Heavy metals, trace elements and sediment geochemistry at four Mediterranean fish farms

Organic and heavy metal pollutants in dredged sediment of Oran Harbor, Algeria

Harbors on all coasts regularly silt up, receiving sedimentary inputs that progressively reduce the water depths available for navigation. Consequently, they are routinely dredged to guarantee the depths necessary for navigation. Sediments act as a reservoir for anthropogenic contaminants such as heavy metals and persistent organic pollutants (POPs) that enter the aquatic system associated with particles or in solution. The objective of this study is to assess the state of pollution by POPs and heavy metals such as copper and zinc, used in large quantities in antifouling paints, in the sediments of the port of Oran. These were characterized by different methods: size, XRD, calcination, FTIR, NMR, GC-MS, and AAS, in order to determine their main characteristics and heavy metals and POPs content. The particle size is determined by laser particle size distribution. Thus, sediments from Oran port are composed of means and end sands, silt, and clay. The XRD analysis shows that the sediments consist mainly of silicates and calcite. The organic matter was determined by ignition loss at 450 and 550 °C; it is about 7%. Analysis by FTIR, 1H and 13C NMR, and GC-MS of POPs excerpts shows that the sediments are highly polluted by aliphatic and aromatic hydrocarbons (3372 mg/kg). Finally, metals were determined by AAS method. The results show significant pollution of Zn (313.5 mg/kg) and moderate pollution by Cu (75.6 mg/kg).

Residual loads from tilapia farming on the sediment of a Brazilian reservoir

This study investigated the sediment geochemistry of a fish farming area in net cage tanks in the Rosário reservoir, Brazil. Three areas were investigated: reference (RA), fish farming (FFA), and dispersion (DA). The results were analyzed through correlation, similarity, principal component analysis, comparison with legislation, sediment quality guidelines, and sediment pollution indices. The mean concentrations for RA, FFA, and DA areas were respectively: Cu (mg.kg-1) 37.74, 62.23, and 71.83; Mn (mg.kg-1) 22.55, 66.48, and 55.90; Zn (mg.kg-1) 9.13, 114.83, and 94.27; Fe (%) 0.28, 0.40, and 0.43; OM (%) 15.84, 21.95, and 18.45; TOC (%) 1.86, 3.69, and 6.05; TN (mg.kg-1) 2365.00, 5015.00, and 3447.51; TP (mg.kg-1) 780.00, 6896.00, and 2585.50; ORP (mV) -95.50, -135.20, and -127.10; pH 6.60, 6.58, and 6.05; <63 μm 90.59, 78.68, and 87.30. Statistically, the influence of fish farming on sediment, organic matter, and pollutant sedimentation was demonstrated. Cu and Zn concentrations were below sediment quality guidelines. Regarding legal limits (resolution 454/2012/CONAMA), nutrients in the FFA area exceeded by 60% (TN) and 100% (TP), while in DA and RA areas they were 100% lower. TOC was 100% lower in all areas. Organic matter exceeded the limit by 100% in all areas. Pollution indices resulted in: low contamination factor 78%; unpolluted for 87% of pollution load and 83% of combined pollution; moderately polluted for 75% of the Nemerow index. The greatest impacts and influence of farming on pollutant sedimentation were more concentrated in the fish farming area. In terms of legal aspects and pollution indices, fish farming produced low levels of trace metal pollution and nutrient concentrations exceeded legal limits.

Utilization of metal and radionuclide concentrations to assess the influence of shrimp farming on the geochemical characteristics of sediments

This article assesses the environmental impacts of aquatic biota cultivation, focusing on shrimp farming in Brazil's Northeast, as this practice has proven to be one of the main sources of economic growth in the region. For this purpose, sediment samples were collected from areas impacted and not directly impacted by shrimp farming, and concentrations of key geochemical parameters such as salinity, various elements (K, P, Cu, Mn, Pb, Zn, Al, Ca, Fe, Mg, and Na), and natural radionuclides (K-40, Ra-226 and Ra-228) were compared using statistical tools. Element concentrations were determined using ICP-OES, and naturally occurring radionuclide concentrations were obtained through gamma spectrometry. Statistical tests, such as ANOVA and/or Mann-Whitney, cluster analysis, and principal component analysis, were applied to the results. Additionally, the ERICA Tool software was employed to estimate deleterious effects on both human and non-human biota. Descriptive statistics reveal variability in sediment parameters around shrimp farming. ANOVA and Mann-Whitney tests compare concentrations of shrimp farm sediment and not directly impacted sediment, showing non-significant differences for most elements. pH and salinity, crucial for shrimp health, exhibit higher values in shrimp farm sediment. Alkali and alkaline earth metals, including K and Na, show no significant differences. Factor and cluster analyses suggest that certain elements, mainly radionuclides, are influenced by sediment variability. Hazard indices for naturally occurring radionuclides indicate negligible risk to both human and non-human biota, reinforcing the absence of adverse effects from shrimp farming activities. This study provides a comprehensive analysis of the environmental impacts of shrimp farming, emphasizing the importance of monitoring geochemical parameters for coastal environmental management.

Trajectories of trace element accumulation in seagrass (Posidonia oceanica) over a decade reveal the footprint of fish farming

To evaluate the effect of trace element (TE) release from fish farms on seagrass Posidonia oceanica, we compared TE concentrations (As, Cd, Co, Cu, Mn, Mo, Ni, Pb, V, Zn) in shoots near fish cages (Station 'Cage') with those away from them (Station 'Control') in two fish farm facilities (Site 1 and Site 2, North Aegean Sea, Greece). We assessed the present (i.e., 2021, year of sampling) and past (reconstructed period 2012-2020) accumulation of TEs using the living compartments (leaf blades, sheaths, rhizomes, roots, epiphytes) and the dead sheaths, respectively. We also assessed possible seagrass degradation by reconstructing past rhizome production. P. oceanica rhizome production at the 'Cage' stations was up to 50% lower than at the 'Control' stations. Most TE concentrations were higher at 'Cage' stations, but the differences often depended on the seagrass living compartment. Significant differentiation between 'Cage' and 'Control' stations was observed based on the TE concentrations of the dead sheaths during 2012-2020. The contamination level at the 'Cage' stations was mostly moderate in Site 1 and low in Site 2, during the reconstructed period, while an increasing contamination trend was found for certain potential phytotoxic TEs (As, Cu, Cd, Mo, V). Our results emphasize the need for the aquaculture industry to work towards a more ecologically aware approach.

Effect of cage culture on sedimentary heavy metal and water nutrient pollution: Case study in Sansha Bay, China

The aquaculture area in China's coastal waters has increased rapidly from 6000 km2 in 1990 to 22,000 km2 in 2020. Despite extensive research regarding the effect of coastal aquaculture on water and sediment pollution, evaluating the quantitative relationship between aquaculture and pollutants remains challenging. Sansha Bay, the world's largest cage aquaculture base for Pseudosciaena crocea, is a typical enclosed bay used for investigating aquaculture pollution. A cage culture database is established from 2000 to 2020 in Sansha Bay. Meanwhile, 236 sediment samples from 3 sediment cores and 67 water samples from 4 transects are obtained from the bay for experiments. The main indicators are five nutrients (NO3-, SiO32-, PO43-, NH4+, and NO2-) in the water samples, the grain size, the heavy metal (Zn, Cu, Pb, Cr, Cd, and As) content, and the 210Pb radioactivity in sediment samples. Based on data obtained and a new calculation method, the annual increment in Zn, Cu, As, Cd, Pb, and Cr contents in the cultured zone is shown to increase by 2137 %, 1881 %, 506 %, 300 %, 202 %, and 118 % in 2000-2018, respectively, as compared with the levels in a noncultured zone. The activities of the cage culture increased NO3- by 9 %, PO43- by 30 %, NH4+ by 115 %, and NO2- by 232 %, compared with natural conservative mixing processes, such as the mixing of SiO32-, in 2020. A novel quantitative approach with broad applicability is proposed to evaluate the magnitude of anthropogenically induced environmental contamination. The effectiveness of the proposed technique is demonstrated through a case study conducted in Sansha Bay, China.

The spatial distribution, health risk, and cytotoxicity of metal(loid)s in contaminated field soils: The role of Cd in human gastric cells damage

The spatial distribution and pollution level of heavy metal(loid)s in soil (0-6 m) from a typical industrial region in Jiangmen City, Southeast China was investigated. Their bioaccessibility, health risk, and human gastric cytotoxicity in topsoil were also evaluated using an in vitro digestion/human cell model. The average concentrations of Cd (87.52 mg/kg), Co (106.9 mg/kg), and Ni (1007 mg/kg) exceeded the risk screening values. The distribution profiles of metal(loid)s showed a downward migration trend to reach a depth of 2 m. The highest contamination was found in topsoil (0-0.5 m), with the concentrations of As, Cd, Co, and Ni being 46.98, 348.28, 317.44, and 2395.60 mg/kg, respectively, while Cd showed the highest bioaccessibility in the gastric phase (72.80 %), followed by Co (21.08 %), Ni (18.27 %), and As (5.26 %) and unacceptable carcinogenic risk. Moreover, the gastric digesta of topsoil suppressed the cell viability and triggered cell apoptosis, evidenced by disruption of mitochondrial transmembrane potential and increase of Cytochrome c (Cyt c) and Caspases 3/9 mRNA expression. Bioaccessible Cd in topsoil was responsible for those adverse effects. Our data suggest the importance to reduce Cd in the soil to decrease its adverse impacts on the human stomach.

Grain size analysis and ecological risk assessment of metals in the sediments of Konsin River and Igboho dam reservoir, Oyo State, Nigeria, under agricultural disturbances

A large amount of agrochemicals and organic manures are applied on agricultural lands which is one of the major pathways of metal contamination in sediments. The present study was an attempt to appraise the grain-size of sediments and metal status of the Konsin River and Igboho dam reservoir sediments using several indexes as contamination factor (CF), degree of contamination (DC), geo-accumulation index (I_geo), enrichment factor (EF), potential ecological risk index (PERI), pollution load index (PLI), and statistical analysis. A total of seven sampling sites were chosen based on prevalent anthropogenic features and analyzed for the concentration of metals, viz., Cd, Cr, Pb, Mn, Fe, Cu, and Zn. The finding from this study showed high presence of very rough grains at the upstream and sand particles at the downstream. The average values of Cd, Cr, Pb, Mn, Fe, Cu, and Zn range from 0.00 - 2.00, 19.50 - 49.90, 20.80 - 65.30, 593.90 - 2532.90, 22,133.60 - 46,058.60, 19.60 - 66.10, and 81.60 - 191.30 mg/kg, respectively. The concentrations of metals in the sediments followed the increasing order of Cd < Cu < Cr < Pb < Zn < Mn < Fe. The observation from this study showed higher affinity of metals to less particle size. The mean concentrations of Cd, Cr, Pb, Mn, Fe, Cu, and Zn were above the toxicity reference value. The I_geo and EF indicated that most of the sites were moderately to strongly polluted due to Cd while the calculated PLI showed progressive deterioration of the environment in most sites. The Pearson's correlation analysis revealed that the presence of metals in the sediments were from anthropogenic and unidentified sources. The status of metals in the study area portends a serious ecological threat to the sediment biota and occupants of the agrarian communities that depend on the water and its produce for survival.

Impacts of the Residual Trace Metals of Aquaculture in Net Cages on the Quality of Sediment

Anthropogenic pollution by trace metals in aquatic environments in semiarid zones is a critical area of investigation. The objective of this study was to investigate the concentration and spatial distribution of trace metals in surface sediments in the Rosário reservoir, which is affected by the intensive aquaculture of Tilápia-do-Nilo (Oreochromis niloticus). Sediment samples were collected in three different areas, postculture (PCTV), cultivation (CTV) and control (CTRL) in the dry season in 2019. The granulometric composition, organic matter and concentrations of Fe, Mn, Zn, Cu, Cr, Cd, Pb and Ni metals were determined. Multivariate statistics were used. Geochemical and ecotoxicological indices and a comparison with sediment quality guidelines (SQG) were used. The sediment was characterized by silty clay loam with an average organic matter of 18.76 ± 4.27. The analytical merit figures demonstrated accuracy (metal recoveries in certified standards) between 89 to 99% and high precision (RSD < 5%). The concentration ranges for the metals were Fe: 0.11-0.85 (%), Mn: 14.46-86.91, Zn: 2.6-220.56, Cu: 26.89-98.75, Cr: 60.18-76.06, Cd: 0.38-0.59, Pb: 18.13-43.13, and Ni: 34.4-46.75, all in (mg/kg^-1). The highest concentration values were found in the CTV areas (Fe: 40 ± 0.22, Mn: 66.48 ± 19.11, Zn: 114.83 ± 59.75 and Cr: 70.85 ± 2.62) and PCTV (Cd: 0.53 ± 0.04, Cu: 71.83 ± 21.20, Pb: 33.71 ± 4.34 and Ni: 44.60 ± 1.79). Pearson's correlation, hierarchical cluster analysis and principal component analysis confirmed the influence of fish farming on metals. Only Ni presented concentration values higher than the reference value established in the SQG. Thus, considering the probable geochemical and ecotoxicological effects, they comprise the two lowest levels of impact.

Mangrove microbial community recovery and their role in early stages of forest recolonization within shrimp ponds

Shrimp farming is blooming worldwide, posing a severe threat to mangroves and its multiple goods and ecosystem services. Several studies reported the impacts of aquaculture on mangrove biotic communities, including microbiomes. However, little is known about how mangrove soil microbiomes would change in response to mangrove forest recolonization. Using genome-resolved metagenomics, we compared the soil microbiome of mangrove forests (both with and without the direct influence of shrimp farming effluents) with active shrimp farms and mangroves under a recolonization process. We found that the structure and composition of active shrimp farms microbial communities differ from the control mangrove forests, mangroves under the impact of the shrimp farming effluents, and mangroves under recolonization. Shrimp farming ponds microbiomes have lower microbial diversity and are dominated by halophilic microorganisms, presenting high abundance of multiple antibiotic resistance genes. On the other hand, control mangrove forests, impacted mangroves (exposed to the shrimp farming effluents), and recolonization ponds were more diverse, with a higher abundance of genes related to carbon mobilization. Our data also indicated that the microbiome is recovering in the mangrove recolonization ponds, performing vital metabolic functions and functionally resembling microbiomes found in those soils of neighboring control mangrove forests. Despite highlighting the damage caused by the habitat changes in mangrove soil microbiome community and functioning, our study sheds light on these systems incredible recovery capacity. Our study shows the importance of natural mangrove forest recovery, enhancing ecosystem services by the soil microbial communities even in a very early development stage of mangrove forest, thus encouraging mangrove conservation and restoration efforts worldwide.

Hazardous toxic metal(loid)s in top- and deep-soils during the transformation of aquaculture ponds restored to farmland

The pollution risks due to the soil migration of toxic metal(loid)s (TMs) are a greatly hazard to ecological environment as well as animal and human health. Previous studies have primarily focused on surface contamination while deep soil layers often contain dangerous levels of TMs. We used restored wheat and rice farmlands from aquaculture ponds as a case study to examine the ecological risk and distribution of TMs in soil profiles. The elements Cu, Zn, Cr, Cd, Hg and As were markedly enriched in the 60-180 cm soil layers of restored farmland, and their concentrations decreased in the several depths as follows: 120-180 cm > 60-120 cm > 0-60 cm. Concentrations of TMs were 9.5-128 % greater in the restored farmlands relative to farmlands not exposed to aquaculture practices. Cadmium and mercury were the most serious contaminants and increased the overall ecological risk. The subsoil of wheat farming system had the highest pollution risk versus the restored rice farmland at 60-120 cm due to elevated levels of Cu, Zn and Pb. Toxic metal(loid)s might be derived from natural sources in deep soil of conventional farmland whereas aquaculture practices were found to constitute the major contribution in the subsoil of restored farmland. Our results indicated that the TMs that were buried in deep soil layers migrated upward and were a significant pollution risk. Urgent actions should be taken to identify and alleviate the contamination sources of these deep soils in addition to the conventional leaching and migration processes of surface contaminants.

Influence of algal organic matter on metal accumulation in adjacent sediments of aquaculture from a tropical coast region

The rapid development of coastal aquaculture in recent decades has led to excessive discharge of organic matter and nutrients into surrounding waters, which could result in eutrophication and potentially affect metal cycling. In our study, the influence of algal organic matter on metal accumulation was examined in three coastal sediment cores taken from a tropical region, Hainan Island, China. Overall, metal pollution adjacent to aquaculture ponds remained at low levels on the coast, except Zn, Cd, and Sn were moderately to highly enriched in the Dongjiao sediments. The δ¹³C values and the atomic C/N ratios indicated a major contribution of phytoplankton to sedimentary organic matter at the Dongjiao site. Moreover, both the algae-derived organic matter and effluent nitrogen were significantly associated with the enriched Zn, Cd, and Sn, suggesting that nutrient-induced phytoplankton growth and its organic matter may act as a "biological pump" to enhance the accumulation of metals. Wastewater treatment for aquaculture ponds should include the control of algal organic matter.

Determination of the effects of environmental pollution on the Balkan terrapin, Mauremys rivulata (Valenciennes, 1833)

The effects of environmental pollution on three populations of the Balkan terrapin [Mauremys rivulata (Valenciennes, 1833)] from the Bozcaada, Gökçeada and Dardanos regions were evaluated. The morphological parameters of Balkan terrapins collected on each site were measured and blood samples were taken for haematological analysis and micronucleus detection. The physicochemical, microbiological and microelement analyses of the water samples from each region were conducted by standard methods. The highest red blood cell, white blood cell and mean corpuscular haemoglobin concentration values were seen in the samples from Gökçeada. The highest haemoglobin value was found in the samples originating from Bozcaada, whereas the highest haematocrit and mean corpuscular volume values were found in the animals from Dardanos. Based on the microbiological analysis of the water samples, the most polluted site was Gökçeada. The microelement contents of the water and blood samples were different at the three sites, the lowest being in the Gökçeada area. It was revealed that the percentage of red blood cell micronuclei and other nucleus abnormalities in the M. rivulata blood samples was the lowest also in the animals living in the region of Gökçeada.

Intensive marine finfish aquaculture impacts community structure and metal bioaccumulation in meso-zooplankton

Commercial aquaculture has a profound impact on coastal marine environments. Here, we investigate the spatial impact of intensive commercial finfish aquaculture on local meso-zooplankton communities and the bioaccumulation of aquaculturally-derived metals (and other elements) within zooplankton samples in the Vourlias Bay, Greece. The results indicate alterations to zooplankton community composition correlate with increased eutrophic compound concentrations in the water column in closer proximity to aquaculture stations (100-300 m from fish cages). During the summer sampling, higher concentrations of accumulated metals within zooplankton samples were found at reference stations furthest from fish cages (>1000 m). During the winter sampling, however, spatial differences in accumulated metal concentrations were limited. We suggest metals are rapidly accumulated at lower trophic levels near aquaculture stations and are then dispersed to greater distances while ascending the trophic chain. This research provides good evidence for future investigations into zooplankton as an environmental impact bioindicator for aquaculture.

Identifying pollution sources of sediment in Lake Jangseong, Republic of Korea, through an extensive survey: Internal disturbances of past aquaculture sedimentation

Lake sediments are important sinks of various pollutants and preserve historical pollution records caused by anthropogenic activities. Recently, the sediments of Lake Jangseong, South Korea were first detected with high concentrations of organic matter (ignition loss [IL]; total organic carbon [TOC]), nutrients (total nitrogen [TN]; total phosphorus [TP]), and some heavy metals (Zn, Cu, Cd, and Hg). Here, we identified the origins of these concentrations accumulated in the sediments using extensive surveys and various assessments. Sediment pollution assessed by sediment quality guidelines, pollution load index, and potential ecological risk index was found to be of serious concern for IL, TN, TP, and Cd. Thus, we assessed pollution sources through spatial, grid, and vertical distributions and found that the high pollutant concentrations detected in 2020 were confirmed only at a certain location in the lake. Additionally, similar results were detected in the sedimentary layer below a sediment core at a depth of 15.0 cm. The high pollutant concentrations locally occurred around a "hotspot" site that was previously frequently used for aquaculture activities, indicating that the pollutants were accumulated in sediments owing to past cage fish farming rather than from influx of externally sourced pollution. Furthermore, chemical fractionation of phosphorus and heavy metals and assessment of stable isotopes (¹³C and ¹⁵N) of organic matter suggested that the pollutants in the sediments at the "hotspot" sites had different origins than those found at other sites. Accordingly, the by-products discharged after cage fish farming, such as residual feed, fish meal, and waste, accumulated in the sediments and were then exposed to natural internal disturbances caused by the effects of climate change-induced drought. This local distribution and the phosphorus and heavy metal chemical fraction results with low elution potential indicated that the pollutants in the sediments of Lake Jangseong had negligible impact on water quality.

Mapping of Greek Marine Finfish Farms and Their Potential Impact on the Marine Environment

The Greek marine aquaculture has a leading role in the Mediterranean mariculture industry, mainly in the export sector and its prominent contribution to the country’s economy. In the present study, the spatial distribution of Greek finfish farming activity and its potential impact zones on the marine environment were estimated and mapped. The Greek coastline was scanned via Google Earth satellite images for the period of June 2016 to May 2017, with 433 fish farm cage arrays being detected. For each cage array, the zones at different distances corresponding to various type of impacts were mapped by means of GIS technologies. Seventy-five spatial clusters of cage arrays (sc) were revealed, including cage arrays with shown connectivity. As per the findings, Greek marine fish farming activity shows a high level of spatial aggregation but with a relative moderate intensity of impacts due to legal constraints, which play a crucial role in controlling the spatial distribution of activity at a local, regional, and national scale. The results reflect an important source of geodata, necessary for the spatial planning of activity, the monitoring of environmental impacts, and the research itself.

Potential and mechanism of glomalin-related soil protein on metal sequestration in mangrove wetlands affected by aquaculture effluents

Aquaculture effluent discharge containing heavy metals affects estuarine mangrove wetlands. Glomalin-related soil protein (GRSP) is recalcitrant organic matter that can be trapped in mangrove wetlands and is critical to metal sequestration. However, studies on the effects of long-term aquaculture effluents on metal pollution in adjacent mangrove wetlands and the ecological role of GRSP are lacking. For the first time, we revealed the effects of discharge histories (0, 8, and 14 years) of shrimp pond effluents on metals (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn), including the entire process from feed to metals binding with GRSP in mangrove soils. Results showed that mangrove soils receiving the effluents generally had higher or similar metal loadings compared to the control, and long-term effluent discharge increased the potential toxicity of the metals. Aquaculture feed could be a main source of metal input. Redundancy analysis indicated that 14-year effluent discharge increased the pH, bulk density, total nitrogen, and total phosphorus of mangrove soils, reducing the potential of GRSP-bound metals. Scanning electron microscopy and infrared spectroscopy characterisation revealed that effluent disturbances changed the surface morphology and functional group contents of GRSP. This study provides insights into using GRSP as an aquaculture pollution bioindicator.

Bioaccumulation of heavy metals in fish species of Iran: a review

Accumulation of heavy metals (HMs) in fish tissues is an important factor in monitoring the health and safety of aquatic ecosystems. Furthermore, fish are important parts of aquatic food chains and play a significant role in human health. Considering the significant role of fish in the diet of humans and their ability to transfer and biomagnify HMs, it is necessary to determine and study these contaminants in fish tissues, especially in the edible parts of the fish. In addition to the other ecological and economic services of aquatic ecosystems, water bodies, especially the Persian Gulf in the south and the Caspian Sea in the north of Iran, are the main sources of seafood for people in nearby areas, as well as people living farther away who have gained access to seafood due to the extensive trade of aquatic organisms. This study provides an overview of the health conditions of the aquatic ecosystems in Iran by monitoring HM bioaccumulation in fish species. For this purpose, we reviewed, summarized, and evaluated papers published on HM concentrations in fish species from different aquatic ecosystems, including the Persian Gulf, the Caspian Sea, wetlands, rivers, qanats, water reservoirs, lakes, and dams, with emphasis on species habitats, feeding habits, and target organs in accumulation of HMs. Generally, the highest concentrations of HMs were observed in fishes collected from the Persian Gulf, followed by species from the Caspian Sea. Species inhabiting the lower zone of the water column and carnivorous and/or omnivorous species showed the highest levels of HMs. Moreover, liver was the main accumulator organ for HMs.

Assessment of Surface Water Quality in the Podu Iloaiei Dam Lake (North-Eastern Romania): Potential Implications for Aquaculture Activities in the Area

The Podu Iloaiei Dam Lake located on the Bahluet River from Bahlui hydrographic basin, north-eastern Romania, is one of the most important water resources used for aquaculture activities in the region of interest. In the present study, the chemical composition related to water-soluble ions and elements was assessed in both water and sediment samples collected from the area of interest during July 2017 and October 2017, representative months for warm and cold seasons, respectively. Water-soluble ions (H3C2O2−, HCO2−, C2O42−, F−, Cl−, NO2−, Br−, NO3−, SO42−, Li+, Na+, NH4+, K+, and Ca2+) were analyzed by ion chromatography, while inductively coupled plasma mass spectrometry was used to quantify water-soluble fractions of elements (Be, B, Mg, Al, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Rb, Sr, Mo, Ru, Pd, Ag, Cd, Sn, Sb, Te, Ba, Ir, Tl, Pb, Bi, and U). Evidence was obtained on the contributions of both anthropogenic and natural (pedologic) related sources in controlling the chemical composition of the water and sediment samples in the area. Analysis of Piper diagrams revealed the existence of CO32−/HCO3− and Ca2+/Mg2+ as dominant species for the sediment samples. The interest water pool was found to be oligotrophic over the warm period and eutrophic over the cold period. Overall, abundances and the association of chemical species in the area seemed to be controlled by a complex interplay between the water body’s main characteristics, meteorological factors, and anthropogenic activities. Moreover, the present results suggest that precautions should be taken for physicochemical parameter monitoring and prevention acts for surface water quality assurance in order to control the potential negative influence of some chemical parameters on fish productivity. Reported data also have a high potential to be used by experts in the field of developing lake water management policies for a sustainable exploitation of various aquatic systems.

Implications of Soil Potentially Toxic Elements Contamination, Distribution and Health Risk at Hunan’s Xikuangshan Mine

A field survey was conducted to determine the pollution grade, sources, potential ecological risk, and health risk of soil potentially toxic elements (PTEs) in Xikuangshan Mine (XKS), the largest antimony (Sb) deposit in the world. A total of 106 topsoil samples were collected from 6 sites in XKS to measure the concentrations of PTEs Cr, Zn, Cd, Pb, As, Hg, and Sb. The results show that the average concentrations of these elements at all six sites were generally greater than their corresponding background values in Hunan province, especially Sb, Hg, and As. Correlation and principal component analyses suggested that Cd, Zn, Pb, Hg, and Sb were primarily released from mining and other industrial and human activities, while Cr and As were mainly impacted by the parent material from pedogenesis. A risk index analysis showed that, overall, sites were at very high ecological risk, and Sb is the highest ecological risk factor, followed by Cd and Hg. According to health risk assessment, oral ingestion is the main non-carcinogenic and carcinogenic risk exposure route. The higher potentially non-carcinogenic and carcinogenic risks happen to the local children who live in the vicinity of mining area. It revealed that the mining and smelting processes of XKS have negatively influenced the local people, therefore, we should pay increasing attention to this practical issue and take effective measures to protect the ecology of XKS.

Benthic foraminifera geochemistry as a monitoring tool for heavy metal and phosphorus pollution - A post fish-farm removal case study

Measuring environmental contaminants in coastal areas is critical for monitoring and managing their impacts. Commonly used techniques involve repetitive field sampling, which provides a single moment in time during each effort. In this study, we examine the potential for using foraminifera in monitoring and risk assessment as recorders of bioavailable pollutants. Geochemical analysis of benthic foraminifera (Operculina ammonoides) shells sampled annually at a previous fish farm location showed extremely high levels of copper (Cu), zinc (Zn), and phosphorus (P) during the three years following the fish cages removal, with a general reduction afterwards. Levels of Cu/Ca were still more than 4-fold higher than background levels 10 years after the removal of the fish cages. Based on our finds, it is concluded that the geochemical analysis of recent benthic foraminifera shells can serve as a powerful monitoring tool of bioavailable contaminants in seawater. Additionally, the results highlight the need for heavy metal monitoring near marine aquaculture facilities and suggest that long-term effects extend spatially and temporally far beyond the original point source. Finally, we observed variations in micro-distribution of elements within the top 1-2 μm of the shells, where Cu/Ca, Zn/Ca and P/Ca are consistently higher in the chamber wall than in the septa. This observation is relevant for studies conducting single chamber analyses.

Development of best practices for more holistic assessments of carrying capacity of aquaculture

Carrying Capacity (CC) has emerged as a potential tool to sustainably manage human activities such as aquaculture. However, interdisciplinary and integrated frameworks for holistic CC assessments are still missing. The goal of this study was to generate expert consensus on best evaluative practices for holistic CC assessments of ocean-based salmon aquaculture. To achieve this goal, a 3-round Delphi study was conducted with 21 aquaculture and carrying capacity experts from around the world. Experts emphasized that the holistic CC process should i) engage all stakeholders in the process, ii) consider the combination of social, political, ecological, and economic aspects, iii) respond to changes over time, iv) consider multiple spatial and temporal scales, and v) be understandable and clear to all stakeholders involved. Furthermore, the expert panel emphasized the need for a cyclical and dynamic process that allows for the incorporation of feedback in the planning stages, embracing adaptive management. Due to the early stages of truly holistic assessments, the experts recognized challenges related to knowledge uncertainties and lack of approaches to integrate socio-economic data with ecological and physical data, potential conflicts arising from a multi-stakeholder process, and ill-equipped governance structures. The proposed guidelines and framework could help address some of the conceptual and procedural barriers to implementing holistic assessments into decision-making and may position CC as a useful decision-support tool for governments seeking sustainable aquaculture management.

Fish farming, metals and antibiotics in the eastern Mediterranean Sea: Is there a threat to sediment wildlife?

Chemical residues released from aquaculture farms may persist in the environment and may pose adverse ecological effects. The aim of this study was to assess the pollution status of marine sediments underneath or close to aquaculture farms in the Eastern Mediterranean Sea, the factors that affect the elemental distribution, and the exceedance of environmental quality standards and factors. To this end, surface sediment samples were collected (underneath fish cages, at 25 m distance and from a reference station) from 48 fish farms in Greece with variable environmental and geochemical characteristics. The content of 29 metals and major and trace elements, and three antibiotics (oxytetracycline, florfenicol, and flumequine), was determined in the sediment samples. Most of the elements found in the sediments originated from geological sources and their concentrations were close to Earth's Crust content. Below and close to fish farm cages, the sediment was enriched with P, Cu, Zn, Mo, and Cd mainly due to the aquaculture biosolid deposition, and changes in environmental conditions (increased organic matter, low redox potential). Cr and As were found to exceed twice the upper threshold limit of the available sediment quality guidelines in 13.5% and 7.3% of sampling stations, respectively. The potential ecological risk of V, Cr, Mn, Co, Ni, Cu, Zn, As and Pb was found to be low in the sediment close to fish cages except for Cd, which may pose a moderate to considerable risk in 12.5% of sampled fish farms. However, the estimated risks for this metal may be influenced by the high background levels found in the investigated areas. This study also shows that the occurrence of antibiotics in sediments below fish farms in the Eastern Mediterranean Sea is very sparse (i.e., only flumequine was found in two farms) and concentration levels are relatively low.

Assessment of mobility and environmental risks associated with copper, manganese and zinc in soils of a dumping site around a Ramsar site

This study reports the environmental fate and ecological hazard of the three heavy metals (HMs), viz. copper (Cu), manganese (Mn) and zinc (Zn) in soil influenced by municipal solid waste (MSW) dumping. The experimental site is situated in the vicinity of Deepor Beel, a Ramsar site located in Guwahati, India. This study assessed (i) the distribution pattern of Cu, Mn and Zn in six geochemical fractionations; (ii) the mobility, bioavailability and toxicity of Cu, Mn and Zn based on eight contamination and ecological indices, and (iii) the impact of Cu, Mn and Zn on soil quality. Altogether, 18 soil samples were collected and analysed from the study site using stratified random sampling. Pollution indices and multivariate statistics were applied on the data to identify the level and source of analysed HMs. Sequential extraction has revealed that the binding strength of Cu, Mn and Zn had a uniform trend. Mobility and potential bioavailability of studied HMs were in the order Mn > Cu > Zn. Analysed HMs were dominantly associated with non-bioavailable fractions. The observed low values of various contamination factors indicated the lesser contamination load posed by these metals. Conversely, their high enrichment factor and geo-accumulation index values indicated the sources of these metals were anthropogenic. Overall, the pollution and ecological indices registered lower contamination. Yet, it would be prudent to adopt efficient MSW management strategies for eliminating any future risk emanating out of this dumping site and posing threat to nearby Deepor Beel and its associated flora and fauna.

Microbial lipases and their industrial applications: a comprehensive review

Lipases are very versatile enzymes, and produced the attention of the several industrial processes. Lipase can be achieved from several sources, animal, vegetable, and microbiological. The uses of microbial lipase market is estimated to be USD 425.0 Million in 2018 and it is projected to reach USD 590.2 Million by 2023, growing at a CAGR of 6.8% from 2018. Microbial lipases (EC 3.1.1.3) catalyze the hydrolysis of long chain triglycerides. The microbial origins of lipase enzymes are logically dynamic and proficient also have an extensive range of industrial uses with the manufacturing of altered molecules. The unique lipase (triacylglycerol acyl hydrolase) enzymes catalyzed the hydrolysis, esterification and alcoholysis reactions. Immobilization has made the use of microbial lipases accomplish its best performance and hence suitable for several reactions and need to enhance aroma to the immobilization processes. Immobilized enzymes depend on the immobilization technique and the carrier type. The choice of the carrier concerns usually the biocompatibility, chemical and thermal stability, and insolubility under reaction conditions, capability of easy rejuvenation and reusability, as well as cost proficiency. Bacillus spp., Achromobacter spp., Alcaligenes spp., Arthrobacter spp., Pseudomonos spp., of bacteria and Penicillium spp., Fusarium spp., Aspergillus spp., of fungi are screened large scale for lipase production. Lipases as multipurpose biological catalyst has given a favorable vision in meeting the needs for several industries such as biodiesel, foods and drinks, leather, textile, detergents, pharmaceuticals and medicals. This review represents a discussion on microbial sources of lipases, immobilization methods increased productivity at market profitability and reduce logistical liability on the environment and user.

Chemical assessment of marine sediments in vicinity of Norwegian fish farms - A pilot study

While aquaculture is growing rapidly all over the world and generating many economic benefits, so have the environmental concerns about the externalities posed by the fish-farming industry. The distribution profiles of organic compounds and inorganic elements were explored in marine surface sediments collected in proximity of two active Norwegian fish farms, Hestøya and Nørholmen (<200-1100 m from the perimeter edge of the installations). Overall, the sediment organic matter (SOM) content was 7.3 ± 4.9%, with 7.9 ± 5.1% and 4.0 ± 0.5% for Hestøya and Nørholmen, respectively. A non-targeted analysis was performed for screening organic compounds in marine sediments, and the presence of 60 compounds was detected. Among suspect compounds were alkanes, alkenes, aromatics, aldehydes, ketones, esters, alcohols, diols, polycyclic aromatic hydrocarbons (PAHs), terpenes and terpenoids. Heptanal, benzaldehyde, 4-oxoisophorone, 1,7-dimethylnaphthalene and 3-bromophenol were the most abundant compounds in marine sediments. In total, concentrations of 47 elements were measured, concentrations of As, Cd, Cr, Cu, Hg, Mo, Ni, Sn and Zn were strongly influenced by anthropogenic inputs, while concentrations of Ce, Co, Al, Fe and Ti were related to the geology of the local bedrock. The chemical composition of marine sediments was different at Hestøya and Nørholmen, indicating different anthropogenic inputs in these areas. In general, concentrations of toxic elements were below the proposed guidelines for Norwegian marine sediment quality and can be characterised as background pollution. Overall, fish-farming activities had only a minor or negligible influence on marine sediments and are unlikely to cause any harm to local aquatic life in the studied area.

Impacts of cage fish farms in a large reservoir on water and sediment chemistry

The Keban Reservoir, which is the second man-made waterbody in Turkey, has the biggest rainbow trout production in the country. In this study, the impacts of rainbow trout farms on water and sediment chemistry were investigated. Water and sediment samples were taken at distances of 0, 10, 25, 50 and 100 m from the edge of the cages at the three fish farms, and at the respective reference stations. Samples were also taken at 0 m stations and reference stations in the late August when there were no fish in the cages. Physico-chemical variables and trace metals were analysed in all samples. Due to likely high dilution rates and recycling processes in the water column of the reservoir, little changes in the water quality parameters associated with wastes of the fish farms were noticed. When compared with those in the sediment samples at the stations near the edge of cages, the lower concentrations of total phosphorus (TP), total nitrogen (TN), organic matter (OM), total carbon (TC), sulfide (S^2-), arsenic (As), cobalt (Co), copper (Cu), manganese (Mn) and zinc (Zn), and higher values of redox potential (Eh) were found at the reference stations. According to organic enrichment classification based on S^2- and Eh values, sediments of the three fish farms in the period when there were fish in the cages fell into the oxic category, whereas sediments in the August (no fish farming activity) fell into the normal category. Also, it was found in the August that most of sediment quality parameters at the 0 m stations had close values to those at the reference stations. These results revealed that a three-month period when there were no fish in the cages allows for sediments to return to reference station conditions.

Heavy metal distribution and bioaccumulation ability in marine organisms from coastal regions of Hainan and Zhoushan, China

We analyzed the distribution and bioaccumulation of six heavy metals (Cu, Pb, Zn, Cr, Cd and Hg) in marine organisms, water, and sediments from China's Hainan and Zhoushan coastal regions. In all marine organism, seawater, and sediment samples, Zn and Hg had the highest and lowest concentrations, respectively. Heavy metals in marine organisms varied by region and species, with concentrations being higher in Zhoushan than in Hainan (except for Zn) and in crab than in fish. Marine organisms' ability to digest and eliminate heavy metals (bioaccumulation ability), based on bioaccumulation factors, was significantly higher for heavy metals in seawater than in sediment. Higher sediment background values may explain the higher heavy metal concentrations in crab. Generally, marine organisms' bioaccumulation ability was higher for Cu and Zn and lower for Pb. Findings specific to the coastal environments may be generalizable to other coastal areas in China or worldwide.

Assessment of heavy metal contamination in surface sediments along the Mediterranean coast of Morocco

In this paper, heavy metal contamination in surface sediments along the Mediterranean coast of Morocco was investigated. Determining pollution degree as well as heavy metal origins were the main objectives of this investigation. For this reason, concentrations of nine heavy metals (Cd, Cu, Cr, Ni, Pb, Zn, Hg, Fe, and Mn) were analyzed at ten stations sampled during three different periods. The obtained concentrations showed significant variation between sampling periods, which was controlled by several environmental and chemical processes. According to contamination indices results using pollution load index (PLI), modified contamination degree (mC_d), geoaccumulation index (I_geo), enrichment factor (EF), and potential ecological risk index (RI), sampling stations were classified between uncontaminated and strongly contaminated without detecting any intense heavy metal pollution in surface sediment. Likewise, the EF values were comprised between no enrichment and moderate to severe enrichment. According to sediment quality guidelines, the calculated M-ERM-Q indicated that heavy metal mixtures have between 9 and 49% probability for being toxic. This result revealed lowest to medium-low potential of adverse effects to biota populations. Regarding heavy metal origins, multivariate statistical investigation showed that Cd, Cu, Hg, Pb, and Zn are derived mainly from anthropogenic activities, while Fe, Mn, Cr, and Ni were derived from natural sources. Despite Cd is considered as a typical anthropogenic metal, the very low concentrations obtained in this study support the involvement of natural factor in the enrichment with this metal. Therefore, the surface sediments contamination along the Mediterranean coasts of Morocco is particularly caused by a combination of anthropogenic and natural factors. As a result, the study area can be considered as not significantly enriched by human activities.

Effects of conversion of mangroves into gei wai ponds on accumulation, speciation and risk of heavy metals in intertidal sediments

Mangroves are often converted into gei wai ponds for aquaculture, but how such conversion affects the accumulation and behavior of heavy metals in sediments is not clear. The present study aims to quantify the concentration and speciation of heavy metals in sediments in different habitats, including gei wai pond, mangrove marsh dominated by Avicennia marina and bare mudflat, in a mangrove nature reserve in South China. The results showed that gei wai pond acidified the sediment and reduced its electronic conductivity and total organic carbon (TOC) when compared to A. marina marsh and mudflat. The concentrations of Cd, Cu, Zn and Pb at all sediment depths in gei wai pond were lower than the other habitats, indicating gei wai pond reduced the fertility and the ability to retain heavy metals in sediment. Gei wai pond sediment also had a lower heavy metal pollution problem according to multiple evaluation methods, including potential ecological risk coefficient, potential ecological risk index, geo-accumulation index, mean PEL quotients, pollution load index, mean ERM quotients and total toxic unit. Heavy metal speciation analysis showed that gei wai pond increased the transfer of the immobilized fraction of Cd and Cr to the mobilized one. According to the acid-volatile sulfide (AVS) and simultaneously extracted metals (SEM) analysis, the conversion of mangroves into gei wai pond reduced values of ([SEM] - [AVS])/f_oc, and the role of TOC in alleviating heavy metal toxicity in sediment. This study demonstrated the conversion of mangrove marsh into gei wai pond not only reduced the ecological purification capacity on heavy metal contamination, but also enhanced the transfer of heavy metals from gei wai pond sediment to nearby habitats.

Distribution of Cu fraction in sediments using Suaeda heteroptera - Nereis succinea combination: A greenhouse study

A knowledge of the total amount of heavy metals is not enough to assess the environmental impact of polluted soils. Therefore, the determination of Cu fractions in sediment is important to evaluate its behavior in the environment and its mobilization capacity. The distribution of Cu (II) fractions in the sediment was studied in a laboratory simulation experiment. The results indicated that the distribution of Cu fractions was related to the concentration of Cu in sediments. In the Suaeda heteroptera group, the content of exchangeable and carbonate-bound were reducing, while the Fe-Mn oxide- and organic matter-bound were basically raising. In the Nereis succinea group, the content of Fe-Mn oxide- and organic matter-bound were from raising to reducing, and the residual was basically reducing with the increasing Cu concentrations. Generally speaking, the existence of N. succinea could enhance the uptake of Cu in the coastal sediment planted with S. heteroptera. When S. heteroptera and N. succinea in combination, effect of S. heteroptera and N. succinea on Cu fractions in sediments was significantly higher than the two working singly.

From collection to discharge: physical, chemical, and biological analyses for fish farm water quality monitoring

The use of chemical substances for the management of fish farming activities may compromise the quality of the tank water itself and of water bodies that receive the effluents. As studies that assess the environmental effect caused by pisciculture are scarce, the present study aimed at evaluating the water quality in two fish farms in the region of Grande Dourados, Brazil, from the site of water collection to the site of water disposal. The tools used for this purpose were the analysis of land use and cover and the determination of physical, chemical, and biological parameters of water samples. Maps of land use and cover were created, and water samples were collected at four sampling sites in two fish farms. The Allium cepa test, assays with Astyanax lacustris, and the Salmonella/microsome assay were performed. In addition, physical and chemical parameters were measured and metal and emerging contaminants in the water samples were investigated. The A. lacustris demonstrated the genotoxicity and the Salmonella/microsome assay suggested the mutagenic potential of water samples from the fish farms and indicated higher genotoxicity in the disposal tanks than in the collection tanks of the Brilhante fish farm. However, all the samples at the Dourados fish farm were genotoxic, and mutagenicity was shown to start at the water collection site. With regard to the A. cepa test, there was no statistical difference between the collection sites in both fish farms. Moreover, the observed genetic damage may be associated with the presence of metals and emerging contaminants in the water samples, which suggests that these chemicals have potential genotoxic and mutagenic effects that are related to the type of land use and cover in the area of the region studied. Considering that contaminated waters can potentially disturb the structure and functioning of natural ecosystems, the present study demonstrated the importance of treating fish farm effluent to minimize the negative effect of this activity on water bodies.

Integrated toxicity evaluation of metals in sediments of Jiaozhou Bay (China): Based on biomarkers responses in clam Ruditapes philippinarum exposed to sediment extracts

To evaluate the integrated toxicity of metals in sediments of Jiaozhou Bay, we exposed clam (Ruditapes philippinarum) to sediments extracts obtained using of sediment extraction with deionised water adjusted to pH 4 which simulated the weak acidity in the digestive juice of clams and tested the selected biomarkers responses in clams for exposure over 15 days. At the same time, the contents of metals in sediments were assessed with method of the mean sediment quality guideline quotient (SQG-Q). The integrated biomarker response version 2 (IBR_v2) was used to assess the integrated toxicity induced by metals in sediment extracts based on biomarkers response in clams: the results demonstrated that site S7 located in the mouth of Nanxin'an River show higher IBR_v2 values compared to the other sites. The IBR_v2 values exhibited the good consistency with SQG-Q values.

Biochemical effects of commercial feedstuffs on the fry of climbing perch (Anabas testudineus) and its impact on Swiss albino mice as an animal model

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Heavy metal levels in fish feedstuffs, fish and also in organs of fish-treated Swiss albino mice were studied.

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For Cu and Pb, the mean values in the feed sample were lower than the respective maximum tolerable value.

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Some elements for example Cr, Zn and in different parts of the A. testudineus fish samples exceeded the respective limits.

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The highest level of Cr was observed in most of the fish samples, Cr and Pb were found above their respective threshold limits in the liver.

This study assesses the biochemical effects of commercially available fish feedstuffs on the fry of climbing perch (Anabas testudineus). Subsequently, its impact on experimental animal, Swiss albino mice, is also examined. In order to access the impact of commercial fish feed and feed consumption fish on the experimental animal, the proximate, biochemical and histopathological analyses were done using standard methods. The proximate composition as well as the concentrations of Pb, Ni, Mn, As, Zn, and Cd in the fish feed, different parts of the A. testudineus fish and different parts of the A. testudineus fish-treated experimental mice liver, were all determined using Energy Dispersive X-ray Fluorescence (EDXRF) Spectrometry. The highest levels of Cr, Pb and As were observed in the liver of Swiss albino mice treated with FFT2 and FFBB2 and their concentrations were 0.156, 0.491, 0.172 μg/g and 0.166, 0.771, 0.157 μg/g respectively. No significant changes of protein, fat, crude fiber, moisture and ash contents were observed after proximate composition analysis of fish feeds, A. testudineus and A. testudineus treated experimental mice.

Significant amounts of heavy metals (Cr, Mn, Zn Cu, Ni) were found in fish feed, different parts of A. testudineus fish and in the experimental mice. However, remarkably high amounts were observed in the A. testudineus fish’s head and bone with body parts. Biochemical analysis of blood samples of A. testudineus fish treated experimental mice indicated that the cholesterol, TG, LDL and glucose levels were significantly higher. Yet no significant alteration in the HDL level was observed when compared to the control. In histopathological analysis, a remarkable degeneration was observed in the liver and kidney of A. testudineus treated mice. It can therefore be concluded that although A. testudineus has nutritional benefits the quality of this fish may be compromised as a consequence of contamination through various anthropogenic activities. This analysis suggests the commercial fish feed producers must take special caution to reduce the toxic metals in various fish feed products and make it nutritionally rich and safe for fish to eat. Finally, it needs to be safe for human consumption as well.

A comparative study of inorganic elements in the blood of male and female Caspian pond turtles (Mauremys caspica) from the southern basin of the Caspian Sea

Due to their bioaccumulation and biomagnification pathways, inorganic elements can accumulate in high-level aquatic organisms in the food web. Then, this species can be used to monitor the quality of the environment. Blood concentration of nine inorganic elements, including possible toxic metals (An, Cu, Mn, Se, As, Ni, Cd, Pb, and Hg), in 20 males and 20 females from eight different locations with high industry and agriculture activities in Iran were evaluated in this work. Additionally, size, sex, condition index, and locations were also included and analyzed. Among the essential elements, Zn and Se presented very high concentrations (56.14 ± 2.66 and 8.44 ± 0.77 μg/g ww, respectively) in all locations. Regarding possible toxic elements, Pb and Cd presented concerning concentrations as well (0.52 and 0.58 μg/g ww); this is especially true for Pb, an element found in very high concentrations in tissues of turtles from the same area in a previous study. The sex and the size of the individuals also had significant differences in concentration of Pb, Cd, As, and Hg.

Developing an environmental water quality monitoring program for Haraz River in Northern Iran

Water quality management plans are an indispensable strategy for conservation and utilization of water resources in a sustainable manner. One common industrial use of water is aquaculture. The present study is an attempt to use statistical analyses in order to prepare an environmental water quality monitoring program for Haraz River, in Northern Iran. For this purpose, the analysis of a total number of 18 physicochemical parameters was performed at 15 stations during a 1-year sampling period. According to the results of the multivariate statistical methods, the optimal monitoring would be possible by only 3 stations and 12 parameters, including NH₃, EC, BOD, TSS, DO, PO₄, NO₃, TDS, temperature, turbidity, coliform, and discharge. In other words, newly designed network, with a total number of 36 measurements (3 stations × 12 parameters = 36 parameters), could achieve exactly the same performance as the former network, designed based on 234 measurements (13 stations × 18 parameters = 234 parameters). Based on the results of cluster, principal component, and factor analyses, the stations were divided into three groups of high pollution (HP), medium pollution (MP), and low pollution (LP). By clustering the stations, it would be possible to track the water quality of Haraz River, only by one station at each cluster, which facilitates rapid assessment of the water quality in the river basin. Emphasizing on three main axes of monitoring program, including measurement parameters, sampling frequency, and spatial pattern of sampling points, the water quality monitoring program was optimized for the river basin based on natural conditions of the study area, monitoring objectives, and required financial resources (a total annual cost of about US $2625, excluding the overhead costs).

Heavy metal concentrations in some gastropods and bivalves collected from the fishing zone of South India

The present study investigates heavy metal concentrations in gastropods and bivalves collected from major fishing centers in South India. Three gastropods, Bursa spinosa, Tibia curta, and Murex trapa, and two bivalves, Perna viridis and Villoritta cyprinoids, were collected for the analysis of heavy metals. The metals in the present study followed the order Mg>Ca>Zn>Fe>Cu>Mn>Cr>Pb>Ni>Co>Cd. Trace metal concentrations in the soft tissue of the molluscs varied as follows: for Cd: 0.04-5.33, Co: 0.09-0.87, Cr: 2.18-7.59, Cu: 9.54-37.02, Mn: 1.30-8.50, Ni: 0.94-3.21, Pb: 1.16-2.64 and Zn: 68.16-113.64mgkg^-1. Metal concentrations in all the species were below the limits proposed by the World Health Organization, except for Pb and Cd. This baseline study suggests that the levels of toxic metals in M. trapa, T. curta, and B. spinosa should be continuously monitored to assess the fate and effects of these metals in this fragile ecosystem.

Geochemistry of recent aragonite-rich sediments in Mediterranean karstic marine lakes: Trace elements as pollution and palaeoredox proxies and indicators of authigenic mineral formation

This study investigates the geochemical characteristics of recent shallow-water aragonite-rich sediments from the karstic marine lakes located in the pristine environment on the island of Mljet (Adriatic Sea). Different trace elements were used as authigenic mineral formation, palaeoredox and pollution indicators. The distribution and the historical record of trace elements deposition mostly depended on the sedimentological processes associated with the formation of aragonite, early diagenetic processes governed by the prevailing physico-chemical conditions and on the recent anthropogenic activity. This study demonstrated that Sr could be used as a proxy indicating authigenic formation of aragonite in a marine carbonate sedimentological environment. Distribution of the redox sensitive elements Mo, Tl, U and Cd was used to identify changes in redox conditions in the investigated lake system and to determine the geochemical cycle of these elements through environmental changes over the last 100 years. The significant enrichment of these elements and the presence of early formed nanostructured authigenic framboidal pyrite in laminated deeper parts of sediment in Malo Jezero, indicate sporadic events of oxygen-depleted euxinic conditions in the recent past. Concentrations of trace elements were in the range characteristic for non-contaminated marine carbonates. However, the increase in the concentrations of Zn, Cu, Pb, Sn, Bi in the upper-most sediment strata of Veliko Jezero indicates a low level of trace element pollution, resulting from anthropogenic inputs over the last 40 years. The presence of butyltin compounds (BuTs) in the surface sediment of Veliko Jezero additionally indicates the anthropogenic influence in the recent past.

Mercury, lead, and cadmium in tissues of the Caspian Pond Turtle (Mauremys caspica) from the southern basin of Caspian Sea

Concentrations of cadmium, lead, and mercury were measured in different tissues (liver, muscle, and shell) of 60 Caspian Pond Turtles collected from Tajan and Shiroud Rivers, southern basin of the Caspian Sea. Based on the results, different tissues showed different capacities for accumulating trace elements. The general trend of metals accumulation was: liver > shell > muscle. Results also showed that accumulation of these elements was not significantly different between sex and river in turtles (p > 0.05). Based on the results, Hg and Pb concentrations recorded in the present study were higher than some of the maximum concentration permissible. To our knowledge, this is the first report into heavy metal accumulation in tissues and organs of Caspian Pond Turtle from the southern basin of Caspian Sea. Further studies are needed to measure different heavy metals and trace metals in this valuable species.

Pollution characteristics and ecological risk of heavy metals in ballast tank sediment

This study was conducted to illustrate the contents and potential ecological risk of heavy metals in ballast tank sediment. Ballast sediment samples were collected from six ships during their stay in shipyard, and the heavy metals were determined by inductive coupled plasma emission spectrometer. Results showed that high concentrations of heavy metals were detected in all six sediment samples following the order: Zn > Cu > Pb > Cr > As > Cd > Hg. The geoaccumulation index explained the average pollution degree of heavy metals decreased as the following: Zn > Pb > Cu > As > Cr > Hg, and the environmental risk indices suggested that concentration found of Zn, Pb, and Cu might be highly toxic to aquatic organisms. Principal component and correlation analysis indicated the metal pollution in ballast tank sediment was affected by complex and different contamination mechanisms, and the corrosion of ballast tank played an important role in this process. In conclusion, this study is very useful for comprehensive consideration and efficient management of ballast tank sediment in order to protect the marine environment.

Contamination, Fractionation and Biological Risk Related to Metals in Surface Sediments from the Largest Deep Freshwater Lake in China

The toxicity and mobility of metals in the environment are driven by their specific chemical forms and binding states. However, heavy metal fractionation in sediments from plateau deep lakes in China is rare. This study analyzed surface sediments collected from Fuxian Lake, the largest deep freshwater lake in China; parameters examined included total metal concentrations, chemical partitioning, and biological risk assessment. The average total concentrations (mg/kg) were 7.9 for Cd, 97.6 for Pb, 102.8 for Cr, 60.8 for Ni, 73.6 for Cu, and 112.9 for Zn; these levels were significantly higher than their corresponding background values. Cd was preferentially associated with the acid-soluble fraction; significant portions of the Pb, Cr, Ni, Cu, and Zn were mainly associated with the residual fractions. Overall, surface sediments of Fuxian Lake were associated with a 21% incidence of toxicity based on the mean effects range-median quotient. Cd was mainly at high or very high risk levels, and Cu and Zn were mainly at medium or high risk levels based on the risk assessment code (RAC).

Trace metals in a sediment core from the largest mariculture base of the eastern Guangdong coast, South China: Vertical distribution, speciation, and biological risk

A sediment core collected from Zhelin Bay, the biggest mariculture base of the eastern Guangdong Province, was analyzed for trace metal concentrations and chemical fractions. Average total concentrations (mg/kg) were 20.7±15.4 (Pb), 74.6±11.6 (Cr), 40.7±6.0 (Ni), 55.9±13.0 (Cu), and 169.0±11.9 (Zn), with the concentrations of Cr, Ni, Cu and Zn being significantly higher than their corresponding background values. We identified two vertical distribution patterns of the trace metals in the sediment core. In all sub-samples, Pb was mainly associated with the reducible fraction, whereas a major portion (62.2 to 95.2%) of Cr, Ni, Cu, and Zn was strongly associated with the residual fractions. Biological risk assessment based on the mean effects range-median quotient suggests that the Zhelin Bay sediment core has a 21% probability of being toxic.

Environmental variability and heavy metal concentrations from five lagoons in the Ionian Sea (Amvrakikos Gulf, W Greece)

Background

Coastal lagoons are ecosystems of major importance as they host a number of species tolerant to disturbances and they are highly productive. Therefore, these ecosystems should be protected to ensure stability and resilience. The lagoons of Amvrakikos Gulf form one of the most important lagoonal complexes in Greece. The optimal ecological status of these lagoons is crucial for the well-being of the biodiversity and the economic prosperity of the local communities. Thus, monitoring of the area is necessary to detect possible sources of disturbance and restore stability.

New information

The environmental variables and heavy metals concentrations, from five lagoons of Amvrakikos Gulf were measured from seasonal samplings and compared to the findings of previous studies in the area, in order to check for possible sources of disturbance. The analysis, showed that i) the values of the abiotic parameters vary with time (season), space (lagoon) and with space over time; ii) the variability of the environmental factors and enrichment in certain elements is naturally induced and no source of contamination is detected in the lagoons.

Limited effectiveness of household sand filters for removal of arsenic from well water in North Vietnam

Since well water utilized for domestic purposes in the Red River Delta of North Vietnam has been reported to be polluted by arsenic, barium, iron, and manganese, household sand filters consisting of various components are used. Information regarding the effectiveness of various sand filters for removal of the four toxic elements in well water is limited. In this study, arsenic levels in 13/20 of well water samples and 1/7 of tap water samples exceeded World Health Organization (WHO) health-based guideline value for drinking water. Moreover, 2/20, 6/20, and 4/20 of well water samples had levels exceeding the present and previous guideline levels for barium, iron, and manganese, respectively. Levels of iron and manganese, but not arsenic, in well water treated by sand filters were lower than those in untreated water, although previous studies showed that sand filters removed all of those elements from water. A low ratio of iron/arsenic in well water may not be sufficient for efficient removal of arsenic from household sand filters. The levels of barium in well water treated by sand filters, especially a filter composed of sand and charcoal, were significantly lower than those in untreated water. Thus, we demonstrated characteristics of sand filters in North Vietnam.

Radionuclides (210Po and 210Pb) and Some Heavy Metals in Fish and Sediments in Lake Bafa, Turkey, and the Contribution of 210Po to the Radiation Dose

The pollution level of Lake Bafa was investigated by collecting fish samples {Dicentrarchus labrax (sea bass), Liza ramada (mullet) and Anguilla anguilla (eel)}, surface sediment, and core samples. In all these samples, ²¹⁰Po and ²¹⁰Pb concentrations were estimated, and total annual dose rates were obtained for each species. Some heavy metal (Cr, Ni, Pb, Cd, Mn, Fe, and Zn) concentration levels were obtained for the fish and a core sample. The sediment mass accumulation rate was found to be 3.27 g·m^-2·day^-1 (0.119 g·cm^-2·y^-1) from a core sample. The heavy metal concentrations in the vertical profile of samples from the core were also observed. The measured concentration of Zn, Pb, Cd, and Cr were between the ERL (effects range low) and ERM (effects range median) limits, while Ni concentrations were higher than the ERM limit. The observed concentrations of Cd, Pb, and Zn in fish samples did not exceed the limits in accordance with Turkish Food Regulations. Further, the maximum effective dose equivalent of ²¹⁰Po in the area was found to be 1.169 µSv·y^-1.

Arsenic and Heavy Metal Contamination in Soils under Different Land Use in an Estuary in Northern Vietnam

Heavy metal contamination of soil and sediment in estuaries warrants study because a healthy estuarine environment, including healthy soil, is important in order to achieve ecological balance and good aquaculture production. The Ba Lat estuary of the Red River is the largest estuary in northern Vietnam and is employed in various land uses. However, the heavy metal contamination of its soil has not yet been reported. The following research was conducted to clarify contamination levels, supply sources, and the effect of land use on heavy metal concentrations in the estuary. Soil samples were collected from the top soil layer of the estuary, and their arsenic (As), chromium (Cr), cadmium (Cd), copper (Cu), lead (Pb), and zinc (Zn) concentrations were analyzed, as were other soil properties. Most soils in the estuary were loam, silt loam, or sandy loam. The pH was neutral, and the cation exchange capacity ranged from 3.8 to 20 cmol·kg^-1. Manganese and iron concentrations averaged 811 µg·g^-1 and 1.79%, respectively. The magnitude of the soil heavy metal concentrations decreased in the order of Zn > Pb > Cr > Cu > As > Cd. The concentrations were higher in the riverbed and mangrove forest than in other land-use areas. Except for As, the mean heavy metal concentrations were lower than the permissible levels for agricultural soils in Vietnam. The principal component analyses suggested that soil As, Pb, Zn, Cd, and Cu were of anthropogenic origin, whereas Cr was of non-anthropogenic origin. The spatial distribution of concentration with land use indicated that mangrove forests play an important role in preventing the spread of heavy metals to other land uses and in maintaining the estuarine environment.

Effect of abalone farming on seawater movement and benthic foraminiferal assemblage of Zostera marina in the inner bay of Wando, South Korea

Tidal current survey as well as geochemical and benthic foraminiferal analyses of sediment cores were conducted in an abalone farm and a Zostera bed to understand the degree to which the abalone farm facilities installed along a channel in a shallow sea affect the benthic environment and ecology. In the abalone farm, Ammonia beccarii-Pseudoparrella naraensis-Elphidium somaense-Rosalina globularis-Trochammina hadai and P. naraensis-E. somaense-A. beccarii-T. hadai assemblages appeared owing to an increase in the total nitrogen content from the biodeposits. The Zostera bed consisted of A. beccarii-P. naraensis-Buccella frigida-T. hadai assemblage owing to the gradual expansion of a brackish shallow-water environment by the rapidly decreasing current speed, and it may have flourished. Moreover, the total sulfur, Zn, Cr, and Cu contents in the sediments decreased remarkably more than those of the pre-abalone farming did, caused by the vigorous activity of Zostera marina physiology.