Abstract：
The Salt River is an important urban river in Kaohsiung, Taiwan. In this study, the source identification and risk and toxicity assessment of the heavy-metal-contaminated sediments in the Salt River were investigated. The geo-accumulation index (Igeo), enrichment factor (EF), sediment quality guidelines (SQGs), potential ecological risk index (RI), pollution load index (PLI), and toxic units (TU) were applied to determine effects of heavy metals on microbial diversities and ecosystems. Results from the ecological and environmental risk assessment show that high concentrations of Zn, Cr, and Ni were detected in the midstream area and the sum of toxic units (ΣTUs) in the midstream (7.2-32.0) is higher than in the downstream (14.0-19.7) and upstream (9.2-17.1). It could be because of the continuous inputs of heavy-metal-contained wastewaters from adjacent industrial parks. Results also inferred that the detected heavy metals in the upstream residential and commercial areas were possibly caused by nearby vehicle emissions, non-point source pollution, and domestic wastewater discharges. Results of metagenomic assays show that the sediments contained significant microbial diversities. Metal-tolerant bacterial phyla (Proteobacteria: 24.4%-46.4%, Bacteroidetes: 1.3%-14.8%, and Actinobacteria: 2.3%-11.1%) and pathogenic bacterial phyla (Chlamydiae: 0.5%-37.6% and Chloroflexi: 5.8%-7.2%) with relatively high abundance were detected. Metal-tolerant bacteria would adsorb metals and cause the increased metal concentrations in sediments. Results indicate that the bacterial composition in sediment environments was affected by anthropogenic pollution and human activities and the heavy-metal-polluted ecosystem caused the variations in bacterial communities. PRACTITIONER POINTS: Microbial community in sediments is highly affected by heavy metal pollution. Wastewaters and vehicle traffic contribute to river sediments pollution by heavy metals. Proteobacteria, Bacteroidota, and Actinobacteria are dominant heavy-metal-tolerant bacterial phyla in sediments. Toxicity assessment is required to study risk levels of heavy-metal contained sediments.
摘要：
盐河是高雄重要的城市河流,台湾。在这项研究中,对盐河重金属污染沉积物的来源识别、风险和毒性评价进行了研究。地理积累指数(Igeo)，富集因子(EF)，沉积物质量准则(SQG)，潜在生态风险指数(RI)，污染负荷指数(PLI)，和有毒单位（TU）用于确定重金属对微生物多样性和生态系统的影响。生态环境风险评价结果表明,高浓度的锌,Cr,在中游区域检测到镍，中游（7.2-32.0）的有毒单位总和（ΣTU）高于下游（14.0-19.7）和上游（9.2-17.1）。这可能是因为来自相邻工业园区的重质废水的不断输入。结果还推断，上游住宅和商业区检测到的重金属可能是由附近的车辆排放引起的，面源污染，和生活废水排放。宏基因组分析结果表明，沉积物中含有明显的微生物多样性。耐金属细菌门（变形杆菌：24.4％至46.4％，拟杆菌：1.3%至14.8%，和放线菌：2.3％至11.1％）和致病性细菌门（衣原体：0.5％至37.6％，和Chloroflexi：5.8％至7.2％）检测到相对较高的丰度。耐金属细菌会吸附金属并导致沉积物中金属浓度增加。结果表明，沉积物环境中的细菌组成受到人为污染和人类活动的影响。重金属污染的生态系统导致了细菌群落的变化。
