Lake Aha Research Articles

The concentration and distribution of different mercury species in the water columns and sediment of Aha Lake

In order to find out whether Aha Lake was polluted by the acid wasted mining water or not, the concentration and distribution of different mercury species in the water columns and sediment porewater collected from the Aha Lake were investigated. The concentrations of HgT ranged from 2.08 to 19.14 ng ·L -1, DGM ranged from 0.04 to 0.09 ng·L -1, HgR ranged from 0.2 to 1.1ng·L -1 and MeHgT ranged from 0.002 to 0.43ng·L -1 in the Aha Lake water columns. In the sediment porewater , however, the concentrations of HgD varied from 1.72 to 19.12 ng·L -1, and MeHgD ranged from 0.03 to 1.57 ng·L -1. The results indicated that highly elevated MeHgD concentrations in the porewater were obtained at the depths from 2 to 5 cm in the sediment profile, and decreased sharply with depth. A positive correlation has been found between MeHgD formation and sulfate-reducing bacterial activity. These highly elevated concentrations of MeHgD obtained in the intersurface between waters and sediments suggesting a favorable methylation conditions. Moreover,even under the conditions of high SO 2-_4concentrations, reaching up to 1100mg·L -1, a strong correlation beteen MeHgD and SO 2-_4was observed as well.

Impact on the remobilization of trace metals in lake sediments by micro-organisms

蓄积在湖泊沉积物中污染物质某些情况下可以成为威胁上覆水体水质安全的二次污染源．根据贵州省阿哈湖季节性缺氧的特性,通过控制氧化还原状况,设计了对该湖沉积物-水柱的原样/抑菌条件的培养实验．实验发现,微生物活动对界面附近氧化还原反应具有控制作用;改变水体的含氧状况可以显著影响上覆水体水质,包括表观性状和水体中污染物含量．聚类分析结果表明,早期成岩过程中Mn,Ga,SO₄^2-,Cu,Cr,Pb和Co,Ni,Fe,Sc,V,Rb两大类分别具有相似的地球化学行为．根据实验结果,计算了厌氧培养过程中,微量元素的最大释放量,发现铁、锰在厌氧过程中可以大量向水体释放．;It is of great concerns on some pollutants cumulated in lake sediments to become the source of pollution, under certain circumstances, causing serious harm on overlying water quality. In this research, experiment was designed based on the fact of seasonal hypoxia near sediment-water interface (SWI) in Lake Aha,Guizhou Province. By means of the control of redox potential, together with microbiological activities, it was found that microbiological activities has significant influences on the redox reactions happened around SWI; and the overlying water quality can be changed remarkably, along with the variation of redox potential, including transparency, odor and poUutant contents. The cluster analysis of experimental data demonstrated that two main groups with similar geochemical behavior during diagenesis process, could be sorted as Mn,Ga, SO₄^2-,Cu,Cr,Pb and Co,Ni,Fe, Sc,V, Rb. Finally, the maximum release of some metals when lake water turned to hypoxia, were calculated, of which plenty of Fe and Mn found can be released into overlying water.

Remobilization of trace metals induced by microbiological activities near sediment-water interface, Aha Lake, Guiyang

The Aha Lake, as a seasonally oxygen-absent man-made reservoir, has been polluted by acidic mining drainage and domestic sewages for a long time, with iron, manganese and sulfate excessively enriched in water and sediment. By means of microbe counting, the analysis of trace metals in pore water and electronic acceptors for organic matter decomposing, we have found that strong biogeochemical remobilization of trace metals occurred near the water-sediment interface. The microbial reduction of iron, manganese and sulfate took place in different parts throughout the sediment core with the extend of iron reduction lower than that of sulfate reduction, which happened in the surficial sediments and hampered the upward release of some trace metals to some extent. Some trace metals in pore water, due to the “dual releasing” effects caused by the reduction of Fe3+ and Mn4+ at varying depth, show a tendency of being enriched excessively in the upper 10 cm of sediment. In this study, we discussed the microbiological mechanism of trace metals enrichment in surficial sediments and the environmental condition, with an attempt to realize the unsteady mobilization of trace metals and their potential harm to overlying lake water in the Aha Lake, Guiyang.

Distribution and variation of ribonucleic acid (RNA) and protein and its hydrolysis products in lake sediments

Protein and RNA in lake sediments tend to be decomposed progressively with time and sedimentation depth. Their concentrations tend to decrease starting from the sedimentation depth of 17 cm and that of 19 cm, respectively. However, the products of their decomposition —amino acids and nucleotides show different rules of variation. At the depth from 27 cm to 30 cm the amino acids are most abundant in the pore waters of lake sediments. Such variation tendency seems to be related to the extent to which microbes utilize amino acids and nucleotides. Due to polymerization in the geological processes and the adsorption of protein on minerals and organic polymers, below the sedimentation depth of 17 cm there is still a certain amount of protein in the sediments. With the time passing by, protein has been well preserved in various sediment layers, indicating that its decomposition is relatively limited. The peak values of protein content in the sediments of the two lakes are produced in the surface layers at the depth of 10 cm, implicating that the surface sediments are favorable to the release of protein. The contents of amino acids in the pore waters of lake sediments are closely related to the activities of microbes. Below the depth of 27 cm, the amino acids are significantly accumulated in Lake Aha sediments, probably indicating the weakening of microbial activities.

Biogeochemical mechanism of postdepositional migration of Fe and Mn in Lake Aha, China

Lake Aha in Guizhou Province, China is a medium-sized artificial reservoir with seasonally anoxic hypolimnion. Long-term sedimentary accumulation of iron and manganese resulted in their enrichment in the upper sediments. In anoxic season, Fe2+ and Mn2+ formed from biological oxidation, would diffuse upto upper water from sediments. However, the concentration of Fe2+ increased later and decreased earlier than that of Mn2+. Generally, sulfate reduction occurred at 6 cm below the sediment-water interface. Whereas, in anoxic season, the reduction reached sediment top, inhibiting the release of Fe2+. As the oxidation of Mn2+ required molecular oxygen as catalyst, serious anoxia caused the violent diffusion of Mn2+. Based on the bio-effects on the accumulation of Mn in natural fresh water, it’s necessary to seek a way to control manganese rerelease through accumulated manganese bacteria action.

Screening effect of the diffusive boundary layer in sediments of Lake Aha in the suburbs of Guiyang city, Guizhou Province

The redox cycle of iron and manganese is a major geochemical process at the boundary layers of lake sediments. Lake Aha, which lies in the suburbs of Guiyang City, Guizhou Province, China, is a medium-sized artificial reservoir with seasonally anoxic hypolimnion. Long-term sedimentary accumulation of iron and manganese resulted in their enrichment in the upper sediments. In the anoxic season, Fe2+ and Mn2+, formed by biological oxidation, would diffuse up to overlying waters from sediments. However, the concentration of Fe2+ increased later and decreased earlier than that of Mn2+. Generally, sulfate reduction occurred at 6 cm below the sediment-water interface. Whereas, in the anoxic season, the reduction reached upper sediments, inhibiting the release of Fe2+. The Fe concentration of anoxic water is quickly decreased from high to low as a result of reduction of the sulphur system.

Biogeochemical Effect on Postdepositional Remobilization of Fe-Mn in Lake Aha, Guizhou Province

贵州阿哈湖是一底层滞水带季节性缺氧的中型人工湖.由于长期积累.沉积物顶部微粒悬浮层出现了Fe、Mn富集.湖底缺氧时,经生物氧化作用形成的Fe²⁺、Mn²⁺自沉积物向上覆水体扩散,水体Fe²⁺浓度增高比Mn²⁺滞后出现且超过前结束.沉积物中硫酸盐还原作用一般在沉积物-水界面以下6cm深度内进行,但在缺氧季节上移至沉积物顶部,并抑制了Fe²⁺的释放.还原态Mn²⁺的氧化作用需分子氧参与.缺氧导致Mn的扩散迁移.基于天然水体中存在聚集Mn的生物效应,可寻求一条通过Mn细菌凝聚作用来控制Mn二次释放的途径.;Lake Aha, located in the suburb of Guiyang? Guizhou Province, is a medium artificial reservoir with seasonally anoxic hypolimina. After a long-term accumulation, iron and manganese are enriched in the upper sediments. When waters of oplimnion and hypolimnion are anoxic in late summer and early autumn, Fe²⁺and Mn²⁺ formed by biological respiration, are diffused upto the overlying waters from the sediments. However, the concentration of Fez+increases later and se-creases earlier than that of Mn²⁺. Generally, sulphate reduction takes place within 6cm depth of the sediments. Whereas in the anoxic season, the reduction reaches the upper sediment, inhibiting the diffusion of Fe²⁺. Meanwhile? manganese oxidation needing molecular oxygen as catalyst, causes the violent diffusion of Mn²⁺. Because manganese can be accumulated by microorganism in natural fresh water, it is important to seek method to control manganese remobilization through manganese accumulated action.