3 research outputs found
Sources and Pathways of Nutrients in the Semi-Arid Region of BeijingāTianjin, China
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
0.3ā5.3 mgP L<sup>ā1</sup> and 3.0ā49 mgN L<sup>ā1</sup>, with toxic levels of nitrite (ā„1 mgNO<sub>2</sub>āN L<sup>ā1</sup>) and ammonia (ā„0.6
mgNH<sub>3</sub>āN L<sup>ā1</sup>). The average NH<sub>4</sub><sup>+</sup> (16.9 mgN L<sup>ā1</sup>) increased by
160% compared to 1996-levels. Mass fluxes and Ī“<sup>15</sup>N-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 1970ā1990, but concentrations were
2ā3 times higher in the BeijingāTianjin 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
Sources and Pathways of Nutrients in the Semi-Arid Region of BeijingāTianjin, China
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
0.3ā5.3 mgP L<sup>ā1</sup> and 3.0ā49 mgN L<sup>ā1</sup>, with toxic levels of nitrite (ā„1 mgNO<sub>2</sub>āN L<sup>ā1</sup>) and ammonia (ā„0.6
mgNH<sub>3</sub>āN L<sup>ā1</sup>). The average NH<sub>4</sub><sup>+</sup> (16.9 mgN L<sup>ā1</sup>) increased by
160% compared to 1996-levels. Mass fluxes and Ī“<sup>15</sup>N-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 1970ā1990, but concentrations were
2ā3 times higher in the BeijingāTianjin 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
Organic Micropollutants in Rivers Downstream of the Megacity Beijing: Sources and Mass Fluxes in a Large-Scale Wastewater Irrigation System
The Haihe River System (HRS) drains the Chinese megacities
Beijing
and Tianjin, forming a large-scale irrigation system severely impacted
by wastewater-borne pollution. The origin, temporal magnitudes, and
annual mass fluxes of a wide range of pharmaceuticals, household chemicals,
and pesticides were investigated in the HRS, which drains 70% of the
wastewater discharged by 20 million people living in Beijing. Based
on Chinese consumption statistics and our initial screening for 268
micropollutants using high-resolution mass spectrometry, 62 compounds
were examined in space and time (2009ā2010). The median concentrations
ranged from 3 ng/L for metolachlor to 1100 ng/L for benzotriazole
and sucralose. Concentrations of carbendazim, clarithromycin, diclofenac,
and diuron exceed levels of ecotoxicological concern. Mass-flux analyses
revealed that pharmaceuticals (5930 kg/year) and most household chemicals
(5660 kg/year) originated from urban wastewaters, while the corrosion
inhibitor benzotriazole entered the rivers through other pathways.
Total pesticide residues amounted to 1550 kg/year. Per capita loads
of pharmaceuticals in wastewater were lower than those in Europe,
but are expected to increase in the near future. As 95% of the river
water is diverted to irrigate agricultural soil, the loads of polar
organic micropollutants transported with the water might pose a serious
threat to food safety and groundwater quality