore. Compared to earlier data on heavy metals, particularly those that are physiologically non-essential and toxic, the current study demonstrates higher amounts of these metals in copepods in the inshore BoB [Ni (avg. 58.7 ± 5.5 µg/g), Pb (avg. 25.6 ± 4.7 µg/g), and Cd (avg. 16.4 ± 0.9 µg/g)]. Considering the strong East India Coastal Currents in the western BoB, trace metal-concentrated copepods could be transported too far along the Indian coastline from the current study area.

PAHs pollution in the outdoor air of areas with various land uses in the industrial city of Iran: distribution, source apportionment, and risk assessment

Shahryar city regions with various land uses had their outdoor air concentrations of PM_2.5-bound PAHs determined. Totally, 32 samples were taken - eight samples from the industrial region air (IS), eight samples from the high-traffic urban regions air (HTS), eight samples from the air of commercial regions (CS), and eight samples from residential areas (RS), which were analyzed by GC-MS. According to the study's findings, in the outdoor air of IS, HTS, CS, and RS, there were mean ƩPAHs concentrations of 23.25 ± 20.22, 38.88 ± 26.53, 6.97 ± 4.26, and 4.48 ± 3.13 ng/m³, respectively. As comparison to CS and RS, mean concentration of ƩPAHs in samples from HTS and IS was substantially greater (p < 0.05). Using the Unmix.6 receptor model, sources of PAHs in the air of Shahryar were allocated. The model's results show that 42% of PAHs come from diesel vehicles and industrial activities, 36% from traffic and other transportation sources, and 22% from heating sources and coal burning. The carcinogenicity suffering resulting from exposure to PAHs was as follows: This value for children of the ingestion, inhalation pathways and dermal contact is (1.90 × 10^-6-1.38 × 10^-4), (5.5 × 10^-11-2.67 × 10^-9) and (2.36 × 10^-6-1.72 × 10^-4), respectively. Also, for adults were (1.47 × 10^-6 - 1.07 × 10^-4), (1.14 × 10^-10 - 5.27 × 10^-9) and (3.68 × 10^-6- 2.87 × 10^-4), respectively. In general, the analyzed region's carcinogenicity risk estimates fell within the range of acceptable limit.

Potential toxic elements in costal sediment of the Persian Gulf: a systematic review-meta-analysis, non-dietary risk assessment and ecological risk assessment

Potential toxic element (PTE) contamination in the Persian Gulf has become an important health concern in recent decades. This investigation aimed to meta-analyses of potential toxic elements including lead (Pb), inorganic arsenic (As), cadmium (Cd), nickel (Ni), and mercury (Hg) in the coastal sediment of the Persian Gulf. In this study, an attempt was made to retrieve papers conducted on the concentration of PTE in the coastal sediment of the Persian Gulf by searching in international databases including Web of Science, Scopus, Embase, and PubMed. Meta-analysis concentration of PTE in the coastal sediment of the Persian Gulf was conducted using random effects model based on the country subgroup. Additionally, non-dietary risk assessment including non-carcinogenic and carcinogenic risks from ingestion, inhalation and dermal contact routes and ecological risk assessment was estimated. Seventy-eight papers with 81 data-reports (1650 sample size) were included in our meta-analysis. The rank order of heavy metals in coastal sediment of the Persian Gulf based on pooled concentration was Ni (65.44 mg/kg) > Pb (58.35 mg/kg) > As (23.78 mg/kg) > Cd (1.75 mg/kg) > Hg (0.77 mg/kg). The highest concentration of As, Cd, Pb, Ni, and Hg was observed in the coastal sediment of Saudi Arabia, Arab Emirates, Qatar, Iran, and Saudi Arabia, respectively. Although the I_geo index in coastal sediment of the Persian Gulf was in grade 1 (uncontaminated) and grade 2 (slightly contaminated) but total target hazard quotient (TTHQ) of adults and adolescent was higher than 1 value in Iran, Saudi Arabic, United Arab Emirates, and Qatar. Total cancer risk (TCR) for adults and adolescent due to As was higher than 1E-6 in Iran, United Arab Emirates, and Qatar but TCR for adolescents due to As was higher than 1E-6 in Saudi Arabic. Therefore, it is recommended to monitor the concentration of PTE and implementation of programs to reduce the emission of PTE from resources in the Persian Gulf.

National-scale monitoring of historic used organochlorine pesticides (OCPs) and current used pesticides (CUPs) in Chinese surface soil: Old topic and new story

Along with the restriction and prohibition of historic used organochlorine pesticides (OCPs), current used pesticides (CUPs) were widely used as alternatives. In order to investigate the pollution characteristics of pesticides, the levels and spatial distributions of OCPs and CUPs in 154 surface soil across China were comprehensively compared. Totally, 107 target pesticides were screened, and 20 OCPs and 34 CUPs were detected. The numbers of co-occurred pesticides in single soil sample were from 17 to 36 indicating the diversity and complexity of pesticides pollution. The concentrations of OCPs in urban soils were higher than rural soils, while rural > urban for CUPs. Furthermore, obviously different spatial distribution patterns were found for OCPs and CUPs. For OCPs, the secondary distribution pattern was dominant. For CUPs, the primary distribution pattern was obviously observed due to their current extensive usage. In addition, higher concentrations of both CUPs and OCPs were accumulated in the Northeast China Plain due to long-range atmospheric transport and deposition. Along with the old topic of OCPs, the study pointed out the preliminary understanding of CUPs pollution characteristic in surface soil of China, which provided a new story with the deep understanding of their environmental fate in both China and the world.

Uptake and distribution of microplastics of different particle sizes in maize (Zea mays) seedling roots

Microplastics (MPs) pollution may be harmful to terrestrial ecosystems and is receiving increasing attention. A microcosm study on the uptake of MPs in maize (Zea mays) seedling roots exposed to small polystyrene (PS) beads (0.2, 0.5 and 1.0 μm) and large PS beads (2.0 and 5.0 μm) at 50 mg L^-1 for 7 d was performed. Additionally, the absorption ability of different parts of the roots was also investigated after 10 d of exposure with 0.2 μm PS beads. The results showed that root and shoot biomass remained unchanged under different particle sizes of PS beads. The small PS beads markedly increased the accumulation and distribution of PS beads in roots more than large ones. Confocal laser scanning micrographs confirmed that strong fluorescence signals from small PS beads (0.2 μm) were seen in all tissues, as compared with the control. Large PS beads (2.0 μm) were mainly distributed in the xylem, and no PS beads were detected in any root tissues when treated with 5.0 μm PS beads. More PS beads were absorbed by the root maturation zone than by the root tip zone. Fluorescence intensity values of PS bead accumulations measured across the tissues further confirmed these results. As seen in scanning electron microscopy images, small PS beads assembled on the cell wall of the xylem, while large PS beads (2.0 μm) were scattered on the cell walls of root xylem. The present study revealed the effects of different PS bead sizes on accumulation and distribution in maize roots, as well as the absorption ability of different positions of the roots. Moreover, fluorescence intensity could be a useful method to evaluate the uptake and distribution of MPs accurately.

Distribution of total petroleum hydrocarbons in superficial sediments of Karun River Basin, southwest of Iran: spatial and seasonal variations, source identification, and ecological risk

Total petroleum hydrocarbons (TPHs) are common environmental pollutants in aquatic ecosystems that tend to adsorb onto the sediments. This study aimed to monitor the concentration and assessment of contamination level of TPHs in the sediments of Karun River and Bahmanshir estuary, which will eventually flow into the Persian Gulf. GIS-mapping technique was used to indicate the distribution of TPHs. The samples were collected during dry and wet seasons at 15 monitoring stations. - The maximum amount of TPHs was obtained at station No. 14 in the dry season (225.29 μg/g). The indices of determining the pollution source showed that hydrocarbons in polluted areas were mainly of biogenic origin. Compared to sediment quality guidelines (SQGs) and contamination factor (Cf), the study area sediments were in the conditions of moderate pollution and had a low ecological risk.

Spatial-temporal variability and influence factors of Cd in soils of Guangxi, China

In this study, the regional spatial-temporal variability of cadmium (Cd) in the topsoil of Guangxi, China from 2010 to 2016 was studied from data obtained from the China Geochemical Baseline Project (CGB Ⅰ and CGB Ⅱ). The driving forces of natural and anthropogenic variables were quantitatively analyzed using a geographically and temporally weighted regression model. The results showed that 1) soil Cd was highly enriched in 2010 and in soils of Hechi city in northwest Guangxi, a non-ferrous metal mining and metallurgy area, ~17% of the samples exceeded the soil contamination risk limit. In contrast, in 2016, the topsoil Cd content decreased significantly, with 7% of sites exceeding the soil risk limit. 2) Multiple factors jointly influenced the regional spatial variability of Cd. pH and organic carbon were found to be the main factors influencing Cd content and were strongly spatially correlated with Cd. Anthropogenic activities, including mining and industrial emissions, resulted in significant Cd enrichment in local areas, whereas agricultural and domestic pollutants were relatively weakly correlated with Cd. The weathering products of carbonates were significantly enriched in Cd; thus, the geological background played a significant role in the spatial variability of Cd. Soil-forming factors, including temperature, precipitation, and elevation influenced the spatial distribution of Cd, especially in the Cd background area. 3) Anthropogenic activities were the key factors influencing temporal changes in Cd. Mining caused significant enrichment of Cd in CGB Ⅰ, while industrial emissions were the primary factor for Cd enrichment in CGB Ⅱ. In addition, natural factors also played an important role; the increased Normalized Difference Vegetation Index suggested reduced desertification and reduction of soil erosion in the watershed and in pollutants transported from upstream.

Optimizing spatial interpolation method and sampling number for predicting cadmium distribution in the largest shallow lake of North China

Cadmium (Cd) pollution has been widely recognized in lake ecosystems. Although the accurate prediction of the spatial distributions of Cd in lakes is important for controlling Cd pollution, the traditional monitoring methods of setting discrete and limited sampling points cannot actually reflect the continuous spatial distribution characteristics of Cd. In this study, we set up 93 sampling points in Baiyangdian Lake (BYDL), and collected surface water, overlying water and sediment samples from each sampling point. Cd contents were measured to predict their spatial distributions in different environmental components by three interpolation methods, inverse distance weighted (IDW), radial basis function (RBF) and ordinary kriging (OK), and the effects of different sampling numbers on the interpolation accuracy were also assessed to optimize the interpolation method and sampling number. The results showed that the interpolation accuracy of IDW decreased with increasing power values. The best basis function for RBF was IMQ, and the best semivariogram models for OK were the spherical model and stable model. The best interpolation method for the waters and sediments was RBF-IMQ compared with OK and IDW. Within the sampling number range of 50-93, the interpolation accuracy for Cd in surface water increased with the increase in sampling number. Comparatively, the interpolation accuracy was the highest for overlying water and sediments when the sampling number was 60. The findings of this work provide a combined sampling and spatial interpolation method for monitoring the spatial distribution and pollution levels of Cd in the waters and sediments of shallow lakes.

Spatial distribution of benthic toxicity and sediment-bound metals and arsenic in Guangzhou urban waterways: Influence of land use

The effects of land use on pollutant loads in sediments have been well documented; however, its influence on spatial variations in sediment toxicity remains largely unknown. In the present study, the toxicological effects of 17 sediments collected from Guangzhou waterways were evaluated using two benthic invertebrates (Chironomus dilutus and Hyalella azteca), along with quantification of heavy metals and arsenic in the sediments. The impacts of land-use configuration on sediment toxicity and occurrence of heavy metals and arsenic were analyzed. The sediments presented moderate lethality (<40 %) in the two test species and significantly altered their enzymatic activity, including the activities of oxidative stress biomarkers and acetylcholine esterase. Metals (Ag, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) and arsenic were detected in all the sediments, with total concentrations ranging from 238 to 1019 mg/kg of dry weight. Both the toxicity and chemical results displayed spatially dependent patterns but were related to different land use types. Toxicity was most influenced by agricultural and aquacultural activities, while metal and arsenic pollution was most influenced by urban land areas. The present findings are expected to provide essential knowledge for developing strategies that reduce the chemical pollution and ecotoxicological risk in sediments.

Maternal and fetal exposure to metal (loid)s, maternal nutrition status, and impact on prenatal growth in an energy rich zone and an urban area along the Persian Gulf

The main purposes of the study were to determine whether maternal and cord blood (MB and CB) levels of metal (loid)s (MLs) are different between industrial and urban areas. Subjects were derived from the petrochemical and gas area (PGA) of Asaluyeh County and the urban area (UA) of Bushehr County in Iran. Adjusted models revealed significant differences between the PGA and UA for maternal Fe, Cu, Mg, Cd, Zn, Ni, V and Pb levels, likewise cord Cu, V, Pb and Ni levels, which were higher in the PGA. Unadjusted models revealed there were decreases in neonatal weight and head circumference by 16.550 g and 0.059 cm, respectively for each Ln unit increase in maternal Cr levels. The mean blood levels of MLs significantly associated with food consumption frequency. The MLs were detected at higher levels in the body's fetuses and their mothers who resided in the PGA than those from the UA. So, the fetuses of mothers living in an industrial areas may be at higher risk from anthropometric measures. The impact of prenatal exposure to MLs on prenatal growth should be considered for better understanding in the further studies.

Health burden and economic loss attributable to ambient PM2.5 in Iran based on the ground and satellite data

We estimated mortality and economic loss attributable to PM_2·5 air pollution exposure in 429 counties of Iran in 2018. Ambient PM_2.5-related deaths were estimated using the Global Exposure Mortality Model (GEMM). According to the ground-monitored and satellite-based PM_2.5 data, the annual mean population-weighted PM_2·5 concentrations for Iran were 30.1 and 38.6 μg m^-3, respectively. We estimated that long-term exposure to ambient PM_2.5 contributed to 49,303 (95% confidence interval (CI) 40,914-57,379) deaths in adults ≥ 25 yr. from all-natural causes based on ground monitored data and 58,873 (95% CI 49,024-68,287) deaths using satellite-based models for PM_2.5. The crude death rate and the age-standardized death rate per 100,000 population for age group ≥ 25 year due to ground-monitored PM_2.5 data versus satellite-based exposure estimates was 97 (95% CI 81-113) versus 116 (95% CI 97-135) and 125 (95% CI 104-145) versus 149 (95% CI 124-173), respectively. For ground-monitored and satellite-based PM_2.5 data, the economic loss attributable to ambient PM_2.5-total mortality was approximately 10,713 (95% CI 8890-12,467) and 12,792.1 (95% CI 10,652.0-14,837.6) million USD, equivalent to nearly 3.7% (95% CI 3.06-4.29) and 4.3% (95% CI 3.6-4.5.0) of the total gross domestic product in Iran in 2018.

Heavy Metals in River Sediments: Contamination, Toxicity, and Source Identification-A Case Study from Poland

This study investigated the spatial distribution, contamination, potential ecological risks and quantities of pollutant sources of six heavy metals (HMs) in sediments of 47 rivers. The catchments of the investigated rivers are situated in Poland, but some of them are located in Slovakia, the Czech Republic, and Germany. Cluster analysis was applied to analyze the spatial distribution of Cd, Cr, Cu, Ni, Pb, and Zn in river sediments. Moran I and Getis-Ord Gi* statistics were calculated to reveal the distribution pattern and hotspot values. Principal component analysis (PCA) and positive matrix factorization (PMF) were used to identify pollution sources. Furthermore, geochemical indices and sediment quality guidelines allowed us to assess sediment contamination and potential toxic effects on aquatic biota. The results showed that in 1/3rd of the rivers, the HM pattern and concentrations indicate sediment contamination. The EF, PLI, and MPI indices indicate that concentrations were at a rather low level in 2/3rd of the analyzed rivers. Only in individual rivers may the HMs have toxic effects on aquatic biota. Spatial autocorrelation analysis using the Moran I statistic revealed a random and dispersed pattern of HMs in river sediments. PCA analysis identified two sources of HMs' delivery to the aquatic environment. Cr, Cu, Ni, Pb, and Zn originate from point and non-point sources, while Cd concentrations have a dominant natural origin. The PMF identified three sources of pollution. Among them, urban pollution sources are responsible for Cu delivery, agricultural pollution for Zn, and industrial pollution for Ni and Cr. Moreover, the analysis showed no relationship between catchment land-use patterns and HM content in river sediments.

Insights into the spatiotemporal differences in tailings seepage pollution by assessing the diversity and metabolic functions of the soil microbial community

The formation of tailings ponds depends on the long-term accumulation of tailing and high terrain. Its seepage pollution characteristics may have gradient variations on spatiotemporal scales. Used three nearby metal tailings ponds with different service times, we aimed to reveal seepage pollution trends on spatiotemporal scales and the response of soil microbial community. The results showed that the degree of seepage pollution was negatively correlated with the distance from the tailings pond on the spatial scale, while the seepage pollution showed higher levels in tailings ponds with longer service times on the temporal scale (RI = 248.04-2109.85). The pollution effect of seepage persisted after the tailings pond was discontinued (RI = 226.72). Soil microbial diversity increased with spatial scale expansion. The proportion of Actinomyces gradually increased and Proteobacteria decreased. Cr (r = 0.21) and Fe (r = 0.22) contributed more to the microbial community changes. Functional predictions showed that pathways related to signal transduction and energy metabolism were more abundant in the tailings pond. In contaminated areas, the proportion of nitrate respiration and cellulolysis functional communities had decreased, and some potentially pathogenic human taxa had accumulated. These results emphasized that there was pollution accumulation on temporal scale and pollution dispersion on spatial scale around tailings ponds, and the response of the microbial community further illustrated these trends.

Health risk assessment of commercial fish and shrimp from the North Persian Gulf

BACKGROUND

Bioaccumulation of trace metals in the food web demands continuous monitoring of seafood safety. Here, the food safety of commercial fish bluespot mullet Crenimugil seheli, deep flounder Pseudorhombus elevates, and Jinga shrimp Metapenaeus affinis was assessed from commercial and industrial region of the West Bandar Abbas, the North Persian Gulf, for the first time.

METHODS

For this purpose, concentrations of trace metals Ni, Zn, Cu, Cr, Cd, and Pb, and their health risks were investigated.

RESULTS

Results showed the average concentration of all trace metals in all species was below concentrations proposed by WHO/FAO/USEPA. The finding on risk assessment of three species indicated three species are safe for daily consumption. Long-term consumption of three species would not pose potential non-carcinogenic health risk. However, it would result in carcinogenic effects from the ingestion of trace metals Ni, Cr, and Cd.

CONCLUSIONS

The data emphasizes the need for the continuous monitoring in this industrial region in the future to manage and control pollutant sources and to ensure the quality of seafood.

Insights into bioaccumulation and bioconcentration of potentially toxic elements in marine sponges from the Northwestern Mediterranean coast of Morocco

The present research aimed to investigate the concentrations and patterns of six potentially toxic elements (PTEs) in three common sponge species collected along the Moroccan Mediterranean coast, as well as their levels in ambient seawater and sediments. Distinct inter-species variability in PTEs bioaccumulation was observed among the three species, suggesting that sponges have distinct selectivity for assimilating PTEs from the surrounding environment. C. crambe had a higher enrichment capacity for Cu, As, Cr and Ni, while P. ficiformis and C. reniformis exhibited the highest concentration of Cd and Pb, respectively. Interestingly, a similar spatial distribution patterns of PTEs was observed in the three media, with high values occurring in Tangier and Al-Hoceima locations. Overall, our results confirm that sponges reliably reflect the bioavailability of PTEs in their immediate environment, especially C. crambe, whose PTE tissue contents were highly and positively correlated with the contents of all PTEs in the sediments.

Effects of land use on the heavy metal pollution in mangrove sediments: Study on a whole island scale in Hainan, China

In recent decades, mangrove ecosystems at coastal zone are experiencing rapid land-use conversion, however effects of land use on the heavy metal pollution in mangrove sediments still are not clear. This study investigated the concentration and distribution of heavy metals (including chromium (Cr), zinc (Zn), lead (Pb), copper (Cu), arsenic (As) and cadmium (Cd)) in different mangrove sediments with different land-use patterns along seashore of the whole Hainan island (with the third largest mangrove area of China). The effects of land use on the accumulation of heavy metals in these mangrove sediments are also analyzed. The results showed contaminations of ∑6Metals in this study following the order of arable lands (ARAB) > aquaculture ponds (AQUA) > riverine area (RIVER) > ecological area (ECOL) > construction area (CONS). Accumulation degree of As and Cd were high in the AQUA, ARAB, and RIVER area. As metal hotspots, ARAB, RIVER and AQUA area showed the deteriorated sediment quality with high pollution load index (>1). Redundancy discriminate analysis revealed that mangrove, paddy lands and aquaculture ponds related activities correlated well with the metal pollution. The results clearly revealed that different land uses would not only change the accumulation capacity of mangrove soil for heavy metals, but also contribute different sources of heavy metal pollution. These findings do help to facilitate land-use planning and contribute to guide a better mangrove wetland management at coastal zone.

Ecological risk and enrichment of potentially toxic elements in the soil and eroded sediment in an organic vineyard (Tokaj Nagy Hill, Hungary)

Potentially toxic elements (PTEs), such as Cu, Zn, Pb, Ni, Cr, and Co, can accumulate in vineyard soils due to repeated uses of inorganic pesticides and chemical or organic fertilizers. In sloping vineyards, PTEs can also be moved by soil erosion resulting in their accumulation in low-energy zones within the landscape, adversely affecting the soil environment. Our study evaluated the ecological risk related to the pseudo-total and bioavailable PTE contents (Zn, Pb, Co, Ni, Cr, and Cu) in the soil and eroded sediment samples from an organic vineyard in Tokaj (NE Hungary). The contamination status and the ecological risk of target PTEs were assessed by calculating the contamination factor, the pollution load index, the ecological risk factor, and the ecological risk index. The median pollution load indices of 1.15, 1.81, and 1.10 for the topsoil, the sediments, and the subsoil, respectively, demonstrate a moderate multi-element contamination case in the organic vineyard. Target PTEs tented to show increased concentrations in eroded sediments with the highest enrichment ratio (3.36) observed for Cu (Cu in the sediment/Cu in the topsoil), revealing a preferential movement of Cu-rich soil particles by overland flow. Moreover, PTEs were present in the sediments in more bioavailable forms (except Ni, Cr), assessed by an extraction procedure with EDTA. The ecological risk index (< 90) based on the studied PTEs showed an overall low ecological risk in the vineyard. Copper was the predominant factor of the ecological risk. Moreover, the highest ecological risk factor (24.6) observed for the bioavailable Cu content in an eroded sediment sample (representing 82% of the total ecological risk) shows that Cu accumulation in sloping vineyards is an ecological risk, particularly in the sedimentation zones. The high proportions of bioavailable Cu in the vineyard's soil represent an increasing ecological risk over time, related to repeated treatments of vine plants with Cu-based pesticides.

Food safety of the green tiger shrimp Penaeus semisulcatus from the Persian Gulf

Seafood is a rich source of essential compounds for human health, but the consumption of aquatic products that are exposed to environmental pollutants, especially trace metals, comes with risk. Therefore, in this study, the levels of nickel, zinc, and lead in the muscle of shrimp Penaeus semisulcatus caught from the north of the Persian Gulf as a polluted environment were measured, and the health risks were assessed. The results showed that the level of Zn (300.88 ± 2.76 µg/g) in the muscle of shrimp was higher than Ni (6.82 ± 0.10) and Pb (1.10 ± 0.09 µg/g), and the amount of accumulation of all three metals is higher than the allowable limit proposed by the FAO/WHO. According to values of estimated daily intake (EDI) and target hazard quotient (THQ), the consumption of shrimp has no or minimal risk for health. However, the target cancer risk (TR) of Ni (adult, 0.00294; child, 0.00196) indicated that Ni accumulation is associated with carcinogenic risks. These findings may be helpful in the proper management of seafood quality and public health in the Persian Gulf.

Factors affecting cadmium accumulation in the soil profiles in an urban agricultural area

Soil Cd pollution is a serious environmental issue associated with human activities. However, the factors determining exogenous Cd dynamics in the soil profile in a complex environment are not well understood. Based on regional observations from 169 soil profiles across the Chengdu Plain, this study explored the key factors controlling Cd accumulation in the soil profile under actual field conditions. Results showed that total soil Cd contents decreased from 0.377 to 0.196 mg kg^-1 with increasing soil depth. The effects of phosphate fertilizer rates, road density and precipitation on the difference in total soil Cd content were only observed in topsoil, while agricultural land-use type and topography had no impact. In contrast, significant differences in the total soil Cd content among different parent material types were found in the 0-20, 40-60 and 60-100 cm soil depths. One sample t-tests showed that significant Cd accumulation occurred in the whole soil profile in soils formed from Q4 (Quaternary Holocene) grey alluvium, while soils formed from Q3 (Quaternary Pleistocene) old alluvium and Q4 grey-brown alluvium showed significant Cd accumulation only in the 0-40 cm soil layers. In the topsoil, acid soluble Cd accounted for the largest proportion of the total Cd in soils formed from Q4 grey alluvium, reducible Cd was the main fraction in soils formed from Q4 grey-brown alluvium, while reducible Cd and residual Cd contributed the largest proportion of the total soil Cd in soils formed from Q3 old alluvium. The above results indicated that parent material was the decisive factor determining the magnitudes and depths of exogenous Cd accumulation in the soil profile due to its impacts on the Cd fraction distributions. These findings suggested that the parent material-induced Cd fraction distributions and accumulation should be considered for effectively exploring targeted remediation strategies for Cd pollution.

Occurrence of microplastics and phthalate esters in urban runoff: A focus on the Persian Gulf coastline

Urban runoff seems an obvious pathway for the transfer of microplastics (MPs) and phthalate acid esters (PAEs) from land-based sources to the marine environment; an issue that still lacks attention. This study presents the first results on MP and PAE levels in the urban runoff into the northern part of the Persian Gulf during the dry season. Average concentrations of MPs and PAEs in the urban runoff of eight selected sampling sites (N = 72) along the Bushehr coast were 1.86 items/L and 53.57 μg/L, respectively. MPs with a size range of 500-1000 μm had the highest abundance, and the mean levels of PAEs in MPs were 99.77 μg/g. The results of this study show that urban runoff is a main source of MP and PAE contaminants that are discharged into the Persian Gulf. Therefore, to decrease these pollutants from entering the aquatic environment, decision-makers in the area should consider this problem and stop the direct discharging of urban runoff into water bodies.

Childhood exposure to metal(loid)s in industrial and urban areas along the Persian Gulf using toenail tissue as a biomarker

Metal(loid)s (MLs) with natural or anthropogenic sources may cause adverse health effects in children. This study aimed to compare the childhood exposure to ΣMLs (essential, non-essential and toxic) in an industrial and an urban area in Southwest Iran using toenail tissue as a biomarker. The present study was carried out with school children in the age range of 7-12 years, who were living in an industrial area in the petrochemical and gas area (PGA) of the Central District of Asaluyeh County and in an urban area (UA) located in the Kaki District. A total of 270 boys and girls were recruited in January to April 2019. The ICP-MS was used for determination of the studied MLs. A multi-linear regression model was constructed to assess the effect of residence area on toenail ML levels. A significantly higher level of ΣMLs in toenail from the PGA was observed compared to the level in the UA (8.839 vs. 7.081 μg/g, β = -0.169 and p < 0.05). However, all of the 15 MLs studied were detected in the toenail samples from both study sites. Significant differences for the mean Cr (β = -0.563), Fe (β = -0.968), Mn (β = -0.501), Ni (β = -0.306), and Pb (β = -0.377) levels were found between toenail samples from the study areas (p < 0.05), with higher levels in the PGA. The results of this study suggest that children in industrial area are prone to a greater risk for ML exposures compared with those living in a non-industrial urban area.

Ecological and human health risk assessment of trace element pollution in sediments and five important commercial fishes of the Oman Sea

The distribution of trace elements in sediments and five commercially important fish species of the Oman Sea were assessed using an atomic absorption spectrometer to determine ecological and human health risk assessment. The ranges of trace elements concentration in sediments were: Cr: 5.42-68.94, Zn: 5.22-18.11, Cu: 1.44-4.87, As: 18.07-79.96, Cd: 0.10-1.27, Ni: 43.0-65.34 and Pb: 8.92-30.53 mg/kg dry weight. Cr, Zn, Cu, Cd and Pb were below the ERL (effects range low) and TEL (threshold effect level) values at all the sampling stations with rarely biological effects. Whereas, As and Ni were higher than ERL and TEL with occasionally biological effects. The patterns of trace elements bioaccumulation in the tissues of all species were: liver> skin> gill> muscle. A significant positive correlation suggests that trace elements accumulation in fish is determined by trace elements in sediments. Estimated Daily Intake (EDI) was significantly lower than the tolerable daily intake (TDI) value. Target Hazard quotient (THQ), total target hazard quotient (TTHQ) and target carcinogenic risk (TR) values indicated no hazard risk from fish consumption. Hence, the consumption of concerned species to people in the Oman Sea is safe.

Measurement and ecological risk assessment of heavy metals accumulated in sediment and water collected from Gomishan international wetland, Iran

This study aimed to measure and ecologically assess heavy metals, including As, Cr, Pb, Cd, and Ni in water and sediment samples taken from Gomishan, an international wetland located in Golestan, Iran. Four sampling stations were selected to cover all parts of the wetland. The analyses of the heavy metals were performed by ICP-MS. Based on the content of the heavy metals in the sediments, the values of risks for individual heavy metals, as Er, and for total heavy metals, as IR, were estimated. Igeo and EF also presented the soil quality in terms of accumulated contamination. The average content of the heavy metals in water was 23.12, 4.14, 10.04, 6.71, and 94.48 μg/L for As, Cd, Cr, Ni, and Pb, respectively. The heavy metal concentrations in sediments were decreased in the following order: Pb (2130 ppb) > As (655 ppb) > Cr (295 ppb) > Ni (148.8 ppb) > Cd (148.8 ppb). The potential risk values for individual heavy metals were in the low range, Er < 40, except for Cd, which mostly posed a moderate ecological risk. The values of EF and Igeo showed that the sediments sampled from the Gomishan wetland were minimally enriched and contaminated. As the Gomishan wetland has a moderate risk of heavy metal contamination, conservative and monitoring activities should be performed.

Polyethylene microplastics increase cadmium uptake in lettuce (Lactuca sativa L.) by altering the soil microenvironment

Little research has focused on the combined pollution of microplastics (MPs) and heavy metals in soil, especially the mechanism of their interaction. We conducted a 45-day microcosm experiment to test the hypothesis that polyethylene (PE) MPs and cadmium (Cd) had a joint toxicity to lettuce fitness. The effects of MPs at different addition ratios on Cd bioavailability and soil properties were also investigated in the microenvironment of three levels of Cd-contaminated soils. The results showed that the 10% MPs had an adverse impact on the plant biomass and significantly decreased soil pH and cation exchange capacity (CEC), but significantly increased soil dissolved organic carbon (DOC). The presence of MPs increased the soil Cd bioavailability and plant Cd concentrations and accumulations across all three levels of Cd-contaminated soils, which potentially aggregated the combined toxicity. The amounts of the bacterial 16SRNA and the fungal ITSRNA genes displayed a hormesis effect in response to the MP addition ratios while the abundance of Cd resistance genes cadA and czcA increased across all three Cd levels. The regression path analysis indicated that MPs affected shoot Cd concentrations by altering soil properties, which directly and indirectly contributed to the alteration mechanism, while the soil pH, DOC, and Cd bioavailability played core roles. The results suggest that the co-exposure of PE MPs in heavy metal-contaminated soil may therefore increase the toxicity, uptake, accumulation, and bioavailability of heavy metals by altering the properties of the soil microenvironment, which deserves further research.

Health Risk Assessment of Trace Elements in Soil for People Living and Working in a Mining Area

The present study used soils collected from a small-scale gold mine area to determine the health risks due to trace elements to the at-risk population in the study area. The work involved 74 soil samples from four sampling categories: 29 samples were from the mining pits (MD), 18 samples from the first washing area (WA), 17 samples from the second washing area (WB), and 10 samples from the control area (C). All samples were analyzed for Cr, Cu, As, Pb, Cd, Co, Ni, Zn, and Hg using the Energy Dispersive X-Ray Florescence (ED-XRF) method. Trace element levels were found to vary across the four sampling categories. The concentrations of trace elements recorded from different sampling categories varied in an increasing order of MD > WA > WB > C. Mercury was detected in the highest levels (max. 3.72 ± 0.15) at WB while it was not detected in the samples from C. Samples from MD indicated that Cu (max. 737.66 ± 1.3 mg/kg) was found in the highest levels whereas Hg (mean = 0.007 mg/kg) was the lowest. At WA, Cu (max. = 178.97 ± 2.46 mg/kg) registered the highest average concentration while Hg (mean = 0.05 mg/kg) had the lowest concentration. For WB, Cu (max. = 230.66 ± 3.99 mg/kg) was found in the highest concentration. The hazard index value for all exposure routes was found to be 1.77, making noncarcinogenic effects significant to the adult population. For children, the hazard index value was 9.11, showing a severe noncarcinogenic effect on children living in the study area. For the noncancer effects through the inhalation pathway, the risk posed by Ni, Cu, Zn, and Pb was negligible for both adults and children, while Co posed the highest noncancer risk for children. Cobalt also indicated the highest noncancer risk for children through the dermal pathway, while As indicated the highest noncancer risk to children through ingestion. For the cancer risk, the adults were more at risk compared to children, except for As and Co through the dermal pathway posing the highest threat. Trace element concentrations, hazard quotient, and hazard index values indicated that the area was polluted and that noncarcinogenic and carcinogenic effects on residents and miners were significant. Therefore, there is a need to put in place mining regulations aimed at protecting the at-risk human population in the study area.

Metal and metallothionein levels in zooplankton in relation to environmental exposure: spatial and temporal variability (Saronikos Gulf, Greece)

Metal and metallothionein (MT) in mixed zooplankton were investigated as means of monitoring metal availability regarding environmental exposure. Spatial and temporal variability of Cd, Cu, Ni, Zn, Fe, Mn and Pb in zooplankton and seawater were studied in Saronikos Gulf (Aegean Sea, Eastern Mediterranean), once every second month during an annual cycle (2011-2012). Particulate organic carbon and chlorophyll α were also measured in seawater samples. Median zooplankton metal concentrations were 0.65, 32.4, 7.1, 864, 1420, 40.2 and 26.8 μg g^-1 dw for Cd, Cu, Ni, Zn, Fe, Mn and Pb, respectively, and 109 μg g^-1 ww for MTs. Metal levels in zooplankton and MTs were higher at sites influenced by human-derived pressures. Additionally, metal concentrations in pelagic fish flesh from the Greek MED-POL data base were used for bioconcentration and biomagnification factors calculation. Bioconcentration from water to zooplankton was higher than metal transfer from either seston to zooplankton or zooplankton to fish.

Assessment of heavy metal content, distribution, and sources in Nansi Lake sediments, China

Much attention has been paid to the heavy metal contamination of lake sediments in rapidly developing regions. In this study, heavy metal (Cd, Cr, Co, Ni, Mn, Pb, As, Cu, and Zn) concentrations in sediment surface samples and cores from the Nansi Lake were investigated to ascertain the potential sources and environmental risks of heavy metals. The average concentration of heavy metals was 0.16-16.04 times background concentrations. The enrichment factor, Tomlinson pollution load index, geo accumulation index, positive definite matrix factor analysis (PMF), and potential ecological risk index were used to assess heavy metal concentrations and explore the evolution of heavy metal sources, and result indicated that Cd reached moderate pollution levels, which is the most polluted heavy metal in the history and present, while the remaining heavy metals are at low or no pollution levels. The contribution of Cd to RI exceeded 76%, which is the decisive factor in the ecological risk of Nansi Lake. The result of ecological risk showed that the risk level for most of Nansi Lake is medium, and some areas of Zhaoyang Lake and Weishan Lake reach high levels. The PMF results showed that there are four main factors influencing heavy metal concentrations in Nansi Lake sediments, including industrial sources, fertilizers, and herbicides used in agricultural production, traffic-related emissions, and mineral mining. Among these factors, industrial and mineral mining sources were found to be the most important, and the highest contribution rate occurred in the -10cm (1960s). Although the contribution of fertilizers and herbicides is lower than that of other sources, increasing trend should be a warning sign that Cd has reached a high ecological risk level in Nansi Lake sediments.

Occurrence, spatial distribution, seasonal variations, potential sources, and inhalation-based health risk assessment of organic/inorganic pollutants in ambient air of Tehran

The present study evaluated the concentrations, spatial distribution, seasonal variations, potential sources, and risk assessment of organic/inorganic pollutants in ambient air of Tehran city. Totally, 180 air samples were taken from 9 sampling stations from March 2018 to March 2019 and were analyzed to determine the concentrations of organic pollutants (BTEX compounds and PM_2.5-bound PAHs) plus inorganic pollutants (PM_2.5-bound metals and asbestos fibers). The results revealed that the mean concentrations of ∑ PAHs, BTEX, ∑ heavy metals, and asbestos fibers were 5.34 ng/m³, 60.55 µg/m³, 8585.12 ng/m³, and 4.13 fiber/ml in the cold season, respectively, and 3.88 ng/m³, 33.86 µg/m³, 5682.61 ng/m³, and 3.21 fiber/ml in the warm season, respectively. Source apportionment of emission of the air pollutants showed that PAHs are emitted from diesel vehicles and industrial activities. BTEX and asbestos are also released mainly by vehicles. The results of the inhalation-based risk assessment indicated that the carcinogenic risk of PAHs, BTEX, and asbestos exceeded the recommended limit by The US environmental protection agency (US EPA) and WHO (1 × 10^-4). The risk of carcinogenesis of heavy metal of lead and chromium also exceeded the recommended limit. Thus, proper management strategies are required to control the concentration of these pollutants in Tehran's ambient air in order to maintain the health of Tehran's citizens.

Identification Sources and High-Risk Areas of Sediment Heavy Metals in the Yellow River by Geographical Detector Method

In order to determine the key influencing factors, risk areas, and source pathways of heavy metals in the sediment of the Yellow River, 37 samples were collected in the surface sediment (0–5 cm) of the Inner Mongolia section of the Yellow River main stream for the determination of heavy metals copper (Cu), nickel (Ni), zinc (Zn), chromium (Cr), lead (Pb), and cadmium (Cd). Based on the geographical detector model (GDM) and ArcGIS 10.2 software, this paper selected 6 heavy metals and 15 influencing factors, including 8 natural factors and 7 anthropogenic factors, to detect key influencing factors, risk areas, and sources of heavy metals. The results showed that: (1) The average contents of heavy metals Cr and Cd in the sediments exceeded the average value in soil, the world average concentration in the shales, and the first-level standard of soil environmental quality in China, and they were the main risk metals; (2) Vegetation coverage (VC) was the largest influencing factor for the spatial distribution of heavy metals in the sediment, followed by per capita income (PI), and land use type (LUT) and road network density (RD) were smaller influencing factors. The interactions of the factors were enhanced; (3) The Wuhai section for a risk area was mainly polluted by Cd and Pb, which were caused by atmospheric deposition and industrial emission. The Baotou section for a risk area was mainly polluted by Cr, which mainly originated from river transportation and industrial discharge. The conclusions can provide a scientific basis for the environmental protection and management of the different areas in the Inner Mongolia section of the Yellow River.

Potential health risks of metals in skin care products used by Chinese consumers aged 19-29 years

Metal contamination of skin care products that occurs during their production poses potential health risks, which are of increasing concern, to consumers. Here, we collected 570 responses to an online survey to analyze the usage pattern of skin care products across China. Then a total of 30 commonly used skin care products with various prices and applications were purchased. The concentrations of metals (Al, Zn, Cu, Ni, Cr, Pb, Hg, and Cd) and metalloid As, were determined. Next, we improved the frequency calculation method and used the weighted exposure frequency to calculate the dermal absorption dose (DAD). The amounts of Zn, Cr, and Al that were assimilated by the human body via uptake were approximately 2 orders of magnitude greater than those of Pb, Hg, Cd, Ni and metalloid As. In addition, younger consumers were at higher risk of metals exposure than older consumers because of their higher frequency of use of skin care products. Al and Zn posed higher risk to consumers because of its high DAD. There was no significant chronic non-carcinogenic health risk (hazard index < 1) posed by skincare product use.

Positive matrix factorization receptor model and dynamics in fingerprinting of potentially toxic metals in coastal ecosystem sediments at a large scale (Persian Gulf, Iran)

Effective pollution control and remediation strategies are the key to providing a major progress in conservation of coastal and marine biodiversity. For the development of such strategies, quantitative assessment of potentially toxic metals (PTMs) and the accurate identification of the pollutant sources are essential. In this study, we seek to find out spatial PTMs distribution in the coastal sediments of the Persian Gulf (Iran), to assess the potential eco-environmental risks and to identify the metal pollution sources. Total and fraction analysis indicated considerable metal (Zn, Cu, Mn, Fe, Al, Hg, Pb, Cd, As, Cr, Co, Ni and V) pollution levels, albeit in most cases PTMs were predominantly associated with the oxidizable and residual fractions. The obtained PTMs concentrations were in the range of 22.8 - 156.3, 16.6 - 161.9; 2.7 - 88; 10.4 - 107.3; 1.1 - 35.8; 0.8 - 27.9; 0.1 - 1.3; 1.1 - 21.3; 0.04 - 1.9 mg.kg^-1 for V, Ni, Cu, Zn, Cr, Co, Hg, Pb, and Cd, respectively. The combined PTM-PCA-PMF modeling approach identified four main metal sources (anthropogenic, vehicle-related, agricultural and lithogenic) in the study area. Several recognizable 'hot-spots' with extremely high metal concentrations were observed in the spatial metal pollution patterns. Some of those locations were predominantly affected by the nearby industrial activities, while others have demonstrated contributions from several sources - not only anthropogenic, but also agricultural and vehicle-related. The same spots of elevated pollution were found to demonstrate higher potential eco-environmental risk. Various indexes indicated more or less similar trends: the eco-environmental risk was gradually increasing towards the northwestern part of the study area with several peaks in the central and eastern parts directly affected by the nearby industrial activities.

Relationship of arsenic and chromium availability with carbon functional groups, aluminum and iron in Little Washita River Experimental Watershed Reservoirs, Oklahoma, USA

Sediment from three reservoirs located in the Little Washita River Experimental Watershed (LWREW) in Oklahoma, USA with contrasting dominant land uses were analyzed for total and extractable concentrations of arsenic (As) and chromium (Cr), and the potential ecologic risk to benthic organisms. Extractable As ranged from 0.24 to 1.21 mg kg^-1, in the order grazing>cropland>forest and 0.13-0.58 mg kg^-1 for extractable Cr, in the order of forest>grazing>cropland. However, only approximately < 1.5% of total As and < 4% of total Cr were extractable. Total As ranged from 16.2 to 141 mg kg^-1 and total Cr ranged from 5.06 to 40.1 mg kg^-1 both in the order of cropland>grazing>forest. The sediment exhibited an alkaline pH (8.0-8.7). As sorption exhibited a positive relationship with Al (r = 0.9995; P = 0.0001), Fe (r = 0.9829; P = 0.0001), and C (r = 0.4090; P = 0.0017) and Cr correlated positively with Al (r = 0.9676 P = 0.0001), Fe (r = 0.9818; P = 0.0001), and C (r = 0.3368; P = 0.0111). In addition, both As and Cr exhibited positive relationships with carbon (C) functional groups in the order of O-alkyl C> methoxyl C> alkyl C> aromatic C> carboxyl C> phenolic C. The sediment concentration analysis results illustrated that As in all reservoirs exceeded their respective Threshold Effect Level (TEL) and/or Probable Effect Level (PEL) indicating that existing concentrations of metals in these sediments were sufficiently high to cause adverse effects. However, Cr concentrations in all reservoirs evaluated was lower compared to the TEL and PEL.

Characterization of the contribution of road deposited sediments to the contamination of the close marine environment with trace metals: Case of the port city of Busan (South Korea)

We examined the concentrations of 12 trace metals in road-deposited sediments (RDS) and their contributions to the pollution of harbor/marine sediments in the port city of Busan, South Korea. The concentrations of Cr, Cu, Zn, Cd, Sn, Sb, and Pb in RDS affected by industrial and traffic activities were 6.7-25.7 times higher than those in marine sediments. The enrichment factors indicate that RDS are extremely polluted with Sb and moderately to strongly polluted with Cr, Cu, As, Sn, Pb, Zn, and Cd. The mean modified pollution index distinguished between unpolluted marine sediments, moderately to heavily polluted harbor sediments, and severely polluted RDS. Furthermore, harbor/marine sediments close to shipyards and the mouths of streams and rivers were found to be moderately polluted with Cu, Zn, Cd, Sb, and Pb. RDS containing trace metals accumulate on impervious surfaces and flow into the marine environment via untreated stormwater runoff.

Occurrence, potential sources, in vitro bioaccessibility and health risk assessment of heavy metal in indoor dust from different microenvironment of Bushehr, Iran

Indoor dust samples were collected from 42 microenvironments of residential buildings (RB, 15 samples), official buildings (OB, 10 samples), laboratory rooms (LR, 7 samples), and school classroom (SCR, 10 samples) in Bushehr, whereby the concentration of zinc, copper, lead, cadmium, nickel, and chromium was studied. The results of this study indicated that the mean concentrations of Zn, Cu, Pb, Cd, Cr, and Ni in the indoor dust samples were 567.18, 186.09, 209.01, 5.31, 143.20, and 57.09 mg/kg in RB, 1077.34, 539.67, 274.89, 8.12, 155.30, and 92.55 mg/kg in OB, 246.40, 149.56, 127.2, 1.96, 43.45, and 91.09 mg/kg in LR and 271.43, 189.84, 164.44, 3.06, 124.20, and 70.09 mg/kg in SCR. The results of principal cluster analysis showed that the heavy metals in indoor environments were mostly originated from smoking tobacco and cigarette, traffic sources, old building materials, and building paint colors. The results of this study also revealed that the concentration of heavy metals in indoor dust had a negative and significant relationship (P value < 0.05 in most cases) with rate of ventilation, and a positive and significant relationship with smoking inside buildings (P value < 0.05 in most cases). The bioaccessibility for zinc, copper, lead, cadmium, nickel, and chromium was 69.12, 40.08, 43.33, 79.81, 31.10, and 6.31%, respectively, in indoor dust. Further, risk assessment showed that the risk values of carcinogenicity and non-carcinogenicity resulting from heavy metals inside the studied microenvironments had exceeded the recommended safe limit by EPA. In terms of potential ecological risks, it was found that heavy metals in these microenvironments have exceeded the hazardous ecological levels presented by different indices and can have considerable negative ecological effects. Thus, it is essential that further and better studies and monitoring be performed on these environments, and suitable control recommendations and solutions should be regulated for this public health threat.

Effective passivation of lead by phosphate solubilizing bacteria capsules containing tricalcium phosphate

Phosphate solubilizing bacteria (PSBs) shows high potential to be used for lead passivation in sediments due to the abilities of releasing phosphate and the subsequent formation of insoluble Pb-phosphate compounds. In this research, microbial capsules implemented with sodium alginate and CaCl₂, containing Leclercia adecarboxylata L15 (a lead resistant PSB) and Ca₃(PO₄)₂, were developed and the performance on lead passivation under different conditions was examined. The optimal concentrations of sodium alginate and CaCl₂ for formulating the capsules were determined to be 0.3% and 10%, respectively. The removal efficiency of Pb²⁺ by capsules containing L15 and Ca₃(PO₄)₂ was up to 98% with a capsule dosage of 2%, initial Pb²⁺ concentration of 1mM and pH of 3.0, which was better than that of free L15 (18%) and capsules containing only L15 (34%). Lead was immobilized via the formation of Pb₅(PO₄)₃Cl on the surface and Pb₃(PO₄)₂ in the interior of the capsules. The simulated sediment remediation experiments showed that the acid soluble fraction of lead reduced from 28% to 14% and transformed into more stable fractions after 10 days. The experiment results indicated that PSBs capsules coupled with phosphate materials have a great promise for application in remediation of lead contaminated sediments.

Geochemical modeling of chromium release in natural waters and treatment by RO/NF membrane processes

In this work, a geochemical approach was used as strong-scientific tool for pre-selection of suitable remediation systems to treat Cr-contaminated groundwaters. The geochemical characterization allowed to select Nanofiltration (NF) and Reverse Osmosis (RO) as suitable remediation processes, whereas through a new geochemical modeling, the evolution of water chemistry during the water-rock interaction was also studied. The new reaction path modelling was performed re-evaluating the role of Fe as main oxidant in the system and the analytic concentrations of relevant solutes, including Cr(VI), were reproduced. The spring with the highest Cr(VI) content was treated to lower its concentration below the threshold values. A laboratory-scale set-up was used to carry out both NF and RO experiments. The experiments were conducted on different commercial membranes varying the operating pressures. The results showed high Cr(VI) rejections (around 95%) for all tested membranes, leading to Cr(VI) concentrations below the threshold limits. The high flux, obtained already at lower operating pressures, combined with high selectivity towards Cr(VI) makes NF a favorable remediation option.

Speciation and risk assessment of selected trace metals in bottom sediment of coral reef ecosystems of the Persian Gulf

To evaluate the hazard assessment of anthropogenic activities on coastal ecosystems, fractionation and bioaccumulation of trace metals were carried out for sediment and coral samples of three distinct habitats including petroleum exploration area of Kharg, the rural harbor of Chirouyeh, and unpopulated area of Hendorabi. Fractionation results suggested that Ni (~ 51%), Pb (~ 49%), and V (~ 45%) in Kharg; Ni (~ 46%), Pb (~ 84%), and Zn (~ 47%) in Chirouyeh; and Cd (~ 51%) in Hendorabi were the predominant metals in the non-resistant fractions of the sediment samples. Risk Assessment Code (RAC), individual contamination factor (ICF), and global contamination factor (GCF) were derived. The highest relative risk for Cd, Cu, and Ti was observed in Kharg, whereas the highest relative risk for Ni, Pb, V, and Zn was recorded in Chirouyeh. The lowest risk for almost all of the trace metals was observed in Hendorabi. Biota-sediment accumulation factor (BSAF) values of coral samples revealed that species examined in the present study are reliable biomonitors for Cd, Ni, Pb, and Zn contamination. Principal component analysis (PCA) and Pearson's correlation coefficient (PCC) suggested that Pb, Ni, and Zn can be considered the main pollutants of the Persian Gulf which originated mainly from petroleum industries. Furthermore, the metal uptake rates of coral samples seemed to be dependent on bioabsorption pathways and coral species. Overall, the present work constitutes a good basis for further studies on trace metal fractionation, risk assessment, and source apportionment in the Persian Gulf, which could contribute to more effective decisions for reducing the anthropogenic trace metal pollution.

Elucidating the differentiation of soil heavy metals under different land uses with geographically weighted regression and self-organizing map

Intensive anthropogenic activity has triggered serious heavy metal contamination of soil. Land use and land cover (LULC) changes bear significant impacts, either directly or indirectly, on the distribution of heavy metal in soils. A total of 180 samples were acquired from various land covers at different depths, namely surface soils (020 cm) and subsurface soils (20-40 cm). Spatial interpolation, geographically weighted regression (GWR) and self-organizing map (SOM) were used to discern how variations in the spatial distributions of soil heavy metals were caused by human activities for different land uses, and how these pollutants contributed to environmental risks. The medium concentrations of Cd, Cr, Cu, Pb and Zn in surface soil all exceeded the corresponding local background values in flat cropland and developed area soil. The overall ecological risk level of the study varied from low to medium. The GWR model indicated that the land use intensity had a certain influence on the accumulation of heavy metals in the surface soil. K-means clustering of the SOM revealed that the type of LULC also contributed to the redistribution of heavy metals in the surface soil.