Lietti E, Marin M G, Matozzo V, Polesello S, Valsecchi S
Water Research Institute, National Research Council, Via Mornera 25, 20047 Brugherio, Milan, Italy.
Arch Environ Contam Toxicol. 2007 Nov;53(4):571-8. doi: 10.1007/s00244-006-0250-9. Epub 2007 Jul 20.
The present study is the first dealing with the accumulation and elimination of 4-nonylphenol (NP) by the Manila clam, Tapes philippinarum. Specimens of T. philippinarum were exposed to NP-spiked seawater, and the NP contents in whole soft tissue, gills, digestive gland, and haemolymph were measured. Actual NP concentrations in seawater and microalgae (Isochrysis galbana) used for feeding were also determined, and the algal bioconcentration factor (BCF) value (640 ml/g) was calculated. Volatilisation was the main cause of dissipation of NP from experimental tanks, attaining up to 78% of the NP added. NP accumulated by algae used for feeding was negligible with respect to the total added NP, and we concluded that in our experiments, clams accumulated NP mainly from water and not food intake. Accumulation followed a two-compartment, first-order rate coefficient model, with an uptake rate coefficient of 13.8 +/- 0.6 mL g(-1)h(-1)(fresh weight [fw]) and an elimination coefficient of 0.0070 +/- 0.0005 h(-1). Ninety percent of the steady state was reached after 14 days of exposure, and the BCF value at the steady state was 1958 +/- 158 mL g(-1) fw (1.8 +/- 0.2 x 10(5) based on lipid weight). Slightly less than 50% of NP bioaccumulated through water was allocated into the gills, whereas the rest was found in the digestive gland. In the first 8 hours, clams eliminated 51% of the NP accumulated, and only 2% of the NP accumulated was detected in the clams at the end of the elimination phase (day 14). Two-compartment first-order decay model described the elimination of the accumulated NP by considering the clam as two compartments each with a different elimination rate. The sudden elimination of NP in the initial hours can be attributed to the elimination of NP accumulated into the gills and readily available for excretion (k ( e ) = 0.30 +/- 0.07 h(-1)). The slower step of the elimination process should be the mobilisation of NP accumulated in internal organs, which must be carried into the haemolymph for excretion (k(e) = 0.0091 +/- 0.0002 h(-1)). Because T. philippinarum has been demonstrated to accumulate NP dissolved in water, high NP levels can be hypothesised in clams from highly contaminated environments. This research was performed according to all national and international guidelines for animal welfare.
本研究首次探讨了菲律宾蛤仔对4-壬基酚（NP）的积累和消除情况。将菲律宾蛤仔样本暴露于添加NP的海水中，测定其整个软组织、鳃、消化腺和血淋巴中的NP含量。还测定了用于投喂的海水和微藻（等鞭金藻）中NP的实际浓度，并计算了藻类生物富集系数（BCF）值（640 ml/g）。挥发是NP从实验水箱中消散的主要原因，占添加NP总量的78%。相对于添加的NP总量，用于投喂的藻类积累的NP可忽略不计，我们得出结论，在我们的实验中，蛤仔积累的NP主要来自水而非食物摄入。积累过程遵循两室一级速率系数模型，摄取速率系数为13.8±0.6 mL g⁻¹ h⁻¹（鲜重[fw]），消除系数为0.0070±0.0005 h⁻¹。暴露14天后达到稳态的90%，稳态时的BCF值为1958±158 mL g⁻¹ fw（基于脂质重量为1.8±0.2×10⁵）。通过水生物积累的NP略少于50%分配到鳃中，其余的则存在于消化腺中。在最初的8小时内，蛤仔消除了积累的NP的51%，在消除阶段结束时（第14天），蛤仔中仅检测到积累的NP的2%。两室一级衰变模型通过将蛤仔视为两个具有不同消除速率的隔室来描述积累的NP的消除情况。最初几小时内NP的突然消除可归因于积累在鳃中且易于排泄的NP的消除（k(e)=0.30±0.07 h⁻¹）。消除过程较慢的步骤应该是动员积累在内脏中的NP，这些NP必须进入血淋巴进行排泄（k(e)=0.0091±0.0002 h⁻¹）。由于已证明菲律宾蛤仔会积累溶解在水中的NP，因此可以推测来自高度污染环境的蛤仔中NP含量较高。本研究是按照所有国家和国际动物福利准则进行的。
