海水养殖用塑料中有机磷酸酯的溶出规律及生物富集特征Release Behavior and Bioaccumulation Characteristics of Organophosphate Esters from Plastics in Marine Aquaculture

Release Behavior and Bioaccumulation Characteristics of Organophosphate Esters from Plastics in Marine Aquaculture

中文关键词: 养殖用塑料  有机磷酸酯  溶出规律  生物富集

英文关键词: Aquaculture plastics  Organophosphate esters  Leaching behavior  Bioaccumulation

中文摘要:

      养殖用塑料的长期使用不可避免地造成塑料添加剂溶出到水环境中。然而,这些塑料添加剂的溶出规律及对水生生物的暴露风险尚不清晰。本研究聚焦典型塑料添加剂有机磷酸酯(Organophosphate esters,OPEs),以在野外海水养殖塘中收集的塑料防渗膜作为研究对象,分别进行室内模拟溶出实验和水生生物暴露实验。结果表明,在240 h的模拟溶出实验中,总OPEs的溶出量为12.24 ng/g。其中,含氯类OPEs的溶出率相对较高,TCEP溶出率达到了40.6%,含氯类OPEs >芳香类OPEs>烷烃类OEPs；塑料防渗膜在0~2 d的溶出实验过程中,OPEs的溶出速率最快,在第6 d后,溶出速率开始达到平衡状态。对于水生生物暴露实验,结果表明,48 h内防渗膜溶出的OPEs在卤虫体内检出5种,其中TCP、TDCPP的log BAF>3.7,具有生物富集效应；TnBP的log BAF值介于3.3～3.7之间,具有潜在的生物富集效应。这些结果表明海水养殖塘中的塑料防渗膜所释放的OPEs会对水生生物造成潜在的风险。

英文摘要:

      In recent years, the rapid development of the Chinese coastal economy and the expansion of aquaculture have led to an increased reliance on plastic materials within marine aquaculture systems. These materials, such as impermeable membranes, fishing nets, buoys, cages, and ropes, are widely used due to their beneficial properties, including being lightweight, durable, and cost-effective. However, the large-scale production and extensive use of plastics in aquaculture have raised concerns about their potential environmental impacts, especially regarding the pollution of the marine environment and the associated risks to ecosystems. Among the primary concerns are the plastic additives that are incorporated into these materials. These additives, including organophosphate esters (OPEs), are often physically mixed into the polymer matrices rather than chemically bonded. This physical integration makes them more susceptible to being released into the surrounding environment through various processes, such as volatilization, leaching, abrasion, and dissolution, during the product’s lifecycle. Despite these risks, the mechanisms and patterns of additive release, as well as the exposure risks posed to marine organisms, remain poorly understood. This study specifically focuses on OPEs, a common group of plastic additives, to investigate their presence and behavior in plastic impermeable membranes utilized in marine aquaculture ponds. The study’s objectives were threefold: (1) to identify the types and concentrations of OPEs present in the plastic impermeable membranes collected from marine aquaculture ponds, (2) to simulate the dynamic dissolution of these OPEs in artificial seawater, and (3) to evaluate the bioaccumulation potential of these OPEs in aquatic organisms, using Artemia as a model species. To achieve these goals, we collected plastic impermeable membranes from wild marine aquaculture ponds and analyzed their OPE content using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). Our analysis revealed the presence of six different types of OPEs, which included two aliphatic OPEs (TnBP, TiBP), one aromatic OPE (TCP), and three chlorinated OPEs (TCEP, TDCPP, TCPP). Among these, TCPP was the most abundant, with a concentration of 395.15 ± 48.05 ng/g, accounting for 63.12% of the total OPEs detected in the membranes. TnBP was the next most prevalent, with concentrations of 73.359 ± 43.99 ng/g and 52.961 ± 5.25 ng/g, respectively. TCP, on the other hand, had the lowest concentration at 2.08 ± 1.35 ng/g, contributing only 0.33% to the total OPEs. In order to understand the dissolution behavior of OPEs in these membranes, we conducted a 240-hour laboratory simulation. The impermeable membranes were submerged in 30‰ artificial seawater, and water samples were collected every 48 hours for analysis. The OPE concentrations in these water samples were determined using solid-phase extraction (SPE) followed by HPLC-MS/MS. By the end of the experiment, the total amount of OPEs dissolved from the membranes reached 12.24 ng/g. Among the different OPEs, chlorinated OPEs exhibited the highest dissolution rates, with TCEP showing a dissolution rate of 40.6%. The general order of dissolution was chlorinated OPEs > aromatic OPEs > aliphatic OPEs. Notably, the dissolution rate was highest during the first 48 hours of the experiment and then gradually decreased over time. By around the 6th day, the dissolution rate reached a near-equilibrium state, likely due to the depletion of OPEs from cracks and pores on the surface of the membrane. At this stage, the membranes had likely reached a dynamic equilibrium between the release and adsorption of OPEs. In addition to the dissolution experiments, we assessed the bioaccumulation potential of OPEs in Artemia, a species commonly used in marine studies. For this purpose, plastic impermeable membranes were added to artificial seawater at concentrations that mimicked those typically found in marine aquaculture ponds. After exposure, samples of both Artemia and the surrounding water were collected, and the OPE concentrations were analyzed using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). Five OPEs—TCP, TDCPP, TnBP, TCPP, and TiBP—were detected in Artemia. We evaluated the degree of bioaccumulation using the bioaccumulation factor (BAF). The results indicated that TCP and TDCPP had significant bioaccumulation potential, with log BAF values greater than 3.7. TnBP exhibited a moderate bioaccumulation effect, with a log BAF between 3.3 and 3.7. However, TCPP and TiBP showed no significant bioaccumulation potential, as their log BAF values were below 3.3. In conclusion, our study identified six distinct OPEs in the plastic impermeable membranes used in marine aquaculture, with chlorinated OPEs being the most prevalent. The results of the dissolution experiments revealed that OPEs are initially released rapidly from surface cracks and pores of the membranes, followed by a slower release as equilibrium is reached. Furthermore, the bioaccumulation experiments demonstrated that certain OPEs, especially TCP and TDCPP, pose bioaccumulation risks to marine organisms like Artemia. These findings underscore the importance of managing plastic additives in marine aquaculture systems to mitigate the potential environmental impacts of plastic waste and its associated contaminants. The study provides valuable insights that can inform future strategies for reducing the ecological risks posed by plastic additives in marine environments.