Research Institute for the Environment & Livelihoods, Charles Darwin University, Darwin, Australia.
Faculty of Engineering, University of Indonesia, Depok, Indonesia.
Sci Total Environ. 2019 Sep 10;682:382-393. doi: 10.1016/j.scitotenv.2019.05.189. Epub 2019 May 16.
Wastewater treatment infrastructure is lacking in many developing countries, often resulting in high loads of contaminants discharged to urban rivers. In these countries, targeted pollution mitigation requires an understanding of where, how and when contaminants enter water bodies. Here we report on contamination of the Ciliwung River, a dynamic, tropical system flowing through the Jakarta metropolitan area (Indonesia). We measured a set of isotopic, chemical and microbial tracers in representative water and contamination sources, as well as longitudinally within the river, to assess the spatial and temporal variations in contaminant levels in and pathways to the river. In the dry season, we observed a tight coupling between locally recharged groundwater sources and the river, whereas in the wet season, one single water source originating from the fractured headwaters predominantly contributed to river flow. Yet, the flushing of upstream waters in the wet season did not always lead to the dilution of contaminants downstream. We delineated several contamination hotspots along the river, particularly active during the wet season due to higher hydrological connectivity between sources and the river. These hotspots may originate from septic tank leakage, as supported by metal ratios and dominant microbial communities, although we could not rule out other potential sources such as urban runoff or sediment resuspension. Bayesian source tracking on the whole microbial community proved useful in outlining processes that conventional tracers did not capture, such as the occurrence of a localised domestic contamination in the upper catchment, and the inflow of agricultural runoff all along the river profile during the wet season. Our study emphasises the role of rivers as biogeochemical reactors that constantly process and transform contaminants and microbial communities. We also demonstrate the value of using isotopic, chemical and microbial tools together to trace the movement of water and contaminants through urban rivers.
许多发展中国家缺乏废水处理基础设施，这往往导致大量污染物排入城市河流。在这些国家，有针对性地减轻污染需要了解污染物是从何处、如何以及何时进入水体的。在这里，我们报告了流经印度尼西亚雅加达大都市区的动态热带 Ciliwung 河的污染情况。我们在代表性的水源和污染源以及河流内部进行了一系列同位素、化学和微生物示踪剂的测量，以评估河流中污染物水平的时空变化及其进入河流的途径。在旱季，我们观察到当地补给地下水源与河流之间的紧密耦合，而在雨季，一条源自断裂源头的单一水源主要为河流提供水流。然而，雨季上游水流的冲刷并不总是导致下游污染物的稀释。我们沿着河流划定了几个污染热点，特别是在雨季，由于水源与河流之间的水文连通性更高，这些热点更为活跃。这些热点可能源于化粪池泄漏，这得到了金属比和主要微生物群落的支持，尽管我们不能排除其他潜在的来源，如城市径流或沉积物再悬浮。对整个微生物群落的贝叶斯源追踪在概述常规示踪剂无法捕捉到的过程方面非常有用，例如在上游集水区局部发生的家庭污染，以及雨季整个河流剖面的农业径流流入。我们的研究强调了河流作为生物地球化学反应器的作用，它们不断处理和转化污染物和微生物群落。我们还展示了使用同位素、化学和微生物工具一起追踪水和污染物通过城市河流的运动的价值。
