International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744, Motooka, Nishi-ku, Fukuoka-City, 819-0395, Japan; Department of Environmental Sciences, Jahangirnagar University, Dhaka, 1342, Bangladesh.
International Institute for Carbon-Neutral Energy Research (WPI-I2CNER), Kyushu University, 744, Motooka, Nishi-ku, Fukuoka-City, 819-0395, Japan; Mechanical Engineering Department, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka-shi, Fukuoka, 819-0395, Japan; Department of Statistics, University of Dhaka, Dhaka, 1000, Bangladesh.
Environ Pollut. 2022 Sep 15;309:119765. doi: 10.1016/j.envpol.2022.119765. Epub 2022 Jul 20.
Mangroves play a vital role in protecting the coastal community from the climate change effect and in the restoration of the coastal ecosystem. This research has been designed to determine the spatial and seasonal changes of potentially toxic elements' (PTEs) concentration in sediments and their potential source contribution among the different human-driven processes in Sundarbans, Bangladesh. Different pollution evaluation indices, random forest (RF) model, conditional inference tree (CIT), self-organizing map (SOM), geographical information system (GIS), and principal component analysis (PCA) were used for the interpretation of sources and risk assessment of PTEs. The mean concentration of PTEs both in winter and monsoon seasons has fallen below the threshold effect level but exceeded the rare effect level of marine sediments quality standards. Results showed that the PTEs were significantly enriched (EF > 1.00 < 70.00) in sediments, whereas the Cd enrichment (7.00% samples) was very alarming (EF = 60-70). Except for Zn and Cd, other PTEs were enriched in 30-60% samples. The highest geoaccumulation and contamination factors for Cd were observed in 46-72% of samples. The ecological risk (ER) factors showed similar results where Cd showed strong to very strong factors (ER = 110-2218) in 80% of samples. The CIT explained the natural/geogenic and anthropogenic sources of pollution, where the higher CIT values for Cd indicated industrial, aquaculture, and coal-based thermal powerplant. The RF model provided that shrimp firms, power plants, industry, and seaport were recognized as the influential sources for Zn, Pb, Cr, Cd, and As in sediments. Though Pb and As were found as the most significant pollutants, Cd was identified as a severe threat to ecology and public health. Based on CIT, RF, SOM and PCA the order of PTEs in mangroves sediment were:industrial/urban > aquaculture/shrimpfirm > powerplant > seaportoperation > tourism > geogenic/natural. The present study will help the policymakers for effective and sustainable management of the mangrove ecosystem.
红树林在保护沿海社区免受气候变化影响和恢复沿海生态系统方面发挥着至关重要的作用。本研究旨在确定孟加拉国桑达班不同人为驱动过程中沉积物中潜在有毒元素（PTEs）浓度的空间和季节变化及其潜在来源贡献。使用不同的污染评价指数、随机森林（RF）模型、条件推断树（CIT）、自组织映射（SOM）、地理信息系统（GIS）和主成分分析（PCA）来解释 PTEs 的来源和风险评估。冬季和季风季节 PTEs 的平均浓度均低于海洋沉积物质量标准的阈值效应水平，但超过了稀有效应水平。结果表明，PTEs 在沉积物中明显富集（EF>1.00<70.00），而 Cd 富集（7.00%的样本）非常令人担忧（EF=60-70）。除 Zn 和 Cd 外，其他 PTEs 在 30-60%的样本中富集。Cd 的最高地质累积和污染因子在 46-72%的样本中观察到。生态风险（ER）因子也显示出类似的结果，其中 80%的样本中 Cd 表现出强到很强的因子（ER=110-2218）。CIT 解释了自然/地球化学和人为污染源，其中 Cd 的更高 CIT 值表明工业、水产养殖和燃煤热电厂。RF 模型提供了虾场、电厂、工业和海港被认为是沉积物中 Zn、Pb、Cr、Cd 和 As 主要影响源的结果。尽管 Pb 和 As 被认为是最重要的污染物，但 Cd 被认为对生态和公共健康构成严重威胁。根据 CIT、RF、SOM 和 PCA，红树林沉积物中 PTEs 的顺序为：工业/城市>水产养殖/虾场>电厂>海港作业>旅游业>地球化学/自然。本研究将有助于决策者对红树林生态系统进行有效和可持续的管理。
