FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch, 7701, South Africa.
FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch, 7701, South Africa.
Sci Total Environ. 2020 Jul 1;724:138310. doi: 10.1016/j.scitotenv.2020.138310. Epub 2020 Mar 30.
To implement effective mitigation measures to stop the flow of litter from land-based sources into the sea, it is important to identify key pollution sources and to monitor litter trends over time. We sampled plastic and other anthropogenic debris in urban stormwater run-off in Cape Town, South Africa, from three catchment areas representing different land-use types: residential, industrial and a mixed commercial/residential area. Sampling was conducted in 2018-19 by placing nets over stormwater outlets during rain events. Organic matter constituted 79% of material by dry mass (industrial: 51 ± 22%, commercial/residential: 86 ± 4%, residential: 88 ± 13%). The nets caught 5-576 anthropogenic litter items·ha·day (2-377 g·ha·day) with significantly higher densities in the industrial and commercial/residential areas than the residential area. Among anthropogenic litter items, 40-78% were made of plastic (52-64% by mass). Most plastic items were single-use packaging, but industrial pellets washed out of the industrial outlet during every rain event. Compared to a similar study conducted in 1996, the number of litter items decreased by ~20% in the industrial and residential areas but tripled in the commercial/residential area. The proportion of plastics in the litter stream was broadly similar to 1996. We extrapolate that some 60-570 t of plastic are released from Cape Town stormwater outlets annually, which is orders of magnitude less than predicted by global models. It is nevertheless clear that stormwater outlets are a significant source of litter into the sea. Intercepting this waste before it reaches the sea would greatly reduce litter loads in coastal waters around Cape Town.
为了实施有效的缓解措施以阻止陆源垃圾流入海洋，确定关键污染源并监测垃圾随时间的变化趋势非常重要。我们在南非开普敦的三个集水区（代表不同的土地利用类型：住宅、工业和混合商业/住宅）中采集了城市雨水径流中的塑料和其他人为垃圾。采样是在 2018-19 年通过在雨水事件期间将网放在雨水出口上来进行的。有机物质占干物质的 79%（工业：51±22%，商业/住宅：86±4%，住宅：88±13%）。网捕获了 5-576 个人为垃圾颗粒·公顷·天（2-377 g·公顷·天），工业和商业/住宅区域的密度明显高于住宅区域。在人为垃圾颗粒中，40-78%由塑料制成（质量占 52-64%）。大多数塑料颗粒是一次性包装，但在每次降雨期间，工业出口都会冲出工业颗粒。与 1996 年进行的类似研究相比，工业和住宅区域的垃圾颗粒数量减少了约 20%，但商业/住宅区域的数量增加了两倍。垃圾流中塑料的比例与 1996 年大致相似。我们推断，每年约有 60-570 吨塑料从开普敦雨水出口释放，这比全球模型预测的数量要小几个数量级。然而，很明显，雨水出口是垃圾进入海洋的重要来源。在垃圾到达海洋之前拦截这些垃圾将大大减少开普敦沿海地区的垃圾负荷。
