Semivolatile organic compounds, organochlorine pesticides and heavy metals in sediments and risk assessment in Huaihe River of China

The concentrations of semivolatile organic compounds, organochlorine pesticides and heavy metals in sediments from Jiangsu reach of Huaihe River, China, were presented. The organic compounds were extracted by acetone： n-hexane using a Soxhlet apparatus and concentrations were performed using HP6890 gas chromatography coupled by FID and ECD detector. The total contents of 8 heavy metals by inductively coupled plasma atomic emission spectrometry or cold-vapor/atomic absorption spectrometry were developed. 30 semivolatile organic compounds were detected, including substituted benzenes, phenols, phthalates and polycyclic aromatic hydrocarbons, from 0.01 to 3.01 mg/kg. 16 organochlorine pesticides were almost detected and from 0.010 to 2.339 μg/kg. Concentrations of major metals were 50 mg/kg or less, mean level of mercury was only 0.055 mg/kg. Compared to sediment quality guidelines （SQGs）, concentrations of some semivolatilc organic compounds were high enough to cause possible toxic effects to living resources. The organochlorine pesticides presented relatively low, lower than threshold effect concentrations （TECs）, harmful effects on sediment-dwelling organisms were not expected. Chromium posed probable toxic effects to the living resources, other heavy metals had no threat temporarily according to SQGs.

Application of Equilibrium Partitioning Approach to the Derivation of Sediment Quality Guidelines for Metals in Dianchi Lake

For the past 20 years, numerous studies have been carried out on the application of equilibrium partitioning approach （EqPA） for the derivation of sediment quality guidelines （SQGs）. However, for metals, few Equilibrium-partitioning- based numerical SQGs have been developed or are currently available because of the confounding factors mediating the bioavailability of metals. A study was conducted at Dianchi Lake, which is a heavily eutrophicated lake on the Yunnan- Guizhou Plateau, China with the focus on the measurement of partitioning coefficient （Kp） and SQGs derivation and normalization to acid volatile sulfide （AVS）, fine material, and organic carbon. Using new normalization methods, SQGs were formulated for seven metals including copper, zinc, lead, cadmium, chromium, mercury, and arsenic in Dianchi Lake. In Dianchi Lake sediments, the fine material contributed 25.4%-36.0% to the SQG values, with the largest contribution to the SQG value of mercury; AVS contributed 2.9%-75.0% to the SQG values, with the largest contribution to the SQG value of cadmium. This indicated that the fine material and the AVS were the most important controlling factors to the bioavailability of mercury and caximium, respectively. The contribution of total organic carbon （TOC） to the SQG values of copper and leaxi was 3.8% and 7.1%, respectively, indicating that at relatively lower concentrations, the contribution of TOC was not significant. In addition to normalization methods, appropriate procedures for the application of EqPA including sample collection, storage, and analysis are also essential to improve the reliability of SQGs. The normalized Dianchi Lake SQGs were higher than most of the empirically based SQGs developed in North America, but lower than Hong Kong interim SQGs except for cadmium and arsenic. The differences could be attributed to the approaches used for derivation of SQGs and the water quality criteria adopted and the differences in the physical and chemical characteristics of the sediments.

Developing sediment quality criteria for heavy metal pollution in the Le An River with equilibrium partitioning approach

Equilibrium partitioning(EqP) approach was selected to establish the sediment quality criteria(SQC) in the Le An River near Dexing Copper Mine. Both freshwater quality criteria (WQC) for some heavy metals regulated by USEPA and national quality standards of surface water recommended by CNEPA were used as protective levels of aquatic organisms in this study. Meanwhile, the partitioning coefficients were derived directly from measured data. Comparison between SQC in this region and concentrations of contaminants in situ clearly indicated the distribution characteristics of metal contamination along the river. And the results also illustrated that measures of some metals exceeded their SQC levels in different degree, especially Cu.

Heavy metal pollution assessment in marine sediments in the Northwest coast of Sabah,Malaysia

Heavy metal contents along the Northwest coast of Sabah were determined to interpret the pollution level in the marine sediment. The metal abundance is regulated by the physico-chemical properties such as the average sediment pH(7.82, 9.00 and 8.99), organic matter(0.62%, 1.60%, and 2.27%), moisture content(25.00%, 29.70%, and 15.00%) and sandy texture in Kota Belud, Kudat and Mantanani Island,respectively. The major elements show Ca>Fe>Mg>Al>Mn for all study sites, while the heavy metals show Ni>Cr>Zn>Cu>Co>Pb, Cr>Ni>Zn>Cu>Pb>Co and Zn>Pb>Cr>Ni, for Kota Belud, Kudat and Mantanani Island, respectively. The pollution degree of heavy metals was evaluated by using the Sediment Quality Assessment(SQA). The SQA parameters indicated none to moderate pollution in Kota Belud that shows Class 0, Class 1 and Class 2 pollution. The parameters also indicated none to low pollution in Kudat and Mantanani Island that show only Class 0 pollution. The enrichment factor(EF) suggested minor to moderately severe metal enrichment by anthropogenic sources in Kota Belud, whereas only minor enrichment in Kudat and Mantanani Island. The modified pollution degree(MCD<1.5) and pollution load index(0 PLI<1) indicating only low pollution level in the marine sediments for all study sites. The objectives of this study are:(1) to determine the physico-chemical parameters of sediments,(2) interpret the heavy metal contents and(3) evaluate the sediment quality.

Sediment quality criteria for heavy metal pollution in the Le An River with triad approach

In this study, integrative traid was used to sediment quality in the Le An River, which has been strongly contaminated by large amount of Cu, Pb, Zn,Cd, As and Cr discharging from mining activities. All available data collected from chemical analyses,toxic tests and field survey on benthic macroinvertebrates were transformed into ratio to reference(RTR) and relevant scales.The responses of receiving environment to mining impacts were illustrated by traid graphs. Traid results indicated that a sectional distribution pattern existed from upstream to downstream:(a) relative clean upstream;(b) serious contaminated middle stream;(c) gradual recovery downstream. This situation was closely related with local mining activities, which caused obvious degradation of sediment quality in some sections, therefore, remediation was required urgently.

Heavy Metals Concentration in Sediments of South Brittany Waters, France: An Ecological Risk Assessment Approach

Distribution patterns of selected heavy metals content in sediments from the Bay of Quiberon and Gulf of Morbihan were studied to understand the current heavy metals contamination due to urbanization and mariculture activities in the coastal area. Therefore, a survey was conducted and 196 sediments collected were characterized for heavy metals content using Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) after mix acid digestion process. The distribution maps of the concentrations of the heavy metals studied were produced as an isopleth map based on data interpolation by the ArcGIS software application. The association with the adverse effects on aquatic organisms was determined by the classification of the sediment according to the sediment quality guidelines. Therefore, two approaches were employed namely: direct comparison with Sediment Quality Guidelines (SQGs) by USEPA (United States Environmental Protection Agency) and comparison with other numerical SQGs, threshold effect level/probable effect level, and effect range low/effect range medium. In order to estimate the effect of multiple contaminations of heavy metals, the mean-ERM-quotient was calculated at each sampling point.

Water and Sediment Quality Assessment of a Multipurpose Reservoir in India

Malampuzha reservoir is a multipurpose reservoir in south India. Seven water samples and four sediment samples were studied for the physico-chemical and bacteriological nature of the Malampuzha reservoir water and sediments. Bacteriological analysis indicated the microbial contamination of the reservoir and the physico-chemical characteristics indicated that the water is non potable directly. Analysis of irrigational water quality by SAR, Kelly＇s ratio and SSP indicates that the reservoir water is suitable for irrigation. Heavy metal pollution of the sediments was evaluated based on Sediment Quality Guidelines （SQG）, Pollution Load Index （PLI） and degree of contamination （Cd） of soil in four stations. Principal Component Analysis （PCA） was done to find out the possible linear combination of the original variables of trace metals. Results of PCA showed that no collinearity existed among the studied metals. However, emphasis on the monitoring of Cu and Ni should be preferred because of its alarmingly higher contamination value.

Geochemistry of Potentially Toxic Elements in Soil and Sediments of a Tanzanian Small-Scale Gold Mining Area

Small-scale gold mining is linked to significant environmental pollution by potentially toxic elements (PTEs). However, research on the pollution caused by such mining activities remains insufficient especially in developing countries. In the present study, a systematic investigation assessed the pollution and level of ecological risk of PTEs in soil and stream sediments in an active small scale gold mining area of Isanga, in Nzega, Tanzania. Samples amounting to 16 soil and 20 sediment were gathered from the study area and analyzed for five PTEs concentrations (As, Cd, Cr, Hg and Pb) using the AAS method. The contamination level and ecological risk were assessed using several pollution indices. The results suggest that the assessed environmental systems of the Isanga mining area and its vicinities are lowly contaminated by PTEs and have a low potential to pose ecological risks. Hg and Cd with mean concentrations of 0.09 mg/kg and 0.26 mg/kg respectively were found to be the most enriched PTEs in soil, compared to their average continental crust concentrations (0.056 mg/kg and 0.102 mg/kg respectively). The levels of the evaluated PTEs in the study area are susceptible to increase over time if proactive steps are not taken to control mining and waste disposal activities.

Potential toxic risk of heavy metals from sediment of the Pearl River in South China

Based on the monitoring of five heavy metal elements in the surface sediments of the Pearl River in South China, potential toxicity of the heavy metals was assessed using consensus-based sediment quality guidelines （SQGs） method and geo-accumulation （Igeo） index method. The monitoring results showed the heavy metal concentrations were significantly and positively correlated with each other, demonstrating a common trend in variation of concentration in the surface sediments. The assessment using the consensus-based SQGs method showed the potential toxicity of Cu was the highest, and Cd was the lowest. The evaluation based on mean probable effect concentration （PEC） quotient showed the region was seriously polluted with high toxicity heavy metals. Correlation analysis revealed a significant and positive correlation between the mean PEC quotient and the average of Igeo with a correlation coefficient of 0.926 （n = 23, P 〈 0.01）. In conclusion, the consensus-based SQGs and mean PEC quotient are applicable to assess potential toxicity risks of heavy metals in freshwater sediments in the Pearl River.

Distribution and Ecological Risk Assessment of HCHs and DDTs in Surface Seawater and Sediment of the Mariculture Area of Jincheng Bay,China

The distribution of hexachloroeyclohexanes （HCHs） and dichlorodiphenyltrichloroethanes （DDTs） in the surface sea- water and sediment of Jincheng Bay mariculture area were investigated in the present study. The concentration of total HCHs and DDTs ranged from 2.98 to 14.87ngL-l and were〈0.032ngL-1, respectively, in surface seawater, and ranged from 5.52 to 9.43 and from 4.11 to 6.72 ng g-l, respectively, in surface sediment. It was deduced from the composition profile of HCH isomers and DDT congeners that HCH residues derived from a mixture of technical-grade HCH and lindane whereas the DDT residues derived from technical-grade DDT and dicofol. Moreover, both HCH and DDT residues may mainly originate from historical inputs. The hazard quotient of α-HCH, β-HCH, γ-HCH and δ-HCH to marine species was 0.030, 0.157, 3.008 and 0.008, respectively. It was estimated that the overall probability of adverse biological effect from HCHs was less than 5%, indicating that its risk to seawater column spe- cies was low. The threshold effect concentration exceeding frequency of γ-HCH, p,p＇-DDD, p,p＇-DDE and p,p＇-DDT in sediment ranged from 8.3% to 100%, and the relative concentration of the HCH and DDT mixture exceeded their probable effect level in sediment. These findings indicated that the risk to marine benthos was high and potentially detrimental to the safety of aquatic prod- ucts, e.g., sea cucumber and benthic shellfish.

Toxicities and risk assessment of heavy metals in sediments of Taihu Lake, China, based on sediment quality guidelines

The occurrence, toxicities, and ecological risks of five heavy metals（Pb, Cu, Cd, Zn and Ni） in the sediment of Taihu Lake were investigated in this study. To evaluate the toxicities caused by the heavy metals, the toxicities induced by organic contaminants and ammonia in the sediments were screened out with activated carbon and zeolite. The toxicities of heavy metals in sediments were tested with benthic invertebrates（tubificid and chironomid）.The correlations between toxicity of sediment and the sediment quality guidelines（SQGs）derived previously were evaluated. There were significant correlations（p 〈 0.0001） between the observed toxicities and the total risk quotients of the heavy metals based on SQGs,indicating that threshold effect level（TEL） and probable effect level（PEL） were reliable to predict the toxicities of heavy metals in the sediments of Taihu Lake. By contrast, the method based on acid volatile sulfides（AVS） and simultaneously extracted metals（SEM）,such as ∑SEM/AVS and ∑SEM-AVS, did not show correlations with the toxicities. Moreover,the predictive ability of SQGs was confirmed by a total predicting accuracy of 77%. Ecological risk assessment based on TELs and PELs showed that the contaminations of Pb, Cu, Cd and Zn in the sediments of Taihu Lake were at relatively low or medium levels. The risks caused by heavy metals in the sediments of northern bay of the lake, which received more wastewater discharge from upper stream, were higher than other area of the lake.

Source analysis and risk evaluation of heavy metal in the river sediment of polymetallic mining area:Taking the Tonglüshan skarn type Cu-Fe-Au deposit as an example,Hubei section of the Yangtze River Basin,China

In this paper,25 sampling points of overlying deposits in Tonglushan mining area,Daye City,Hubei Province,China were tested for heavy metal content to explore pollution characteristics,pollution sources and ecological risks of heavy metals in sediments.A geo-accumulation index method was used to evaluate the degree of heavy metal pollution in the sediment.The mean sediment quality guideline quotient was used for evaluating the ecological risk level of heavy metal in the sediment.And a method of correlation analysis,clustering analysis,and principal component analysis was used for preliminary analysis on the source of heavy metal in the sediment.It was indicated that there was extremely heavy metal pollution in the sediment,among which Cd was extremely polluted,Cu strongly contaminated,Zn,As,and Hg moderately contaminated,and Pb,Cr,and Ni were slightly contaminated.It was also indicated by the mean sediment quality guideline-quotient result that there was a high ecological risk of heavy metals in the sediment,and 64%of the sample sites had extremely high hidden biotoxic effects.For distribution,the contamination of branches was worse than that of the main channel of Daye Dagang,and the deposition of each heavy metal was mainly influenced by the distance from this sample site to the sewage draining exit of a tailings pond.The source analysis showed that the heavy metals in the sediment come from pollution discharging of mining and beneficiation companies,tailings ponds,smelting companies,and transport vehicles.In the study area,due to the influence of heavy metal discharging from these sources,the ecotoxicity of heavy metals in the sediment was extremely high,and Cd was the most toxic pollutant.The research figured out the key restoration area and elements for ecological restoration in the sediment of the Tonglüshan mining area,which could be referenced by monitoring and governance of heavy metal pollution in the sediment of the polymetallic mining area.

Assessment of Metals Concentration and Ecotoxicology of the Sediment Core of Rehri Creek, Karachi Coast, Pakistan

Trace metal concentrations were investigated in a recent sediment core collected from the Rehri Creek area of the Karachi coast, Sindh - Pakistan. The core was sliced horizontally at 2.5-cm intervals to determine grain size, sediment composition, pH, organic matter, and acid-leachable trace metals： cadmium, chromium, copper, lead, and zinc. The trace metals were analyzed by ICP. To separate anthropogenic from geogenic input, several approaches were made, including comparison with sediment quality guidelines--ecotoxicological sense of heavy metal contamination and classification by quantitative indexes. Grain-size analysis and sediment composition of core sample show a sandy nature with neutral pH. Elemental sequence （ES） of the trace metals is in the order of Zn （19.2-109.56 ppm） 〉 Si （66.46-101.71 ppm） 〉 Ba （12.05-26.86 ppm） 〉 As （8.18-17.36 ppm） 〉 Ni （4.2- 14.69 ppm） 〉 Cr （3.02-9.62 ppm） 〉 Pb （2.79-6.83 ppm） 〉 Cu （2.2-5.29 ppm） 〉 Co （0.9-2.05 ppm）. Thus it is likely that the area may face a serious threat of metal pollution with the present deposition rates unless stringent pollution control norms are adopted. The Sediment Geo-accumulation Index shows that there is no Cr, Cu, Ni, Pb, Zn, or Fe pollution; however, the former index and the Pollution Load Index indicate arsenic pollution in the sediments.

Production of Pacific White Shrimp Polycultured with Swimming Crab at Different Densities, and Nutrient Budget in the Enclosure System

This study was to evaluate the effect of stocking densities on the nitrogen and phosphorus budgets for a polyculture of the crab Portunus trituberculatus and the Pacific white shrimp Litopenaeus vannamei.The shrimps(initial weight,0.012 g)were cultured at a density of 45 shrimp m^(-2),and juvenile crabs(initial weight,0.024 g)were cultured at five densities of 0,3,6,9,and 12 crabs m^(-2).The treatments were grouped as C0S45,C3S45,C6S45,C9S45,and C12S45,respectively.Water quality parameters,growth of shrimp and crabs,and nitrogen and phosphorus budget were measured.The results indicated that the shrimp performances in polyculture treatments C3S45 and C6S45 were superior to those in the crab-free treatment(C0S45).The crab in treatments C3S45 and C6S45 exhibited a significantly higher final mean weight and carapace width/length than those in treatments C9S45 and C12S45.The final size and survival of crabs had a negative correlation with the increasing crab stocking density.The contents of total phos-phorus and total nitrogen and the comprehensive contamination index values were higher in the C9S45 and C12S45 treatments than in the other treatments.The conversion ratios of nitrogen for crab and shrimp growth in treatment C3S45 were significantly higher than those in the crab-free treatment.These findings indicate that polyculturing shrimp with crabs at suitable densities can improve productivity,profitability,nutrient utilization,and the environmental quality.From the 60-day treatments,the optimal culture densi-ties were 3-6 crabs m^(-2) and 45 shrimps m^(-2).

Spatial and vertical variations of perfluoroalkyl substances in sediments of the Haihe River,China

The levels of six perfluoroalkyl substances（PFASs） in surface sediment and their vertical variations in dated sediment cores from the Haihe River were investigated; studied substances included perfluorooctanoic acid（PFOA）,perfluorononanoic acid（PFNA）,perfluorooctane sulfonate（PFOS）,perfluorodecanoic acid（PFDA）,perfluoroundecanoic acid（PFUnA）,and perfluorododecanoic acid（PFDoA）. Results showed that the total PFAS concentration in surface sediment ranged between 0.52 and 16.33 ng/g dry weight（dw） with an average of3.47 ng/g dw,with PFOS and PFOA as the dominant PFASs. In general,the PFAS concentrations in the mainstream increased from the upper to the lower reaches,except that a drop occurred downstream of the Erdao dam. Although the PFASs in the sediment cores did not show a clear decreasing or increasing trend with depth,the three cores had a similar vertical variation.The PFAS levels were relatively low in the surface sediment,and reached the first high point at8–20 cm as a result of the wide use of PFASs from 1990 to 2000. After that the PFAS levels decreased,and then increased to a second high point at about 40–48 cm,which might be caused by the leaching of PFASs in sediment. Because PFASs have hydrophilic groups and relatively high solubility,the PFASs will transfer from the upper to lower layers of sediment when water infiltration occurs,leading to the fluctuation of PFAS levels in sediment cores. This study suggests that both the temporal variation of sources and transfer processes of PFASs in sediments are important factors influencing the vertical variation of PFASs in sediment cores.

Integration of chemical and biological methods:A case study of polycyclic aromatic hydrocarbons pollution monitoring in Shandong Peninsula,China

Polycyclic aromatic hydrocarbons(PAHs),as persistent toxic substances(PTS),have been widely monitored in coastal environment,including seawater and sediment.However,scientific monitoring methods,like ecological risk assessment and integrated biomarker response,still need massive researches to verify their availabilities.This study was performed in March,May,August and October of 2018 at eight sites,Yellow River estuary(S1),Guangli Port(S2),Xiaying(S3),Laizhou(S4),Inner Bay(S5),Outer Bay(S6),Hongdao(S7)and Hongshiya(S8)of Shandong Peninsula,China.The contents of 16 priority PAHs in local seawater and sediment were determined,by which ecological risk assessment risk quotient(RQ)for seawater and sediment quality guidelines(SQGs)were calculated to characterize the PAHs pollution.Meanwhile,multiple biomarkers in the digestive gland of clam Ruditapes philippinarum were measured to represent different biological endpoints,including ethoxyresorufin-O-deethylase(EROD),glutathione S-transferase(GST),sulfotransferase(SULT),superoxide dismutase(SOD)and lipid peroxidation(LPO),by which integrated biomarker response(IBR)was calculated to provide a comprehensive assessment of environmental quality.Taken together,these results revealed the heaviest pollution at S2 as both PAHs concentrations and biomarkers responses reflected,and supported the integrated biomarker response as a useful tool for marine environmental monitoring,through its integration with SQGs.