Lacerda Luiz D, Bastos Wanderley R, Almeida Marcelo D
Instituto de Ciências do Mar, Universidade Federal do Ceará, Fortaleza, CE, Brasil.
An Acad Bras Cienc. 2012 Mar;84(1):69-78. doi: 10.1590/s0001-37652012000100007.
Changes in hydrochemistry and Hg distribution in the Madeira River from Porto Velho to the confluence with the Amazon River were studied in two cruises in 1997 and 2002. Water conductivity was similar in both periods, but the pH was significantly higher in 2002, in particular along the middle reaches of the river. Total suspended matter concentrations also increased from 1997 to 2002 along the same river portion, which is a result of forest conversion to other land uses, in particular pastures and agriculture accelerated during the interval between the cruises. Dissolved Hg concentrations were similar along the river in both cruises, but particulate Hg concentrations increased significantly along the middle portion of the river, although the suspended matter from 2002 was relatively poorer in Hg compared to that from 1997. Since particulate Hg represents more than 90% of the total Hg present in the river water, there was a significant increase in the total Hg transport in the Madeira River. Although gold mining has nearly ceased to exist in the region, the remobilization of Hg from forest soils through conversion to other land uses is responsible for maintaining relatively high Hg content in the Madeira River environment.
1997年和2002年的两次航行研究了马德拉河从波多韦柳到与亚马逊河交汇处的水化学变化和汞分布。两个时期的水电导率相似，但2002年的pH值明显更高，特别是在河流中游。1997年至2002年，同一河段的总悬浮物浓度也有所增加，这是森林转变为其他土地用途的结果，特别是在两次航行间隔期间加速发展的牧场和农业。两次航行中沿河溶解汞浓度相似，但河流中部颗粒汞浓度显著增加，尽管2002年的悬浮物汞含量比1997年的相对要低。由于颗粒汞占河水中总汞的90%以上，马德拉河的总汞运输量显著增加。尽管该地区的金矿开采几乎已不复存在，但森林土壤中的汞通过转变为其他土地用途而重新活化，这使得马德拉河环境中的汞含量维持在相对较高的水平。
