Human activities directly alter watershed dissolved silica fluxes
Human activities directly alter watershed dissolved silica fluxes
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DOI：
10.1007/s10533-011-9671-2
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发表时间：
2012-11-01
期刊：
影响因子：
4
通讯作者：
Fulweiler, R. W.
中科院分区：
文献类型：
--
作者：
Carey, J. C.;Fulweiler, R. W.
化学风化的控制，如基岩地质、径流和温度，被认为是硅从大陆向海洋运输的主要驱动因素。然而，最近的研究表明，陆地植被是硅循环的重要控制因素。研究表明，在区域尺度（美国新英格兰南部），土地利用/土地覆盖（LULC）是控制硅从陆地向海洋净输送的重要变量，至少占溶解硅（DSi）通量的40%。利用25条河流（bbb2,300个观测值）的平均DSi通量的多元线性回归模型显示，森林覆盖百分比以及开发和农业用地利用是DSi通量的显著驱动因素（p < 0.05）。无论流域大小和岩性如何，这都是正确的。此外，森林覆盖与Si浓度和通量呈显著负相关，而发展与Si浓度和通量呈显著正相关。我们假设这些关系是由于几种机制造成的，特别是陆地植被在其生物量中储存大量硅的能力，伴随LULC变化的流域水文变化，以及城市地区作为水生系统硅来源的能力。因此，我们得出结论，人类活动可能通过土地利用变化直接干扰全球硅循环，并提出了一个概念模型，该模型强调了理解硅通量的非地球化学控制的新方法。
Controls on chemical weathering, such as bedrock geology, runoff, and temperature, are considered to be the primary drivers of Si transport from the continents to the oceans. However, recent work has highlighted terrestrial vegetation as an important control over Si cycling. Here we show that at the regional scale (Southern New England, USA), land use/land cover (LULC) is an important variable controlling the net transport of Si from the land to the sea, accounting for at least 40% of dissolved Si (DSi) fluxes. A multiple linear regression model using average DSi fluxes from 25 rivers (> 2,300 observations) shows the percent forest cover, as well as development and agricultural land use, to be significant (p < 0.05) drivers of DSi flux. This was true regardless of watershed size and lithology. Furthermore, forest cover is significantly negatively correlated, while development is significantly positively correlated, with Si concentrations and fluxes. We hypothesize that these relationships are due to several mechanisms, specifically the ability of terrestrial vegetation to store large amounts of Si within its biomass, the altered watershed hydrology that accompanies LULC change, and the capability of urban regions to serve as sources of Si to aquatic systems. Thus, we conclude that anthropogenic activities may be directly perturbing the global Si cycle through land use change and we offer a conceptual model which highlights a new approach to understanding the non-geochemical controls on Si fluxes.