{"title":"Mixed response of trace element concentrations in fluvial sediments to a flash flood in a former mining area","authors":"Alexandra Weber, Frank Lehmkuhl","doi":"10.1186/s12302-024-00926-5","DOIUrl":null,"url":null,"abstract":"<div><h3>Background</h3><p>Floods, especially flash floods, are the major transporting agent for fluvial sediments, whose pollution is a global concern. As floods result in the dispersion of and exposure to these sediments, a profound understanding of sedimentary dynamics during flood events and the related pollutant dispersion is of relevance. However, the characteristics of extreme flood events concerning pollutant dynamics are insufficiently known so far.</p><h3>Results</h3><p>In a Central European catchment impacted by intense industrial activities and former mining, over the course of five years, we surveyed six high-discharge events, five of them approx. bankfull discharge and one major flash flood event, supplemented by sampling of bank sediments. Fluvial sediments were analyzed for elemental composition by X-Ray fluorescence and for grain size distribution of the fine faction by laser diffraction. By applying a local enrichment factor, trace metal(loid) signatures in these sample sets were compared. Furthermore, Positive Matrix Factorization was used to investigate the trace metal(loid)s’ sources.</p><p>The sediments deposited by minor flooding had continual trace metal(loid) signatures. However, for the extreme event, significant divergencies arose and persisted for the following years: The enrichment of anthropogenically influenced elements increased, with a slowly decreasing trend in the subsequent two years. Naturally dominated metal(oid)s decrease in enrichment without indicating a return to original levels. In contrast, other elements were insensitive to the extreme event. Positive Matrix Factorization identified anthropogenic influences in elements originating from copper and lead processing and mining activities. Furthermore, bed sediments and a natural background factor were found to dominate the non-anthropogenically influenced metal(loid)s.</p><h3>Conclusions</h3><p>In between extreme events, winnowing processes slowly alter the elemental composition of bed sediments. The depletion of such sediments due to the flash flood proves catchment-wide flushing, which induces a natural resetting of the geochemical signals. This ability to renew is an integral part of resilience in fluvial systems. This mechanism is disturbed by industrial activities in floodplains. The exceptional flooding reaches infrastructure that is assumed to be safe and, therefore, unprotected. These additional sources can shift flood sediments’ trace metal(loid) signature, which has a long-lasting impact on the catchment sediments. However, the modifications depend on the flooding extent, possible emitters, and protection measures.</p></div>","PeriodicalId":546,"journal":{"name":"Environmental Sciences Europe","volume":null,"pages":null},"PeriodicalIF":6.0000,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://enveurope.springeropen.com/counter/pdf/10.1186/s12302-024-00926-5","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Environmental Sciences Europe","FirstCategoryId":"93","ListUrlMain":"https://link.springer.com/article/10.1186/s12302-024-00926-5","RegionNum":3,"RegionCategory":"环境科学与生态学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENVIRONMENTAL SCIENCES","Score":null,"Total":0}
引用次数: 0
Abstract
Background
Floods, especially flash floods, are the major transporting agent for fluvial sediments, whose pollution is a global concern. As floods result in the dispersion of and exposure to these sediments, a profound understanding of sedimentary dynamics during flood events and the related pollutant dispersion is of relevance. However, the characteristics of extreme flood events concerning pollutant dynamics are insufficiently known so far.
Results
In a Central European catchment impacted by intense industrial activities and former mining, over the course of five years, we surveyed six high-discharge events, five of them approx. bankfull discharge and one major flash flood event, supplemented by sampling of bank sediments. Fluvial sediments were analyzed for elemental composition by X-Ray fluorescence and for grain size distribution of the fine faction by laser diffraction. By applying a local enrichment factor, trace metal(loid) signatures in these sample sets were compared. Furthermore, Positive Matrix Factorization was used to investigate the trace metal(loid)s’ sources.
The sediments deposited by minor flooding had continual trace metal(loid) signatures. However, for the extreme event, significant divergencies arose and persisted for the following years: The enrichment of anthropogenically influenced elements increased, with a slowly decreasing trend in the subsequent two years. Naturally dominated metal(oid)s decrease in enrichment without indicating a return to original levels. In contrast, other elements were insensitive to the extreme event. Positive Matrix Factorization identified anthropogenic influences in elements originating from copper and lead processing and mining activities. Furthermore, bed sediments and a natural background factor were found to dominate the non-anthropogenically influenced metal(loid)s.
Conclusions
In between extreme events, winnowing processes slowly alter the elemental composition of bed sediments. The depletion of such sediments due to the flash flood proves catchment-wide flushing, which induces a natural resetting of the geochemical signals. This ability to renew is an integral part of resilience in fluvial systems. This mechanism is disturbed by industrial activities in floodplains. The exceptional flooding reaches infrastructure that is assumed to be safe and, therefore, unprotected. These additional sources can shift flood sediments’ trace metal(loid) signature, which has a long-lasting impact on the catchment sediments. However, the modifications depend on the flooding extent, possible emitters, and protection measures.
背景洪水,尤其是山洪,是河道沉积物的主要运输工具,而河道沉积物的污染是全球关注的问题。由于洪水会导致这些沉积物的扩散和暴露,因此深入了解洪水事件期间的沉积动力学以及相关的污染物扩散具有重要意义。结果 在中欧一个受激烈工业活动和前采矿业影响的集水区,我们用五年时间调查了六次高排水量事件,其中五次接近河岸满排水量,还有一次山洪暴发事件,并对河岸沉积物进行了取样。我们用 X 射线荧光分析了冲积物的元素组成,并用激光衍射分析了细颗粒的粒度分布。通过应用局部富集因子,对这些样本集中的痕量金属(loid)特征进行了比较。小洪水沉积的沉积物具有持续的痕量金属(loid)特征。小洪水沉积的沉积物具有持续的痕量金属(loid)特征,但在极端事件中,出现了明显的差异,并在随后几年中持续存在:受人类活动影响的元素富集增加,随后两年呈缓慢下降趋势。自然界占主导地位的金属元素富集度下降,但没有恢复到原来的水平。相比之下,其他元素对极端事件并不敏感。正矩阵因式分解确定了铜和铅加工及采矿活动对元素的人为影响。此外,还发现河床沉积物和自然背景因素在非人为影响的金属(loid)中占主导地位。山洪暴发造成的沉积物损耗证明了整个流域的冲刷,从而引起地球化学信号的自然重置。这种更新能力是河川系统恢复能力的一个组成部分。这一机制受到洪泛区工业活动的干扰。特殊的洪水会到达被认为是安全的基础设施,因此这些基础设施没有受到保护。这些额外的来源会改变洪水沉积物的痕量金属(loid)特征,从而对流域沉积物产生长期影响。不过,这种改变取决于洪水范围、可能的排放源和保护措施。
期刊介绍:
ESEU is an international journal, focusing primarily on Europe, with a broad scope covering all aspects of environmental sciences, including the main topic regulation.
ESEU will discuss the entanglement between environmental sciences and regulation because, in recent years, there have been misunderstandings and even disagreement between stakeholders in these two areas. ESEU will help to improve the comprehension of issues between environmental sciences and regulation.
ESEU will be an outlet from the German-speaking (DACH) countries to Europe and an inlet from Europe to the DACH countries regarding environmental sciences and regulation.
Moreover, ESEU will facilitate the exchange of ideas and interaction between Europe and the DACH countries regarding environmental regulatory issues.
Although Europe is at the center of ESEU, the journal will not exclude the rest of the world, because regulatory issues pertaining to environmental sciences can be fully seen only from a global perspective.