期刊
JOURNAL OF HYDROLOGY
卷 553, 期 -, 页码 188-198出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.jhydrol.2017.07.058
关键词
Seepage; Permeable sediments; Submarine groundwater discharge; Radon
资金
- Australian Research Council [DE140101733, DP150103286, LE140100083]
- Herman Slade Foundation
- Australian Research Council [LE140100083] Funding Source: Australian Research Council
We hypothesise that mangroves play an important role in groundwater exchange processes in subtropical and tropical estuarine waters. To investigate this, multiple high resolution time series measurements of radium across a tidal estuary (Coffs Creek, NSW, Australia) were performed as well as a spatial survey in both bottom and surface layers. Results from the spatial survey revealed increasing radium concentrations in parts of the estuary surrounded by mangroves. The average radium concentration in estuary areas lined with mangroves was 2.5 times higher than the average concentration at the mouth of the estuary and 6.5-fold higher than upstream freshwater areas. Additionally, the area enriched in radium coincided with low dissolved oxygen concentrations, implying that porewater exchange may drive anoxia. A radium mass balance model based on Ra-223 and Ra-224 isotopes at different sections of the estuary confirmed higher porewater exchange rates from areas fringed with mangrove vegetation. Estimated porewater exchange rates were 27.8 +/- 5.3 and 13.6 +/- 2.1 cm d(-1) (0.8 +/- 0.1 and 0.4 +/- 0.1 m(3) s(-1)) based on 223Ra and 224Ra isotopes, respectively. The average saline porewater exchange was similar to 10-fold larger than the upstream surface freshwater inputs to the estuary. We suggest that mangrove environments within subtropical estuaries are hotspots for porewater exchange due to the complex belowground structure of crab burrows and the effect of tidal pumping. Because porewater exchange releases carbon and nitrogen from coastal sediments, development and modification of mangrove areas in subtropical estuaries have a significant effect on coastal biogeochemical cycles. (C) 2017 Elsevier B.V. All rights reserved.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据