弓獭蛤(Lutraria arcuata)的重金属富集特征及其对镉胁迫的生理响应

底播经济贝类对重金属的高富集能力与食品安全问题密切相关，本研究对北部湾重要经济贝类弓獭蛤(Lutraria arcuata)的重金属污染指数、富集系数以及弓獭蛤对镉的生理响应进行探讨，为弓獭蛤的安全食用和底播经济贝类的安全养殖提供理论基础。研究测定北海市3处海域12个站位的海水和弓獭蛤中7种常见重金属Hg、As、Zn、Cd、Pb、Cu、Cr的含量，计算富集系数；对弓獭蛤进行不同浓度的Cd胁迫，检测弓獭蛤体内对Cd富集的组织-时间-剂量效应，同时检测其体内超氧化物歧化酶(SOD)、谷胱甘肽过氧化物酶(GPx)、过氧化氢酶(CAT)和丙二醛(MDA)等生理生化指标随胁迫时间的变化情况。结果显示，弓獭蛤对Cd的富集系数在7种重金属中最高，个别站位的弓獭蛤Cd污染指数达到轻度污染水平。弓獭蛤不同组织中的Cd含量均和胁迫浓度、时间呈正相关关系，内脏团对Cd的富集能力最强。SOD、GPx、CAT酶活力及MDA的含量整体上呈现前期上升后期下降的趋势，但4种指标受应激影响的变化并不强烈，各浓度实验组和对照组之间的差异不显著。弓獭蛤对环境中的重金属Cd吸收能力极强，若海水中的Cd浓度增加，则易造成食品安全问题，应引起警醒。

Enrichment Characteristics of Heavy Metals in Lutraria arcuata and Its Physiological Response to Cadmium Stress

The high enrichment ability of heavy metals in bottom-sowing economic shellfish is closely related to food safety issues. In this study, the heavy metal pollution index and enrichment coefficient of Lutraria arcuata, an important economic shellfish in Beibu Gulf, and the physiological response of L. arcuata to cadmium were discussed to provide a theoretical basis for the safe consumption of L. arcuata and the safe breeding of bottom-sowing economic shellfish. The contents of seven common heavy metals Hg, As, Zn, Cd, Pb, Cu and Cr in seawater and L. arcuata from 12 stations in three sea areas of Beihai City were determined, and the enrichment coefficient was calculated. The tissue-time-dose effect of Cd enrichment in L. arcuata was detected by different concentrations of Cd stress. At the same time, the changes of physiological and biochemical indexes such as superoxide dismutase (SOD), glutathione peroxidase (GPx), catalase (CAT) and malondialdehyde (MDA) with stress time were detected. The results showed that the enrichment coefficient of Cd was the highest among the seven heavy metals, and the Cd pollution index of L. arcuata at individual stations reached a mild pollution level. The contents of Cd in different tissues were positively related with the stress concentration and time, and the visceral mass had the strongest enrichment ability of Cd. Although SOD, GPx, CAT enzyme activities and MDA content showed a trend of increasing at the early stage and decreasing at the later stage, the changes of the four indicators affected by stress were not strong, and the difference between the experimental group and the control group was not significant. L. arcuata has a strong ability to absorb heavy metal Cd in the environment. If the concentration of Cd in seawater increases, it is easy to cause food safety problems and should be alerted.