Contaminated Surface Sediments Research Articles

Evaluation of Metal Contamination and Ecological Risk in Surface Sediments within an Industrialized Catchment

Evaluation of Metal Contamination and Ecological Risk in Surface Sediments within an Industrialized Catchment

Contrasting platinum trajectories in three major French rivers using dated sediment cores (1910–2021): From geochemical baseline to emerging source signals

Platinum (Pt) is a Technology Critical Element (TCE) which, since the 1990s, has been mainly used in the industry in catalytic converters for automobile emission control. Previous studies have shown Pt contamination of road-side sediments and surface sediments in urban rivers and lakes but few of them have addressed temporal variations. The present work presents historical Pt concentration trends in 137Cs-dated sediment cores from floodplains or secondary channels at the outlets of three major French watersheds (Loire, Rhone, and Seine Rivers) covering the past ∼110 years, i.e., from the 1910s to 2021. Platinum baseline levels in the sediment were estimated for the Loire River (0.76 ± 0.22 μg kg−1 for the period ∼1910-∼1955) and the Rhone River (1.64 ± 0.41 μg kg−1), and historical Pt variations seem to reflect variations in hydrodynamics and grain size composition. Since the early 2000s, Pt concentrations in the Loire and the Rhone River sediments tend to increase (>2.5 μg kg−1) and were attributed to the use of car catalytic converters, an emerging technology since the 1990s using >50 % of European Pt demand. High and variable historical Pt concentrations (up to 14.6 μg kg−1) in the Seine River sediments may reflect legacy Pt sources due to former anthropogenic activities in this watershed, such as the use of Pt-based catalysts for petroleum refinery since the end of the 1940s, coal handling and precious metals refining, probably concealing the likely presence of an emerging traffic-related Pt signal. This first comparison of historical Pt concentration trends in sediments from contrasting watersheds allows to distinguish signals originating from different natural and anthropogenic sources (background level, historical sources, road traffic).

Analysis of Heavy Metals and Petroleum Based Contaminants in Surface Water and Sediment near two Illegal Refining Sites in Niger Delta, Nigeria

The pollution of the environment from heavy metals and petroleum based contaminants in surface water and sediments resulting from illegal refining activities were looked at. The study was aimed at assessing the levels of heavy metals (Pb, Zn, Cu, Co, Cr, As, Cd and Ni), Benzene, Toluene, Ethyl-Benzene, and Xylene (BETX), Polycyclic Aromatic Hydrocarbons (PAHs) and Total Hydrocarbon Content (THC) in surface water and sediments. Samples were collected from two deactivated sites of illegal refineries in Oshika and Egbalor communities of Rivers State, Nigeria. The samples were analyzed for the contaminants which were compared with the World Health Organization (WHO) standard. The findings indicate that the surface water and sediments were highly polluted and may pose a health hazard to the community members that may use it for drinking.

Identification of toxic metal contamination in surface sediments of the Xiaoqing River under a long-term perspective (1996–2020): Risks, sources and driving factors

The contamination of sediments by toxic metals poses a significant threat to both river ecosystems and human health. In this study, the geo-accumulation index (Igeo), biotoxicity evaluation method, and potential ecological risk index (RI) were employed to analyze the contamination level, biotoxicity risk, and potential ecological risk of toxic metals in surface sediments of the Xiaoqing River. To identify toxic metal sources, Spearman correlation and principal component analysis with multiple linear regression analysis (PCA−MLR) were employed. Additionally, redundancy analysis (RDA) was utilized to investigate potential driving factors affecting toxic metal accumulation in sediments. The results revealed that the levels of the five investigated metals (Cr, Pb, As, Hg, and Cd) showed constant fluctuations during the period 1996–2020. The midstream was found to be more polluted than the upstream and downstream. In the research area, Hg was identified as the primary contaminant with high levels of contamination, posing a biotoxicity risk and potential ecological risk. Pollution sources were identified for two periods: A (1996–2010) and B (2011–2020), with industrial, agricultural, traffic, and natural sources being the main contributors. During period A, industrial sources accounted for the highest proportion (40.8%), followed by agricultural sources (36.6%), and geological natural sources (22.6%). During period B, agricultural sources accounted for the highest proportion (42%), followed by industrial and traffic sources (32.4%), and geological natural sources (25.6%). The distribution of toxic metals in the basin was significantly influenced by water pH, sediment organic matter, population density, and per capita GDP. The study results provide fundamental data for preventing pollution and managing water resources contaminated with toxic metals in the sediments of the Xiaoqing River in Jinan. Additionally, it serves as a reference for analyzing related ecological and environmental issues in the basin.

Occurrence of halogenated organic contaminants in surface sediments of the Yangtze River estuary and its adjacent marine area

Halogenated organic contaminants, such as chlorinated and brominated polycyclic aromatic hydrocarbons (Cl/Br-PAHs), are some of the most important emerging environmental pollutants. However, empirical data on Cl/Br-PAHs in estuarine and marine ecosystems are limited, rendering assessments of Cl/Br-PAH contamination in estuarine and offshore environments uncertain. Here the occurrence, sources, and ecological risks of 7 Cl-PAHs and 18 Br-PAHs were determined in surface sediments of the Yangtze River Estuary (YRE), a highly urbanized and industrialized area, and its adjacent marine area. The concentrations of Cl-PAHs ranged from 4.50 to 18.38 ng g−1 (average 7.19 ng g−1), while those of Br-PAHs ranged from 4.80 to 61.18 ng g−1 (average 14.11 ng g−1). The dominant Cl-PAH and Br-PAH in surface sediment were 9-chlorofluorene (17.79%) and 9-bromofluorene (58.49%), respectively. The distributions and compositions of Cl/Br-PAHs in the surface sediments varied considerably due to complex hydrodynamic and depositional conditions in the YRE and its adjacent marine area, as well as differences in physicochemical properties of different Cl/Br-PAHs. Positive matrix factorization revealed that the primary sources of Cl/Br-PAHs in the study area were e-waste dismantling (33.6%), waste incineration (23.2%), and metal smelting (11.0%). According to the risk quotient, the Cl/Br-PAHs in sediments posed no toxic risk to aquatic organisms.

Spatial Distribution, Risk Index, and Correlation of Heavy Metals in the Chuhe River (Yangtze Tributary): Preliminary Research Analysis of Surface Water and Sediment Contamination

This comprehensive study aimed to evaluate the water quality and sediment contamination in the Chuhe River in Nanjing. The spatial assessment of 10 samples collected in September highlighted that, in surface water, Copper (Cu) > Nickel (Ni) > Zinc (Zn) > Chromium (Cr) > Lead (Pb) > Arsenic (As) > Cadmium (Cd) > Mercury (Hg), whereas in sediments, Zn > Cr > Cu > Pb > Ni > As > Cd > Hg. The coefficient of variation (CV) for Ni and Zn in surface water was >15, whereas As, Cu, Pb, and Ni had a CV that was higher than 15 in sediments, indicating variability in contamination sources. The Pollution Load Index values ranged between 2.16 and 3.05, reflecting varying contamination levels across samples. The Geoaccumulation Index data also showed moderate-to-considerable contamination, especially for elements such as Cd and Cu. Correlation analyses in water and sediments unearthed significant relationships, with notable links between Cu and Pb in the water and strong correlations between As and Cu and between Cr and Ni in sediments. In sediments, Total Nitrogen and Phosphorus were significantly correlated with As, Cu, Pb, and Ni. The Potential Ecological Response Index for sediments indicated that they are at medium to high risk (307.47 ± 33.17) and could be potentially detrimental to aquatic life in the tributary. The tributary, influenced by agricultural runoff, residential areas, and other anthropogenic activities, showed that despite Nemerow pollution index values for water samples being below 1, sediment analysis indicated areas of concern. Principal Component Analysis (PCA) was conducted to identify the potential sources of heavy metal contamination. In surface water, shared negative loadings on PC 1 (60.11%) indicated a unified influence, likely from agricultural runoff, while PC 2 (14.26%) revealed additional complexities. Sediments exhibited a unique signature on PC 1 (67.05%), associated with cumulative agricultural impacts, with PC 2 (18.08%) providing insights into nuanced factors, such as sediment composition and dynamic interactions. These findings offer a complete insight into the Chuhe River tributary’s condition, underlining the urgency for ongoing monitoring and potential remediation measures.

Assessment of Heavy Metals Contamination and Potential Ecological Risk in Surface Sediments of the El Bey Wadi, Tunisia

ABSTRACT Sebkhat Soliman included in the Ramsar Convention is a wetland of international importance. This area is of great ecological interest considering the quality and the richness of the flora and the diversity of the avifauna. This site receives a large amount of water through the EL Bey River. In order to assess the levels of contamination, concentrations of six heavy metals, including Cr, Cu, Pb, Ni, Mn, and Zn, were examined in 25 surface sediment samples from El Bey Wadi. These concentrations, which were expressed in mg/kg of dry weight, showed that Pb ranged from 5.52 to 41.66, Zn from 26.94 to 1471.89, Cu from 91.97 to 260.05, Ni from 9.35 to 140.45, Cr from 25. It’s important to note that the highest metal concentrations have been found in site 5 which is frequently exposed to local industrial pollutant sources and in sites that are frequently inundated by river water that is carrying away industrial waste from the cities of Grombalia and Bou-Argoub. The mean EF values for Cu, Mn and Ni were between 3 and 5 in the sediments of the El Bey River, suggesting moderate enrichment, while the mean EF values for Pb, Zn and Cr indicating respectively moderate to severe enrichment and very severe enrichment. CF values for Cr, Cu and Zn were > 6 in sediments taken from the fifth site, which denotes a very high contamination by these metals. At site 5, PLI value (4.09), reflecting that its sediment is heavily polluted. Hierarchical cluster analysis-based complementary statistical methods have demonstrated that Mn is lithogenic and other analyzed metals are anthropogenic.

Contamination and risk assessment of trace metals and As in surface sediments from abandoned gold mining sites of Bekao, Adamawa-Cameroon

This paper assesses the spatial distribution and the trace metal and As contamination in surface sediments along the Lom River in the abandoned gold mining sites of Bekao (Adamawa Cameroon). A total of thirty one (31) surface sediment samples is collected and analyzed to determine the concentrations of Cr, Mn, Fe, Ni, Cu, Zn, Sn, Pb and As. The results obtained are compared with the Average Shale Values (ASVs) and Sediment Quality Guidelines (SQGs) as the threshold effect concentration (TEC), the probable effect concentration (PEC), the Effect Range Low (ERL) and the Effect Range Median (ERM). To assess the trace metal and As pollution level in sediments, nine environmental pollution indices, namely geoaccumulation index (Igeo), enrichment factor EF, contamination factor (CF), contamination degree CD, modified degree of contamination (mCD), Nemerow index (NI), contamination severity index (CSI), probability of toxicity (MERMQ) and potential ecological risk RI are used. In addition, Pearson’s correlation matrix and General Linear Model (GLM) are used to determine the pollution indices which adjust better with the trace metals and As concentrations. The results reveal that the sequence of trace metals and As mean concentrations was Fe ¿ Mn ¿ Cu ¿ Ni ¿ Sn ¿ Cr ¿ Zn ¿ Pb ¿ As, and the mean concentrations of Zn, Ni, Sn, and Cu exceed the ASVs. Based on the sediments quality guidelines (SQGs), sediments are polluted in Ni and Cu. According to the Igeo, EF and CF, Sn and Cu reveal a high level of contamination with significant enrichment and Ni a moderate level of contamination and enrichment. The results of the calculation of CD, mCD, and NI indices suggest significant contamination, high contamination and high pollution of trace metals and As in sediments, respectively. Globally, CSI demonstrates an ultra-high severity contamination, MERMQ a high-medium priority with a toxic probability of 49% and RI show a moderate ecological risk. Pearson’s correlation matrix and GLM suggest that CSI and MERMQ are the indices which adjust better with trace metals and As in sediments.

Evaluation of metal contamination in surface sediments and macroalgae in mangrove and port complex ecosystems on the Brazilian equatorial margin.

This study evaluated metal contamination in surface sediments and macroalgae of mangroves and port complexes on the Brazilian equatorial margin. Samples were collected between August 2020 and February 2021 at seven points in a mangrove swamp under the influence of port activity and at two points without port activity. Metal concentrations in the macroalgae and sediments were determined using inductively coupled plasma‒optical emission spectrometry. All macroalgal species bioaccumulated metals, as demonstrated by their bioaccumulation factors. The geochemical contamination indices indicated that the estuarine complex was influenced by port activity as moderately contaminated by Pb, Cr, Mn, and Fe and considerably contaminated by Zn and Cu. The enrichment factor confirmed significant mineral enrichment of Zn and Cu in this environment. The concentrations of the metals in the sediment followed the order Fe > Mn > Cr > Zn > Cu > Pb at most sampling points. Cladophoropsis membranacea recorded the highest bioaccumulation values for Pb (0.44), Rhizoclonium africanum for Zn (1.08), Cr (0.55), and Fe (0.30), and Bostrychia radicans for Mn (2.22). The bioaccumulation pattern of metals in the most abundant macroalgal species followed the order Bostrychia radicans (Mn > Zn > Cu > Cr > Pb > Fe) and Rhizoclonium africanum (Zn > Mn > Cr > Cu > Pb > Fe).

Contamination and health risk assessment of surface sediments along Ras Abu Ali Island, Saudi Arabia

The coastline of the Arabian Gulf attracts people throughout the year for tourism and fishing activities. The present work aimed to document the contamination and human health assessment of heavy metals (HMs) in 34 surface sediment samples collected along Ras Abu Ali coastline, Saudi Arabia. Enrichment factor (EF), contamination factor (CF), and sediment quality guideline (SQG) were calculated to estimate the sediment contamination, while the hazard index (HI), cancer risk (CR), and total lifetime cancer risk (LCR) were determined for human health assessment via ingestion and dermal contact pathways on both adults and children. The averages of the HMs (μg/g dry weight) were in the following order: Fe (4808) > Ni (13.00) > Zn (6.89) > Cr (7.86) > V (6.67) > Cu (4.14) > Pb (3.50) > As (2.47) > Co (1.43). Results of EF indicated minor enrichment with Ni, Pb, and As, and no enrichment with the remaining HMs. Based on CF, the coastal sediments of Ras Abu Ali showed low contamination with HMs. Reported values of As, Cr, Cu, Pb, and Zn were lower than the ISQG-Low values, however, 4 samples of Ni reported values between the ISQG-Low and ISQG-High values, indicating some anthropogenic effects with Ni. HI values were higher among children in comparison to adults, suggesting that children were at higher risk of non-carcinogenic exposure than adults. LCR values indicated that no significant health hazards for people inhabited the study area from the carcinogenic Pb, Cr, and As.

Heavy metal contamination in surface sediments of the Upper Bhima Basin, Maharashtra, India

Heavy metal contamination in surface sediments of the Upper Bhima Basin, Maharashtra, India

Multi-index assessment of heavy metal contamination in surface sediments of the Pearl River estuary intertidal zone

Surface sediments from 21 stations within the Pearl River estuary (PRE) intertidal zone were sampled for heavy metal contamination analysis. Average heavy metal concentrations (mg/kg) in the PRE intertidal zone were 118.5 (Cr), 860.4 (Mn), 19.5 (Co), 72.5 (Ni), 128.1 (Cu), 198.5 (Zn), and 73.0 (Pb), with the concentrations of Mn, Co, Ni, Cu, and Zn being significantly higher than their corresponding background values. The enrichment factor (EF) and geo-accumulation index (Igeo) reveal the same contamination status, with Pb, Ni, Co, Mn, and Cu showing slight to moderate contamination. Overall, the combined heavy metal concentration in the PRE intertidal surface sediments had a 24.7 % probability of toxic effects on aquatic biota based on the joint probabilistic risk (JPR) approach. Principal component analysis (PCA) coupled with the correlation analysis (CA) revealed that the heavy metal contamination in the PRE intertidal zone might originate from natural and anthropogenic sources.

Evaluation of heavy metals contamination and pollution indices levels in surface sediments of the Bizerte coastal line, Tunisia

Heavy metal concentrations in surface sediments collected from 17 stations samples in Bizerte coastal line were determined in order to evaluate the contamination status in the region. Heavy metal concentrations (mg/kg) of Bizerte coast line followed the decreasing trend of Fe>Pb>Zn>Mn>Cu>Cr>Ni>Co>Cd. The pollution degree of the surface sediment collected from 17 samples station in Bizerte coast line by heavy metals was evaluated on the basis of pollution indices (EF, Igeo, CF, PLI and CD). Results of Igeo, EF, CF, PLI and DC demonstrated that pollution levels of Pb and Cd were moderate, which should require more attentiveness as main pollution factors. However, no pollution was found for Zn, Cu, Ni, Cr, Co and Mn. Hierarchical cluster analysis was used to identify the influence of anthropogenic activities on the surface sediment.

Non-corresponding contaminants in marine surface sediments as a factor of ARGs spread in the Sea of Azov.

The present study aims to analyze the level and total toxicity of the most common pollutants in surface sediments and assess their impact on the occurrence of antibiotic resistance genes (ARGs) in the Sea of Azov. Biotesting using the whole-cell bacterial lux-biosensors showed high integral toxicity of surface sediments and the presence of genotoxicants and substances that cause oxidative stress and protein damage. Using cluster analysis, it was shown that the distribution of pollutants in the Sea of Azov depends on the type of surface sediments. The relative abundance and distribution of 14 ARGs in surface sediments were shown. Principle component analyses results suggest that non-corresponding contaminants do not exert direct influence on the ARGs abundance in the surface sediments of the Sea of Azov. Thus, the need to investigate the significance of non-corresponding pollutants in the selection and distribution of ARGs in the aquatic environment remains a pressing problem.

Polycyclic aromatic hydrocarbons in terrestrial and aquatic environments following wildfire: a review

Wildfires are a natural landscape disturbance in many climates and forest types, but the cumulative impact of human-caused climate change, historical fire management and suppression, and changing species diversity in forests has led to an increase in the size and (or) severity of wildfires in certain regions across the globe. There are a significant number of research studies on the effects of wildfire on human health, forest ecology, hydrology, and the physical, chemical, and biological properties of soils. However, research on the impact of wildfire on watersheds including toxicity in aquatic organisms, water chemistry, and fluvial sediment quality is less extensive, focusing primarily on water quality indicators such as nutrients and sediment flux. Recent research has shown that wildfires contribute to the environment significant amounts of polycyclic aromatic hydrocarbons (PAHs), which are compounds produced during the incomplete combustion of organic material, and are known to be toxic and mutagenic compounds. The primary objective of this paper is to review the recent literature that pertains to the contamination of surface waters and sediments and source apportionment of wildfire-derived PAHs to determine where research gaps remain. Additional objectives are to assess the use of molecular ratios to apportion PAH sources and, finally, to create a roadmap for future studies in designing and conducting research that seeks to determine sources of wildfire-derived PAHs in water and sediment.

Distribution of trace metals and radionuclides contamination in two sections of sediment cores from the Nyong estuary, Cameroon, southern Atlantic coast

This study investigated the spatial distribution of trace metals (Fe, Mn, Ni, Cr, Co, Sc and V) and radionuclides (Th and U) contamination in surface and bottom sediments from the Nyong estuary, Cameroon southern Atlantic coast, to provide informations on the pollution status of these sediments and the possible sources of pollutants. Salinity were measured in situ in interstitial water and dried sediment were analyzed for grain size parameters and geochemical composition. Salinity decreases from downstream to upstream, with 19.88 PSU as the highest value and sand is the main constituent (79.25 %). The concentrations of these elements varied significantly among depth (surface and bottom section), with a preferential contribution from the surface. In this surface section, several elements (Fe, Mn, Co, Sc and V) contributed about 80 % to the distribution of each of them in the estuary. Enrichment Factor (EF), Geo-accumulation Index (Igeo) and Contamination Factor (CF) of Nyong estuary surface sediments revealed a moderate pollution, while bottom sediment were unpolluted to moderate polluted. The pollution load index (PLI) show that surface sediments (3.86) and bottom sediments (1.19) are polluted. Pearson correlation and component principal analysis confirmed the natural origin of selected elements (Fe, Mn, Ni, Cr, Co, Sc, V, Th and U) through the weathering and the erosion of sources rocks. However, Pearson correlation analysis and the high Ni (3.91) and Cr (3.54) EF values in bottom sediments suggest a reception of other contaminants from the same emission sources or similar sources, may be agronomic inputs.

Assessment of Heavy Metal Pollution Associated with Surface Sediment Contamination in the Bhima River, Karnataka, India

The quality of the sediment is negatively impacted by the concentration of potentially toxic elements (PTEs). The Bhima River, which supports a sizable population and is a significant location for agricultural production, is susceptible to PTEs pollution. In this research, we examined concentration of potentially toxic elements (PTEs) with Zinc(Zn), Copper(Cu), Iron(Fe), Manganese(Mn), Cadmium(Cd), and Lead(Pb) in sediment samples collected from eight different chosen sites near temples where rituals are performed, close to farming activities, bridge structures, and sewage sludge dumping areas during the period of October 2020 to September 2021. PTEs were detected using Atomic Absorption Spectrophotometry (AAS). The obtained results have been out into succeeding arrangement Fe>Mn>Cu>Zn>Pb>Cd. To evaluate the pollution status, the geo accumulation index (Igeo), enrichment ratio (ER), and pollution load index (PLI) were used for measuring sediment contamination. ER values for Cu, Mn, Pb, and Cd were greater than 5, indicating a significant level of contamination by these metals. The ER demonstrated that high Cd was present at almost all sampling sites. Cu had the greatest Igeo values at the S3 site, while Cd had the highest Igeo values in all the sites. According to the PLI, site S4 was more polluted. This evidence points to a lithogenic effect on the river's metal contamination. Cu, Mn, and Cd concentrations are expected to have a negative impact on benthic organisms. Furthermore, principal component analysis and cluster analysis discovered as agricultural run-off, bridge building, lead battery use, and sewage sludge were the leading causes of sediment quality degradation in the research area. It is vital to monitor the PTEs concentration in this sediment regularly because of its long-term effect.

Heavy metals in lake surface sediments in protected areas in Poland: concentration, pollution, ecological risk, sources and spatial distribution

This paper presents the state and spatial distribution of surface sediment contamination of 77 lakes in Poland by Cr, Ni, Cd, Pb, Zn, and Cu. The analyzed lakes were located within a network of nature protection areas in the territory of the European Union (EU). Spatial distribution of the heavy metals (HMs), factors favoring the delivery/accumulation of HMs in surface sediments, and pollution sources were analyzed. The results indicate the contamination of lake sediments by HMs, but the potentially toxic effects of HMs are only found in single lakes. The spatial distribution of Cr indicates predominant impacts of point sources, while for Pb, Ni, and Zn, the impact of non-point sources. The analysis showed the presence of areas with very high values of particular HMs (hot spots) in the western part of Poland, while a group of 5 lakes with very low values of Ni, Pb, and Zn (cold spots) was identified in the central part of Poland. Principal component analysis showed that presence of wetlands is a factor limiting HMs inflow to lakes. Also, lower HMs concentrations were found in lake surface sediments located in catchments with a higher proportion of national parks and nature reserves. Higher HMs concentrations were found in lakes with a high proportion of Special Protection Areas designated under the EU Birds Directive. The positive matrix factorization analysis identified four sources of HMs. High values of HMs concentrations indicate their delivery from industrial, urbanized, and agricultural areas. However, these impacts overlap, which disturbs the characteristic quantitative profiles assigned to these pollution sources.

Pollution levels and risk assessment of thallium in Chinese surface water and sediments

Thallium (Tl) is one of the most toxic metals and can cause chronic and acute damage to humans. Due to occurrences of incidents involving Tl pollution in China, its potential environmental impacts are receiving increased attention. However, there is still limited information on Tl concentrations in the environment and their risks to human health and wildlife. This paper provides an overview of the contamination of surface water and sediments by Tl across China and assesses the potential risks using several methods. The acute and chronic aquatic life criteria for Tl were determined to be 13.25 and 1.65 μg/L, respectively. The acute and chronic risk quotients (RQs) of Tl in surface water near mining areas were 0.01–41.51 and 0.20–666.67, respectively, indicating medium to high ecological risks to aquatic organisms. Tl in sediments of Pearl and Gaofeng rivers pose a high risk based on the higher geo-accumulation index (Igeo) and potential ecological risk index (EI) values. Exposure parameters for the Chinese population were used to derive health criteria and assess non-carcinogenic risk posed by Tl in centralized drinking water sources. Tl criteria for protection of human health were calculated to be 0.18 μg/L for water+organisms and 0.30 μg/L for organisms only. The non-carcinogenic risk posed by Tl was acceptable. The human health criteria of Tl for children were the lowest among all age groups. The risks posed by Tl to health of children are greater than those for adults. Therefore, emphasis should be placed on protecting children from exposure to Tl. For the Chinese population, the drinking water guidance value to ensure protection of human health was determined to be 0.44 μg/L. The availability of multiple Tl guidance values for designated water uses will improve the environmental regulation and surveillance of Tl pollution in China and other countries.

Assessment of heavy metal contamination in surface sediments off the Dongying coast, Bohai Sea

In this study, 214 surface sediment samples were collected from the offshore area of the Dongying coast and were analysed for heavy metals; particularly, their concentrations and pollution status were evaluated. The copper (Cu) and chromium (Cr) distributions were similar, their concentrations were the highest in the northeast areas and the Xiaoqing River estuary, where dominated by fine-grained sediments. Higher concentrations of lead (Pb), zinc (Zn), cadmium (Cd), and arsenic (As) were generally found in the offshore area of the study location, and the highest Cd concentration was observed in the Xiaoqing River estuary. The sediments were not polluted by Cu, Pb, Zn, and Cr; they were not polluted or moderately polluted by Cd and As. Results of the principal component analysis indicated that Cu, Pb, Zn, and Cr were derived from natural sources and Cd and As were derived from anthropogenic sources.