Chinese Technical Guideline for Deriving Water Quality Criteria for Protection of Freshwater Organisms.

In recent years, China has determined the national goal of "developing national environmental criteria", thereby promoting the rapid development of environmental quality criteria research in China. In 2017, the Ministry of Ecology and Environment of China (MEEC, formerly the Ministry of Environmental Protection of China) issued the technical guideline for deriving water quality criteria (WQC) for protection of freshwater organisms (HJ 831-2017), and in 2022, they organized the guideline revision and issued an updated version (HJ 831-2022). The primary contents of the revision included the following. The minimum toxicity data requirements were upgraded from 6 to 10, and the species mean toxicity value was replaced by the same effect toxicity value for the criteria calculation. It is now required that the tested organisms must be distributed in China's natural fresh waters, and the toxicity data of non-native model species will no longer be used. The list of freshwater invasive species in China that cannot be used as test species was added into the guideline. The acute/chronic ratio (ACR) method for the criteria derivation and the extreme value model were deleted, and the provisions for testing the toxicity data distribution were also deleted. The exposure time of the toxicity test of various tested organisms was refined, and the priority of the toxicity data was clearly specified. This paper introduces the framework and specific technical requirements of HJ 831-2022 in detail, including data collection, pre-processing of toxicity data, criteria derivation, fitting models, and quality control. This introduction is helpful for international peers to understand the latest research progress of China's WQC.

Co-occurrence trend and association study of Internet addiction and depressive symptoms among students in Inner Mongolia Autonomous Region / 中国学校卫生

Objective@#To investigate the prevalence of Internet addiction and depression of students, and to analyze the co-occurrence and trend, so as to provide a theoretical basis for prevention and controlling measures of Internet addiction and depression.@*Methods@#A total of 6 317,7 152,81 808,71 180 and 89 932 students aged 10 to 24 years from 12 leagues (103 banners) in Inner Mongolia Autonomous Region were selected by stratified random cluster sampling in September each year from 2017 to 2021. The Internet Addiction Scale and the Central for Epidemiologic Studies Depression Scale(CES-D) was used to measure Internet addiction and depression. And the annual inspection rate, group difference and annual change trend in students were calculated. Multivariate linear regression and restricted cubic spline analysis were used to estimate the linear and non linear associations between Internet addiction and depression in students.@*Results@#The Internet addiction proportion in students gradually decreased from 4.1% in 2017 to 2.1% in 2020, but increased to 3.9% in 2021. And the depressive symptoms proportion increased from 20.9% in 2017 to 28.0% in 2020 and 27.0% in 2021. The detection rate of Internet addiction and depression comorbidities remained at 1.8% to 2.5 %. The Internet addiction proportion in boys was higher than that in girls( χ 2=42.82， P <0.05). The depressive symptoms prevalence in girls was higher than that in boys( χ 2= 553.90， P <0.05). Taking reversal in prevalence of Internet addiction in urban and rural areas was observed in 2019. The detection rates of depressive symptoms and comorbidity were higher in urban areas than these in suburban counties on the whole, and the difference showed a trend of decreasing or even equalizing year by year. Internet addiction was positively correlated with depressive symptoms score ( B=1.67, 95%CI =1.64-1.71), the proportion of depressive symptoms ( OR=1.39, 95%CI =1.38-1.41) and the proportion of major depressive symptoms ( OR=1.35, 95%CI =1.33-1.36) among students in 2021 ( P <0.05). An N-shaped curve was found in the significant nonlinear associations between internet addiction and depression across sex, region and school stage.@*Conclusion@#Internet addiction and depression in students show significant linear and non-linear associations, which are consistent in different sexes, regions and school stages. Therefore, relevant measures should be made and implemented in each region, especially in suburb areas, so as to prevent the increasingly development of adolescents and children s Internet addiction and depression.

[Dynamic Mechanisms of Groundwater Quality by Residual Contaminants of the Tanghe Wastewater Reservoir in Xiong'an New Area].

Tanghe wastewater reservoir(TWR) is located on the west side of Baiyangdian Lake in Xiong'an New Area, where sewage infiltration and irrigation has been taking place for 40 years, and a large number of contaminants have accumulated in the unsaturated zone. Identifying the mechanisms by which this combined system contributes to groundwater hydrochemical dynamics is important for the protection of the water environment in the area. Hydrogeochemical methods such as tracing and improved chlor-alkali index are used to analyze the spatial and temporal characteristics and evolution mechanisms of shallow groundwater. The study shows that the groundwater chemistry in the sewage reservoir area is SO4·HCO3-Na type, with an average sewage fraction of 48.4%, and the contribution of Na+ from ion exchange and halite dissolution is 29.9% and 8.6%, respectively. The chemical type of groundwater in the sewage irrigation area is SO4·HCO3-Na·Mg, the average sewage fraction is 58.3%, and Na+ consumption of ion exchange is 8.1%. The mix dilution of precipitation and irrigation leads to a reduction in the effluent fraction and saturation index in the groundwater, and promotes the adsorption of Na+ from groundwater into the soil. Denitrification in aquifers can effectively reduce groundwater nitrate pollution. In addition, the sewage fraction before and after the restoration of the reservoir was 61.5% and 49.3%, respectively. Pollutants retained in the sewage infiltration and irrigation combined system will continue to affect the quality of shallow groundwater with varying degrees of mixing and water-rock interaction driven by rainfall and irrigation.

[Characteristics of Carbon and Nitrogen in the Downstream Columnar Sediment of Maozhou River, Shenzhen].

Based on the determinations of total nitrogen (TN), organic matter (OM), carbon-nitrogen ratio (C/N), δ15 N, and δ13 C on 12 sediment cores, the distribution characteristics and the sources of nitrogen and organic matter were analyzed in sediments from the lower reaches and main tributaries of the Maozhou River. The results showed that the average concentrations of total nitrogen (TN) and organic matter (OM) were 1815.37 mg·kg-1 and 22 401.68 mg·kg-1, respectively, in the Maozhou River sediments, which were higher than in TaihuLake and ChaohuLake. The levels of TN and OM in the study area were high and varied greatly with the increase of depth. The δ15 N content in the sediments of the MaozhouRiver downstream ranged from 2.20 ‰ to 32.78 ‰, while the δ13 C content ranged from -27.53 ‰ to -21.95 ‰. The average concentrations of δ15 N and δ13 C were 6.78 ‰ and -25.41 ‰. Moreover, the C/N ratio ranged from 0.49 to -18.23. The δ13 C varied slightly with the increase of depth, while δ15 N and C/N varied greatly. A source analysis in the study area indicated that C3 plants and chemical fertilizer were the main sources in the surface sediments (0-40 cm) downstream of the Maozhou River. Furthermore, algae were the main sources of organic matter in the deep sediments downstream of the Maozhou River and in tributary sediments of the Shajing River. Nitrogen in the surface sediments (0-40 cm) downstream of the Maozhou River mainly comes from inorganic fertilizer and soil organic nitrogen, while nitrogen in the Maozhou River deep sediments and Shajing River sediments mainly come from soil erosion and soil organic nitrogen.

[Modeling of Water Quality Response to Land-use Patterns in Taizi River Basin Based on Partial Least Squares].

Land use change in river basin is one of the most significant factors that influence river water quality. Based on remote sensing images and river water quality data of Taizi River Basin, partial least squares (PLS) model was applied to explore the relationship between water quality and land use patterns at sub-watershed scale. In this study, PLS model was established by using the percentage of area of land use patterns from seven different sub-watersheds as the variables and the concentrations of four water quality parameters as the observations. The established model was further tested with the data from other sub-watersheds in Taizi River Basin. The results indicated that total nitrogen (TN) and nitrate (NO3-) were significantly associated with land use types in Taizi River Basin with determination coefficient (R2) greater than 0.62. As for chloride (Cl-) and sulfate (SO42-), measured values and fitted values had a relatively low fitting precision (R2<0.5), which meant land use pattern was not the main factor affecting the concentrations of Cl-and SO42- in river water. Meanwhile, river water quality had a strong correlation with the percentage of area of unused land at the sub-basin scale (influence coefficient>0.24), although unused land area in the Taizi river basin was small.

[Spatial distribution and risk assessment of atrazine in Taizi River basin, China].

Atrazine (AT) has been detected in surface water and groundwater in many countries and regions around the world. Concentrations of AT in surface water, suspended particulate matter (SPM) and groundwater samples collected from the Taizi River basin, in northeast China, were analyzed using a gas chromatograph-mass spectrometer (GC-MS) in order to clarify their spatial distribution and environmental behavior, and to assess their potential ecological risk. Concentrations of AT varied from 0-734.0 ng x L(-1) for surface water, 0-1 493.6 ng x g(-1) for SPM and 30.0-245.0 ng x L(-1) for groundwater, with averages of 335.3 ng x L(-1), 382.9 ng x L(-1), and 104.4 ng x L(-1), respectively. The logarithm in situ SPM-water partition coefficients (lg k(oc)) of AT were in the range of 3.50-4.14 indicating that adsorption of AT from the aqueous phase to SPM plays an important role in dissipating AT in surface water. Fluxes of AT in surface water ranged from 1.5-184.7 mg x s(-1) in the basin, calculated based on the measured flow velocity and concentrations in surface water and SPM. The maximum value of AT flux was found in the middle stream of the Taizi River (S7). The risk assessment suggested that the ecological risk of AT in surface water was low, with more than 95% of the species protected from risk in the Taizi River basin. However, the residue levels of AT in surface water of the Taizi River basin may cause potential environmental risks.

Occurrence and partitioning of phenolic endocrine-disrupting chemicals (EDCs) between surface water and suspended particulate matter in the north Tai Lake basin, eastern China.

Concentrations and distribution of octylphenol (OP), nonylphenol (NP), and bisphenol A (BPA) in surface water and suspended particulate matter (SPM) from the north Tai Lake basin, China were studied. Aqueous and particulate (dry weight) concentrations for OP, NP, and BPA varied from 10.5-1,175 ng/L to <1.52-5,365 ng/g, respectively. The spatial distribution of endocrine-disrupting chemicals (EDCs) in dissolved and particulate phases showed that the amount of EDCs in water that were adsorbed to SPM gradually increased from upstream to downstream. There were good correlations between particulate EDCs and particulate organic carbon, with correlation coefficients of 0.46-0.57. Regression analysis of in situ SPM-water partition coefficients (log K' oc) and log K ow for EDCs indicated that the hydrophobicity of chemicals greatly contributed to their SPM-water partitioning. Strong positive correlations (r = 0.68-0.82) among in situ log K' oc of OP, NP, and BPA and flow velocity of water were observed, indicating the critical importance of riverine hydrodynamics on the sorption of these compounds.

Behavior, mass inventories and modeling evaluation of xenobiotic endocrine-disrupting chemicals along an urban receiving wastewater river in Henan Province, China.

Historically, the locations of cities mainly depend on the available water source and the urban river not only supplies the fresh water to city but also receives its wastewaters. To analyze the influences of urban zone on its receiving water river, the Jialu River in Henan Province, China, a typical urban river was chosen. Water and sediment samples were collected along the river in 2007 to analyze the concentrations of xenobiotic endocrine-disrupting chemicals (XEDCs) including nonylphenol (NP), octylphenol (OP) and bisphenol A (BPA) in surface water and sediment. The results showed that the concentrations of OP, NP and BPA in surface water were 20.9-63.2 ng L(-1) (mean 39.8 ng L(-1)), 75.2-1520 ng L(-1) (mean 645 ng L(-1)), 410-2990 ng L(-1) (mean 1535 ng L(-1)), respectively. The lowest and highest concentrations of XEDCs in surface water were found in the upper stream and downstream of Zhengzhou urban zone, which was regarded as the major discharge source of these chemicals to this river. The concentrations of OP, NP and BPA in the sediment were 15.9-31.1 ng g(-1), 145-349 ng g(-1) and 626-3584 ng g(-1) with the average concentrations of 21.4 ng g(-1), 257 ng g(-1) and 2291 ng g(-1), respectively. The results of in situ sediment-water partition of XEDCs showed that the partition coefficients (log K(oc)') in the downstream were higher than that in the upstream, which was mainly caused by the retransfer of surface sediment from the upper stream to the downstream. Comparison of measured and theoretical inventories of XEDCs in sediment indicated that the residual time of XEDCs in sediment in the river was about 5 years, which was in the same order of magnitude with its big flood frequency. In order to predict concentration variances of XEDCs in surface water, a fugacity-hydrodynamic model was developed according to the concept of in series completely stirred tank reactors (CSTR). The model results showed that about 29-65% of XEDCs derived from the urban zone (about 2.0 t yr(-1)) would finally dissipate from aqueous phase in the 170 km downstream of the river. Assuming the discharge amount of XEDCs from the urban zone remaining constant, the predicted concentrations of the total XEDCs in the over 90% river reach would be higher than 1.0 µg L(-1) under all normal, high water and low water season in 2007.

Behavior and fate of alkylphenols in surface water of the Jialu River, Henan Province, China.

The behavior and fate of alkylphenols (APs) were studied in surface water from the Jialu River, Henan Province, China. Located at its upper stream, Zhengzhou city is regarded as the major discharge source to this river with its annual effluents containing 726 kg for nonylphenol (NP) and 30.2 kg for octylphenol (OP). The concentrations of NP and OP in surface water ranged from 75.2 to 1520 ngL(-1) and from 20.9 to 63.2 ngL(-1), respectively. To assess the behavior of APs along the river, a mass balance equation based on chloride was adopted, due to its relative conservation. The results showed that dilution effect was prevailing in determining the APs concentrations in surface water along the river. The effect of potential biodegradation was also estimated with an assumption of the optimized biodegradation. The contributions of dilution and biodegradation to the decline of APs concentrations were 38.8%, 23.7% for NP and 57.8%, 24.3% for OP, respectively. The other contribution to the decline of APs concentrations along the river was considered as an integrated effect of adsorption and air-water exchange with the values of 37.5% for NP and 17.9% for OP. The decay half-lives of NP and OP from surface water bodies were 1.6 and 2.4d, respectively. About 70.2% of total NP and 24.1% of total OP were finally eliminated from water phase to surrounding matrix in the downstream. The results suggested that the downstream river channel served as the net sink of APs in the study area.