各国的采矿业,特别是在撒哈拉以南非洲地区,面临着小规模无证手工矿山出现的重大影响。这一趋势受到矿物需求和价格上涨的影响,以及普遍的贫困水平。因此,这些手工地雷对自然环境的有害影响(即,河流)仍然知之甚少,特别是在津巴布韦的背景下。为了了解这种情况的后果,在Umzingwane集水区进行了一项研究,位于津巴布韦南部,重点关注受沿岸地区非法采矿活动影响的河流中水养分和金属浓度的变化。在GoogleEarthEngine云计算平台上使用多年Sentinel-2复合数据和随机森林机器学习算法,我们绘制了受影响地区非法地雷的空间分布和七个不同的土地利用类别,包括手工矿山,裸露的表面,定居点,官方地雷,农田,和自然植被,具有可接受的总体和类别精度的±70%被确定。发现手工矿山位于河流沿岸,这归因于采矿过程中需要大量的水。水质分析显示养分浓度升高,例如铵和硝酸盐(范围为0.10-20.0mgL-1),这可能归因于采矿活动中使用硝酸铵炸药产生的矿井排水。此外,该地区农田的流行可能导致养分浓度增加。主成分分析和层次聚类分析揭示了三个聚类,其中一个簇显示像Ca这样的参数,Mg,K,Hg和Na,通常与在选定河流中的手工矿山排水中发现的矿物石膏有关。集群2由B组成,Cu,Fe,Pb,Mn,可能来自自然环境,最后,集群3包含As,Cd,Cr,Zn,这可能与合法和非法采矿作业有关。这些发现为研究河流系统的健康以及人类活动对该地区的影响提供了重要的见解。它们进一步成为制定和实施旨在保护河流系统的监管措施的基础,根据可持续发展目标15.1,该目标侧重于保护和保护陆地和内陆淡水生态系统,包括河流。通过对这些信息采取行动,当局可以努力保护这些重要的自然资源,促进该地区的可持续发展。
The mining sector in various countries, particularly in the sub-Saharan African region, faces significant impact from the emergence of small-scale unlicensed artisanal mines. This trend is influenced by the rising demand and prices for minerals, along with prevalent poverty levels. Thus, the detrimental impacts of these artisanal mines on the natural environment (i.e., rivers) have remained poorly understood particularly in the Zimbabwean context. To understand the consequences of this situation, a study was conducted in the Umzingwane Catchment, located in southern Zimbabwe, focusing on the variations in water nutrient and metal concentrations in rivers affected by illegal mining activities along their riparian zones. Using multi-year Sentinel-2 composite data and the random forest machine learning algorithm on the Google Earth Engine cloud-computing platform, we mapped the spatial distribution of illegal mines in the affected regions and seven distinct land use classes, including artisanal mines, bare surfaces, settlements, official mines, croplands, and natural vegetation, with an acceptable overall and class accuracies of ±70 % were identified. Artisanal mines were found to be located along rivers and this was attributed to their large water requirements needed during the mining process. The water quality analysis revealed elevated nutrient concentrations, such as ammonium and nitrate (range 0.10-20.0 mg L-1), which could be attributed to mine drainage from the use of ammonium nitrate explosives during mining activities. Additionally, the prevalence of croplands in the area may have potentially contributed to increased nutrient concentrations. The principal component analysis and hierarchical cluster analysis revealed three clusters, with one of these clusters showing parameters like Ca, Mg, K, Hg and Na, which are usually associated with mineral gypsum found in the drainage of artisanal mines in the selected rivers. Cluster 2 consisted of B, Cu, Fe, Pb, and Mn, which are likely from the natural environment and finally, cluster 3 contained As, Cd, Cr, and Zn, which were likely associated with both legal and illegal mining operations. These findings provide essential insights into the health of the studied river system and the impacts of human activities in the region. They further serve as a foundation for developing and implementing regulatory measures aimed at protecting riverine systems, in line with sustainable development goal 15.1 which focuses on preserving and conserving terrestrial and inland freshwater ecosystems, including rivers. By acting on this information, authorities can work towards safeguarding these vital natural resources and promoting sustainable development in the area.