Dieldrin is legacy organochlorine insecticide, which was listed in the Stockholm Convention because of its persistence, bioaccumulation and toxicity. However, it is still present in the environment and in organisms two decades after its ban. The current criteria used for risk assessment in China are based on acute toxicity data in water columns without considering the bioavailability and bioaccumulation, which accordingly lead to the under-protection of aquatic organisms and wildlife. In this study, the water quality criteria (WQC) for dieldrin were derived from a combination of tissue-based toxicity data and the bioaccumulation factor (BAF) to better protect aquatic ecosystems. The dieldrin residue data in surface water in China were obtained by literature review and the ecological risk was assessed using the quotient method. Combined with a BAF of 58,884.37 L/kg estimated by the model, the WQC were calculated as needing to be 3.86 and 1.4 ng/L to protect aquatic life and aquatic-dependent wildlife, respectively. The results of the risk assessment revealed the potential high risk posed by dieldrin bioaccumulation. This study provides scientific guidance for the determination of the water quality standard for dieldrin and to ensure the risk management of the aquatic environment in China.

Urban agglomerations rely on both direct physical water intake and substantial virtual water embedded in cross-regional traded commodities and services to meet water demand. It is important to analyze the complex virtual water flows in urban agglomerations to advance sustainable water utilization and coordinated regional sustainable development. In this study, we constructed a multi-scale hierarchical analysis framework covering industrial sectors, internal cities and external hinterland regions by coupling multi-regional input–output (MRIO), ecological network analysis (ENA), and structural decomposition analysis (SDA). The framework was adopted to quantify consumption-driven virtual water flows across the Pearl River Delta (PRD) urban agglomeration in 2012, 2017 and 2022. Furthermore, we quantified the economic value of virtual water flows by considering water rights trading prices, which mainly reflect the scarcity value of regional water resources, aiming to provide new perspectives for water resources compensation and sustainable water management decision making. The results showed that the virtual water flows mainly satisfied food-related water requirements in the PRD. Declining water use intensity in external supply regions was the dominant factor reducing the water footprint in the PRD. The virtual water flows had greater economic value in the water-scarce northern provinces. On this basis, we put forward targeted financial subsidy recommendations for water-supplying external regions; the above economic quantification serves as the core evidence supporting this subsidy proposal. This work provides decision support for formulating sustainability-oriented water policies, balancing interregional water ecological benefits, and realizing long-term sustainable utilization of water resources.

Dieldrin is legacy organochlorine insecticide, which was listed in the Stockholm Convention because of its persistence, bioaccumulation and toxicity. But it is still present in the environment and in organisms two decades after its ban. The current criteria used to risk assessment in China are based on acute toxicity data in water column without considering the bioavailability and bioaccumulation, which accordingly lead to under-protection of aquatic organisms and wildlife. In this study, the water quality criteria (WQC) for dieldrin were derived in combination of tissue-based toxicity data and bioaccumulation factor (BAF) to better protect aquatic ecosystems. The dieldrin residue data in surface water in China were obtained by literature review and the ecological risk was assessed using quotient method. Combined with the BAF estimated by the model of 58884.37 L/kg, the WQC were calculated to be 3.07 and 1.5 ng/L to protect aquatic life and aquatic-dependent wildlife, respectively. The results of the risk assessment revealed the potential high risk posed by dieldrin bioaccumulation. This study provides a scientific guidance for the determination of water quality standard for dieldrin and ensure the risk management of aquatic environment in China.