School of Environment, Faculty of Science, the University of Auckland, Auckland, New Zealand.
School of Environment, Faculty of Science, the University of Auckland, Auckland, New Zealand.
Mar Pollut Bull. 2022 Jul;180:113793. doi: 10.1016/j.marpolbul.2022.113793. Epub 2022 May 31.
Buoyant plastics enter estuaries largely from urban streams and an unknown fraction is retained before further transport to the open ocean. Plastic drifters were launched in a well-mixed estuary to simulate the movement of surface buoyant plastics. Two experiments were conducted, one during spring tides and one during neap tides, both with similar river flows and winds. Stronger tidal currents during spring tides resulted in larger dispersion and further downstream transport of the drifters. Half of the drifters were grounded within two tidal cycles. During the neap experiment, even more of the drifters (87%) were retained in the estuary. The grounding of such a high proportion of drifters suggests that much of the plastic pollution in estuaries of this type remains close to the riverine source. These findings imply that local clean-up programs removing grounded litter can reduce over half of the plastic pollution input to these estuaries.
漂浮塑料主要从城市溪流进入河口，在进一步输送到开阔海域之前，有一部分会被截留。为了模拟表面漂浮塑料的运动，我们在一个混合良好的河口投放了塑料漂移物。进行了两项实验，一次是在涨潮期间，一次是在小潮期间，两次实验的河流流量和风向都相似。涨潮期间的强潮流导致漂移物的扩散更大，输送到更远的下游。有一半的漂移物在两个潮汐周期内搁浅。在小潮实验中，更多的漂移物（87%）滞留在河口。如此高比例的漂移物搁浅表明，这种类型的河口的大部分塑料污染仍然靠近河流源头。这些发现表明，清除搁浅垃圾的地方清洁计划可以减少这些河口一半以上的塑料污染输入。
