Geochemical characteristics and organic carbon sources within the upper reaches of the Xi River, southwest China during high flow
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- 作者：Junyu Zou
- 关键词：Organic carbon ; carbon isotopes ; headwater basins ; Xi River ; southwest China.
- 刊名：Journal of Earth System Science
- 出版年：2017
- 出版时间：February 2017
- 年：2017
- 卷：126
- 期：1
- 全文大小：
- 刊物类别：Earth and Environmental Science
- 刊物主题：Earth Sciences, general; Space Sciences (including Extraterrestrial Physics, Space Exploration and Astronautics);
- 出版者：Springer India
- ISSN：0973-774X
- 卷排序：126
文摘
Carbon (POC, DOC) and carbon isotopes (δ13C) within two headwater tributaries to the Xi River Basin, southwest China were analyzed to document the geochemical characteristics and sources of organic carbon (C) within basins characterized by a monsoonal climate and karst landforms. δ13CPOC value and C/N ratio data indicate that suspended soil organic carbon (SOC) was an important source of POC in both the Nanpan and Beipan rivers (i.e., the studied tributaries). However, differences in C sources exist between the Nanpan and Beipan River Basins. Higher terrestrial plants supplied a portion of the POC within the Beipan River. In contrast, the Nanpan River was characterized by an inverse correlation between POC and DOC, and a positive relationship between the δ13C values. These trends indicate that DOC within the Nanpan River was partly derived from the degradation of soil C within the water column. In addition, the interception of C by hydrological projects (e.g., dams) positioned along the Nanpan River led to higher DOC/POC ratios. In contrast, within the Beipan River δ13C DOC values range from −20 to −25.2 ‰ and are consistent with ratios associated with soil C, suggesting that leaching of C from catchment soil was the dominant source of DOC. Organic C in tributaries to the Beipan River may also have been derived from intense upland soil erosion, a process that resulted in the lowest DOC/POC ratios. The collected data indicate that land-use changes have potentially influenced regional- to local-scale organic C budgets within subtropical basins subjected to karstification.