Different Sensitivity of Flower-Visiting Diptera to a Neonicotinoid Insecticide: Expanding the Base for a Multiple-Species Risk Assessment Approach

Insects play an essential role as pollinators of wild flowers and crops. At the same time, pollinators in agricultural environments are commonly exposed to pesticides, compromising their survival and the provision of pollination services. Although pollinators include a wide range of species from several insect orders, information on pesticide sensitivity is mostly restricted to bees. In addition, the disparity of methodological procedures used for different insect groups hinders the comparison of toxicity data between bees and other pollinators. Dipterans are a highly diverse insect order that includes some important pollinators. Therefore, in this study, we assessed the sensitivity of two hoverflies (Sphaerophoria rueppellii, Eristalinus aeneus) and one tachinid fly (Exorista larvarum) to a neonicotinoid insecticide (Confidor®, imidacloprid) following a comparative approach. We adapted the standardized methodology of acute contact exposure in honey bees to build dose-response curves and calculate median lethal doses (LD50) for the three species. The methodology consisted in applying 1 µL of the test solution on the thorax of each insect. Sphaerophoria rueppelli was the most sensitive species (LD50 = 10.23 ng/insect), and E. aeneus (LD50 = 18,176 ng/insect) the least. We then compared our results with those available in the literature for other pollinator species using species sensitivity distribution (SSD). Based on the SSD curve, the 95th percentile of pollinator species would be protected by a safety factor of 100 times the Apis mellifera endpoint. Overall, dipterans were less sensitive to imidacloprid than most bee species. As opposed to most bee species, oviposition and fecundity of many dipteran species can be reliably assessed in the laboratory. We measured the number of eggs laid following exposure to different insecticide doses and assessed the potential trade-off between oviposition and survival through the sublethal sensitivity index (SSI). Exposure to imidacloprid had a significant effect on fecundity, and SSI values indicated that oviposition is a sensitive endpoint for the three dipteran species tested. Future studies should integrate this information related to population dynamics in simulation models for environmental risk assessment.

Neonicotinoids Persisting in the Sea Pose a Potential Chronic Risk to Marine Organisms: A Case from Xiangshan Bay, China (2015-2019)

Neonicotinoid insecticides (neonics) are extensively employed in agriculture and pervade various environmental matrices. However, few studies have documented the occurrence and potential chronic ecological risks of these chemicals in the marine environment. We collected 720 seawater samples from Xiangshan Bay during 2015-2019 and the integrated concentrations of seven neonics were determined using the relative potency factor method. Trend analyses using the Mann-Kendall test in time series, along with the estimation of the flux of neonics into the sea, were conducted. At last, the ecological risk of neonics was evaluated by water quality criteria derivation based on species sensitivity distribution. Our findings revealed that 47.6% of samples contained at least one neonic, with the integrated concentration of neonics ranging from 63.30 to 1684.14 ng/L. Imidacloprid and dinotefuran exhibited the highest frequency of detection in the analysis. The significance level of the Mann-Kendall test ranged from 2.16 × 10-10 to 1.21 × 10-5 (S > 0), indicating all neonics behaved with sharply increasing trends. Approximately 8.47 × 10-2 tons of neonics were discharged into Xiangshan Bay. Notably, the integrated concentrations of neonics represented a potential chronic ecological risk to marine organisms. This study provided novel insights into the spatial distribution, source, and migration of neonic species and their impacts on marine ecosystems.

[Biological Evaluation and Key Stress Factor Diagnosis of Compound Contaminated Soil Based on Environmental DNA]

Healthy biological community composition and diversity are the basis for soil ecosystems to provide complete ecological functions and services. The current technical bottleneck in soil pollution control is the lack of systematic and comprehensive biodiversity indicators. In this study, the compound-polluted soil in an industrial park was taken as the object, and environmental DNA (eDNA)technology was used to monitor and analyze the composition of the biological community in the polluted soil. The environmental DNA-species sensitivity distribution (eDNA-SSD) method was constructed to diagnose the key stress factors and their ecological threshold. The results showed that:① compound pollution did not have a significant impact on the α-diversity of soil organisms in the park but led to changes in the composition of biological communities and dominant species with high relative abundance. The dominant groups in the polluted soil were Proteobacteria (25.54%), Ascomycota (15.65%), Actinobacteria (8.75%), and Chloroflexi (7.64%). ② Environmental factors accounted for 51.27% of the differences in soil biodistribution, and aniline, sulfate, petroleum hydrocarbon, and lead were the key stress factors for soil biomes. Among them, aniline had the most significant effect on the community distribution of bacteria (P=0.030), sulfate on fungi (P=0.025), and metazoans (P=0.032). ③ The ecological risk threshold (hazardous concentration for 5% of species, HC₅) of pollutants with 95% species as the protection target showed a gradient decreasing trend of sulfate (470.00 mg·kg^-1), petroleum hydrocarbon (17.00 mg·kg^-1), lead (13.00 mg·kg^-1), arsenic (6.20 mg·kg^-1), 4-chloroaniline (0.16 mg·kg^-1), and aniline (0.11 mg·kg^-1). Nevertheless, the existing soil risk control value was significantly higher than the ecological risk value, indicating that the existing control standards targeting human health were not suitable for protecting soil health. The comprehensive pollution index showed that the soil pollution in the park was mostly mild pollution accompanied by heavy pollution at individual points. The biological evaluation method based on eDNA-SSD could achieve the comprehensive evaluation of composite pollution in the absence of the benchmark value of pollutants and at the same time better distinguish the differences in soil biological community structure and composition under different pollution levels (P=0.053). In conclusion, the environmental DNA soil biomonitoring and assessment method developed in this study has guiding significance and application value for soil ecosystem restoration assessment.

Effects of Nitrogen Emissions on Fish Species Richness across the World's Freshwater Ecoregions

The increasing application of synthetic fertilizer has tripled nitrogen (N) inputs over the 20th century. N enrichment decreases water quality and threatens aquatic species such as fish through eutrophication and toxicity. However, the impacts of N on freshwater ecosystems are typically neglected in life cycle assessment (LCA). Due to the variety of environmental conditions and species compositions, the response of species to N emissions differs among ecoregions, requiring a regionalized effect assessment. Our study tackled this issue by establishing regionalized species sensitivity distributions (SSDs) of freshwater fish against N concentrations for 367 ecoregions and 48 combinations of realms and major habitat types globally. Subsequently, effect factors (EFs) were derived for LCA to assess the effects of N on fish species richness at a 0.5 degree × 0.5 degree resolution. Results show good SSD fits for all of the ecoregions that contain sufficient data and similar patterns for average and marginal EFs. The SSDs highlight strong effects on species richness due to high N concentrations in the tropical zone and the vulnerability of cold regions. Our study revealed the regional differences in sensitivities of freshwater ecosystems against N content in great spatial detail and can be used to assess more precisely and comprehensively nutrient-induced impacts in LCA.

Acute Toxicity Assessment and Prediction Models of Four Heavy Metals

Water quality criteria (WQC) are developed to protect aquatic organisms. Toxicity data of local fish are essential to improve the applicability of WQC derivatives. However, the paucity of local cold-water fish toxicity data limits the development of WQC in China. Brachymystax lenok is a representative Chinese-endemic cold-water fish, which plays an important role in the characterization of metal toxicity in the water environment. Whereas, the ecotoxicological effects of copper, zinc, lead and cadmium, as well as its potential as a test species for the metal WQC, remain to be investigated. In our study, acute toxicity tests of copper, zinc, lead and cadmium were performed on this fish according to the OECD method and 96 h-LC₅₀ values were calculated. The results showed that the 96 h-LC₅₀ values of Cu²⁺, Zn²⁺, Pb²⁺ and Cd²⁺ for B. lenok were 134, 222, 514 and 734 μg/L, respectively. Toxicity data for freshwater species and Chinese-native species were collected and screened, and the mean acute values of each metal for each species were ranked. The results showed that the accumulation probability of zinc by B. lenok was the lowest and less than 15%. Thus, B. lenok was sensitive to Zn and can be considered as the test cold-water fish for derivation of Zn WQC. In addition, B. lenok in comparison with warm-water fish, we found that cold-water fish are not always more sensitive to heavy metals than warm-water fish. Finally, the models for toxic effects prediction of different heavy metals on the same species were constructed and evaluated the reliability of the model. We suggest that the alternative toxicity data provided by the simulations can be used to derive WQC for metals.

Toxicity and Environmental Risk Assessment of Polycarbamate and Its Main Components to Marine Algae and Crustaceans

Polycarbamate is commonly used as an antifoulant coating on fishing nets in Japan. Although its toxicity to freshwater organisms has been reported, its toxicity to marine organisms is currently unknown. We conducted algal growth inhibition and crustacean immobilization tests to assess the effects of polycarbamate on marine organisms. We also evaluated the acute toxicity of the main components of polycarbamate, namely, dimethyldithiocarbamate and ethylenebisdithiocarbamate, to algae, which are the most sensitive tested organisms to polycarbamate. The toxicities of dimethyldithiocarbamate and ethylenebisdithiocarbamate partially explain that of polycarbamate. To assess the primary risk, we derived the predicted no-effect concentration (PNEC) for polycarbamate in a probabilistic manner using species sensitivity distributions. The 72 h no observed effect concentration (NOEC) of polycarbamate to the alga Skeletonema marinoi-dohrnii complex was 0.45 μg/L. The toxicity of dimethyldithiocarbamate may have contributed up to 72% of the toxicity observed for polycarbamate. The fifth percentile of hazardous concentration (HC₅) derived from the acute toxicity values was 0.48 μg/L. Comparison of previously reported environmental polycarbamate concentrations in Hiroshima Bay, Japan, to the PNEC estimated using the minimum NOEC and HC₅ suggest that polycarbamate currently poses a high ecological risk. Therefore, reducing the risk by restricting polycarbamate use is necessary.

Freshwater Water-Quality Criteria for Chloride and Guidance for the Revision of the Water-Quality Standard in China

The chloride in water frequently exceeds the standard; directly quoting foreign water-quality criteria (WQC) or standards will inevitably reduce the scientific value of the water-quality standard (WQS) in China. Additionally, this may lead to the under- or overprotection of water bodies. This study summarized the sources, distribution, pollution status, and hazards of chloride in China's water bodies. Additionally, we compared and analyzed the basis for setting WQS limits for chloride in China; we systematically analyzed the basis for setting the WQC for chloride in foreign countries, especially the United States. Finally, we collected and screened data on the toxicity of chloride to aquatic organisms; we also used the species sensitivity distribution (SSD) method to derive the WQC value for chloride, which is 187.5 mg·L-1. We put forward a recommended value for freshwater WQS for chloride in China: less than 200 mg·L-1. The study of a freshwater WQC for chloride is not only a key point of environmental research, but also an urgent demand to ensure water ecological protection in China. The results of this study are of great significance for the environmental management of chloride, protection of aquatic organisms, and risk assessment, especially for the revision of WQSs.

Reliable and Representative Estimation of Extrapolation Model Application in Deriving Water Quality Criteria for Antibiotics

Deriving water quality benchmarks based on the species sensitivity distribution (SSD) is crucial for assessing the ecological risks of antibiotics. The application of extrapolation methods such as interspecies correlation estimation (ICE) and acute-to-chronic ratios (ACRs) can effectively supplement insufficient toxicity data for these emerging contaminants. Acute-to-chronic ratios can predict chronic toxicity from acute toxicity, and ICE can extrapolate an acute toxicity value from one species to another species. The present study explored the impact of two extrapolation methods on the reliability of SSDs by analyzing different scenarios. The results show that, compared with the normal and Weibull distributions, the logistic model was the best-fitting model. For most antibiotics, SSDs derived by extrapolation have high reliability, with 82.9% of R² values being higher than 0.9, and combining ICE and ACR methods can bring a maximum increase of 10% in R² . Based on the results of Monte Carlo simulation, the statistical uncertainty brought by ICE in SSD is 10-40 times larger than that brought by ACR, and combining the two methods could reduce uncertainty. In addition, the sensitivity test showed that whether the toxicity data came from extrapolation or actual measurement, the lower the value of toxicity endpoints was, the greater the bias caused by the corresponding species in every scenario. Combining the two aforementioned extrapolation methods could effectively increase the stability of SSD, with their bias nearly equal to 1. Environ Toxicol Chem 2023;42:191-204. © 2022 SETAC.

Advancing Fifth Percentile Hazard Concentration Estimation Using Toxicity-Normalized Species Sensitivity Distributions

The species sensitivity distribution (SSD) is an internationally accepted approach to hazard estimation using the probability distribution of toxicity values that is representative of the sensitivity of a group of species to a chemical. Application of SSDs in ecological risk assessment has been limited by insufficient taxonomic diversity of species to estimate a statistically robust fifth percentile hazard concentration (HC5). We used the toxicity-normalized SSD (SSDn) approach, (Lambert, F. N.; Raimondo, S.; Barron, M. G. Environ. Sci. Technol.2022,56, 8278-8289), modified to include all possible normalizing species, to estimate HC5 values for acute toxicity data for groups of carbamate and organophosphorous insecticides. We computed mean and variance of single chemical HC5 values for each chemical using leave-one-out (LOO) variance estimation and compared them to SSDn and conventionally estimated HC5 values. SSDn-estimated HC5 values showed low uncertainty and high accuracy compared to single-chemical SSDs when including all possible combinations of normalizing species within the chemical-taxa grouping (carbamate-all species, carbamate-fish, organophosphate-fish, and organophosphate-invertebrate). The SSDn approach is recommended for estimating HC5 values for compounds with insufficient species diversity for HC5 computation or high uncertainty in estimated single-chemical HC5 values. Furthermore, the LOO variance approach provides SSD practitioners with a simple computational method to estimate confidence intervals around an HC5 estimate that is nearly identical to the conventionally estimated HC5.

Pollution Assessment and SSD-Based Ecological Assessment of Heavy Metals in Multimedia in the Coast of Southeast China

Heavy metals in the ocean exist in various media and assessing heavy metal pollution in the multimedia in seawater is important for proposing effective strategies to protect marine ecosystem health. However, comprehensive coastal pollution assessments and SSD-based assessments of heavy metals have been limited from an international perspective. This study discusses the distribution, sources, interactions, associated environmental factors, and potential ecological risks related to heavy metal pollution. To attain this objective, several tools and models were considered. The partition coefficient between sediment and water was used to understand the ability of heavy metals to be adsorbed from seawater by sediment. The water quality index was applied to evaluate the comprehensive heavy metal pollution at different sampling sites. The species diversity index was calculated by calculating the concentration of chlorophyll a. The geo-accumulation and potential ecological risk indexes were employed for the sediments' general pollution characteristic of heavy metals. Species sensitivity distribution was used for ecological risk evaluation. The results indicated that heavy metal pollution and ecological risk (Cu, Pb, Zn, Cd, As, Cr and Hg) are not serious, and the pollution conditions remain safe. Only Cu, Pb, and Hg concentrations in seawater exceed the Nation Class I Water Quality Standard. The concentrations of heavy metals showed significant spatial characteristics. Fisheries activities and industrial effluent discharges were identified as the main anthropogenic sources. This study provides a comprehensive assessment of heavy metals in multi-media, and the results will provide valuable information for nearshore ecological management and risk avoidance.

Development of a Site-Specific Guideline Value for Copper and Aquatic Life in Tropical Freshwaters of Low Hardness

Copper (Cu) is a contaminant of potential concern for a uranium mine whose receiving waters are in the World Heritage-listed Kakadu National Park in northern Australia. The physicochemical characteristics of the freshwaters in this region enhance metal bioavailability and toxicity. Seven tropical species were used to assess the chronic toxicity of Cu in extremely soft freshwater from a creek upstream of the mine. Sensitivity to Cu was as follows: Moinodaphnia macleayi > Chlorella sp. > Velesunio sp. > Hydra viridissima > Amerianna cumingi > Lemna aequinoctialis > Mogurnda mogurnda. The 10% effect concentrations (EC10s) ranged from 1.0 µg/L Cu for the cladoceran Moinodaphnia macleayi to 9.6 µg/L for the fish M. mogurnda. The EC50s ranged from 6.6 µg/L Cu for the mussel Velesunio sp. to 22.5 µg/L Cu for M. mogurnda. Geochemical modeling predicted Cu to be strongly bound to fulvic acid (80%-99%) and of low bioavailability (0.02%-11.5%) under these conditions. Protective concentrations (PCs) were derived from a species sensitivity distribution for the local biota. The 99% PC (PC99), PC95, PC90, and PC80 values were 0.5, 0.8, 1.0, and 1.5 µg/L Cu, respectively. These threshold values suggest that the current Australian and New Zealand default national 99% protection guideline value for Cu (1.0 µg/L) would not provide adequate protection in freshwaters of low hardness, particularly for this area of high conservation value. The continuous criterion concentration predicted by the Cu biotic ligand model for conditions of low pH (6.1), low dissolved organic carbon (2.5 mg/L), low hardness (3.3 mg/L), and 27 °C was 0.48 µg/L Cu, comparable with the PC99. Consideration of the natural water quality conditions of a site is paramount for protective water quality guidelines. Environ Toxicol Chem 2022;41:2808-2821. © 2022 Commonwealth of Australia. Environmental Toxicology and Chemistry © 2022 SETAC.

Comprehensive Ecological Risk Assessment of Heavy Metals Based on Species Sensitivity Distribution in Aquatic of Coastal Areas in Hong Kong

In recent decades, the ecological environment of some coastal areas in China has been seriously affected by terrestrial pollutants, and there is an urgent need for ecological risk assessment of China's coastal environment. The assessment of heavy metal pollution in Hong Kong waters was carried out using different environmental and ecological indicators. The heavy metal contents (Cu, Pb, Zn, Cd, As, Cr, and Hg) in the near coast of Hong Kong were analyzed for two different seasons of the year 2018 (April-spring and September-autumn). We assessed the distribution and enrichment of heavy metals in the near coast of Hong Kong, and the potential biohazardous effects were assessed using the species sensitivity distribution method. The results showed that only Pb, Zn, and Hg in seawater exceeded the Class I standard. Pb, Zn, Cd, and As in organisms exceeded the standard, and no heavy metals exceeded the standard in sediments. The species sensitivity distribution method indicated that the biohazardous factor of heavy metals of the Hong Kong coast is higher in spring than in autumn, and the potential hazard ratio has the characteristics of high northwest and low southeast, which leads to its msPAF also having these characteristics. From the correlational analyses among heavy metals, we found that the pH change in seawater was related to the concentration of heavy metals, the concentration of heavy metals in seawater was proportional to the salinity of seawater, Pb and Cu were likely to have the same source, and Zn and Cd may not have the same emission sources as the other heavy metals. Overall, heavy metal contamination of seawater, sediments, and organisms near the Hong Kong coast was within acceptable limits, but the problem of heavy metal dispersion should be prevented.

Avoidance Behaviour of Six Collembolan Species Shows Species-Specific Sensitivity-Impact of Ag NM300K

Although standard testing guidelines use a species as a representative surrogate, species-specific sensitivity is well-known. The aim of this study was to investigate the species-specific difference in avoidance behaviour among Collembola species exposed to silver (Ag) nanomaterials (NM) (Ag NM300K). The avoidance test was performed with Folsomia candida, an international standard species in laboratory tests, and five widely distributed species with different life history traits, commonly used in small multispecies systems (Folsomia fimetaria, Proisotoma minuta, Mesaphorura macrochaeta, Protaphorura fimata and Ceratophysella denticulata). There was higher avoidance in euedaphic species, such as F. candida and F. fimetaria, compared to the epiedaphic species C. denticulata, which showed the least avoidance behaviour. An explanation may be that euedaphic species (living in deeper soil layers) are more directly exposed within the soil pores and have developed a pronounced avoidance behaviour. In contrast, species living on the surface are likely less directly exposed and hence only avoid at higher total concentrations. Additionally, difference in cuticula between the groups, providing different degrees of protection against exposure, can explain the different behaviours. The present results highlight the importance of biodiversity for the ecosystem and raise awareness on species sensitivity.

[Neonicotinoid Insecticides Threaten Surface Waters at the National Scale in China]

This study was conducted in response to the current situation in our country in which neonicotinoid pesticides (NNIs) are used in large quantities and their concentration in surface water is gradually increasing. Based on the species sensitivity distribution (SSD), the hazard quotient (HQ) and probabilistic risk assessment (PRA) were used to compare single and mixture risks of NNIs in the surface water in China. The target and recommended values of NNIs in China's surface water quality supervision were also presented. The results showed that:① in the single acute hazard assessment, imidacloprid (IMI) was the most harmful insecticide, and in the single chronic hazard assessment, imidacloprid (IMI) and acetamiprid (ACE) were more harmful. Furthermore, insects were the most sensitive creatures. ② Hainan province was the region with the highest single acute and chronic hazard in the study area. ③ Based on the joint probability curves of five neonicotinoids, the probability in which 5% of species would be affected by long-term exposure was approximately 91.12%. Thus, the combined ecological risk of these five neonicotinoids cannot be ignored. ④ Based on the toxicity reference value from SSD and the combined results of HQ and PRA, the regulatory values of surface water quality in China were as follows:acetamiprid (ACE) 0.04 μg·L^-1, clothianidin (CLO) 0.22 μg·L^-1, imidacloprid (IMI) 0.01 μg·L^-1, thiacloprid (THI) 0.03 μg·L^-1, and thiamethoxam (THIA) 0.24 μg·L^-1. In short, the concentration of NNIs in the surface water in China has threatened the safety of aquatic organisms, and its supervision must be improved.

Hardness-Dependent Water Quality Criteria for Protection of Freshwater Aquatic Organisms for Silver in China

Silver is toxic to freshwater aquatic organisms and aquatic ecosystems, and it is necessary to develop regional water quality criteria (WQC) for silver to protect the freshwater aquatic organisms in China. The toxicity database of silver for freshwater aquatic organisms involved 121 acute toxicity values for 35 species (6 phyla and 27 families) and 15 chronic toxicity values for 4 species (2 phyla and 4 families). Teleost fish showed the most sensitivity to silver after both short-term and long-term exposure. Significant correlations between the natural logarithms of hardness and the natural logarithms of acute silver toxicity were found for Daphnia magna, Oncorhynchus mykiss, and Pimephales promelas. The criterion maximum concentration (CMC) was calculated by the species sensitivity distribution method with sigmoid as the best fitting model (Adj R² 0.9797), and the criterion continuous concentration (CCC) was obtained by the acute-to-chronic ratio method. The CMC and CCC of silver were e1.58ln(HCaCO3)−8.68, and e1.58ln(HCaCO3)−10.28 respectively, in China, with water hardness (HCaCO3, mg/L) as an independent variable. This research can provide a basis and reference for the management of silver to protect freshwater aquatic organisms in China.

Temporal and regional variability of cumulative ecological risks of pesticides in Japanese river waters for 1990-2010

We quantitatively evaluated the cumulative ecological risks from multiple pesticides used in paddy fields in Japan. Moreover, we visualized the temporal and regional variability of those risks for 1990-2010. Considering the region-specific parameters of environmental conditions, region-specific predicted environmental concentrations were estimated at 350 river-flow monitoring sites in Japan. Then the multi-substance potentially affected fraction (msPAF) was calculated as a risk index of multiple pesticides by using the computation tool NIAES-CERAP. The median msPAF values for insecticides and herbicides decreased by 92.4% and 53.1%, respectively, from 1990 to 2010. This substantial reduction in ecological risk was attributed to the development of low-risk pesticides by manufacturers, the efforts of farmers in risk reduction, and tighter regulation by the Japanese government. In particular, the substantial reduction of the ecological risk from insecticides was largely due to the decrease in the use of organophosphorus insecticides.

Could Contamination Avoidance Be an Endpoint That Protects the Environment? An Overview on How Species Respond to Copper, Glyphosate, and Silver Nanoparticles

The use of non-forced multi-compartmented exposure systems has gained importance in the assessment of the contamination-driven spatial avoidance response. This new paradigm of exposure makes it possible to assess how contaminants fragment habitats, interfering in the spatial distribution and species’ habitat selection processes. In this approach, organisms are exposed to a chemically heterogeneous scenario (a gradient or patches of contamination) and the response is focused on identifying the contamination levels considered aversive for organisms. Despite the interesting results that have been recently published, the use of this approach in ecotoxicological risk studies is still incipient. The current review aims to show the sensitivity of spatial avoidance in non-forced exposure systems in comparison with the traditional endpoints used in ecotoxicology under forced exposure. To do this, we have used the sensitivity profile by biological groups (SPBG) to offer an overview of the highly sensitive biological groups and the species sensitive distribution (SSD) to estimate the hazard concentration for 5% of the species (HC₅). Three chemically different compounds were selected for this review: copper, glyphosate, and Ag-NPs. The results show that contamination-driven spatial avoidance is a very sensitive endpoint that could be integrated as a complementary tool to ecotoxicological studies in order to provide an overview of the level of repellence of contaminants. This repellence is a clear example of how contamination might fragment ecosystems, prevent connectivity among populations and condition the distribution of biodiversity.

Seawater intrusion: an appraisal of taxa at most risk and safe salinity levels

Seawater intrusion into low-lying coastal ecosystems carries environmental risks. Salinity levels at these coastal ecosystems may vary substantially, causing ecological effects from mortality to several sublethal endpoints, such as depression of rates of feeding, somatic growth, or reproduction. This review attempts to establish safe salinity levels for both terrestrial and freshwater temperate ecosystems by integrating data available in the literature. We have four specific objectives: (i) to identify the most sensitive ecological taxa to seawater intrusion; (ii) to establish maximum acceptable concentrations-environmental quality standards (MAC-EQSs) for sea water (SW) from species sensitivity distributions (SSDs); (iii) to compile from the literature examples of saline intrusion [to be used as predicted environmental concentrations (PECs)] and to compute risk quotients for the temperate zone; and (iv) to assess whether sodium chloride (NaCl) is an appropriate surrogate for SW in ecological risk assessments by comparing SSD-derived values for NaCl and SW and by comparing these with field data. Zooplankton, early life stages of amphibians and freshwater mussels were the most sensitive ecological receptors for the freshwater compartment, while soil invertebrates were the most sensitive ecological receptors for the terrestrial compartment. Hazard concentration 5% (HC₅ ) values, defined as the concentration (herein measured as conductivity) that affects (causes lethal or sublethal effects) 5% of the species in a distribution, computed for SW were over 22 and 40 times lower than the conductivity of natural SW (≈ 52 mS/cm) for the freshwater and soil compartment, respectively. This sensitivity of both compartments means that small increments in salinity levels or small SW intrusions might represent severe risks for low-lying coastal ecosystems. Furthermore, the proximity between HC₅ values for the soil and freshwater compartments suggests that salinized soils might represent an additional risk for nearby freshwater systems. This sensitivity was corroborated by the derivation of risk quotients using real saline intrusion examples (PECs) collected from the literature: risk was >1 in 34 out of 37 examples. By contrast, comparisons of HC₅ values obtained from SSDs in field surveys or mesocosm studies suggest that natural communities are more resilient to salinization than expected. Finally, NaCl was found to be slightly more toxic than SW, at both lethal and sublethal levels, and, thus, is suggested to be an acceptable surrogate for use in risk assessment.

Stochastic Framework for Addressing Chemical Partitioning and Bioavailability in Contaminated Sediment Assessment and Management

Passive sampling to quantify net partitioning of hydrophobic organic contaminants between the porewater and solid phase has advanced risk management for contaminated sediments. Direct porewater (Cfree) measures represent the best way to predict adverse effects to biota. However, when the need arises to convert between solid-phase concentration (Ctotal) and Cfree, a wide variation in observed sediment-porewater partition coefficients (KTOC) is observed due to intractable complexities in binding phases. We propose a stochastic framework in which a given Ctotal is mapped to an estimated range of Cfree through variability in passive sampling-derived KTOC relationships. This mapping can be used to pair estimated Cfree with biological effects data or inversely to translate a measured or assumed Cfree to an estimated Ctotal. We apply the framework to both an effects threshold for polycyclic aromatic hydrocarbon (PAH) toxicity and an aggregate adverse impact on an assemblage of species. The stochastic framework is based on a "bioavailability ratio" (BR), which reflects the extent to which potency-weighted, aggregate PAH partitioning to the solid-phase is greater than that predicted by default, KOW-based KTOC values. Along a continuum of Ctotal, we use the BR to derive an estimate for the probability that Cfree will exceed a threshold. By explicitly describing the variability of KTOC and BR, estimates of risk posed by sediment-associated contaminants can be more transparent and nuanced.

A Novel Approach to Derive the Predicted No-Effect Concentration (PNEC) of Benzophenone-3 (BP-3) Using the Species Sensitivity Distribution (SSD) Method: Suggestion of a New PNEC Value for BP-3

The necessity for the aquatic ecological risk assessment for benzophenone-3 (BP-3) is increasing due to its high toxic potential and high detection frequency in freshwater. The initial step in the ecological risk assessment is to determine predicted no-effect concentration (PNEC). This study derived PNEC of BP-3 in freshwater using a species sensitivity distribution (SSD) approach, whilst existing PNECs are derived using assessment factor (AF) approaches. A total of eight chronic toxicity values, obtained by toxicity testing and a literature survey, covering four taxonomic classes (fish, crustaceans, algae, and cyanobacteria) were used for PNEC derivation. Therefore, the quantity and quality of the toxicity data met the minimum requirements for PNEC derivation using an SSD approach. The PNEC derived in this study (73.3 μg/L) was far higher than the environmental concentration detected in freshwater (up to 10.4 μg/L) as well as existing PNECs (0.67~1.8 μg/L), mainly due to the difference in the PNEC derivation methodology (i.e., AF vs. SSD approach). Since the SSD approach is regarded as more reliable than the AF approach, we recommend applying the PNEC value derived in this study for the aquatic ecological risk assessment of BP-3, as the use of the existing PNEC values seems to unnecessarily overestimate the potential ecological risk of BP-3 in freshwater.

Differences in Bifenthrin and Fipronil Susceptibility Among Invasive Latrodectus spp. (Araneae: Theridiidae) and Nontarget Spiders in Japan

Prompt responses to invasive Latrodectus spiders introduced unintentionally are needed worldwide due to their medical and ecological importance. Latrodectus species are chemically controlled using pyrethroid insecticides despite concerns about the ecological impacts of these compounds on biodiversity/ecosystems. Here, the relative sensitivities (acute toxicity: 48-h LC50) of Latrodectus hasseltii Thorell and Latrodectus geometricus C.L. Koch from Japan to the conventional neurotoxic insecticide bifenthrin (pyrethroid) and a new candidate insecticide, fipronil (phenylpyrazole), were examined. Acute residual toxicity tests of these compounds in two nontarget spiders (Parasteatoda tepidariorum C.L. Koch (Araneae: Theridiidae), Badumna insignis L. Koch (Araneae: Desidae)) were conducted for comparison. To test whether bifenthrin and fipronil toxicities differed among the four spiders, corresponding species sensitivity distributions (SSDs) were compared, and hazardous concentrations were determined. Sensitivity (especially in the nontarget species) was two to four orders of magnitude higher for bifenthrin than for fipronil. The SSD patterns of the two insecticides differed significantly, with the spider communities being more sensitive to bifenthrin than to fipronil. The lethal bifenthrin concentration for Latrodectus may reduce spider populations by over 70-90%. If L. hasseltii (established throughout Japan) is targeted for effective population suppression rather than L. geometricus (with a limited distribution range) using the specified insecticide concentration (LC50 value) for fipronil, less than 20% of spider communities will be impacted. Chemical operations aimed at the effective population management and subsequent eradication of invasive Latrodectus spiders while supporting local biodiversity conservation would benefit from considerations of fipronil dosages and target species sensitivities.

Quantification of pesticide residues in the topsoil of Belgian fruit orchards: terrestrial environmental risk assessment

BACKGROUND

Pesticides are widely used in fruit orchards. In the context of integrated pest management (IPM) Flemish farmers are advised to restrict the use of pesticides. However, pesticide residues could still pose a threat to beneficial organisms. To date, it is not well known which residues are present in IPM orchards. This study focuses on the pesticide concentration in the topsoil and the implications for soil-dwelling organisms.

RESULTS

Topsoil was sampled in ten sweet cherry (Prunus avium (L.) L.) and eight apple (Malus domestica Borkh.) orchards in Flanders (Belgium), to quantify the concentration of pesticide residues. Topsoil was selected because it is a major exposure route for beneficials. Both pesticides from both current spraying schedules and those used previously were found. In addition, an environmental risk assessment was performed using species sensitivity distribution (SSD) and toxicity/exposure ratio (TER) approaches. The SSD approach led to a more conservative outcome. None of the pesticides in the spraying schedule revealed a risk, although some of the persistent and banned pesticides may continue to do so.

CONCLUSION

Spraying schedules are good predictors of environmental contamination. Monitoring of residues remains essential to determine the real residue concentration in the topsoil. SSDs proved valuable. It was inferred that in addition to the standard test with the earthworm Eisenia fetida (Savigny, 1826), an arthropod test organism such as Folsomia candida (Willem, 1902) should be used in future risk assessments because it displays higher sensitivity towards insecticides.

Ecological Risk Assessment of Heavy Metals in Water Bodies around Typical Copper Mines in China

In order to understand the heavy metal pollution status and ecological effect in aquatic environment around copper mine areas, seven heavy metals (Cd, Cd, Cr, Cu, Hg, Zn, the Ni, and Pb) in aquatic environments in seven representative copper mine regions were selected from the literature in 2005–2013 for ecological risk assessment by using potential ecological risk index, geoaccumulation index, nemerow index and species sensitivity distribution method (Potential Affected Fraction (PAF) and Multi-Substance PAF (MSPAF)). The results of sediment ecological risk analysis showed that Cd, Cu and Pb were the main pollutants in sediments. The results of species sensitivity distribution analysis showed that the HC5 values (Hazardous Concentration for 5% of species) of seven heavy metals were different with order Zn > Cr > Cd > Pb > Cu > Ni > Hg. The MSPAF of seven copper mines in the following order with species sensitivity distribution method was as follows: Dabaoshan (99%) = Dahongshan (99%) = Baiyin (99%) > Dexing (97%) > Jinchuan (92%) > Tongling (39%) > Daye (24%). This study analyzes the impact of copper mining on the aquatic environment, and the results of this study will be great value for the comprehensive pollution governance of mining.

[Derivation of the Thresholds of Available Concentrations of Heavy Metals in Soil Based on Agricultural Product Safety]

Based on the total and available concentrations of heavy metal elements in agricultural soil, and the concentrations of heavy metals in rice collected from Daye city, Hubei province, and the thresholds of available concentrations of heavy metals were derived by species sensitivity distribution (SSD). The over-standard rates of Cd and Cu in the soil were 90.7% and 42.6%, respectively, which indicates that agricultural soil in Daye city exhibits signs of Cd and Cu pollution. The rates of Cd and Pb were 50.9% and 89.8% in brown rice samples, respectively, which exceeds the safety standards of agricultural products. The SSD curves for Cd and Pb were fitted with BurrⅢ distribution based on the ratio of the concentration in brown rice and the available concentration in the soil. The hazardous concentrations (HC₅) were derived inversely from the agriculture product safety standards. The thresholds of available Cd and Pb were 0.02 mg·kg^-1 and 0.005 mg·kg^-1, respectively. Compared with those of available Cd in other countries and studies, the threshold of available Cd is scientifically shown to be reasonable. Soil is not necessarily the main source of Pb in rice; thus, the rice species does not represent the derivation of the threshold of available Pb. Moreover, a lack of the accumulation data of Pb at low accumulation levels and multiple soil pollution levels leads to unreliable derivation. The results indicate that the threshold of available Pb does not have practical significance in soil pollution control.

[Prediction of Cd in vegetables and soil Cd threshold derivation based on transfer function.]

The construction of transfer function of cadmium (Cd) in the soil-vegetable system is important for risk management. This study investigated the Cd concentration in 745 paired soils and vegetable samples, aiming to determine the influences of major soil properties on uptake of Cd by vegetables, and to derive the soil Cd threshold for vegetable cultivation based on China foodstuff regulations. Results of species sensitivity distribution model showed that the Cd accumulation potential of leafy vegetables was greater than that of rootstalk vegetables. Stepwise multiple regression analysis showed soil total Cd, pH, and soil organic matter (SOM) were major factors contributing to Cd accumulation in vegetables. The derived transfer function explained 54.2% and 69.1% of the variance for the accumulation of Cd in leafy and rootstalk vegetables, respectively. The derived soil threshold increased with soil pH and SOM contents. The rootstalk vegetables were potentially hazardous when grown in strong acidic areas. For soils in the southern China with excessive acidic nature and low SOM contents, the soil Cd limits for vegetables cultivation might be over-estimated.

[Comprehensive Risk Evaluation of Cadmium in Soil-rice System Based on Uncertainty Analysis]

Cadmium (Cd) can cause adverse health effects and is a subject of concern in rice consumption. The uncertainty analysis helps improve the accuracy in the risk assessment for Cd in soil-rice system. A regional investigation on Youxian prefecture, southern China, was conducted to analyze the Cd concentration in rice. Based on the species sensitivity distribution model (SSD), health risk assessment model, and Monte Carlo simulation, the accumulation characteristic of Cd in soil-rice system, accumulation risk of Cd in soil, and health risk of Cd concentration in rice were determined. The results showed that the plant uptake factor (PUF) of Cd of rice was well fitted by the SSD model. The mean level of PUF was 1.86, with a significant spatial heterogeneity. The rice produced in WL county tended to accumulate a high level of Cd. There was no significant relationship between concentrations of Cd in soil and rice, suggesting that of rice renders the Cd risk management very difficult. The pollution load index of Cd in soil was 2.4, which belonged to a moderate contamination level. Under current accumulation condition of Cd in soil, there would be a 90.4% probability for soil Cd concentration to be higher than the national soil quality standard after 10 years. Health risk assessment showed that the average daily dose (ADD) was 2.9 μg·(kg·d)^-1, 3.5 fold higher than the WHO limit. About 93.9% of the adult populations consuming rice cropping in affected areas had the risk that the daily Cd intake was above the WHO limit. The health risk index (HRI) was around 2.1 to 4.7. The probability for health risk index (HRI) higher than 5 was 21.5%, suggesting a high health risk. When the soil pH was lower than 5.5, the probability for HRI higher than 1 was 95.3%, and when the soil pH was higher than 6, the probability for HRI higher than 1 reduced to 68.1%. An improved management of soil pH values would be needed for a better and safer rice production. The combination of uncertainty analysis, species sensitivity model and health risk assessment model was validated to be feasible and reliable in the risk analysis.

Ecological screening indicators of stress and risk for the Llobregat river water

The objective of this article is to develop and apply several simple and rough indicators for river aquatic ecosystems assessment in order to screen potential chemical stressors. Several indicators, based on toxicity (PNEC) and on legislation levels (EQS) have been developed. All these indicators are ratios that were calculated by using public and private data of concentrations of a large list of compounds during a period of five years, including metals and organic compounds in the lower part of the Llobregat river basin at the intake of the drinking water treatment plant. Additionally, new campaigns were executed for increasing the information available on the presence of compounds not routinely analyzed, such as some other pesticides and pharmaceuticals. In the case of inorganic pollutants, the indicators obtained in this river section showed significant risk especially for zinc, but also for copper, nickel and barium. For organic pollutants, the pesticides terbuthylazine, diazinon, 2-methyl-4-chlorophenoxyacetic (MCPA), and in a few cases, chlorpyrifos and lindane, also showed indexes above the threshold. Among the pharmaceuticals, the antibiotics clarithromycin and ciprofloxacin were the only ones with risk indicators adverse to ecosystems. The specific values of the indexes obtained rely on the quantity and quality of the data available, so their interpretation should take into account that some values can be high due to the use of too conservative toxicological information.