ABSTRACT

Muddy, faecally-contaminated river flood plumes in coastal waters are a hazard to contact recreation and bivalve shellfish consumption but are difficult to study, being episodic and transient. We used a new underway flow-through sampler in a small, fast boat, to map a flood plume within Wellington Harbour, while simultaneously sampling water in the Hutt River inflow. Faecal contamination (indexed by E.coli) correlated with flow, salinity, coloured dissolved organic matter, total suspended solids (TSS) and water clarity (light beam attenuation and visual clarity). The freshwater content of the plume agreed well with time-integrated river discharge. Despite the relatively short time-scale (<12 h) of the event, a 21% loss of TSS (particle flocculation and settling), and 30% loss in E. coli (suggesting some die-off) occurred in the plume compared to river loads. E. coli relative to TSS varied up to two orders of magnitude over a year of river flood sampling. A rapid survey of plumes combined with long-term river observations is expected to augment monitoring and inform the extension of remote sensing and modelling efforts to faecal contamination of New Zealand coastal waters.

摘要

沿海水域中被粪便污染的泥泞河流洪水羽流对接触娱乐活动和双壳贝类食用是一种危害，但由于是偶发性和短暂性的，因此难以研究。我们在一艘小型快艇上使用了一个新的正在进行的流通式采样器，以绘制惠灵顿港内的洪水羽流，同时对赫特河流入的水进行采样。粪便污染（由大肠杆菌索引）与流量、盐度、有色溶解有机物、总悬浮固体 (TSS) 和水透明度（光束衰减和视觉清晰度）相关。羽流的淡水含量与时间整合的河流流量吻合得很好。尽管事件的时间尺度相对较短（<12 小时），但 TSS（颗粒絮凝和沉降）损失 21%，大肠杆菌损失 30%与河流负荷相比，羽流中发生了（暗示一些死亡）。在一年的河流洪水采样中，相对于 TSS 的大肠杆菌变化高达两个数量级。对羽流的快速调查与长期河流观测相结合，预计将加强监测，并为将遥感和建模工作扩展到新西兰沿海水域的粪便污染提供信息。