ABSTRACT
China has formulated several policies to alleviate the water pollution load, but few studies have quantitatively analyzed their impacts on future water pollution loads in China. Based on grey water footprint (GWF) assessment and scenario simulation, we analyze the water pollution (including COD, NH3-N, TN and TP) in China from 2021 to 2035 under different scenarios for three areas: consumption-side, production-side and terminal treatment. We find that under the current policy scenario, the GWF of COD, NH3-N, TN, and TP in China could be reduced by 15.0 % to 39.9 %; the most effective measures for GWF reduction are diet structure change (in the consumption-side area), and the wastewater treatment rate and livestock manure utilization improvement (in the terminal treatment area). However, the GWF will still increase in 8 provinces, indicating that the current implemented policy is not universally effective in reducing GWF across all provinces. Under the technical improvement scenario, the GWF of the four pollutants will decrease by 54.9 %-71.1 % via improvements in the current measures related to current policies and new measures in the production-side area and the terminal treatment area; thus, GWF reduction is possible in all 31 provinces. However, some policies face significant challenges in achieving full implementation, and certain policies are only applicable to a subset of provinces. Our detailed analysis of future water pollution scenarios and response options to reduce pollution loads can help to inform the protection of freshwater resources in China and quantitatively assess the effectiveness of policies in other fields.
ABSTRACT
The threshold effect in the relationship between impervious surfaces and water quality has been a focus in past decades, but little attention has been paid to how the threshold effect changes during a rapid urbanization period. This study reveals the temporal variation of threshold effect in the relationship between the percentage of total impervious area (PTIA) and water quality indicators in a reticular river network area in Shanghai, China. The PTIA was surveyed and defined using the ISC method (impervious surface coefficients). A segmented regression model was used to disclose the non-linear relationship between PTIA and water quality. It is confirmed that the threshold effect was different in terms of water quality indicators, but the effect size became smaller as the threshold increased with urbanization level during the period of 1989-2010. Meteorological conditions make influence on the threshold effect, it can be found that the effect is more significant under higher air temperature conditions, while in the lower temperature situation, there is no significant threshold effect.
