Unraveling the role of land use and microbial activity in shaping dissolved organic matter characteristics in stream ecosystems
Unraveling the role of land use and microbial activity in shaping dissolved organic matter characteristics in stream ecosystems
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DOI：
10.4319/lo.2010.55.3.1159
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发表时间：
2010-05-01
影响因子：
4.5
通讯作者：
Xenopoulos, Marguerite A.
中科院分区：
文献类型：
--
作者：
Williams, Clayton J.;Yamashita, Youhei;Xenopoulos, Marguerite A.
地表水样品收集了43个溪流分布在整个流域的混合土地利用在加拿大南部安大略。采用吸光度-荧光光谱平行因子分析法（PARAFAC）对溶解性有机物（DOM）进行了表征。DOM特性与环境变量，微生物活性指标（细菌产量和细胞外亮氨酸氨肽酶活性），河岸土地利用，以更好地了解这些因素如何影响流DOM。PARAFAC制作了一个六组分模型（C1至C6）。温度与每个PARAFAC组件，这表明水源，流域面积和透光率广泛影响DOM特性。C1和C2代表陆地，腐殖类DOM荧光基团，并包括流DOM荧光的41-65%。C5，一种类似于C5的成分，与腐殖化指数呈负相关，但与亮氨酸氨肽酶活性和最近产生的DOM呈正相关，这表明C5由本地微生物产生的DOM组成。C3、C4和C6显示出醌样、腐殖样和微生物可转化荧光团的迹象。这些潜在的氧化还原活性的PARAFAC组件的分布表明，DOM是在一个更减少的状态，在流与更高的细菌生产和农业土地利用比在流与湿地面积增加，其中有更大的相对丰度的氧化醌样组分。人为的土地利用和微生物活动改变了从森林和湿地为主的河流中观察到的受人类影响的河流中输出的DOM的数量和质量。DOM在农业影响的流可能更不稳定和访问的微生物群落比DOM在湿地流，这支持低速率的微生物活性。
Surface water samples were collected from 43 streams distributed throughout watersheds of mixed land use in southern Ontario, Canada. Absorbance and fluorescence spectroscopy with parallel factor analysis (PARAFAC) was used to characterize dissolved organic matter (DOM). DOM characteristics were related to environmental variables, microbial activity indicators (bacterial production and extracellular leucine aminopeptidase activity), and riparian land use to understand better how these factors influence DOM in streams. PARAFAC produced a six-component model (C1 to C6). Temperature correlated with each PARAFAC component, suggesting that water source, drainage area, and light penetration broadly affected DOM characteristics. C1 and C2 represented terrestrial, humic-like DOM fluorophore groups and comprised 41-65% of stream DOM fluorescence. C5, a tryptophan-like component, related negatively to a humification index but positively to leucine-aminopeptidase activity and recently produced DOM, suggesting that C5 consisted of autochthonous, microbially produced DOM. C3, C4, and C6 showed signs of quinone-like, humic-like, and microbial transformable fluorophores. The distribution of these potentially redox-active PARAFAC components indicated that DOM was in a more reduced state in streams with higher bacterial production and agricultural land use than in streams with increased wetlands area, which had greater relative abundance of the oxidized quinone-like component. Anthropogenic land use and microbial activity altered the quantity and quality of DOM exported from human-affected streams from that observed in forest-and wetland-dominated streams. DOM in agriculturally affected streams was likely more labile and accessible to the microbial community than DOM in wetland streams, which supported low rates of microbial activity.