To clarify whether microplastics contribute to elevated bioaccumulation of methylmercury (MeHg) in aquatic organisms, we studied the sorption pattern of MeHg on polystyrene beads (PBs) and evaluated MeHg accumulation, via uptake of MeHg-adsorbed PB, in the oyster Crassostrea gigas. MeHg-cysteine conjugates were added to seawater at 10, 100, and 1000 µg/L as Hg. Polystyrene beads (φ = 0.02, 0.2, and 2 µm) were immersed in the seawater for 24 h. The concentrations of total mercury (T-Hg) adsorbed onto the PBs were then measured using the reduction vaporization method. T-Hg concentrations for the PBs with diameters of 0.02, 0.2, and 2 µm were 10.6 ± 0.4, 1.8 ± 0.1, and 1.3 ± 0.1 ng/mg-PBs, respectively, when immersed in 2 mL of MeHg-added seawater (100 µg/L as Hg). Thus, the adsorption efficiency of MeHg onto PBs was higher in the presence of smaller diameter PBs. Next, 1 mg of PBs immersed in 2 mL of seawater containing 100 µg/L of MeHg for 24 h was added to an oyster tank containing 1 L of seawater. The T-Hg concentration of the oysters was measured after 6 h of exposure. No significant difference was found in the T-Hg concentration of oysters in the presence of PBs (0.30 ± 0.01 to 0.37 ± 0.05 ng/mg as dry weight) with MeHg and in the absence of PBs (0.36 ± 0.03 ng/mg as dry weight). Our results suggest that the presence of PBs in seawater has little effect on MeHg uptake by oysters.

为了弄清微塑料是否有助于提高水生生物中甲基汞（MeHg）的生物富集性，我们研究了MeHg在聚苯乙烯珠（PBs）上的吸附模式，并通过吸收MeHg吸附的PB评估了牡蛎Crassostrea gigas中MeHg的积累。将MeHg-半胱氨酸结合物以10、100和1000 µg / L的Hg浓度添加到海水中。聚苯乙烯珠（φ = 0.02、0.2和2 µm）在海水中浸泡24小时。然后使用还原汽化法测量吸附在PB上的总汞（T-Hg）的浓度。浸入2 mL添加MeHg的海水中时，直径0.02、0.2和2μm的PB的T-Hg浓度分别为10.6±0.4、1.8±0.1和1.3±0.1 ng / mg-PBs（100 µg / L（以Hg计）。因此，在较小直径的PBs存在下，MeHg在PBs上的吸附效率更高。接下来，将1 mg PBs浸入2 mL含100 µg / L MeHg的海水中24小时，然后将其添加到包含1 L海水的牡蛎罐中。暴露6小时后测量牡蛎的T-Hg浓度。在PB存在下，牡蛎的T-Hg浓度没有发现显着差异（0.30±0.01至0.37±0。含MeHg且无PBs（干重0.36±0.03 ng / mg）的干重为5 ng / mg）。我们的结果表明，海水中多溴联苯的存在对牡蛎摄取甲基汞的影响很小。