Groundwater Research Center, Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon 34132, Republic of Korea; Department of Mineral and Groundwater Resources, Korea University of Science and Technology (UST), Daejeon 34113, Republic of Korea.
Groundwater Research Center, Geologic Environment Division, Korea Institute of Geoscience and Mineral Resources (KIGAM), Daejeon 34132, Republic of Korea.
Sci Total Environ. 2020 Feb 10;703:134741. doi: 10.1016/j.scitotenv.2019.134741. Epub 2019 Oct 31.
Recent increases in the frequency of extreme floods and droughts associated with climate change can affect fluctuating groundwater or wetland water levels and wetland plant growth, and consequently cause redox condition changes in nitrogen dynamics in wetland sediments. Here, we studied the fate of nitrate (NO), dissolved organic carbon (DOC), and the microbial characteristics at different sediment depths in response to water levels (i.e., 5 or 2.5 cm) above the sediment surface and in the presence or absence of plants (Phragmites communis Trin) for four months in three wetland mesocosms. Results showed that mesocosm A (MA) with a high water level (5 cm above the surface) and plants had significantly higher DOC concentrations (17.57 ± 8.22 mg/L) in sediment that were actively consumed by microorganisms than other mesocosms with low water level (MB) and without plant (MC) (8.77 ± 2.38 mg/L and 7.87 ± 2.72 mg/L in MB and MC, respectively). Consequently, the most of influent NO (20 mg-N/L) dramatically reduced in the vicinity of plant roots (-20 to -15 cm sediment depth) where active denitrification was expected in MA. Moreover, the functional genes involved in denitrification such as narG (2.4 × 10 -3.5 × 10 copies·g) and nirS (5.6 × 10-1.1 × 10 copies·g) were more abundant in this mesocosm. The profile of the microbial community structure at the class level revealed that Alphaproteocbacteria (MA: 14.19 ± 1.19%; MB: 14.01 ± 0.51%; MC: 15.21 ± 2.76%) and Actinobacteria (MA: 8.21 ± 1.91%; MB: 13.91 ± 2.13%; MC: 11.75 ± 3.43%) were predominant in all three mesocosms. Interestingly, the clustered heatmap supported the obvious difference in microbial composition of MA from other mesocosms showing relatively more abundant Clostridia (6.71 ± 1.54%) and Deltaproteobacteria (7.05 ± 0.68%). These results can provide an insight to understand the biogeochemical nitrogen cycle associated with climate change in wetland systems.
最近与气候变化相关的极端洪水和干旱频率的增加会影响地下水或湿地水位的波动以及湿地植物的生长，从而导致湿地沉积物中氮动态的氧化还原条件发生变化。在这里，我们研究了硝酸盐 (NO)、溶解有机碳 (DOC) 的命运，以及在三种湿地中，水位（即高于沉积物表面 5 或 2.5 厘米）和是否存在植物（香蒲）的情况下，不同沉积物深度的微生物特征在四个月内的变化在三个中观模型中。结果表明，高水位（高于表面 5 厘米）和植物的中观模型 A（MA）的沉积物中 DOC 浓度（17.57±8.22mg/L）明显高于低水位（MB）和无植物（MC）的中观模型（8.77±2.38mg/L 和 7.87±2.72mg/L 在 MB 和 MC 中），这是因为这些沉积物中 DOC 被微生物积极消耗。因此，大部分进水 NO（20mg-N/L）在预期有活性反硝化的植物根附近（MA 的-20 到-15cm 沉积物深度）急剧减少。此外，参与反硝化的功能基因，如narG（2.4×10-3.5×10 拷贝·g）和 nirS（5.6×10-1.1×10 拷贝·g）在这个中观模型中更为丰富。在类水平上的微生物群落结构的图谱表明，α变形菌（MA：14.19±1.19%；MB：14.01±0.51%；MC：15.21±2.76%）和放线菌（MA：8.21±1.91%；MB：13.91±2.13%；MC：11.75±3.43%）在所有三个中观模型中占主导地位。有趣的是，聚类热图支持 MA 与其他中观模型在微生物组成上的明显差异，表明相对更丰富的梭菌（6.71±1.54%）和δ变形菌（7.05±0.68%）。这些结果可以帮助我们深入了解湿地系统中与气候变化相关的生物地球化学氮循环。
