Systemic Physiological & Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
Systemic Physiological & Ecotoxicological Research, Department of Biology, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium.
Chemosphere. 2019 Feb;216:832-843. doi: 10.1016/j.chemosphere.2018.10.211. Epub 2018 Oct 30.
The present study describes total mercury (THg) levels in surface water, sediment and biota from the Olifants River Basin (ORB) (South Africa) and investigates the trophic transfer of THg by means of trophic magnification factors (TMFs) in the subtropical ORB food web. Although levels in surface water, sediment and invertebrates were low, elevated levels of THg were measured in fish species of higher trophic levels (0.10-6.1 μg/g dw). This finding supports the biomagnificative character of mercury. THg concentrations in fish from the present study were find to be higher than most values reported in fish from other African aquatic ecosystems and comparable or lower compared to more industrialized regions. Fish length, trophic level, sediment THg levels and TOC in sediment were determining factors for THg levels in fish tissue. Concentrations were found to be higher in larger (and older) fish. Mercury has a high affinity for organic matter and will bind with the TOC in sediment, thus reducing the bioavailability of THg for aquatic biota which is reflected in the significant negative correlation between THg and TOC in sediment. A significant positive relationship between relative trophic level and THg concentrations was observed and also TMFs indicate biomagnification in the ORB food web. However, the trend of lower TMFs in tropical areas compared to temperate and arctic regions was not supported by the results. The consumption of fish from higher trophic levels at the average South African consumption rate is expected to pose a significant health risk.
本研究描述了南非奥兰治河盆地（ORB）地表水、沉积物和生物体内的总汞（THg）水平，并通过亚热带 ORB 食物网中的营养放大因子（TMF）研究了 THg 的营养转移。尽管地表水、沉积物和无脊椎动物中的水平较低，但在营养水平较高的鱼类物种（0.10-6.1μg/g dw）中测量到了较高水平的 THg。这一发现支持了汞的生物放大特征。本研究中鱼类的 THg 浓度高于大多数来自非洲其他水生生态系统鱼类的报道值，与工业化程度较高的地区相比，本研究中的鱼类 THg 浓度相当或更低。鱼的长度、营养水平、沉积物 THg 水平和沉积物中的 TOC 是鱼组织中 THg 水平的决定因素。研究发现，较大（和较老）的鱼中的浓度更高。汞对有机物有很高的亲和力，会与沉积物中的 TOC 结合，从而降低 THg 对水生生物的生物利用度，这反映在沉积物中 THg 与 TOC 之间存在显著的负相关关系。观察到相对营养水平与 THg 浓度之间存在显著的正相关关系，并且 TMF 还表明 ORB 食物网中的生物放大作用。然而，热带地区的 TMF 低于温带和北极地区的趋势并未得到结果的支持。以南非的平均消费水平食用来自较高营养水平的鱼类预计会对健康造成重大风险。
