Modelling nitrogen and phosphorus export by the Pearl River in China 1970–2050

Abstract

China is a country with a rapid economic development and fast population growth. This is causing environmental pollution. Eutrophication has been a problem in the coastal waters of southern China since the 1970s. This is a result of increased nitrogen (N) and phosphorus (P) inputs from rivers such as the Pearl River (Zhujiang). The Pearl River is the third largest river in China. It serves as an important water supplier for irrigation and human water consumption. Human activities on land, however, have increased the nutrient content of the Pearl River water considerably. The objective of our study is to quantify the relative contribution of the anthropogenic and non-anthropogenic sources of dissolved inorganic N and P export by the Pearl River to coastal seas. We describe a method to model dissolved N and P export at the sub-basin scale. Results indicate that in 2000 about 90% of the dissolved N and P inputs exported by the Pearl River to the coastal waters were from anthropogenic sources (e.g. agriculture, sewage, and biological N 2 -fixation by agricultural crops). In the future the relative share of anthropogenic sources may increase. We show that nutrient inputs from land to rivers vary among sub-basins. We conclude that modelling and scenario analyses may support the formulation of effective strategies to reduce N and P export by the Pearl River, and thus to effective management of coastal eutrophication in the coming decades.

Alarming nutrient pollution of Chinese rivers as a result of agricultural transitions

“…In this study we used model inputs that reflect a global orchestration scenario assuming globalized trends towards socio-economic development and reactive management of environmental problems. This scenario was implemented in the sub-basin Global NEWS-2 model as a starting point [16,45]. The total population is assumed to have increased slightly by 2050 because of better education (e.g., low mortality and fertility rates, and high migration).…”

Increasing dissolved nitrogen and phosphorus export by the Pearl River (Zhujiang): a modeling approach at the sub-basin scale to assess effective nutrient management

“…In a recent study (Strokal et al 2014b) we evaluated further the model for DIN and DIP export by Chinese rivers (including the Pearl River). We used the Pearson's coefficient of determination (R P 2 ), R NSE 2 and Model error (ME) (see Moriasi et al (2007) and Strokal et al (2014a) for detailed descriptions). We calculated R P 2 of 0.96, R NSE 2 of 0.42 and ME of 18 % for DIN and DIP export by the Chinese rivers.…”

Reducing nutrient pollution in water systems in China: challenges, trends and solutions

“…Agricultural greenhouse gas emissions (e.g., N2O) contributed 17% to the national emissions from China (Chai et al, 2013;IEA, 2007;Nayak et al, 2013). Discharge of N and P to rivers results in eutrophication in many Chinese rivers (e.g., Yangtze, Yellow and Pearl rivers) and seas such as the Bohai Gulf, Yellow sea and South China sea Müller et al, 2008;Qu and Kroeze, 2010;Strokal et al, 2014a;Strokal et al, 2014b;Sumei et al, 2008;Xie et al, 2014). This pollution will likely continue to increase in the future, as a result of the food demand by a growing population in China (Alexandratos and Bruinsma, 2012).…”