In China, increased human activities have successfully resulted in sufficient food and energy to meet the large population. However, these activities - together with poor nutrient management - have led to considerable nutrient losses from land to aquatic ecosystems, causing water pollution (Ma et al., 2012; Strokal et al., 2014). This situation will likely worsen in the future due to the continuously growing population and economy (Jiang, Xu, & Song, 2007). To address environmental problems related to nutrient losses in China, a quantitative understanding of nutrient flows from land to sea as affected by human activities is required.
In November 2014, Wageningen University (WU), Chinese Academy of Sciences (CAU) and Peking University of China (PKU) started a joint PhD research on river export of nutrients to coastal waters of China by linking three complementary models (Figure 1).
The main research objective is to better understand nutrient export from land to Chinese coastal waters as affected by human activities and to provide options to reduce coastal water pollution in China. This will be done by linking and applying three complementary models in Chinese river basins to get insights in the whole process of nutrient export from land to sea as affected by human activities. We will also develop new scenarios aimed at identifying nutrient management strategies to reduce nutrient inputs to land, rivers and coastal waters.
We use the Global NEWS, NUFER and MAREM models in this research. Global NEWS (Global Nutrient Export from WaterSheds) is a spatially explicit model that calculates nutrient (N, P, C and Si) export by rivers taking into account anthropogenic and natural drivers (Mayorga et al., 2010). NUFER (NUtrient flows in Food chains, Environment and Resources use) quantifies N and P use efficiencies and their losses in the food chain in China, considering agricultural drivers in food production and consumption (Ma et al., 2012). MAREM (Multi-agent Agricultural household model for Rural Environmental Management) is an agent-based model that simulates agricultural households’ behavior and their environmental impacts in rural China (Yang, Qu, Luan, & Kroeze, 2014).
We will link Global NEWS and NUFER models and validate this linked model system using available measurement data. This model system enables to examine how do past, present and future N and P use efficiencies in the food chain affect nutrient export from land to coastal waters. We will perform a sensitivity analysis to identify the determine factors influencing nutrient export from land to coastal waters. New scenarios will be developed by interpreting the new SSPs-RCPs scenarios (Kriegler et al., 2013) and by incorporating farmer’s behavior that is simulated by the MAREM model. These new scenarios will be implemented in the NUFER-NEWS model system to identify the effective nutrient management strategies to reduce coastal water pollution in China.
Jiang, Z., Xu, K., & Song, J. (2007). The report on China's national strategy on population (in Chinese). Beijing: China population development research group.
Kriegler, E., Edmonds, J., Hallegatte, S., Ebi, K. L., Kram, T., Riahi, K., . . . van Vuuren, D. P. (2013). A new scenario framework for climate change research: the concept of shared climate policy assumptions. Climatic Change, 1-14.
Ma, L., Velthof, G., Wang, F., Qin, W., Zhang, W., Liu, Z., . . . Ma, W. (2012). Nitrogen and phosphorus use efficiencies and losses in the food chain in China at regional scales in 1980 and 2005. Science of the Total Environment, 434, 51-61.
Mayorga, E., Seitzinger, S. P., Harrison, J. A., Dumont, E., Beusen, A. H., Bouwman, A., . . . Van Drecht, G. (2010). Global nutrient export from WaterSheds 2 (NEWS 2): model development and implementation. Environmental Modelling & Software, 25(7), 837-853.
Strokal, M., Yang, H., Zhang, Y., Kroeze, C., Li, L., Luan, S., . . . Zhang, Y. (2014). Increasing eutrophication in the coastal seas of China from 1970 to 2050. Marine Pollution Bulletin, 85(1), 123-140.
Yang, S., Qu, H., Luan, S., & Kroeze, C. (2014). Environmental implications of rural policies in China: a multi-agent model at the level of agricultural households. Journal of Integrative Environmental Sciences(ahead-of-print), 1-21.