Estimation of the nonpoint source nitrogen load in a strongly disturbed watershed of the North China Plain.

Identification of nonpoint source (NPS) pollution is a great challenge in the North China Plain, which has modified rivers and insufficient data. In this study, a simple and reasonable method was developed to estimate the total nitrogen (TN) load in rural areas of the North China Plain. The method was found to work well and produce results consistent with monitoring data when considering various TN sources and transfer mechanisms. The annual TN loads from rural living, livestock and the farmlands were 121.9 × 10(3), 45.6 × 10(3) and 78.5 × 10(3) kg/yr, respectively. The TN load in the region along the river contributed much more to the NPS pollution than that in areas far from the river, with average TN loads of approximately 3394 and 602 kg km(-2) yr(-1), respectively. Overall, the results indicate that this method is suitable for NPS load estimates in severely disturbed watersheds with insufficient data.

Spatio-temporal variation analysis of hydrochemical characteristics in the Luanhe River Basin, China.

The analysis of river pollution and assessment of spatial and temporal variation in hydrochemistry are essential to river water pollution control in the context of rapid economic growth and growing pollution threats in China. In this study, we focused on hydrochemical characteristics of the Luanhe River Basin (China) and evaluation of 12 hydrochemical variables obtained from 32 monitoring stations during 2001-2010. In each study year, the streams were monitored in the three hydrological periods (April, August, and October) to observe differences in the impacts of agricultural activity and rainfall pattern. Multivariate statistical methods were applied to the data set, and the river water hydrochemical characteristics were assessed using the water quality identification index (WQIIM). The results showed that parameters had variable contribution to water quality status in different months except for ammonia nitrogen (NH4-N) and total nitrogen (TN), which were the most important parameters in contributing to water quality variations for all three periods. Results of WQIIM revealed that 18 sites were classified as 'meeting standard' while the other 14 sites were classified as 'not meeting standard', with most of the seriously polluted sites located in urban area, mainly due to discharge of wastewater from domestic and industrial sources. Sites with low pollution level were located primarily in smaller tributaries, whereas sites of medium and high pollution levels were in the main river channel and the larger tributaries. Our findings provide valuable information and guidance for water pollution control and water resource management in the Luanhe River Basin.

Sources and mass fluxes of the main contaminants in a heavily polluted and modified river of the North China Plain.

Many rivers in China and other newly industrialized countries have suffered from severe degradation of water quality in the context of rapid economic growth. An accounting method was developed to investigate the source and mass fluxes of the main contaminants in the Ziya River, a severely polluted and heavily modified river in a semiarid area of the North China Plain, where chemical oxygen demand (COD) and ammonia nitrogen (NH4-N) were the most important indicators of pollution. The results showed that the urban sewage with high concentration of COD and NH4-N dominated the streams, contributing to 80.7 % of the streamflow, 92.2 % of COD, and 94.5 % of NH4-N. The concentrations of COD and NH4-N in streams varied from 24.0-195.0 to 5.8-43.8 mg/L, respectively. Mass fluxes of COD and NH4-N of all pathways were quantified. Much of the polluted water was diverted to irrigation, and some eventually flowed into the Bohai Sea. Installation of adequate wastewater treatment facilities and making strict discharge standards can help improve the water quality. Our findings imply that a simple accounting method provides an extremely well-documented example for load estimation and can be useful for intervention strategies in heavily polluted and modified rivers in newly industrialized countries.