Department of Earth Sciences, Dartmouth College, Hanover, NH 03755;
Department of Earth Sciences, Dartmouth College, Hanover, NH 03755.
Proc Natl Acad Sci U S A. 2019 Nov 26;116(48):23936-23941. doi: 10.1073/pnas.1907842116. Epub 2019 Nov 11.
In recent years, rising gold prices have exacerbated the global proliferation of artisanal-scale gold mining (ASGM), with catastrophic consequences for human and ecological health. Much of this burgeoning industry has occurred in biodiversity hot spots, notably in the tropical forests of South America. While the loss of tropical forests and floodplains as a result of ASGM has been well characterized, ASGM impacts on riverine hydrological properties are less understood. Previous fieldwork on ASGM-affected and gully-eroded tropical streams and rivers has demonstrated that increases in suspended-sediment concentration (SSC) can substantially impact fish diversity and aquatic community structure, yet our understanding of the timing and scope of impacts of such increases is limited by the lack of long-term records of SSC. To address this challenge, we present a 34-y analysis of the direct effect of ASGM on 32 river reaches in the Madre de Dios region of Peru, which has been heavily impacted by ASGM since the 1980s. We evaluate spatial and temporal patterns of impacts using estimated SSC derived from Landsat satellite imagery. We find that 16 of 18 stretches of river impacted by ASGM show significant increasing trends in SSC ( < 0.05), while only 5 of 14 unaffected sites do so. Additionally, ASGM appears to reverse natural seasonal cycles of SSC, which may imperil aquatic species. Overall, our findings indicate that ASGM is fundamentally altering optical water quality dynamics of a critical tropical biodiversity hot spot and provide guidance for future regulation of these activities.
近年来，金价上涨加剧了小规模手工采金（ASGM）在全球范围内的扩散，对人类和生态健康造成了灾难性的后果。该行业的大部分增长发生在生物多样性热点地区，特别是在南美洲的热带森林。虽然由于 ASGM 导致的热带森林和洪泛区的丧失已经得到很好的描述，但 ASGM 对河流水文特性的影响还不太了解。以前对受 ASGM 影响和沟壑侵蚀的热带溪流和河流的实地工作表明，悬浮泥沙浓度（SSC）的增加会对鱼类多样性和水生群落结构产生重大影响，但由于缺乏 SSC 的长期记录，我们对这种增加的时间和范围的了解受到限制。为了解决这一挑战，我们对秘鲁马德雷德迪奥斯地区 32 个河流断面进行了 34 年的分析，该地区自 20 世纪 80 年代以来受到 ASGM 的严重影响。我们使用从 Landsat 卫星图像中估计的 SSC 来评估空间和时间模式的影响。我们发现，受 ASGM 影响的 18 个河段中有 16 个显示出 SSC 的显著增加趋势（<0.05），而不受影响的 14 个河段中只有 5 个有这种趋势。此外，ASGM 似乎逆转了 SSC 的自然季节性周期，这可能危及水生物种。总的来说，我们的研究结果表明，ASGM 正在从根本上改变一个关键的热带生物多样性热点地区的光学水质动态，并为未来对这些活动的监管提供指导。
