Sources and features of particulate organic matter in tropical small mountainous rivers (SW China) under the effects of anthropogenic activities
Sources and features of particulate organic matter in tropical small mountainous rivers (SW China) under the effects of anthropogenic activities
复制标题
DOI：
10.1016/j.ecolind.2021.107471
复制
发表时间：
2021-06
影响因子：
6.9
通讯作者：
Yao Zhang;Xian-wei Meng;Yazhi Bai;Xiangqin Wang;Peng Xia;Yang Gang;Zhiwei Zhu;Haitao Zhang
中科院分区：
文献类型：
--
作者：
Yao Zhang;Xian-wei Meng;Yazhi Bai;Xiangqin Wang;Peng Xia;Yang Gang;Zhiwei Zhu;Haitao Zhang
小型山区河流（SMR），特别是热带地区的河流，在全球碳循环中发挥着不成比例的作用，并在人类世期间受到人类活动的严重干扰。确定小尺度海洋生态系统中颗粒有机物（POM）的来源及其影响因素，对于填补有关POM在热带陆地-海洋生态系统中归宿的认识空白，以及对环境管理和生态评价的实用价值具有重要的科学意义。本研究调查了中国西南部广西省防城、茅岭、钦、大丰、南流等五个小流域的总悬浮物浓度、颗粒有机碳和颗粒氮含量、稳定碳同位素（δ 13 C）和悬浮颗粒物的C/N比。土壤（OMsoil）、C3植物（OMC 3）和本地生产（OMauto）是潜在的POM来源，并通过基于δ 13 C和C/N的端元混合模型定量分析了它们的相对贡献。结果表明，土壤是南流河、沁河和茂陵河中POM的最大贡献者，而方城河中OMC 3的贡献更大。与其他流域相比，防城河流域有机物在POM来源中所占比例很小。南流和防城分别作为农业和森林流域的典型代表，在POM来源方面表现出明显的差异。以农业扩张为主的土地利用方式、植被破坏和工程建设造成的土壤侵蚀以及水流速度和养分浓度等水文特征都对到达不同SMR的POM来源有很大影响。这些影响因素主要来自于人类活动，其对热带小尺度区域生态系统乃至全球地球化学循环的影响可能超出我们的预期。
Small mountainous rivers (SMRs), particularly those in the tropics, play a disproportionate role in global carbon cycling and have been heavily disturbed by anthropogenic activities during the Anthropocene. Identifying the sources of particulate organic matter (POM) in SMRs and their influencing factors have crucial scientific significance in terms of filling a cognitional gap concerning the fate of POM in tropical land–ocean ecosystems and practical values regarding environmental management and ecological evaluation. In this study, total suspended solids concentration, particulate organic carbon and particulate nitrogen contents, stable carbon isotope (δ13C), and C/N ratio of suspended particulates were investigated from five SMRs (Fangcheng, Maoling, Qin, Dafeng, and Nanliu) in Guangxi Province, southwest China. The soil (OMsoil), C3plants (OMC3), and autochthonous production (OMauto) were identified as potential POM sources, and their relative contributions were quantified via the use of end-member mixing models that were based on the classic indicators of δ13C and C/N. The results showed that soil was the biggest POM contributor in Nanliu, Qin, and Maoling rivers, whereas OMC3was more important in Fangcheng River. Compared to other watersheds, the OMautoaccounted for a very minor proportion of the POM sources in Fangcheng River. Nanliu and Fangcheng, as typical representatives of agricultural and forest watersheds, respectively, exhibited remarkable differences in terms of POM sources. Land use patterns that were dominated by agricultural expansion, the soil erosion that resulted from the destruction of vegetation and engineering construction, and hydrological characteristics such as flow velocity and nutrient concentration were all found to vastly impact the sources of POM reaching the different types of SMR. These influencing factors are mainly derived from anthropogenic activities, whose effects on the tropical SMRs ecosystems and even the global biogeochemical cycle, may exceed our expectation.