[Estimation of Agricultural Non-point Source TN and TP Export Coefficients Based on Soil Loss].

Taking the Yellow River Delta as a typical research area, we constructed a coastal agricultural TN and TP non-point source pollution estimating model by analyzing the relationship between the surface soil pollutant loss risks and the monitored pollutant flux into the sea. On this basis, TN and TP non-point source export coefficients of paddy fields, irrigated land, and dry land were calculated, and the verification showed that the estimated export coefficients were acceptable. In the study area, the TN and TP export coefficients into the sea of arable land were 18.33 kg·(hm2·a)-1 and 1.02 kg·(hm2·a)-1, respectively. The agricultural non-point source pollution loads of arable land were relatively high in summer. The sub-basins with larger agricultural non-point source pollution loads were mainly located in the control areas of the Zhimai River, Guangli River, and Xiaodao River. The administrative regions with larger total agricultural TN and TP loads were mainly in the northern Huanghekou Town and Yong'an Town, and areas with larger loads per unit area were in the southwest. Therefore, it is necessary to pay more attention to the temporal effects of agricultural non-point source pollution, simultaneously coordinate the social and economic development, and formulate comprehensive agricultural non-point source pollution prevention and control strategies from the perspective of sub-basins and administrative units. This will allow us to improve the offshore pollution status from the perspective of land and sea coordination.

Integrated assessment of coastal ecological security based on land use change and ecosystem services in the Jiaozhou Bay, Shandong Peninsula, China.

Land use-based development activities can change the quality of coastal environment and the supply pattern of ecosystem services, negatively affecting the ecological security of coastal zones. Coastal ecosystem research has generally used terrestrial ecosystem research models which cannot actually reflect the features of the coastal zone─An independent environmental system combining land and sea. A scientific explanation is lacking for the complex relationship among driving factor of land-based activities, the response of ecosystem services, and the realization of ecological security in the coastal zone. Here, we presented an integrated assessment model for coastal ecological security that was established following the route of "Land use-Ecosystem services-Ecological security" and considering the spatial heterogeneity and mobility of coastal ecosystem services. The proposed model was used to assess the impacts of land use-based activities on coastal ecosystem services and regional ecological security and reveal the associated spatiotemporal variations in the Jiaozhou Bay, Shandong, China. Land use change around Jiaozhou Bay, as the main representation of pressure in the ecological security system, exhibited certain association and tendency with the states of ecosystem services and ecological security in the corresponding sea area. Owing to massive land transfer to built-up lands during urbanization, the ecosystem services declined in the sea areas of Jiaozhou Bay and thus resulted in the deterioration of coastal ecological security. The integrated assessment model of coastal ecological security based on pressure-state-response (PSR) frame could effectively reflect the spatial distribution and trends of coastal ecological security. Meanwhile, this model could clarify the response relationship of ecosystem services and ecological security in the sea portion with the land-based driving factor, i.e., land use, in the coastal ecosystems. Unlike the methods commonly used in previous studies on coastal ecological security, the model established here overcomes the shortcomings of others that only focus on the land portion and ignore the link and interaction between the land and sea. This model was therefore of improvement to the evaluation of coastal ecological security.