Research on aquatic microcosm: Bibliometric analysis, toxicity comparison and model prediction.

Recently, aquatic microcosms have attracted considerable attention because they can be used to simulate natural aquatic ecosystems. First, to evaluate the development of trends, hotspots, and national cooperation networks in the field, bibliometric analysis was performed based on 1841 articles on aquatic microcosm (1962-2022). The results of the bibliometric analysis can be categorized as follows: (1) Aquatic microcosm research can be summarized in two sections, with the first part focusing on the ecological processes and services of aquatic ecosystems, and the second focusing on the toxicity and degradation of pollutants. (2) The United States (number of publications: 541, proportion: 29.5%) and China (248, 13.5%) are the two most active countries. Second, to determine whether there is a difference between single-species and microcosm tests, that is, to perform different-tier assessments, the recommended aquatic safety thresholds in risk assessment [i.e., the community-level no effect concentration (NOECcommunity), hazardous concentrations for 5% of species (HC5) and predicted no effect concentration (PNEC)] were compared based on these tests. There was a significant difference between the NOECcommunity and HC5 (P < 0.05). Moreover, regression models predicting microcosm toxicity values were constructed to provide a reference for ecological systemic risk assessments based on aquatic microcosms.

Derivation of aquatic predicted no-effect concentration and ecological risk assessment for triphenyl phosphate and tris(1,3-dichloro-2-propyl) phosphate.

Triphenyl phosphate (TPhP) and tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) are common organophosphate esters (OPEs), which are used as additives in various industries. These compounds have been widely detected in aquatic environment, raising concerns about their adverse effects on aquatic organisms. In order to protect aquatic ecosystems, a total of 7 species were selected for acute and chronic toxicity tests in this study. The results indicated that TPhP and TDCIPP exhibited varying degrees of toxicity to aquatic organisms. The 96-h LC50 values ranged from 1.088 mg/L to 1.574 mg/L for TPhP and from 2.027 mg/L to 17.855 mg/L for TDCIPP. The 28-d LC10 values ranged from 0.023 mg/L to 0.177 mg/L for TPhP and from 0.300 mg/L to 1.102 mg/L for TDCIPP. The tested toxicity data, combined with collected toxicity data, were used to investigate the predicted no-effect concentration in water (PNECwater) of TPhP and TDCIPP by species sensitivity distribution (SSD) method. The results revealed PNECwater values of 6.35 and 38.0 µg/L for TPhP and TDCIPP, respectively. Furthermore, the predicted no-effect concentrations in sediment (PNECsed) were derived as 110 µg/kg dry weight (dw) for TPhP and 424 µg/kg dw for TDCIPP using the equilibrium partitioning (EqP) approach. Based on the toxicity data and PNECs, the ecological risk of these two chemicals in surface waters and sediments worldwide over the last decade were evaluated. The results indicated that TDCIPP posed negligible risk in aquatic ecosystems. However, TPhP showed potential risk in sediments, as indicated by the hazard quotients (HQs) exceeding 0.1. The results of joint probability curves (JPC) indicated that the probabilities of exceeding hazardous concentration for 1 % of species for TPhP in water and sediment were 0.33 % and 5.2 %, respectively. Overall, these findings highlight the need for continued monitoring and assessment of the presence and potential impacts of TPhP and TDCIPP in aquatic ecosystems.

Bioavailability (BA)-based risk assessment of soil heavy metals in provinces of China through the predictive BA-models.

The real biological effect is not generated by the total content of heavy metals (HMs), but rather by bioavailable content. A new bioavailability-based ecological risk assessment (BA-based ERA) framework was developed for deriving bioavailability-based soil quality criteria (BA-based SQC) and accurately assessing the ecological risk of soil HMs at a multi-regional scale in this study. Through the random forest (RF) models and BA-based ERA framework, the 217 BA-based SQC for HMs in 31 Chinese provinces were derived and the BA-based ERA was comprehensively assessed. This study found that bioavailable HMs extraction methods (BHEMs) and total HMs content play the predominant role in affecting HMs (As, Cd, Cr, Cu, Ni, Pb, and Zn) bioavailability by explaining 27.55-56.11% and 9.20-62.09% of the variation, respectively. The RF model had accurate and stable prediction ability for the bioavailability of soil HMs with the mean R2 and RMSE of 0.83 and 0.43 for the test set, respectively. The results of BA-based ERA showed that bioavailability could avoid the overestimation of ecological risks to some extent after reducing the uncertainty of soil differences. This study confirmed the feasibility of using bioavailability for ERA and will utilised to revise the soil environmental standards based on bioavailability for HMs.

Microbial community composition and degradation potential of petroleum-contaminated sites under heavy metal stress.

Total petroleum hydrocarbons (n-alkanes), semi-volatile organic compounds, and heavy metals pose major ecological risks at petrochemical-contaminated sites. The efficiency of natural remediation in situ is often unsatisfactory, particularly under heavy metal pollution stress. This study aimed to verify the hypothesis that after long-term contamination and restoration, microbial communities in situ exhibit significantly different biodegradation efficiencies under different concentrations of heavy metals. Moreover, they determine the appropriate microbial community to restore the contaminated soil. Therefore, we investigated the heavy metals in petroleum-contaminated soils and observed that heavy metals effects on distinct ecological clusters varied significantly. Finally, alterations in the native microbial community degradation ability were demonstrated through the occurrence of petroleum pollutant degradation function genes in different communities at the tested sites. Furthermore, structural equation modeling (SEM) was used to explain the influence of all factors on the degradation function of petroleum pollution. These results suggest that heavy metal contamination from petroleum-contaminated sites reduces the efficiency of natural remediation. In addition, it infers that MOD1 microorganisms have greater degradation potential under heavy metal stress. Utilizing appropriate microorganisms in situ may effectively help resist the stress of heavy metals and continuously degrade petroleum pollutants.

Ecotoxicity stress and bioaccumulation in Eisenia fetida earthworms exposed to vanadium pentoxide in soil.

As an important commercial form of vanadium, vanadium pentoxide (V2O5) is widely used in various modern industries, and its environmental impacts and ecotoxicity have been extensively studied. In this research, the ecotoxicity of V2O5 to earthworms (Eisenia fetida) in soil was tested by exposure to V2O5 at a series of doses, and biochemical response indices, such as the superoxide dismutase (SOD) and catalase (CAT) enzyme activity and malondialdehyde (MDA) content, were analysed to determine the mechanism by which antioxidant enzymes respond to V2O5 exposure. The bioaccumulation factor (BAF) of vanadium pentoxide in the earthworms and soil was also measured to explore the bioaccumulation process of V2O5 in the test period. The results showed that the acute and subchronic lethal toxicity values of V2O5 towards E. fetida were 21.96 mg/kg (LC50, 14 days) and 6.28 mg/kg (LC10, 28 days), respectively. For the antioxidant enzymes, SOD and CAT were synchronously induced or inhibited within the time period, and the enzyme activity had a dose-effect relationship with the V2O5 concentration. MDA analysis indicated that lipid peroxidation in earthworms mainly occurred at the early stage and was eliminated slowly in the later stage during the test time. In addition, the BAFs were much less than 1, which indicated that V2O5 did not easily accumulate in earthworms, and the BAF was positively correlated with the exposure time and negatively linearly correlated with the V2O5 concentration in the soil. These results indicated that the bioconcentration and metabolic mechanism of V2O5 in earthworms differed with the different exposure concentrations, and bioaccumulation became balanced after 14-28 days in earthworms exposed to a relatively lower dose of V2O5. The analysis of the integrated biomarker response (IBR) index indicated that the trends of IBR values were positively related to the changing V2O5 concentration, and the IBR index could reflect the organism's sensitivity to the external stimulus of V2O5. The toxicity of V2O5 is mainly caused by V5+, which is also an important factor in formulating guidelines regarding vanadium levels in soil, and the test earthworm species (Eisenia fetida) is a sensitive biological indicator for risk assessments of vanadium oxidation in the soil.

Assessment of soil heavy metal pollution in provinces of China based on different soil types: From normalization to soil quality criteria and ecological risk assessment.

Ecological risks can vary dramatically depending on abiotic factors, such as soil properties and the background values of elements. This study developed a framework for an integrated risk assessment system to derive soil quality criteria (SQC) for heavy metals (HMs) applicable to different soil types and to assess ecological risks at a multi-regional scale. Through the construction of normalization and species sensitivity distribution models, 248 SQC values for Cd, Pb, Zn, As, Cu, Cr, Sb, and Ni in 31 Chinese provinces were derived. These SQC considered the soil types and background values of the elements and effectively reduced the uncertainty caused by spatial heterogeneity. Using the derived SQC values, the qualitative and quantitative ecological risks of HMs in the terrestrial environment of China were comprehensively assessed using a three-level ecological risk assessment (ERA) approach. Compared to traditional ERA methods, the new methodology reached a more quantitative conclusion. The mean overall probabilities of ecological risk in China were 2.42 % (Cd), 2.82 % (Pb), 12.17 % (Zn), 14.89 % (As), 10.42 % (Cu), 32.20 %(Cr), and 8.88 % (Ni). The new framework could be useful for the ERA of various soil types.

Human health ambient water quality criteria and risk assessment of pentachlorophenol in Poyang Lake Basin, China.

Pentachlorophenol (PCP) has been widely used as an insecticide for killing oncomelania (the intermediate host of schistosome) in China and leads to severe environmental contamination. Poyang Lake, as the largest freshwater lake and bird habitat in China, was once a schistosomiasis epidemic area. In this study, the concentrations of PCP in water and aquatic products from Poyang Lake were determined and analyzed, and then the human health ambient water quality criteria (AWQC) was derived based on native parameters of Poyang Lake basin. Finally, a comprehensive analysis of the health risks of drinking water and different types of aquatic products consumption was carried out. The results showed that PCP concentrations were ranged from 0.01 to 0.43 µg/L in surface water and 3.90 to 85.95 µg/kg in aquatic products. Due to the carcinogenicity of PCP, the human health AWQC for PCP are 0.02 µg/L for consumption of water and organisms and 0.03 µg/L for consumption of organisms only. Deterministic and probabilistic risk analysis indicated that the non-carcinogenic risk of PCP were acceptable in Poyang Lake, while the carcinogenic risk cannot be ignored. The health risks of PCP caused by aquatic products consumption were higher than that by drinking water. The percentages of acceptable risk for the population in Poyang Lake Basin were 99.95% at acceptable level of 10-4. Based on the sensitivity analysis, the impact of PCP concentrations on health risk values ranged from 53 to 82%. The study provided valuable information for regional water quality criteria development and water quality assessment.

[Human Health Risk Assessment of Phenol in Poyang Lake Basin].

Phenol is widely used in the production of insulation and thermal insulation materials, adhesives, perfumes, coatings for food containers, paints, and pharmaceutical production, and is also widely detected in the aquatic environment. Long-term exposure to phenol can elicit adverse effects, such as skin burn, liver and central system damage. Here, phenol concentrations in the water and aquatic products of Poyang Lake were investigated. Human health risks from phenol to adults and adolescents were also assessed based on local population exposure parameters. The exposure concentration range of phenol in the studied water and aquatic products was not detected (ND)-556.26 ng·L-1 and 11.98-255.51 µg·kg-1, respectively. Human health risk based on drinking water in different areas ranged from 3.80×10-7-8.46×10-5. Higher human health risks from drinking water was detected in the southern area of Poyang Lake and at the confluence of the Yangtze River to the north. Health risks caused by different types of aquatic products ranges 2.65×10-5-1.47×10-4. In particular, human health risks from the consumption of yellow catfish and catfish are an order of magnitude higher than for other aquatic products. Probabilistic risk assessment was also conducted through Monte Carlo simulation to analyze the health risk to the population in the Poyang Lake Basin and assess its sensitivity of different exposure parameters. The 95th percentile health risk of drinking water and aquatic product consumption in the Poyang Lake Basin was calculated as being acceptable. Overall, the concentrations of phenol had the greatest impact on the calculated health risk values. This study provides valuable information for phenol risk management in the Poyang Lake basin.

Exposure and tiered ecological risk assessment of phthalate esters in the surface water of Poyang Lake, China.

Phthalate esters (PAEs) are a class of endocrine disruptors that are produced and used extensively in China. Given its presence in various products, a great quantity of PAEs flows into different aquatic systems each year. Hence, it is important to study the pollution levels and ecological risk of PAEs. This study investigated the distribution and seasonal variation of six priority PAEs in the surface water of Poyang Lake, the largest freshwater lake in China. In the wet season, the mean concentration of the total PAEs was 0.544 ± 0.173 µg/L, while the dry season concentration (1.003 ± 0.451 µg/L) nearly doubled. The most abundant PAE congeners were di-n-butyl phthalate (DBP), followed by bis (2-ethylhexyl) phthalate (DEHP). To evaluate the ecological risks in Poyang Lake, the predicted no-effect concentrations (PNECs) of four PAEs based on non-lethal effects were derived. For diethyl phthalate (DEP), butyl benzyl phthalate (BBP), DBP, and DEHP, the PNECs were 31.6, 3.30, 2.31, and 0.0210 µg/L, respectively. The tiered ecological risk assessment showed that DEP and BBP posed no risk in Poyang Lake. Meanwhile, DBP posed a potential risk in Poyang Lake, but the risk of DEHP was unacceptable and requires more actions. Specifically, the probabilities of exceeding the threshold for the protection of 95% of the aquatic organisms (HC5) were 3.30% and 4.43% for DEHP in the wet and dry season, respectively. This study provides an appropriate reference for the surface water management of PAE pollution in China.

Ammonia spatiotemporal distribution and risk assessment for freshwater species in aquatic ecosystem in China.

Ammonia has been of concern for its high toxicity to aquatic species and frequent detection in waters worldwide. This study calculated the national aquatic life criteria for ammonia in China. The temporal and spatial distributions were investigated and the multi-tier ecological risks were assessed for ammonia and un-ionized ammonia (NH3) during 2014-2018 based on a total of 18989 ammonia monitoring data from 110 monitoring sites in seven river basins. The sensitivity comparison of different species taxa to ammonia showed that Perciformes fish should be listed as a priority protected species in the derivation of ammonia criteria. The participation of introduced aquaculture species have no significant impact on the final criteria values (t-test, p > 0.05). The final criterion maximum concentration (CMC) and criterion continuous concentration (CCC) were 10.24 and 3.31 mg/L for ammonia (pH 7.0 and 20 °C). The interannual variation showed that decreasing trends were observed for ammonia and NH3 pollutions in the past five years. However, the increasing trends were observed for ammonia in Liao River basin, for NH3 in Yangtze River and Pearl River basins (2014-2018). The significant seasonal and geographical differences of ammonia and NH3 pollution were found. Moreover, the pollutions of ammonia and NH3 in some monitoring points of Huai River, Yellow River and Songhua River basins at the provincial borders were significant. The result of ecological risk assessment showed that the average exceedance probability for 5% affected species by NH3 in long-term exposure was 28.96% in the past five years.

Ecological and health risk assessment of perfluorooctane sulfonate in surface and drinking water resources in China.

Perfluorooctane sulfonate (PFOS) is a synthetic substance with a great number of applications. However, it persists in the environment and is potentially toxic to organisms. Although China has been the main manufacturer and consumer for PFOS, the national pollution level and potential risk of this chemical are yet to be determined. This study aimed to provide an overview of PFOS contamination in surface and drinking water across China and to assess the potential ecological and health risks. Available monitoring data for PFOS in surface and drinking water were evaluated. PFOS was found to be ubiquitous in China, but the overall level of contamination was low compared with that in other countries. The southeast coastal area of China, with major PFOS-related companies, was characterized by relatively high PFOS exposure concentrations. The most sensitive effects was screened and applied to assess the ecological risk using the joint probability curve method. The probability of exceeding the growth and development toxicity for 5% of aquatic species was 0.65% in Chinese surface waters, while the highest probability of 0.90% was in Tai Lake in east China. Considering the average daily dose (ADD) for the Chinese population, the health risk posed by PFOS through drinking water ranged from 1.31 × 10-4 to 13.91. Besides the relatively high health risk existed in east China, most health risks in China were acceptable.

Aquatic life criteria derivation and ecological risk assessment of DEET in China.

N,N-diethyl-meta-toluamide (DEET) is the most widely used active ingredient in commercial insect repellents. In addition to its adverse effects in insects, DEET can affect non-target organisms in surface water systems. Nevertheless, the aquatic life criteria of DEET are not available. This study conducted both acute and chronic toxicity tests on DEET in native Chinese aquatic species, and derived its criterion maximum concentration (CMC) and criterion continuous concentration (CCC). The determined CMC and CCC of DEET were 21.53 and 0.52 mg/L, respectively. The toxicity data indicated that DEET exposure posed a higher toxicity to some algae than other aquatic species. Compared with other insect repellents, DEET exposure posed a moderate toxicity to aquatic species. Therefore, the exposure concentration of DEET in Chinese surface water was collected to assess the potential ecological risk. The preliminary ecological risk assessment showed that DEET posed negligible risk to aquatic ecosystems in China. However, considering its toxic effects on the growth and reproduction to aquatic organisms, the ecological risk posed by DEET is worth further concern.

Study of aquatic life criteria and ecological risk assessment for triclocarban (TCC).

Triclocarban (TCC) is used as a broad-spectrum antimicrobial agent, the intensive detection of TCC in aquatic environments and its potential risks to aquatic organisms are concerned worldwide. In this study, 8 Chinese resident aquatic organisms from 3 phyla and 8 families were used for the toxicity tests, and four methods were employed to derive the aquatic life criteria (ALC). A criterion maximum concentration (CMC) of 1.46 µg/L and a criterion continuous concentration (CCC) of 0.21 µg/L were derived according to the USEPA guidelines. The acute predicted no effect concentrations (PNECs) derived by species sensitivity distribution (SSD) methods based on log-normal, log-logistic and Burr Type Ⅲ models were 2.64, 1.88 and 3.09 µg/L, respectively. The comparisons of ALCs derived with resident and non-resident species showed that the CMC and CCC of TCC derived with Chinese resident species could provide a sufficient protection for non-resident species. The higher toxicity of TCC on aquatic organisms was found compared with other antimicrobial agents (except for Clotrimazole) in aquatic environment. The strong positive linear correlation was observed between the TCC and TCS concentrations in aquatic environment with a correlation coefficient (R2) of 0.8104, it is of great significance in environmental monitoring and risk assessment for TCC and TCS. Finally, the ecological risk assessment showed that the TCC in Yellow River basin and Pearl River basin had higher risk with the mean potential affected fractions (PAFs) of 9.27% and 7.09%, and 22.10% and 15.00% waters may pose potential risk for 5% aquatic organisms, respectively. In general, the risk of TCC in Asian waters was higher than that in Europe and North America.