Department of Geology and Environmental Earth Science, Miami University, Oxford, OH, USA.
Nuclear Agriculture Research School, Nuclear Science and Technology Research Institute (NSTRI), Karaj, Iran.
Environ Monit Assess. 2024 Sep 4;196(10):887. doi: 10.1007/s10661-024-13048-5.
To estimate a watershed's response to climate change, it is crucial to understand how human activities and climatic extremes have interacted over time. Over the last century, the Zarivar Lake watershed, Iran, has been subjected to various anthropogenic activates, including deforestation and inappropriate land-management practices alongside the implementation of conservation measures like check dams. To understand the effects of these changes on the magnitude of sediment, organic carbon (OC), and phosphorus supplies in a small sub-watershed connected to the lake over the last century, a lake sediment core was dated using Pb and Cs as geochronometers. The average mass accumulation rate (MAR), organic carbon accumulation rates (OCAR), and particulate phosphorus accumulation rates (PPAR) of the sediment core were determined to be 6498 ± 2475, 205 ± 85, and 8.9 ± 3.3 g m year, respectively. Between the late 1970s and early 1980s, accumulation rates were significantly higher than their averages at 7940 ± 3120, 220 ± 60, and 12.0 ± 2.8 g m year respectively. During this period, the watershed underwent extensive deforestation (12%) on steep slopes, coinciding with higher mean annual precipitations (more than double). Conversely, after 2009, when check dams were installed in the sub-watershed, the sediment load to the lake became negligible. The results of this research indicate that anthropogenic activities had a pronounced effect on MAR, OCAR, and PPAR, causing them to fluctuate from negligible amounts to values twice the averages over the last century, amplified by climatic factors. These results imply that implementing climate-smart watershed management strategies, such as constructing additional check dams and terraces, reinforcing restrictions on deforestation, and minimum tillage practices, can facilitate protection of lacustrine ecosystems under accelerating climate change conditions.
为了估算流域对气候变化的响应，了解人类活动和气候极值随时间的相互作用至关重要。在上个世纪，伊朗的 Zarivar 湖流域经历了各种人为活动，包括森林砍伐和不当的土地管理实践，以及实施了一些保护措施，如挡水坝。为了了解这些变化对过去一个世纪连接到该湖的一个小次流域中泥沙、有机碳（OC）和磷供应的幅度的影响，使用 Pb 和 Cs 作为地质年代计对一个湖底沉积物岩芯进行了定年。确定了岩芯的平均质量堆积率（MAR）、有机碳堆积率（OCAR）和颗粒状磷堆积率（PPAR）分别为 6498 ± 2475、205 ± 85 和 8.9 ± 3.3 g m-1 year-1。在 20 世纪 70 年代末至 80 年代初，堆积率明显高于平均值，分别为 7940 ± 3120、220 ± 60 和 12.0 ± 2.8 g m-1 year-1。在此期间，流域在陡坡上进行了大规模的森林砍伐（12%），同时年平均降水量也增加了一倍以上。相反，在 2009 年在次流域安装了挡水坝之后，流入湖中的泥沙量可忽略不计。这项研究的结果表明，人为活动对 MAR、OCAR 和 PPAR 有显著影响，导致它们在上个世纪的波动幅度从微不足道到平均值的两倍，而气候因素放大了这种波动。这些结果表明，实施智能流域管理策略，如建造更多的挡水坝和梯田、加强对森林砍伐的限制以及最小耕作实践，可以在加速气候变化条件下保护湖泊生态系统。
