Research Status of Water Quality Criteria and Standards and Analysis on the Transformation Methods

Under the vision of development for the new era,China has entered a stage of high-quality economic development and an important window period in which we have the conditions and ability to address the prominent issue of economic development and ecological protection in a coordinated way.However,all kinds of environmental benchmark values in China are lacking and need to be constantly supplemented and improved.Therefore,exploring and putting forward a simple and efficient method for the transformation of environmental criteria into environmental standards is an important basis for the rapid establishment of relevant environmental criteria system and the effective promotion of the development of environmental standards system towards a scientific and reasonable direction.In this paper,the water environment is taken as the research object.By analyzing the research progress of environmental criteria and standards at home and abroad,and the foreign method of transforming environmental criteria into environmental standards,combined with the problems faced in the process of transforming environmental criteria into environmental standards in China,an effective method to transform China's environmental criteria into environmental standards is analyzed.After analysis and comparison,it is found that the pollution reduction accounting method could achieve their simple and efficient conversion.Under the premise of obtaining environmental criteria for certain pollutants,environmental criteria for certain pollutants could be obtained by distributing pollutants reduction costs,and accounting economic benefits after reaching standard,thus obtaining the environmental standard of this type of pollutant,which provides reference to determine the environmental standard limits of such pollutants.

Resilient water quality management: Insights from Japan's environmental quality standards for conserving aquatic life framework

Currently,chemicals and waste are recognized as key drivers of habitat degradation and biodiversity loss in aquatic ecosystems.To ensure vibrant habitats for aquatic species and maintain a sustainable aquatic food supply system,Japan promulgated its Environmental Quality Standards for the Conservation of Aquatic Life(EQS-CAL),based on its own aquatic life water quality criteria(ALWQC)derivation method and application mechanism.Here we overview Japan's EQS-CAL framework and highlight their best practices by examining the framework systems and related policies.Key experiences from Japan's EQS-CAL system include:(1)Classifying six types of aquatic organisms according to their adaptability to habitat status;(2)Using a risk-based chemical screening system for three groups of chemical pollutants;(3)Recommending a five-step method for determining ALWQC values based on the most sensitive life stage of the most sensitive species;(4)Applying site-specific implementation mechanisms through a series of Plan-Do-Check-Act loops.This paper offers scientific references for other jurisdictions,aiding in the development of more resilient ALWQC systems that can maintain healthy environments for aquatic life and potentially mitigate ongoing threats to human societies and global aquatic biodiversity.

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.

Water quality criteria research and progress

Water quality criteria (WQC) are threshold limits for pollutants or other hazard factors in the ambient water environment, which are based on scientific experiments and extrapolations. Until now, there is limited information available regarding the study of water quality criteria in China. It is imperative to launch national-level systematic WQC studies that focus on the regional characteristics of China and provide scientific support for the enactment or revision of water quality standards and environmental management. This article reviews the concept of WQC and discusses the methodology and global progress of WQC research. The article also summarizes the key scientific issues in WQC research, including species sensitivity distribution, toxicological endpoint selection, and models selection. Furthermore, we can adopt the derivation method used in the USA and divide WQC into acute and chronic criteria. Finally, considering the current status of WQC research in China, we point out important directions for future national studies, including the selection of native species and the comprehensive use of models.

Human health ambient water quality criteria for 13 heavy metals and health risk assessment in Taihu Lake

Heavy metals are widely concerning because of their toxicity,persistence,non-degradation and bioaccumulation ability.Iluman health ambient water quality criteria(AWQC)are specific levels of chemicals that can occur in water without harming human health.At present,most countries do not consider the effects of aquatic vegetables in deriving human health AWQC.Therefore,the intake of aquatic vegetables(Brasenia schreberi)was added to the derivation of human health AWQC and a health risk assessment for 13 heavy metals in Taihu Lake.The human health AWQC(consumption of water,fish and aquatic vegetables)values of 13 heavy metals ranged from 0.04(Cd)to 710.87μg/L(Sn),and the intake of B.schreberi had a very significant effect on the human health AWQC for Cu,with a more than 62-fold difference.The hazard quotients of As(2.8),Cd(1.6),Cr(1.4)and Cu(4.86)were higher than the safe level(HQ=1),indicating that As,Cd,Cr and Cu in Taihu Lake posed a significant health risk.Sensitivity analysis showed that the contribution rate of B.schreberi intake to the human health risk from Cu was 91.6%,and all results indicated that the risk of Cu in B.schreberi to human health should be of particular concern.This study adds the consideration of aquatic vegetable consumption to the traditional method of human health AWQC derivation and risk assessments for the first time,and this approach can promote the development of risk assessments and water quality criteria.

Determination of water environment standards based on water quality criteria in China:Limitations and feasibilities

There is a need to formulate water environment standards（WESs） from the current water quality criteria（WQC） in China.To this end,we briefly summarize typical mechanisms applied in several countries with longer histories of developing WESs,and three limitations to formulating WESs in China were identified.After analyzing the feasibility factors including economic development,scientific support capability and environmental policies,we realized that China is still not ready for a complete change from its current nation-wide unified WES system to a local-standard-based system.Thus,we proposed a framework for transformation from WQC to WESs in China.The framework consists of three parts,including responsibilities,processes and policies.The responsibilities include research authorization,development of guidelines,and collection of information,at both national and local levels;the processes include four steps and an impact factor system to establish water quality standards;and the policies include seven specific proposals.

The Derivation of Nutrient Criteria for the Adjacent Waters of Yellow River Estuary in China

Ecological protection and high-quality development of the Yellow River basin are becoming part of the national strategy in recent years.The Yellow River Estuary has been seriously affected by human activities.Especially,it has been severely polluted by the nitrogen and phosphorus from land sources,which have caused serious eutrophication and harmful algal blooms.Nutrient criteria,however,was not developed for the Yellow River Estuary,which hindered nutrient management measures and eutrophication risk assessment in this key ecological function zone of China.Based on field data during 2004-2019,we adopted the frequency distribution method,correlation analysis,Linear Regression Model(LRM),Classification and Regression Tree(CART)and Nonparametric Changepoint Analysis(nCPA)methods to establish the nutrient criteria for the adjacent waters of Yellow River Estuary.The water quality criteria of dissolved inorganic nitrogen(DIN)and soluble reactive phosphorus(SRP)are recommended as 244.0μg L^(−1) and 22.4μg L^(−1),respectively.It is hoped that the results will provide scientific basis for the formulation of nutrient standards in this important estuary of China.

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.