The University of Sydney, School of Geosciences, NSW 2006, Australia.
The University of Sydney, School of Geosciences, NSW 2006, Australia.
Sci Total Environ. 2022 Aug 1;832:154900. doi: 10.1016/j.scitotenv.2022.154900. Epub 2022 Apr 1.
Mangrove forests sequester organic carbon, nutrients and toxic metals sorbed to fine sediment, and thus restrict the mobility of pollutants through estuarine environments. However, mangrove removal and environmental degradation caused by industrial activity and urban growth can impact the ability of mangrove communities to provide these critical ecosystem services. Here, we use sediment profiles from an impacted tropical estuary in southwest India to provide a c. 70-year record of carbon, nutrient and trace metal burial in the context of rapid urban development and the systemic removal of mangrove communities. Our results show that carbon and nutrient accumulation rates increase sharply during the 1990's in accordance with the high rates of deforestation. Nitrogen and phosphorus accumulation rates increased fourfold and twofold, respectively, during the same period. Organic carbon accumulation was fivefold higher than the global average during this period, reflecting intense deforestation during the last three decades. The enrichment of Hg, Zn, Pb, Mo, Ni, Cu and Mn demonstrate clear anthropogenic impact starting in the 1950's and peaking in 1990. Mercury, the trace metal with the highest enrichment factor, increased sevenfold in the most recent sediments due to increased fossil fuel emissions, untreated water and incineration of medical waste and/or fertilizers used in aquaculture. Organic carbon isotope (δC) and C:N molar ratios indicate shifts to more terrestrial-derived source of organic matter in the most recent sediments reflecting growing deforestation of which may be prevalent in southeast Asia due to increasing development. This study emphasizes the critical role played by mangrove ecosystems in attenuating anthropogenically-derived pollutants, including carbon sequestration, and reveals the long-term consequences of mangrove deforestation in the context of rapidly developing economies.
红树林森林固存有机碳、营养物质和被细沉积物吸附的有毒金属，从而限制污染物在河口环境中的迁移。然而，工业活动和城市发展导致的红树林砍伐和环境退化，可能会影响红树林群落提供这些关键生态系统服务的能力。在这里，我们利用来自印度西南部一个受影响的热带河口的沉积剖面，在快速城市发展和系统性去除红树林群落的背景下，提供了大约 70 年的碳、营养物质和痕量金属埋藏记录。我们的结果表明，在 1990 年代，随着森林砍伐率的升高，碳和营养物质的积累速率急剧增加。氮和磷的积累速率分别增加了四倍和两倍。在同一时期，有机碳的积累量是全球平均水平的五倍，反映出过去三十年里强烈的森林砍伐。Hg、Zn、Pb、Mo、Ni、Cu 和 Mn 的富集表明，从 20 世纪 50 年代开始，人类活动的影响明显增加，并在 1990 年代达到顶峰。痕量金属中富集因子最高的汞，由于化石燃料排放的增加、未经处理的水以及医疗废物的焚烧和/或水产养殖中使用的肥料，在最近的沉积物中增加了七倍。有机碳同位素 (δC) 和 C:N 摩尔比表明，最近的沉积物中有机质的来源更多地来自陆地，这反映了森林砍伐的增加，这种情况可能在东南亚很普遍，因为那里的发展速度在加快。本研究强调了红树林生态系统在减缓人为来源的污染物方面所起的关键作用，包括碳固存，并揭示了在快速发展的经济体背景下，红树林砍伐的长期后果。
