Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Provincial Key Laboratory of Applied Marine Biology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China; Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clearwater Bay, Kowloon, Hong Kong.
Division of Life Science, Hong Kong University of Science and Technology (HKUST), Clearwater Bay, Kowloon, Hong Kong; Marine Environmental Laboratory, HKUST Shenzhen Research Institute, Shenzhen 518057, China.
Sci Total Environ. 2018 Mar;616-617:594-601. doi: 10.1016/j.scitotenv.2017.10.292.
In the present study, the arsenic (As) biokinetics and bioavailability in two deposit-feeding invertebrates (clams Gafrarium tumidum and polychaetes Nereis succinea) were quantified. Radiotracer techniques were applied to measure the dissolved uptake rate, dietary assimilation efficiency and efflux of As by the clams and polychaetes. Simultaneously, arsenic species analysis was conducted to examine the As biotransformation following dietary uptake. The radiotracer results showed that the uptake rate constant and efflux rate constant were 0.068L/g/d and 0.07d, and 0.173L/g/d and 0.09d, in the clams and polychaetes, respectively. Sediments labeled for different times (1.5-60 d) with different inorganic/organic As percentages led to diverse assimilation efficiencies of As (35.1-56.1% in the clams, and 51.6-72.6% in the polychaetes). Modeling calculations showed that sediment was a significant source for As bioaccumulation in the two deposit-feeders. After feeding on the spiked sediments, inorganic As (75.6%) was initially the predominant form, but arsenobetaine (AsB) became the predominant compound (>90%) in the clams and polychaetes during depuration, suggesting biotransformation of inorganic As. Combined with the biokinetics and biotransformation measurements, we showed that AsB was more efficiently assimilated and tended to be accumulated, whereas As(III) was less efficiently assimilated and more rapidly eliminated by the two invertebrates. This study demonstrated that As speciation in the sediments as a significant source for As bioaccumulation caused different bioavailability in deposit-feeding clams and polychaetes.
在本研究中，我们量化了两种摄食沉积物的无脊椎动物（蛤类 Gafrarium tumidum 和多毛类 Nereis succinea）体内砷的生物动力学和生物利用度。我们应用放射性示踪技术来测量蛤类和多毛类的溶解吸收速率、饮食同化效率和砷的外排率。同时，我们进行了砷形态分析，以研究摄食后砷的生物转化。放射性示踪结果表明，在蛤类和多毛类中，吸收速率常数和外排速率常数分别为 0.068L/g/d 和 0.07d，以及 0.173L/g/d 和 0.09d。用不同无机/有机砷百分比标记不同时间（1.5-60d）的沉积物导致砷的同化效率不同（在蛤类中为 35.1-56.1%，在多毛类中为 51.6-72.6%）。模型计算表明，沉积物是两种摄食沉积物的无脊椎动物砷生物累积的重要来源。在摄食添加了砷的沉积物后，无机砷（75.6%）最初是主要形态，但在蛤类和多毛类中，在清除过程中，砷甜菜碱（AsB）成为主要化合物（>90%），这表明无机砷发生了生物转化。结合生物动力学和生物转化测量，我们表明 AsB 被更有效地同化并倾向于积累，而 As(III)则被这两种无脊椎动物更有效地同化和更迅速地消除。本研究表明，沉积物中的砷形态作为砷生物累积的重要来源，导致了摄食沉积物的蛤类和多毛类之间不同的生物利用度。
