In flux: Annual transport and deposition of suspended heavy metals and trace elements in the urbanised, tropical Red River Delta, Vietnam.
In flux: Annual transport and deposition of suspended heavy metals and trace elements in the urbanised, tropical Red River Delta, Vietnam.
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DOI：
10.1016/j.watres.2022.119053
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发表时间：
2022-09
期刊：
影响因子：
12.8
通讯作者：
L. Roberts;N. Do;V. Panizzo;Sarah Taylor;M. Watts;E. Hamilton;S. McGowan;D. Trinh;M. Leng;Jorge Salgado
中科院分区：
文献类型：
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作者：
L. Roberts;N. Do;V. Panizzo;Sarah Taylor;M. Watts;E. Hamilton;S. McGowan;D. Trinh;M. Leng;Jorge Salgado
由于沉积环境，河流三角洲被认为是污染物的过滤器和汇。然而，许多三角洲人口密集，城市化迅速，造成了新的和更多的污染源。这些污染源有可能使这些环境从污染汇变成污染源，进而变成世界海洋。我们提供了详细的季节性和年度评估河流悬浮颗粒物（SPM）在人口稠密的红河三角洲（RRD），越南。RRD对全球元素的贡献率均小于0.2%，其中许多元素通量小于0.01%，表明RRD不是海洋元素污染的主要来源。然而，人类活动造成的金属污染“热点”和热带风暴Son Tinh（2018年7月）的影响超出了国家级法规和国际毒性指标（例如富集因子）。有广泛的“极端污染”的镉（富集系数>40）和浓度的As高于国家规定的限制（>17毫克/公斤），在所有网站以外的上游，农业为主的支流在旱季。这些“热点”的特点是有机物（如粪肥和城市废水）的高投入，这影响了颗粒和溶解相中的元素流动性，并可能成为下游污染的重要来源。此外，在海水和淡水混合区，盐度影响金属与有机物的络合作用，增加颗粒相中的金属。我们的计算表明，三角洲目前是作为一个污染物汇（如确定的高水平的污染物沉积超过50%）。然而，污染物的增加以及未来季风强度、盐水入侵和人类活动的预计增加可能会使三角洲成为有毒金属的来源。我们显示的重要性，监测环境参数（主要是溶解有机物和盐度）在RRD评估的风险，运输和积累的有毒金属在三角洲沉积物中，这可能会导致净增加人为污染在沿海地区和纳入有毒元素的食物链。
Due to the depositional environment, river deltas are said to act as filters and sinks for pollutants. However, many deltas are also densely populated and rapidly urbanizing, creating new and increased sources of pollutants. These sources pose the risk of tipping these environments from pollution sinks to sources, to the world's oceans. We provide detailed seasonal and annual assessments of metal contaminants in riverine suspended particulate matter (SPM) across the densely populated Red River Delta (RRD), Vietnam. The global contributions of elements from the RRD are all <0.2% with many elemental fluxes <0.01%, suggesting the RRD is not a major source of elemental pollution to the ocean. However, ‘hotspots’ of metal pollution due to human activity and the impacts of tropical storm Son Tinh (July 2018) exceed both national level regulations and international measures of toxicity (e.g. enrichment factors). There is widespread ‘extreme pollution’ of Cd (enrichment factor >40) and concentrations of As higher than national regulation limits (>17 mg/Kg) at all sites other than one upstream, agricultural-dominated tributary in the dry season. These ‘hotspots’ are characterised by high inputs of organic matter (e.g. manure fertiliser and urban wastewater), which influences elemental mobility in the particulate and dissolved phases, and are potentially significant sources of pollution downstream. In addition, in the marine and fresh water mixing zone, salinity effects metal complexation with organic matter increasing metals in the particulate phase. Our calculations indicate that the delta is currently acting as a pollutant sink (as determined by high levels of pollutant deposition ∼50%). However, increased in-washing of pollutants and future projected increases in monsoon intensity, saline intrusion, and human activity could shift the delta to become a source of toxic metals. We show the importance of monitoring environmental parameters (primarily dissolved organic matter and salinity) in the RRD to assess the risk of transport and accumulation of toxic metals in the delta sediments, which can lead to net-increases in anthropogenic pollution in the coastal zone and the incorporation of toxic elements in the food chain.