Research Center for Radiation Process Technology, National Research and Innovation Agency (BRIN), Central Jakarta, Indonesia.
Research Center for Limnology, National Research and Innovation Agency (BRIN), Central Jakarta, Indonesia.
Environ Monit Assess. 2023 Jun 27;195(7):897. doi: 10.1007/s10661-023-11455-8.
In general, lakes provide various ecosystem services that support biotic habitats and human life. Lake Toba, the largest caldera volcanic lake in the world, has been functioning as a tourism destination and for fish farming, a fresh water source, and for power supplies. The lake has maximum depth of about 505 m. Stratification in the lake water column especially in a tropical region like Indonesia is a common phenomenon. Stratification of the lake is one important factor which will influence the next stage in the biological processes and water quality of the lake. The objective of the current study was to analyze and elucidate the stratification of Lake Toba through the variations of physical, chemical, and isotopic parameters. Water temperature, dissolved oxygen concentrations, water chemical contents, and isotopic parameters were observed periodically from 2016 until 2019. Fourteen sampling points evenly distributed across the surface of the lake were predetermined to represent the North, South, East, and West of the lake. A conductivity, temperature, and depth (CTD) device and Baro-divers were used to measure temperature and conductivity at various depths in the water column for each sampling point. The water samples for isotopic and chemical parameter measurements were collected from water depths of 0, 20, 40, 60, 80, and 100 m using a horizontal transparent acrylic water sampler at each sampling point. Some results from isotope analysis showed that all the water at all levels along the water column had undergone evaporation. Although there were some slight fluctuations, the chemical composition of the lake water was relatively homogenous up to 100 m of depth. The chemical pattern suggested that there was no other secondary process that altered the chemical composition of the lake water, thus the lake water and river water had the same facies. The stratification of Lake Toba was found to be permanent. The depth of the hypolimnion layer was consistently at about 80 m below the surface. However, the depth of the upper layer, the epilimnion, was strongly affected by the climate at the surface of the lake.
一般来说，湖泊提供了各种生态系统服务，支持生物栖息地和人类生活。多巴湖是世界上最大的破火山口湖，一直是旅游胜地，也是鱼类养殖、淡水供应和电力供应的基地。该湖最大深度约为 505 米。在印度尼西亚等热带地区，湖泊水柱的分层现象是很常见的。湖泊的分层是影响湖泊下一阶段生物过程和水质的一个重要因素。本研究的目的是通过分析物理、化学和同位素参数来阐明多巴湖的分层情况。从 2016 年到 2019 年，定期观测水温、溶解氧浓度、水化学成分和同位素参数。在湖泊表面均匀分布的 14 个采样点预先确定，以代表湖泊的北、南、东、西。使用 CTD 设备和 Baro-divers 测量每个采样点各个水深的温度和电导率。在每个采样点，使用水平透明亚克力采水器从 0、20、40、60、80 和 100 米的水深采集用于同位素和化学参数测量的水样。一些同位素分析结果表明，水柱中所有各层的水都经历了蒸发。尽管有一些轻微的波动，但湖水的化学成分相对均匀，深度可达 100 米。化学模式表明，没有其他次要过程改变了湖水的化学成分，因此湖水和河水具有相同的相态。多巴湖的分层是永久性的。下分层的深度始终在水面以下约 80 米处。然而，上分层——表水层的深度受到湖面气候的强烈影响。
