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Chiba University (2014)

Study on the Regional Hydrological and Hydrochemical Processes Affected by the Human Activities in the North China Plain

DUN Yu

Titre : Study on the Regional Hydrological and Hydrochemical Processes Affected by the Human Activities in the North China Plain

中国華北平原における広域水文・水質特徴およびそれに関わる人間活動の影響について

Auteur : DUN Yu

Université de soutenance : Chiba University

Grade : Doctoral Thesis 2014

Présentation
The North China Plain (NCP) is one of the most water scarce areas in China. Groundwater is the main water source in the NCP. Water resource problems are mainly manifested in water quantity and water quality degradation, impacting on economic development in the NCP. In this study, the Xiaohe River basin was chosen to understand the movement of water and to evaluate water quality in the semi-arid area of the NCP. Environmental isotopes, chlorofluorocarbons (CFCs) and hydrochemistry were used to study the influence of surface water on regional groundwater. Based on a mass balance approach with chloride charged by surface water was estimated as 50–60 %. CFC results indicated that the resident time of groundwater that recharged by the river varied from 22.5 to 39.5 years. The vertical flow velocity of groundwater was estimated at about 1.8–3.5 m year–1. Nitrate concentrations in groundwater varied from 9 to 157 mg L–1, and exceeded WHO drinking water standard of 50 mg L–1 in most aquifers shallower than 80 m bordering the Xiaohe River. The δ15N–NO3 data indicates that the major sources of nitrogen in groundwater are human sewage and animal excreta. To understand the distribution and behavior of phenolic endocrine-disrupting chemicals (EDCs) in surface water and suspended particulate matter (SPM), the Xiaohe River in the NCP was investigated. The river concentrations (means ; ng/L) of EDCs varied from 21–83 (54) for octylphenol (OP), from 39–1819 (570) for nonylphenol (NP), and from 49–775 (391) for bisphenol A (BPA). Particulate concentrations (means ; ng/L) for OP, NP and BPA were in the range of 12–20 (23), 14–1197 (785), and 18–32 (23), respectively. SPM accounted for 23–54%, on average, of the total phenolic EDCs pollution in surface water. The averaged particulate OP, NP and BPA proportions were 24, 61 and 11%, respectively, of their total concentration in water columns. A mass balance equation based on chloride was used to evaluate the mixing effect on the behavior of EDCs along the river, showing that mixing process was the predominant factor to determine EDCs concentrations in the Xiaohe River. Based on the combined effect models, potential environmental risks were assessed showing that most surface waters contaminated by EDCs have a medium effect on aquatic organisms in the Xiaohe River basin.

Mots clés : surface water, groundwater, environmental isotopess, nitrate, CFCs, hydrochemistry, endocrine-disrupting chemicals, NCP

Annonce

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Page publiée le 25 janvier 2018