Variation in dissolved organic matter (DOM) stoichiometry in U.K. freshwaters: Assessing the influence of land cover and soil C:N ratio on DOM composition
Variation in dissolved organic matter (DOM) stoichiometry in U.K. freshwaters: Assessing the influence of land cover and soil C:N ratio on DOM composition
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DOI：
10.1002/lno.11186
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发表时间：
2019-05
影响因子：
4.5
通讯作者：
C. Yates;P. Johnes;A. Owen;F. Brailsford;H. Glanville;C. Evans;M. Marshall;David L. Jones;C. Lloyd;T. Jickells;R. Evershed
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作者：
C. Yates;P. Johnes;A. Owen;F. Brailsford;H. Glanville;C. Evans;M. Marshall;David L. Jones;C. Lloyd;T. Jickells;R. Evershed
溶解有机物(DOM)在淡水生物地球化学中起着重要的作用。为了研究集水特征对淡水中DOM质量和数量的影响，在一年的时间里，对一个以陆地为主的大流域和一个以低地为主的大流域的45个样点进行了排水对比土壤类型、水文和土地覆盖的次流域的采样。每个子流域的主要土地覆盖包括：耕地和园艺、毛毯泥炭地、针叶林地和改良的、未改良的、酸性和石灰性草地。C、N和P池的组成与无机营养物质(NO3−、NO2−、NH4+和PO43−)和溶解有机营养物质(溶解有机碳、溶解有机氮和溶解有机磷)浓度有关。通过计算DOC：DON和DOC：DOP的摩尔比值和比紫外线吸光度(SUVA254)来评价DOM的质量。在几乎没有人为养分输入的流域，DON和DOP通常占总溶解氮(TDN)和总溶解磷(TDP)浓度的80%。相比之下，在受严重影响的农业集水区，DON和DOP通常占TDN的5%-15%和TDP浓度的10%-25%。DOC/DON和DOC/DOP比值在不同土地覆盖类型之间存在显著差异，且DOC：DON和DOC：DOP摩尔比与SUVA254显著相关(rs值分别为0.88和0.84)。土壤C/N比与河流DOC：DON/DOP呈显著正相关，相关系数分别为0.79和0.71。由此我们推断，土壤性质，特别是土壤有机质库的C/N比，对流经这些景观的溪流中DOM的组成有显著的影响。
Dissolved organic matter (DOM) plays an important role in freshwater biogeochemistry. To investigate the influence of catchment character on the quality and quantity of DOM in freshwaters, 45 sampling sites draining subcatchments of contrasting soil type, hydrology, and land cover within one large upland‐dominated and one large lowland‐dominated catchment were sampled over a 1‐yr period. Dominant land cover in each subcatchment included: arable and horticultural, blanket peatland, coniferous woodland, and improved, unimproved, acid, and calcareous grasslands. The composition of the C, N, and P pool was determined as a function of the inorganic nutrient species (NO3−, NO2−, NH4+, and PO43−) and dissolved organic nutrient (dissolved organic carbon [DOC], dissolved organic nitrogen [DON], and dissolved organic phosphorus [DOP]) concentrations. DOM quality was assessed by calculation of the molar DOC : DON and DOC : DOP ratios and specific ultraviolet absorbance (SUVA254). In catchments with little anthropogenic nutrient inputs, DON and DOP typically composed > 80% of the total dissolved nitrogen (TDN) and total dissolved phosphorus (TDP) concentrations. By contrast, in heavily impacted agricultural catchments DON and DOP typically comprised 5–15% of TDN and 10–25% of TDP concentrations. Significant differences in DOC : DON and DOC : DOP ratios were observed between land cover class with significant correlations observed between both the DOC : DON and DOC : DOP molar ratios and SUVA254 (rs = 0.88 and 0.84, respectively). Analysis also demonstrated a significant correlation between soil C : N ratio and instream DOC : DON/DOP (rs = 0.79 and 0.71, respectively). We infer from this that soil properties, specifically the C : N ratio of the soil organic matter pool, has a significant influence on the composition of DOM in streams draining through these landscapes.