Department of Chemistry, University of Surrey, Guildford, Surrey GU2 7XH, UK.
Department of Civil and Environmental Engineering, University of Surrey, Guildford, GU2 7XH, UK.
Environ Sci Process Impacts. 2022 Apr 21;24(4):504-524. doi: 10.1039/d1em00541c.
The laundering of synthetic fabrics has been identified as an important and diffuse source of microplastic (<5 mm) fibre contamination to wastewater systems. Home laundering can release up to 13 million fibres per kg of fabric, which end up in wastewater treatment plants. During treatment, 72-99% of microplastics are retained in the residual sewage sludge, which can contain upwards of 56 000 microplastics per kg. Sewage sludge is commonly disposed of by application to agricultural land as a soil amendment. In some European countries, application rates are up to 91%, representing an important pathway for microplastics to enter the terrestrial environment, which urgently requires quantification. Sewage sludge also often contains elevated concentrations of metals and metalloids, and some studies have quantified metal(loid) sorption onto various microplastics. The sorption of metals and metalloids is strongly influenced by the chemical properties of the sorbate, the solution chemistry, and the physicochemical properties of the microplastics themselves. Plastic-water partition coefficients for the sorption of cadmium, mercury and lead onto microplastics are up to 8, 32, and 217 mL g respectively. Sorptive capacities of microplastics may increase over time, due to environmental degradation processes increasing the specific surface area and surface density of oxygen-containing functional groups. A range of metal(loid)s, including cadmium, chromium, and zinc, have been shown to readily desorb from microplastics under acidic conditions. Sorbed metal(loid)s may therefore become more bioavailable to soil organisms when the microplastics are ingested, due to the acidic gut conditions facilitating desorption. Polyester (polyethylene terephthalate) should be of particular focus for future research, as few quantitative sorption studies currently exist, it is potentially overlooked from density separation studies due to its high density, and it is by far the most widely used fibre in apparel textiles production.
合成纤维的洗涤已被确定为向废水系统中排放微塑料（<5 毫米）纤维污染的一个重要且广泛的来源。家庭洗涤每公斤织物可释放多达 1300 万根纤维，这些纤维最终进入废水处理厂。在处理过程中，72-99%的微塑料会被截留到剩余的污水污泥中，每公斤污泥中可含有超过 56000 个微塑料。污水污泥通常通过施用到农业用地作为土壤改良剂来处理。在一些欧洲国家，施用量高达 91%，这代表了微塑料进入陆地环境的一个重要途径，迫切需要对此进行量化。污水污泥通常还含有较高浓度的金属和类金属，一些研究已经量化了各种微塑料对金属（类）金属的吸附。金属（类）金属的吸附强烈受吸附物的化学性质、溶液化学和微塑料本身的物理化学性质的影响。塑料-水分配系数用于表示镉、汞和铅在微塑料上的吸附，分别高达 8、32 和 217 mL g。由于环境降解过程会增加含氧官能团的比表面积和表面密度，微塑料的吸附容量可能会随时间而增加。已经证明，在酸性条件下，包括镉、铬和锌在内的一系列金属（类）金属很容易从微塑料中解吸。因此，当微塑料被摄入时，由于酸性肠道条件有利于解吸，吸附的金属（类）金属可能会对土壤生物更具生物可利用性。聚酯（聚对苯二甲酸乙二醇酯）应该是未来研究的重点，因为目前几乎没有定量吸附研究，而且由于其高密度，它可能会从密度分离研究中被忽视，而且它是迄今为止服装纺织品生产中使用最广泛的纤维。
