Válega M, Lillebø A I, Pereira M E, Duarte A C, Pardal M A
CESAM-Centre for Environmental and Marine Studies, Department of Chemistry, University of Aveiro, 3810-193 Aveiro, Portugal.
Chemosphere. 2008 Mar;71(4):765-72. doi: 10.1016/j.chemosphere.2007.10.013. Epub 2007 Dec 3.
During four decades, the Ria de Aveiro was subjected to the loading of mercury from a chlor-alkali industry, resulting in the deposition of several tons of mercury in the sediments. The present study evaluates the impact of this disturbance and the recovery processes, temporally and spatially, by means of examining the richness of the species of salt marsh plants and mercury concentrations in sediments over the last fifty years. The temporal assessment showed that the mercury loading induced a shift in the species composition of the salt marsh from a non-disturbed salt marsh with higher species richness to an alternative state dominated by Phragmites australis. The horizontal assessment, through a mercury gradient, presents the same trend, indicating that P. australis is the species most tolerant to higher mercury concentrations, comparative to Halimione portulacoides, Arthrocnemum fruticosum, Triglochin maritima, Juncus maritimus and Scirpus maritimus. After the reduction of mercury discharges in 1994, the salt marsh shows a slowly return path recovery response. The hysteresis in the response results in the temporal gap between the reduction in mercury concentrations in the sediment and the salt marsh species richness response, comparatively to the existing diversity in the local reference marsh.
四十年来，阿威罗泻湖一直承受着来自氯碱工业的汞负荷，导致数吨汞沉积在沉积物中。本研究通过考察过去五十年来盐沼植物物种丰富度和沉积物中汞浓度，从时间和空间上评估了这种干扰的影响以及恢复过程。时间评估表明，汞负荷导致盐沼物种组成从物种丰富度较高的未受干扰盐沼转变为以芦苇为主导的替代状态。通过汞梯度进行的水平评估呈现出相同趋势，表明与滨藜、灌木状节肢藻、海三棱藨草、滨海灯心草和糙叶薹草相比，芦苇是最耐受高汞浓度的物种。1994年汞排放减少后，盐沼呈现出缓慢的恢复路径响应。响应中的滞后导致沉积物中汞浓度降低与盐沼物种丰富度响应之间存在时间间隔，与当地参考沼泽现有的多样性相比。
