Marine ecological risk assessment for the herbicide sulfometuron-methyl based on species sensitivity distribution approach

In recent years,herbicide sulfometuron-methyl(SM)has been used to kill the invasive plant Spartina alterniflora in some coastal areas of China,which may lead to the toxic effects on non-target marine organisms.The 96-h median effective concentrations(96-h EC50)of SM on six species of marine microalgae were measured in growth inhibition tests,and were then compared with other published toxicity data,based on which a method of species sensitivity distribution(SSD)was built to estimate the hazardous concentration of SM for 5%of species(HC5)and potentially affected fraction(PAF)for a certain concentration.Results indicate that SM exhibited a high toxicity to two species of green algae(Chlorella pacifica and Dunaliella salina)with a 96-h EC50 of 0.11 and 0.13 mg/L respectively,had a medium toxicity to two species of golden algae(Diacronema viridis and Isochrysis galbana)with a 96-h EC50 of 14.24 and 21.48 mg/L respectively,and showed a low toxicity to two species of diatoms(Skeletonema costatum and Phaeodactylum tricornutum)with a 96-h EC50 of 148.99 and>100 mg/L,respectively.The estimated values of HC5 and the predicted no-effect concentrations(PNEC)for SM were 0.077 and 0.015 mg/L,respectively.According to the current dosage for killing S.alterniflora in tidal flats in Fujian Province,China,SM entering the sea by spraying might cause the acute injury or death of 14%of marine species.This hazard could last for about a month for those sensitive species.Therefore,on the premise of inhibiting the growth of this invasive plant,the dosage of SM should be reduced as much as possible to avoid severe damage to the marine ecosystem.The results provide a valuable information for marine ecological risk assessment on SM and for marine environmental management.

Derivation and validation of soil total and extractable cadmium criteria for safe vegetable production

Determining the appropriate soil cadmium(Cd)criteria for vegetable production is important for ensuring that the Cd concentrations of the vegetables meet food safety standards.The soil extractable Cd criteria for vegetable production are also essential for both food safety and environmental management,especially in areas with a high natural background level.In the present study,soil total and extractable Cd criteria were derived using the approach of species sensitivity distribution integrated with soil aging and bioavailability as affected by soil properties.A dataset of 90 vegetable species planted in different soils was compiled by screening the published in literature in five bibliographic databases using designated search strings.The empirical soil-plant transfer model was applied to normalize the bioaccumulation data.After normalization,the intra-species variability was reduced by 18.3 to 84.4%.The soil Cd concentration that would protect 95%(HC_(5))of the species was estimated by species sensitivity distribution curves that were fitted by the Burr III function.The soil Cd criteria derived from the added approach for risk assessment were proposed as continuous criteria based on a combination of organic carbon and pH in the soil.Criteria for total Cd and EDTA-extractable Cd in the soil ranged from 0.23 to 0.61 mg kg^(-1)and from 0.09 to 0.25 mg kg^(-1),respectively.Field experimental data were used to validate the applicability and validity of these criteria.Most of the predicted HC5 values in the field experimental sites were below the 1:1 line.These results provide a scientific basis for soil Cd criteria for vegetable production that will ensure food safety.

Preliminary analysis of species sensitivity distribution based on gene expression effect

Species sensitivity analysis is one of the major techniques applied to derive water quality criteria. Presently, the toxicity data used for development of water quality criteria are mainly in the biological individual level. With the increase of ecotoxicogenomics toxicity data, it is worth studying whether the gene expression effect data can be used to derive water quality criteria. Taking cadmium, copper and zinc as examples, we analyzed the toxic effects of the three heavy metals by constructing the species sensitivity distribution curves on the basis of extensive toxicity data. The results showed that the rank of species sensitivity for the acute, chronic and gene expression effect toxicity data of cadmium is "chronic>gene>acute". Although the gene expression effect data of copper and zinc are insufficient, the trend of data sensitivity of zinc is similar to cadmium. However, the trend of species sensitivity of copper is different from that of cadmium and zinc with higher sensitivity of gene expression data. It suggested that though the existing data of gene expression effects are not sufficient enough, they have the potential to be used in the development of chronic water quality criteria. For application in the derivation of water quality criteria, illogical test concentration design and insufficient target genes are two main weaknesses in the study of gene expression effects.

Comprehensive Investigation and Assessment of Nutrient and Heavy Metal Contamination in the Surface Water of Coastal Bohai Sea in China

With the rapid development of industrialization and urbanization of coastal regions,eutrophication and metal pollution have caused serious environmental problems in China.To better understand the potential environmental risks associated with nutrients and heavy metals,the surface water was comprehensively investigated in the coastal Bohai Sea.A total of 150 sites were sampled from seven coastal regions,and the concentrations of nutrients(DIN and DIP)and metals(Cd,Pb,Zn,Cu,Cr,As and Hg)in the surface seawater were measured.The results showed that the DIN concentration of about 50%sites exceeded the Grade-I of Seawater Quality Standard of China.Due to high concentrations of DIN,the status of eutrophication was serious in the Bohai Bay and Shuangtaizi Estuary.According to Seawater Quality Standard of China,Pb,Zn,Hg and Cu were the main metal pollutants in the coastal Bohai Sea.There was generally low ecological risk caused by heavy metals,but certain hotspots existed near Shuangtaizi Estuary and Changxingdao Island.

Determining soil conservation strategies:Ecological risk thresholds of arsenic and the influence of soil properties

The establishment of ecological risk thresholds for arsenic(As)plays a pivotal role in developing soil conservation strategies.However,despite many studies regarding the toxicological profile of As,such thresholds varying by diverse soil properties have rarely been established.This study aims to address this gap by compiling and critically examining an extensive dataset of As toxicity data sourced from existing literature.Furthermore,to augment the existing information,experimental studies on As toxicity focusing on barley-root elongation were carried out across various soil types.The As concentrations varied from 12.01 to 437.25 mg/kg for the effective concentrations that inhibited 10%of barley-root growth(EC10).The present study applied a machine-learning approach to investigate the complex associations between the toxicity thresholds of As and diverse soil properties.The results revealed that Mn-/Fe-ox and clay content emerged as the most influential factors in predicting the EC10 contribution.Additionally,by using a species sensitivity distribution model and toxicity data from 21 different species,the hazardous concentration for x%of species(HCx)was calculated for four representative soil scenarios.The HC5 values for acidic,neutral,alkaline,and alkaline calcareous soils were 80,47,40,and 28 mg/kg,respectively.This study establishes an evidence-based methodology for deriving soil-specific guidance concerning As toxicity thresholds.

Application of the health risk assessment of acetochlor in the development of water quality criteria

Acetochlor is a widely used herbicide in agricultural production. Studies have shown that acetochlor has obvious environmental hormone effects, and long-term exposure may pose a threat to human health. To quantify the hazards of acetochlor in drinking water, a health risk assessment of acetochlor was conducted in major cities of China based on the data of acetochlor residue concentrations in drinking water. The approach of the Species Sensitivity Distributions(SSD) method is used to extrapolate from animal testing data to reflect worst case human toxicity. Results show that hazard quotients related to acetochlor residues in drinking water for different age groups range from 1.94 × 10-4 to 6.13 × 10-4, so, there are no indication of human risk. Compared to the total estimated hazard quotient from oral intake of acetochlor, the chronic exposure imputed to acetochlor residues in drinking water in China accounts for 0.4%. This paper recommends 0.02 mg/L to be the maximum acetochlor residue concentration level in drinking water and source water criteria.

Derivation of water quality criteria for representative water-body pollutants in China

In this study, toxicological data for zinc （Zn）, cadmium （Cd）, hexavalent chromium （Cr （VI））, benzene, and nitrobenzene were collected from various databases and publications, screened and then constructed into species sensitivity distribution （SSD） curves. Then water quality criteria （WQC） were derived for protection of the freshwater aquatic life in China against five representative pollutants. The values derived in this study were compared with those issued by the US Environmental Protection Agency and the Chinese national environmental standard for surface water to identify factors underlying the differences. The results showed that the SSD curves for the five pollutants differed significantly, with the examined aquatic species being gen- erally more sensitive to Zn, Cd, and Cr （VI） than benzene and nitrobenzene. The acute WQC were： 48.43 μg L-1 for Zn, 0.4218 μg L-1 for Cd, 45.79μg L-1 for Cr （VI）, 2651 μg L-1 for benzene, and 1426 μg L-1 for nitrobenzene. The chronic WQC were： 20.01μg L-1 for Zn, 0.2428 μg L-j for Cd, 14.22 μg L-1 for Cr （VI）, 530.2 μg L J for benzene, and 286.2 μg L-1 for nitroben- zene. The results of this comparative study of representative pollutants may offer guideline values for future WQC studies for China.

Occurrence, variations, and risk assessment of neonicotinoid insecticides in Harbin section of the Songhua River, northeast China

Neonicotinoid insecticides(NNIs)have been intensively used and exploited,resulting in their presence and accumulation in multiple environmental media.We herein investigated the current levels of eight major NNIs in the Harbin section of the Songhua River in northeast China,providing the first systematic report on NNIs in this region.At least four NNIs in water and three in sediment were detected,with total concentrations ranging from 30.8 to 135 ng L^(-1) and from 0.61 to 14.7 ng g^(-1) dw,respectively.Larger spatial variations in surface water NNIs concentrations were observed in tributary than mainstream(p<0.05)due to the intensive human activities(e.g.,horticulture,urban landscaping,and household pet flea control)and the discharge of wastewater from many treatment plants.There was a significant positive correlation(p<0.05)between the concentrations of residual imidacloprid(IMI),clothianidin(CLO),and S4NNIs in the sediment and total organic carbon(TOC).Due to its high solubility and low octanol-water partition coefficient(Kow),the sediment-water exchange behavior shows that NNIs in sediments can re-enter into the water body.Human exposure risk was assessed using the relative potency factor(RPF),which showed that infants have the highest exposure risk(estimated daily intake(SIMIeq EDI):31.9 ng kg^(-1) bw$d^(-1)).The concentration thresholds of NNIs for aquatic organisms in the Harbin section of the Songhua River were determined using the species sensitivity distribution(SSD)approach,resulting in a value of 355 ng L^(-1) for acute hazardous concentration for 5%of species(HC5)and 165 ng L^(-1) for chronic HC5.Aquatic organisms at low trophic levels were more vulnerable to potential harm from NNIs.

Research trends of microplastics in the soil environment: Comprehensive screening of effects

We collated and synthesized previous studies that reported the impacts of microplastics on soil parameters.The data were classified and integrated to screen for the proportion of significant effects,then we suggest several directions to alleviate the current data limitation in future experiments.We compiled 106 datasets capturing significant effects,which were analyzed in detail.We found that polyethylene and pellets(or powders)were the most frequently used microplastic composition and shape for soil experiments.The significant effects mainly occurred in broad size ranges(0.1–1 mm)at test concentrations of 0.1%–10%based on soil dry weight.Polyvinyl chloride and film induced significant effects at lower concentrations compared to other compositions and shapes,respectively.We adopted a species sensitivity distribution(SSD)and soil property effect distribution(SPED)method using available data from soil biota,and for soil properties and enzymes deemed relevant for microplastic management.The predicted-no-effect-concentration(PNEC)-like values needed to protect 95%of soil biota and soil properties was estimated to be between 520 and 655 mg kg^(-1).This study was the first to screen microplastic levels with a view toward protecting the soil system.Our results should be regularly updated(e.g.,quarterly)with additional data as they become available.