In situ, high-resolution imaging of labile phosphorus in sediments of a large eutrophic lake
In situ, high-resolution imaging of labile phosphorus in sediments of a large eutrophic lake
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大型富营养化湖泊沉积物中不稳定磷的原位高分辨率成像
DOI：
10.1016/j.watres.2015.02.008
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发表时间：
2015-05-01
期刊：
影响因子：
12.8
通讯作者：
Zhang, Chaosheng
中科院分区：
文献类型：
--
作者：
Ding, Shiming;Han, Chao;Zhang, Chaosheng
了解沉积物中磷 (P) 的不稳定状态对于管理富营养化湖泊至关重要，但由于缺乏现场数据（尤其是流域规模的数据）而受到阻碍。在这项研究中，我们首次利用薄膜中的氧化锆扩散梯度（氧化锆DGT）技术以二维（2D）、亚毫米分辨率对大型富营养化湖泊（中国太湖，面积为2338 km(2)）沉积物中的不稳定磷进行了原位表征。沉积物剖面中DGT不稳定磷的浓度变化较大，范围大多为0.01～0.35 mg L-1，热点数量较多。不稳定磷的水平异质性指数在0.04至4.5之间变化。高值出现在 0-30 毫米的深度，可能反映了沉积物-水界面 (SWI) 下的不稳定磷活性层。从靠近 SWI 的沉积物和上覆水层的高分辨率一维 DGT 剖面中观察到了不稳定磷的浓度梯度。计算了-21至65 ng cm(-2) d(-1)之间的P穿过SWI的表观扩散通量，这表明沉积物往往分别是藻类和水生植物为主区域上覆水P的源和汇。 0-30 mm 活性层中的 DGT 不稳定磷与上覆水磷的相关性优于异位化学萃取方法测量的不稳定磷。这意味着使用 DGT 对不稳定磷进行原位高分辨率分析是一种更可靠的方法，并将显着扩展我们对现场沉积物中不稳定磷状态进行原位监测的能力。 (C) 2015 Elsevier Ltd. 保留所有权利。
Understanding the labile status of phosphorus (P) in sediments is crucial for managing a eutrophic lake, but it is hindered by lacking in situ data particularly on a catchment scale. In this study, we for the first time characterized in situ labile P in sediments with the Zr-oxide diffusive gradients in thin films (Zr-oxide DGT) technique at a two-dimensional (2D), submillimeter resolution in a large eutrophic lake (Lake Taihu, China, with an area of 2338 km(2)). The concentration of DGT-labile P in the sediment profiles showed strong variation mostly ranging from 0.01 to 0.35 mg L-1 with a considerable number of hotspots. The horizontal heterogeneity index of labile P varied from 0.04 to 4.5. High values appeared at the depths of 0-30 mm, likely reflecting an active layer of labile P under the sediment -water interface (SWI). Concentration gradients of labile P were observed from the high-resolution 1D DGT profiles in both the sediment and overlying water layers close to the SWI. The apparent diffusion flux of P across the SWI was calculated between -21 and 65 ng cm(-2) d(-1), which showed that the sediments tended to be a source and sink of overlying water P in the algal- and macrophyte-dominated regions, respectively. The DGT-labile P in the 0-30 mm active layer showed a better correlation with overlying water P than the labile P measured by ex situ chemical extraction methods. It implies that in situ, high-resolution profiling of labile P with DGT is a more reliable approach and will significantly extend our ability in in situ monitoring of the labile status of P in sediments in the field. (C) 2015 Elsevier Ltd. All rights reserved.