珠三角地区养殖及野生淡水鱼类的甲基汞积累现状

为探明珠三角地区淡水鱼类甲基汞累积的真实状况，本研究对该地区养殖及野生淡水鱼类进行了采样分析，评估了摄入鱼肉的甲基汞暴露风险，并揭示了影响鱼类甲基汞积累的关键因素。实验于珠三角地区15个样点采集不同养殖(包括饲料)及野生鱼类，取肌肉、肝脏和肠道组织，甲醇-KOH消解后用气相-冷原子荧光联用仪测定甲基汞含量。结果显示：(1)珠三角地区鱼类甲基汞含量总体较低，均未超过我国水产品食用安全标准，其中养殖鱼类肌肉甲基汞含量为0.26～331.27 ng/g dw (dry weight，干重)，平均含量为61.53 ng/g dw；野生鱼类肌肉甲基汞含量为0.71～1 006.05 ng/g dw，平均含量为110.77 ng/g dw，养殖鱼类甲基汞含量显著低于野生鱼类。(2)养殖鱼类饲料中甲基汞浓度与肌肉甲基汞水平呈显著正相关(R²=0.39)，野生鱼类的营养层级与肌肉甲基汞水平呈显著正相关(R²=0.23)，表明食物组成及食物中甲基汞含量是决定鱼类甲基汞累积的主要因素。(3)食用该地区鱼肉的甲基汞摄入水平总体较低，其中食用野生鱼类的甲基汞摄入水平...

Accumulation of methylmercury in the farmed and wild freshwater fish from the Pearl River Delta Region

Mercury (especially methylmercury) is easy to be accumulated by fish, thus posing a great threat to human health. To investigate the accumulation of MeHg in freshwater fish in the Pearl River Delta (PRD), the present study collected samples of farmed and wild fish from this region and determined MeHg concentrations in different tissues (muscle, liver and intestine). The fish tissues were digested by 25% KOH/methanol solution at 80^oC for 4 h, and MeHg in the digested solution was ethylated by 1% NaBEt4 solution and then detected by Gas Chromatography-Cold Vapor Atomic Fluorescence Spectrometry (GC-CVAFS). The results showed that MeHg concentrations in freshwater fish were generally low and did not exceed the limit in the Food Safety Standard of China (GB 2762-2017). Particularly, MeHg concentrations in muscle tissues of farmed fish (mean value: 62 ng g^-1 dw, ranged from 0.26 to 331 ng g^-1 dw) were significantly lower (P<0.05) than those of wild fish (mean value: 111 ng g^-1 dw, ranged from 0.71 to 1006 ng g^-1 dw). The factors involved in the MeHg accumulation in fish were also explored. The MeHg accumulation in fish was majorly dependent on the feeding habit and food composition, and MeHg concentration in fish diet was the key factor affecting the MeHg level of farmed fish. Risk assessment showed that the MeHg exposure to human through fish consumption was low in the PRD region. However, it should be noted that the MeHg intake through fish consumption was higher in wild fish than that of farmed fish. There is a risk of MeHg exposure to human by consuming some specific species of wild carnivorous fish (e.g. Siniperca chuatsi).