Biogeochemical patterns in a river network along a land use gradient
Biogeochemical patterns in a river network along a land use gradient
复制标题
DOI：
10.1007/s10661-013-3247-7
复制
发表时间：
2013-11-01
影响因子：
3
通讯作者：
Weitere, Markus
中科院分区：
文献类型：
--
作者：
Kamjunke, Norbert;Buettner, Olaf;Weitere, Markus
博德流域（德国）显示出从国家公园森林地区（占总土地覆盖率的 23%）到农业地区（70%）和城市化地区（7%）的强烈土地利用梯度。它是德国亥姆霍兹协会陆地环境观测站的一部分。我们对整个河网进行了生物地球化学分析。在生长季节之前（早春）和生长季节期间（夏末），在 21 个源头和 10 个下游地点采集了地表水样本。许多参数显示，源头的浓度低于下游河段，其中包括营养物（铵、硝酸盐和磷）、溶解铜和干物质。硝酸盐和磷浓度与流域内农业面积比例呈正相关。准时的人为负荷影响了一些参数，例如氯化物和砷。地表水中叶绿素a浓度与总磷呈正相关。夏季溶解有机碳（DOC）浓度高于春季，而DOC分子尺寸较小。表明腐殖质含量的254 nm处的特定紫外吸收，源头高于下游河段，并且与流域内森林的比例呈正相关。下游水体二氧化碳过饱和度高于源头，且夏季高于春季。它与氧饱和度呈负相关，与 DOC 浓度呈正相关，但与 DOC 质量（分子大小和腐殖质含量）呈负相关。主成分分析清楚地区分了场地 (44%) 和季节 (15%) 的影响，证明了土地利用对生物地球化学参数的强烈影响。
The Bode catchment (Germany) shows strong land use gradients from forested parts of the National Park (23 % of total land cover) to agricultural (70 %) and urbanised areas (7 %). It is part of the Terrestrial Environmental Observatories of the German Helmholtz association. We performed a biogeochemical analysis of the entire river network. Surface water was sampled at 21 headwaters and at ten downstream sites, before (in early spring) and during the growing season (in late summer). Many parameters showed lower concentrations in headwaters than in downstream reaches, among them nutrients (ammonium, nitrate and phosphorus), dissolved copper and seston dry mass. Nitrate and phosphorus concentrations were positively related to the proportion of agricultural area within the catchment. Punctual anthropogenic loads affected some parameters such as chloride and arsenic. Chlorophyll a concentration and total phosphorus in surface waters were positively related. The concentration of dissolved organic carbon (DOC) was higher in summer than in spring, whereas the molecular size of DOC was lower in summer. The specific UV absorption at 254 nm, indicating the content of humic substances, was higher in headwaters than in downstream reaches and was positively related to the proportion of forest within the catchment. CO2 oversaturation of the water was higher downstream compared with headwaters and was higher in summer than in spring. It was correlated negatively with oxygen saturation and positively with DOC concentration but negatively with DOC quality (molecular size and humic content). A principle component analysis clearly separated the effects of site (44 %) and season (15 %), demonstrating the strong effect of land use on biogeochemical parameters.