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.

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.

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.

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.

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.