Chemical speciation of metals from marine sediments: Assessment of potential pollution risk while dredging, a case study in southern Sweden

Chemical Fingerprinting of PM2.5 via Sequential Speciation Analysis Using Electrochemical Mass Spectrometry

Chemical fingerprinting to characterize the occurrence state and abundance of organic and inorganic constituents within fine particulate matter (PM2.5) is useful in evaluating the associated health risks and tracing pollution sources. Herein, an analytical strategy for the rapid analysis of metal and organic constituents in PM2.5 was developed employing a combination of sequential chemical extraction coupled with mass spectrometry detection. H2O, CH3OH, EDTA-2Na, electrochemical oxidation, and electrochemical reduction were sequentially utilized to extract the chemical constituents in PM2.5 samples on a homemade device employing simultaneous online detection using two linear trap quadrupole mass spectrometers (LTQ-MS) with electrospray ionization (ESI) in positive and negative modes. After a single analytical procedure, dozens of metals (e.g., Pb, Cr, and Cu), organic compounds (e.g., amines, polycyclic aromatic hydrocarbons, and aliphatic acids), and negative ions (e.g., NO3-, NO2-, and Cl-) were comprehensively detected in the water-soluble, liposoluble, insoluble, oxidizable, and reducible fractions of PM2.5 samples, and their physical and chemical relationships were established.

Impact of sediment mobilization on trace elements release in Galician Rías (NW Iberian Peninsula): insights into aquaculture

In the latest years, the concentration levels of certain metals and metalloids in the sediments of the Galician Rías have shown an increasing trend (e.g., As, Zn, Cu, Pb, Hg). These areas are also characterized by their richness in nutrients and their great aquaculture or mariculture activity, with the presence of more than 3500 mussel rafts in the Rías Baixas. The inner areas of the Galician Rías are subjected to activities that resuspend the sediment such as high levels of maritime traffic and dredging or cleaning operations. It is likely that a transfer of these elements to the water column happens during the resuspension of sediments caused by natural events or anthropogenic activities. In this study, selected samples of surface sediments of the Ría de Pontevedra (NW Spain) were subjected to a procedure of aerobic oxidation to determine the concentration of some elements (Fe, Mn, Cu, Cr, Pb, Hg, and Zn) released from the sediment to the aqueous phase. The experiment was carried out within 5 days. Measurements of pH and total concentration were taken both in water and sediment samples. Furthermore, speciation of trace elements was carried out in the sediment samples. Trace element concentrations were lower in the sediments during aerobic oxidation, being released to the aqueous phase. From an environmental point of view, Cu was the only trace element released in quantities that may be toxic for the organisms in the area. This problem of sediment oxidation related to dredging activities or natural storm conditions should be considered in environmental impact studies and transferred to stakeholders.

Levels of Potentially Toxic and Essential Elements in Water and Estimation of Human Health Risks in a River Located at the Interface of Brazilian Savanna and Amazon Biomes (Tocantins River)

The Tocantins-Araguaia basin is one of South America's largest river systems, across three Brazilian states (Maranhão, Tocantins, and Pará), within the Legal Amazon region. Despite draining extensive Cerrado savanna and rainforest ecosystems, it has suffered significant degradation, notably in the past 40 years. Human activities, including agricultural expansion, deforestation, and the introduction of non-native species, have worsened the environmental damage, which is alarming since many residents and villages along the middle Tocantins River rely on it for water supply, recreation, and fishing. This study assessed the concentration of potentially toxic and essential elements in water samples from four sampling sites distributed along the middle Tocantins River. The monitoring occurred throughout 2023, involving the measurement of parameters both on-site and in the laboratory. Water quality and its health implications were evaluated using the Weighted Arithmetic Water Quality Index (WAWQI), the Water Quality Index (WQI), and the health risk assessment index. The levels of aluminum, copper, iron, magnesium, and selenium exceeded legal standards. Seasonal fluctuations indicate a complex dynamic influenced by climatic or seasonal factors, with February showing the highest values. Site P1, located in urban areas, exhibited elevated mean concentrations for conductivity, total dissolved solids (TDS), and chlorophyll, indicating the need for continuous monitoring. The nitrogen concentrations at P1 raise concerns regarding drinking water quality, which is a concern for the region's residents who use untreated river water. Despite seasonal variations in element concentrations, the overall WAWQI categorized all sections as "Excellent," and the WQI rated as "Good." Human health risk assessments detected no risks, but continuous monitoring and interventions are crucial for sustained water quality improvement.

Influence of mineralized organic carbon in marine sediments on ecological heavy metal risk: Bohai Bay case study

The organic matter in sediments can mineralize over time, which impacts the morphology of the heavy metals therein, which in turn affects the assessment of the risks posed by heavy metals. We used the sediments of Bohai Bay as the study object and analyzed the effects of different organic carbon mineralization levels on the concentrations of heavy metals (Cr, Pb, Cu, Zn, and Cd) using water extraction and potassium permanganate oxidation. The mean concentrations of Cd, Pb, Cu, and Zn in Bohai Bay were within the limits recommended by the World Health Organization. The proportions of the active and inert organic carbon fractions were 61.72% and 32.94%, respectively. Organic carbon mineralization most strongly impacted Cd and Pb levels, with releases accounting for 47.92% and 25.75%, respectively, of the oxidizable fractions. The release of all heavy metals, except for Cr, increased with increases in organic carbon mineralization, and heavy metals were released at a maximum rate of 12.94% when the organic carbon was highly mineralized, whereas Cr was released at a maximum of 0.023% during the first stage of organic carbon mineralization. In terms of spatial distribution, the concentration of mineralizable organic carbon in the sediments of the estuaries was substantially higher than that in other marine areas. Estuary sediments were more easily affected by organic carbon mineralization; therefore, the heavy metals in the oxidizable fraction of the estuarine region were more easily transformed into unstable heavy metal forms, posing high risk levels. Therefore, this study highlights the effects of organic carbon mineralization on heavy metal morphology and stability, when evaluating the ecological risk of heavy metals in marine sediments.

Assessing the ecological risk of heavy metal sediment contamination from Port Everglades Florida USA

Port sediments are often contaminated with metals and organic compounds from anthropogenic sources. Remobilization of sediment during a planned expansion of Port Everglades near Fort Lauderdale, Florida (USA) has the potential to harm adjacent benthic communities, including coral reefs. Twelve sediment cores were collected from four Port Everglades sites and a control site; surface sediment was collected at two nearby coral reef sites. Sediment cores, sampled every 5 cm, were analyzed for 14 heavy metals using inductively coupled plasma-mass spectrometry. Results for all three locations yielded concentration ranges (µg/g): As (0.607-223), Cd (n/d-0.916), Cr (0.155-56.8), Co (0.0238-7.40), Cu (0.004-215), Pb (0.0169-73.8), Mn (1.61-204), Hg (n/d-0.736), Mn (1.61-204), Ni (0.232-29.3), Se (n/d-4.79), Sn (n/d-140), V (0.160-176), and Zn (0.112-603), where n/d = non-detected. The geo-accumulation index shows moderate-to-strong contamination of As and Mo in port sediments, and potential ecological risk indicates moderate-to-significantly high overall metal contamination. All four port sites have sediment core subsamples with As concentrations above both threshold effect level (TEL, 7.24 µg/g) and probable effect level (PEL, 41.6 µg/g), while Mo geometric mean concentrations exceed the background continental crust level (1.5 µg/g) threshold. Control site sediments exceed TEL for As, while the reef sites has low to no overall heavy metal contamination. Results of this study indicate there is a moderate to high overall ecological risk from remobilized sediment due to metal contamination. Due to an imminent dredging at Port Everglades, this could have the potential to harm the threatened adjacent coral communities and surrounding protected habitats.

Metal speciation in sediments and bioaccumulation in edible bivalves to assess metal toxicity in a sand mining impacted tropical (Aghanashini) estuary, southern India

The study aims to understand the metal toxicity through the relationship between bioavailability in sediments and bioaccumulation in edible bivalves in an estuary subjected to extensive sand mining. The higher deposition of total Fe, Mn, Ni and Zn in the middle region (core M) was ascribed to estuarine processes and proximity to anthropogenic sources. EF revealed moderate to severe enrichment of Ni and Cu in sediments. Igeo showed moderate degree of pollution from Co, moderate to strong pollution from Ni and strong to extreme level of pollution from Cu. In core N, the average bioavailable concentration of Fe, Mn, Zn, Cu, Co and Ni was 1.76 %, 43.18 %, 59.14 %, 62.11 %, 60.42 % and 27.33 % respectively. The average bioavailable concentration of Fe (61.23 %), Mn (56.87 %), Cu (67.98 %), Co (69.77 %) and Ni (40.99 %) was higher in the core M as compared to core N except for Zn (56.98 %). The significant (>25.00 %) proportion of metals in bioavailable fractions in cores N and M construed their non-natural sources. Metal speciation study indicated bioavailability to fauna that likely to enhance by extensive sand mining. The level of Fe, Mn, Zn, Cu and Ni in Saccostrea cucullate, Meretrix casta and Villorita cyprinoides revealed toxicity to bivalves and probably to humans.

Natural and anthropogenic radionuclides concentration with heavy metals analysis of the sediments collected around Novaya Zemlya

The Dispersal profile of the radioisotopes (226Ra, 232Th, 235U, 40K, 137Cs) along with potentially toxic elements (Cd, Co, Cr, Cu, Ni, Pb, V, Zn, and Hg) in the sediments around the Novaya Zemlya was determined. The task was fulfilled with the aid of HPGe gamma spectrometry, inductively coupled plasma optical emission spectroscopy, DMA-80 Direct Mercury Analysis System, X-ray diffraction and statistical tools. At most of the locations, the radionuclides activity was higher than the world average activity concentration for the respective nuclei, 40K being the most abundant. From all the potentially toxic elements detected, Cr and Ni were usually observed on higher levels compared to their background values, indicating the probability of the detrimental biological effects. Thus, the present situation at the studied area might be a threat to the neighboring marine life.

An investigation on mobility of heavy metals for assessing the reusability of soil-like material reclaimed from mining of municipal solid waste dumpsites

Landfill mining, often referred to as "bio-mining", enables the recovery of resources, including combustible, compostable, and recyclable fractions from landfills. However, most of the materials mined from old landfills mainly consist of soil-like materials (SLM). The reuse of SLM depends on the concentration of contaminants, such as heavy metals, soluble salts, etc. A sound risk assessment requires sequential extraction to determine the bioavailability of heavy metals. This study focuses on the mobility and chemical speciation of heavy metals in SLM from four old municipal solid waste dumpsites in India by performing selective sequential extraction. Additionally, the study compares the results with those of four previous investigations to identify international similarities. It has been observed that Zn was mainly available in the reducible phase (average 41%), whereas Ni and Cr proved to have the highest distribution in the residual phase (64% and 71%, respectively). Pb analysis showed a large portion in the oxidizable phase (39%), while Cu was mainly present in the oxidizable (37%) and residual (39%) phases. Similarities with previous investigations were observed for Zn (primarily reducible 48%), Ni (residual 52%), and Cu (oxidizable 56%). Correlation analysis showed that Ni correlated with all heavy metals (ρ = 0.71-0.78), except with Cu. The present study suggested that Zn and Pb are associated with a high risk of pollution due to their maximum distribution in the bioavailable phase. The findings of the study can be used to assess the heavy metal contamination potential of SLM prior to its reuse in offsite applications.

Preliminary study of geochemical speciation of copper and nickel in coastal sediments in Surabaya, Indonesia

Surabaya is one of the big coastal cities in Indonesia with rapid municipal development. Thus, the investigation on the metal's geochemical speciation in the coastal sediment is required to assess the environmental quality by studying their mobility, bioavailability, and toxicity. This study is aimed at evaluating the condition of the Surabaya coast by assessing copper and nickel fractionations and total concentrations of both metals in sediments. Environmental assessments were performed by using geo-accumulation index (Igeo), contamination factor (CF), and pollution load index (PLI) for existing total heavy metal data and by using individual contamination factor (ICF) and risk assessment code (RAC) for metal fractionations. Copper speciation was observed geochemically in the fraction order of residual (9.21 - 40.08 mg/kg) > reducible (2.33 - 11.98 mg/kg) > oxidizable (0.75 - 22.71 mg/kg) > exchangeable (0.40 - 2.06 mg/kg), while the detected fraction order of nickel was residual (5.16 - 13.88 mg/kg) > exchangeable (2.33 - 5.95 mg/kg) > reducible (1.42 - 4.74 mg/kg) > oxidizable (1.62 - 3.88 mg/kg). Different fraction levels were found for nickel speciation wherein its exchangeable fraction was higher than copper, even though the residual fraction was dominant for both copper and nickel. The total metal concentrations of copper and nickel were found in the range of 13.5 - 66.1 mg/kg dry weight and 12.7 - 24.7 mg/kg dry weight, respectively. Despite the fact that almost all index values are detected low through total metal assessment, the port area is indicated to be in the moderate contamination category for copper. Through the assessment of metal fractionation, copper is classified into the low contamination and low-risk category, while nickel is categorized into the moderate contamination level and medium risk to the aquatic environment. Although the coast of Surabaya generally remains in the safe category for living habitat, certain sites had relatively high metal concentrations estimated to have originated from anthropogenic activities.

Online Sequential Determination of Organic/Inorganic Lead Speciation in PM2.5 Using Electrochemical Mass Spectrometry

The information regarding the occurrence and abundance of lead (Pb) in PM2.5 is useful for the evaluation of air pollution status and tracing the pollution source. Herein, electrochemical mass spectrometry (EC-MS) for sequential determination of Pb species in PM2.5 samples without sample pretreatment has been developed using the combination of online sequential extraction with mass spectrometry (MS) detection. Four kinds of Pb species including water-soluble Pb compounds, fat-soluble Pb compounds, water/fat-insoluble Pb compounds, and a water/fat-insoluble Pb element were sequentially extracted from PM2.5 samples, in which water-soluble Pb compounds, fat-soluble Pb compounds, and water/fat-insoluble Pb compounds were extracted sequentially by elution using H₂O, CH₃OH, and EDTA-2Na as the eluent respectively, while the water/fat-insoluble Pb element was extracted by electrolysis using EDTA-2Na as the electrolyte. The extracted water-soluble Pb compounds, water/fat-insoluble Pb compounds, and water/fat-insoluble Pb element were transformed into EDTA-Pb in real time for online electrospray ionization mass spectrometry analysis, while the extracted fat-soluble Pb compounds were directly detected by electrospray ionization mass spectrometry. The advantages of the reported method include the obviation of sample pretreatment, high speed of analysis (<60 min/sample), low detection limit (0.16 pg), low sample consumption (30 μg), and high accuracy (>90%), which indicates the potential of this method for the rapid quantitative species detection of metals in environmental particulate matter samples.

Zero-Waste Approach for Heavy Metals' Removal from Water with an Enhanced Multi-Stage Hybrid Treatment System

The aim of the work was to develop a zero-waste technological solution for hybrid removal of heavy metals from river sediments. The proposed technological process consists of sample preparation, sediment washing (a physicochemical process for sediment purification), and purification of the wastewater produced as a by-product. A suitable solvent for heavy metal washing and the effectiveness of heavy metal removal were determined by testing EDTA and citric acid. The process for removing heavy metals from the samples worked best with citric acid when the 2% sample suspension was washed over a 5-h period. The method was chosen of the adsorption of heavy metals from the exhausting washing solution on natural clay. Analyses were performed of the three main heavy metals, Cu(II), Cr(VI), and Ni(II), in the washing solution. Based on the laboratory experiments, a technological plan was prepared for the purification of 100,000 tons of material per year.

Effect of hydraulic binders' addition on trace metals stabilization in the S/S process of dredged sediments

The Solidification/Stabilization method for dredged sediments remediation can be very effective for the immobilization of trace metal (TM) pollutants. The ordinary Portland cement (OPC) is largely used in this process. Nevertheless, the mechanical performance of treated sediments can be considerably improved at long term using ground granulated blast furnace slag (GGBS) as was shown in (Gutsalenko et al., 2018). Therefore, it is worth investigating whether this new binder is also relevant in terms of stabilization and mechanisms involved in this process. To meet this objective, leaching test, total attack, sequential extraction (SE) and X-ray Adsorption Near-Edge Structure (XANES) experiments measurements were performed. The results of the leaching tests conducted as part of the study are promising for the use of GGBS in the treatment of the real case project Dublin sediment and it outperforms the OPC-based treatment.. The sequential extraction method was applied to evaluate the potential risks of toxic elements according to their repartition in the Dublin sediment matrix and predicts the release of metals under different environmental conditions. It shows a lower perturbation rate of pollutants with the GGBS-based binder. Finally, XANES experiments demonstrate changes in the chemical environment of Zn and Cu after the treatment of the sediment with OPC compared to the GGBS rich binder. Consequently, this study finds that it is more pertinent to use the GGBS-based binder in terms of trace metal stabilization.

Dredged sediments as a plant-growing substrate: Estimation of health risk index

Dredging of sediments is conducted worldwide to maintain harbours and water bodies. As a result, large amounts of materials generated require proper management and could have useful applications in a circular economy context. The current use of peat as organic material in cultivating plants requires urgent replacement by more sustainable alternatives. In this context, using nutrient-rich sediments generated by dredging could be an attractive option. However, due to contaminants in dredged sediments, more investigations are required. The present study investigated the potential to employ dredged material as a plant-growing substrate to cultivate lettuce (Lactuca sativa). The study employed compost and dredged sediments from Malmfjärden Bay, Sweden, with low and high nutritional content (LN and HN, respectively), with and without polymer (PO) used for dewatering. The tests were carried out under controlled conditions in a greenhouse, and the studied substrates were (% vol): (1) 100 % sediment (100SHN); (2) 50 % sediment +50 % compost (50SLN-50C); (3) 70 % sediment +30 % compost (70SLN-30C); (4) 50 % polymer sediment +50 % compost (50SPO-50C); and (5) 100 % compost (100C). Fertilisers were added to 50SLN-50C and 70SLN-30C during the experiment. Lettuces with the highest weight were harvested from substrates 100C, 50SPO-50C and 50SLN-50C. However, the lettuces only reached a weight of 18.57 ± 4.67 g. The results showed that a main limitation of the growth was probably a lack of aeration of the sediments during sampling and development of the experiment. The low aeration possibly caused a lack of available forms of N in the substrates, hindering the growth. Lettuces harvested from substrates containing sediments presented Cd concentrations slightly overpassing the Swedish thresholds, and the health risk index was marginally exceeding 1. Hence, sediments need to be pre-treated before using them to cultivate edible crops, or they could be employed to cultivate ornamental or bioenergy plants.

Thinking for the future: Phytoextraction of cadmium using primed plants for sustainable soil clean-up

Cadmium (Cd) soil contamination is a global problem for food security due to its ubiquity, toxicity at low levels, persistence, and bioaccumulation in living organisms. Humans' intake of heavy metals is usually due to direct contact with contaminated soil, through the food chain (Cd accumulation in crops and edible plants) or through drinking water in cases of coupled groundwater-surface water systems. Phytoextraction is one of the eco-friendly, sustainable solutions that can be used as a method for soil clean-up with the possibility of re-use of extracted metals through phytomining. Phytoextraction is often limited by the tolerance level of hyperaccumulating plants and the restriction of their growth. Mechanisms of hyperaccumulation of heavy metals in tolerant species have been studied, but there are almost no data on mechanisms of further improvement of the accumulation capacity of such plants. Priming can influence plant stress tolerance by the initiation of mild stress cues resulting in acclimation of the plant. The potential of plant priming in abiotic stress tolerance has been extensively investigated using different types of molecules that are supplemented exogenously to plant organs (roots, leaves, etc.), resulting in enhanced tolerance of abiotic stress. This review focuses on mechanisms of enhancement of plant stress tolerance in hyperaccumulating plants for their exploitation in phytoextraction processes.

Partitioning and Availability of Metals from Water Suspended Sediments: Potential Pollution Risk Assessment

The water management initiatives in freshwater systems focus on water availability to preserve this resource for human uses and the health of aquatic ecosystems. This work presents an assessment of the potential pollution risk caused by the metal availability in suspended sediments. The objective of this study was to determine the partitioning, association, and geochemical fractionation of metals in suspended sediments from a surface water body. Additionally, the environmental assessment for this reservoir was estimated using geoaccumulation, enrichment, and pollution indices of metals and the related potential risk by their elemental availability (RAC). Chemical, mineralogical, and morphological characterizations were obtained by inductively coupled plasma spectrometry, alpha spectroscopy, X-ray crystallography, and scanning electron microscopy. Clay, quartz, montmorillonite, and calcite were the main minerals of suspended sediments. Chemical fractionation was the parameter affecting the concentrations of metals in suspended sediments. The sediment composition is of natural origin; however, these finer particles can promote the scavenging of toxic metals. It contributes to obtaining moderate to high levels for enrichment/contamination indices. Although Ca, Mg, Sr, and U were the most accessible metals for aquatic biota, Pb and Mn in the exchangeable phase of suspended sediments are the potentially toxic elements in this aquatic ecosystem.

An overview and assessment of the existing technological options for management and resource recovery from beach wrack and dredged sediments: An environmental and economic perspective

The present work discusses the problems and management options of beach wrack and dredged sediments. Beach wrack and dredged sediments near the shores have affected the coastal ecosystem, badly. The piles of beach wrack residues might be a significant emitter of greenhouse gases (GHGs) and dredged sediment is a substantial source of heavy metals and other pollutants. The recovery of valuable resources such as metals and nutrients from these so-called "wastes" is a sustainable strategy to enhance the resilience of the coastal ecosystem and management. The beach wrack meadows can be a potential source for green energy production. Even the demand for biodegradable polymers can be supplied by utilizing the waste beach wracks. The residues of beach wrack species like Posidonia oceanica, Zostera marina, Ulva spc. and Enhalus acorodies can be very beneficial species in terms of economic growth. Red algae have been the most favored and efficient candidate for methane yield. In case of dredged sediment, dewatering of sediment is an essential step for successful resource extraction. Although, extraction methods are almost similar to that applied for soil treatment, which includes pretreatment, physical partitioning, washing, thermal treatment, biological extraction, and immobilization. The fractionation study can be a beneficial tool for determining the metal species present in the sediment. Immobilization techniques are successful but continuous monitoring is required. The vitrification technique is highly effective but very expensive. Thermal treatment is useful for volatile metals such as mercury (Hg), but costs are high. Biological extractions are comparatively cheap but time-consuming. Henceforth, very few extraction methods are available for sediment and required further advancement in this field.

Chemical Fractionation, Environmental, and Human Health Risk Assessment of Potentially Toxic Elements in Soil of Industrialised Urban Areas in Serbia

The primary focus of this research was the chemical fractionation of potentially toxic elements (PTEs) and their presence in several industrialised cities in Serbia. Furthermore, their origin, contamination levels, and environmental and human health risks were assessed. The results indicated that the examined soils were characterised by slightly higher Cu, Ni, Pb, and Zn levels than those set by European and national regulations. These elevated Cu, Pb, and Zn concentrations were caused by intensive traffic and proximity to industry, whereas the higher Ni levels were a result of the specific geological substrate of the soil in the study area. The environmental risk was found to be low and there was no enrichment/contamination of the soil with these elements, except in the case of Pb, for which moderate to significant enrichment was found. Lead also poses a potential non-carcinogenic risk to children through ingestion and requires special attention due to the fact that a significant proportion of this element was present in the tested soil samples in a potentially available form. Analysis of the health risks showed that children are more at risk than adults from contaminants and that ingestion is the riskiest exposure route. The carcinogenic risk was within the acceptable limits.

New normal baseline data during nationwide lock down due to Covid 19 pandemic in the world's largest ship recycling yard at Alang, India

A detailed study to generate the new normal baseline data has been carried out during nationwide lockdown (May 12 to May 16, 2020) covering sampling for ambient air, coastal water, coastal sediments, fish and bioaccumulation of heavy metals, in an around Alang, the world's biggest ship recycling yard. The lockdown data were compared with 2018 and 2019 observed data. PM10 values during lockdown were reduced by 3.75 to 4.5 times as compared with previous 2 years. Similarly, four-fold reduction of PM2.5 and SPM values was observed during lockdown. The gaseous pollutants like NO2 and O3 are within safe limit. Overall air quality index (AQI) improved significantly during lockdown. Similarly, there was drastic reduction in the majority of the nutrient parameters in the coastal water. Different heavy metal concentration in the coastal sediments samples also showed strong reduction during lockdown sampling in comparison with other two sampling. This proves that the coastal environment has its efficient self-cleaning potentials if there is considerable reduction in the anthropogenic as well as industrial activities. Diversity of phytoplankton and zooplankton also increased. The results were validated using statistical techniques like analysis of variance and least significance difference (LSD).