赣南典型矿区河流沉积物钨的赋存特征及释放规律

Occurrence and release of tungsten from river depositions in typical mining areas of southern Jiangxi Province

赣南钨矿开采已有百年历史,矿区周边河流沉积物重金属污染对水体环境构成威胁。为探究赣南河流沉积物钨的富集、赋存形态及释放规律,本文选择赣南典型钨矿区河流桃江为研究对象,采集桃江丰水期-平水期-枯水期3个水期36个表层沉积物样品进行钨总量的测定,采用BCR三步法和电感耦合等离子体质谱法进行钨的形态分析,运用模拟实验探究沉积物钨的释放规律。结果表明,3个水期表层沉积物中钨的含量变化范围为0.91~159.94mg/kg,均值为25.36mg/kg,其中重金属总量大小顺序为枯水期>丰水期>平水期,且3个水期平均有79.67%的采样点钨含量超出江西省土壤背景值,最高超出39倍;形态分析结果显示,3个水期钨的主要赋存形态均为残渣态,所占比例均值分别为80.38%、91.59%和86.71%,生物有效态占比相对较小,表明目前桃江沉积物中重金属钨生态风险较小。单因子实验结果表明,沉积物中钨在弱酸、高温和NH4+浓度高的条件下释放量均有所增加,且3个水期钨的释放量大小顺序为丰水期>平水期>枯水期,表明赣南独特的水质环境利于沉积物中钨的释放。

The tungsten mining in southern Jiangxi has a history of 100 years. The heavy metal pollution of river depositions in the mining area poses a threat to the water environment. In order to explore the enrichment, occurrence and release of tungsten in the depositions of the Gannan River, the typical tungsten mining area in southern Jiangxi is selected. The Taojiang River was used as the research object. 36 surface deposition samples from the three water periods of Taojiang wet period-flat water period - dry season were collected and the total amount of tungsten was measured. The morphology of tungsten was analyzed by BCR three-step method and inductively coupled plasma mass spectroscopy. The simulation experiment explored the release law of deposition tungsten. The results showed that the content of tungsten in the surface depositions of the three water periods ranged from 0.91mg/kg to 159.94mg/kg, and the average value was 25.36mg/kg . The total content order of heavy metals was in dry season > wet period > flat water period, and the average tungsten content of 79.67% of the three water periods exceeded the soil background value of Jiangxi Province, the highest exceeded 39 times;the morphological analysis results showed that the main occurrence forms of tungsten in the three water periods were residual state, the proportion values were 80.38%, 91.59% and 86.71%, respectively, and the proportion of bioavailable states was relatively small, indicating that the ecological risk of heavy metal tungsten in the depositions of Taojiang was small. The results of single factor experiment showed that the release of tungsten in the depositions increased under the conditions of weak acid, high temperature and high concentration of NH4+, and the order of release of tungsten in the three water periods was in the wet season > flat water period > dry season, indicating that the unique water quality environment in Gannan was conducive to the release of tungsten from depositions.