Sources and Pathways of Nutrients in the Semi-Arid Region of Beijing–Tianjin, China

Abstract

Semiarid regions worldwide are particularly prone to eutrophication, which causes immense ecological and economic problems. One region that is in transition and requires systematic research for effective intervention is the dry landscape of Beijing-Tianjin (P. R. China). We investigated the sources and spatiotemporal loads of nitrogen and phosphorus species over a one-year period in the Haihe catchment that drains the megacity of Beijing. Although wastewater treatment was improved in recent years, the rivers were heavily contaminated by 0.3–5.3 mgP L–1 and 3.0–49 mgN L–1, with toxic levels of nitrite (≥1 mgNO2–N L–1) and ammonia (≥0.6 mgNH3–N L–1). The average NH4+ (16.9 mgN L–1) increased by 160% compared to 1996-levels. Mass fluxes and δ15N-signatures revealed that nutrients originated almost exclusively from sewage. Furthermore, the water balance demonstrated that >90% of the polluted river water was diverted for irrigation, thereby threatening food safety and groundwater quality. Per capita loads of 1.42 kgN/yr and 115 gP/yr were comparable to the peak discharges typical of Europe and the United States in 1970–1990, but concentrations were 2–3 times higher in the Beijing–Tianjin region. Our research identified sewage as the predominant nutrient source in this semiarid region, which suggests that state-of-the-art wastewater treatment would drastically mitigate eutrophication and even more rapidly than was previously observed in Europe.

Oxygenated, nitrated, methyl and parent polycyclic aromatic hydrocarbons in rivers of Haihe River System, China: Occurrence, possible formation, and source and fate in a water-shortage area

“…The total concentrations of SPAHs and PAHs decreased along the Wenyu River and North Canal (RW-1 to RW-12). In the Yongdingxin River (RW-13 to RW-15), the concentrations were higher than before probably as a result of the sewage discharges from Tianjin (Pernet-Coudrier et al, 2012).…”

“…A large amount of water was channeled between RW-5 and RW-9 to the Chaobaixin and Qinglongwan rivers for irrigation. Similarly, another large amount of water vanished between RW-9 and RW-13 due to irrigation (Pernet-Coudrier et al, 2012). In the heating season, however, the water fluxes at both RW-9 and RW-13 were 0, demonstrating that all the water from the WWTPs and upstream were discharged to the Chaobaixin and Qinglongwan rivers.…”

“…The mass flows of MPAHs, OPAHs, and PAHs at certain sampling sites were calculated based on the water discharge in 2011 (Table S6), which in 2009 was established in the study of Pernet-Coudrier et al (2012). December in Beijing and Tianjin is a season when domestic combustion is required, increasing the emission of PAHs.…”

“…However, the effluent from the WWTPs was also found to be a major source for the dissolved PAHs in the river . Meanwhile, over 90% of WWTP effluent is discharged to the agricultural land area within 100 km downstream of Beijing (Pernet-Coudrier et al, 2012). Thus, the PAHs probably enter the soil and even the crops and vegetables through irrigation (Tao et al, 2004), which may pose potential risks to human health from food, vegetables (Wang et al, 2011c), and groundwater consumption.…”

Phosphorus speciation of sediments from lakes of different tropic status in Eastern China

“…As a result, anthropogenically mobilized P in watersheds enters lakes and increases the risk of algal blooms (Pernet-Coudrier et al 2012). The consequences of eutrophication include deterioration of water quality and aquatic ecosystems.…”