塑料碎片会影响并受到其积聚的海滩的影响。大多数关于海滩沙子中的微塑料(MP)的研究都集中在沿海海滩或人口中心附近的大型湖泊的海滩上。这里,我们评估了密西西比州北部一个相对无人居住的主要防洪水库(萨迪斯湖)出口附近的沙滩上的MP污染,美国,集中在两个突出的混乱区域和中间区域。通过密度分离和基质消化分离出推定的MPs,然后用立体显微镜检查,样品的子集还通过μ-FTIR分析。MP丰度(颗粒/kg±1标准误差(SE),n=15),平均590±360,下部破坏区950±100,上部裂缝区域540±40,和270±30之间的地区;这些差异有统计学意义(p<0.01)。MP通常在各个地点具有相似的大小和形状特征。大多数是纤维(64%),其次是碎片(23%),珠子(7%)和胶片(6%),与之间的区域相比,包裹区域中的纤维比例略高。议员人数随着人数的减少而急剧增加。仅在<500μm尺寸部分中发现珠。透明和蓝色是所有国会议员的主要颜色。共检测到29种不同类型的聚合物,超过一半的颗粒由聚乙烯和聚酰胺组成,其次是聚(甲基丙烯酸甲酯),聚对苯二甲酸乙二醇酯,聚碳酸酯,聚丙烯,和其他人;尽管这种分布根据大小分数和位置而有所不同。因为没有大量废水排放到萨迪斯湖,国会议员的来源可能是不小心丢弃的塑料的降解,以及大气沉降。总的来说,我们发现,MP浓度在破坏区最高,并受水库排放速率和持续时间的影响。因此,像沿海海滩,水库沿线或下游的淡水海滩上的杂乱区积聚了大型和微型塑料,是塑料清理的主要场所。最后,我们表明,由自然风化的LDPE塑料薄膜制成的MP在预处理过程中容易碎裂,这可能会导致其高估。
Plastic debris both affects and is affected by the beaches it accumulates on. Most studies of microplastics (MPs) in beach sand are focused on coastal beaches or beaches of large lakes near population centers. Here, we assessed MP pollution at a sandy beach near the outlet of a major flood control
reservoir (Sardis Lake) in a relatively unpopulated area in north Mississippi, USA, focusing on two prominent wrack zones and areas in-between. Putative MPs were isolated by density separation and matrix digestion, and then examined using stereomicroscopy, with a subset of samples additionally analyzed by μ-FTIR. MP abundance (particles/kg ± 1 standard error (SE), n = 15) averaged of 590 ± 360, with 950 ± 100 in the lower wrack zone, 540 ± 40 in the upper wrack zone, and 270 ± 30 in areas between; these differences were statistically significant (p < 0.01). The MPs generally had similar size and shape characteristics across sites. The majority were fibers (64%), followed by fragments (23%), beads (7%) and films (6%), with a slightly greater proportion of fibers in the wrack zones compared to areas in-between. The number of MPs rose dramatically with decreasing size. Beads were only found in the < 500 μm size fraction. Clear and blue were the predominant colors for all MPs. A total of 29 different types of polymers were detected, with more than half of the particles being composed of polyethylene and polyamide, followed by poly(methyl methacrylate), polyethylene terephthalate, polycarbonate, polypropylene, and others; although this distribution varied some depending on size fraction and location. Because there are no major wastewater discharges into Sardis Lake, the source of the MPs is likely degradation of carelessly discarded plastic, as well as atmospheric fallout. Overall, we found that MP concentrations were highest in the wrack zones and influenced by rates and duration of discharge from the
reservoir. Thus, like coastal beaches, wrack zones on freshwater beaches along or downstream of reservoirs accumulate both macro- and micro-plastics and are prime locations for plastic cleanup. Finally, we show that MPs made from naturally weathered LDPE plastic film are prone to fragmentation during pretreatment procedures, which may result in its overestimation.