US Pakistan Center for Advanced Studies in Water, Mehran University of Engineering and Technology, Jamshoro, Sindh, 76062, Pakistan.
Faculty of Engineering, Balochistan University of Information Technology, Engineering, and Management Sciences (BUITEMS), Quetta, Balochistan, Pakistan.
Environ Monit Assess. 2023 Oct 19;195(11):1340. doi: 10.1007/s10661-023-11917-z.
Manchar Lake, Pakistan's biggest lake in the arid zone, faces human-induced salinity issues. This study investigated its effects on the multifaceted ecosystem services, including serving as a source of drinking and irrigation water and aquatic health through assessing fish diversity and characteristics. Analyses of 189 water samples from 21 sites revealed spatiotemporal variations in major ions contributing to lake water salinity. The study assessed water suitability for drinking and agriculture using the water quality index (WQI), sodium adsorption ratio (SAR), magnesium hazard (MH), sodium percent (Na%), and Kelly's ratio (KR). The WQI, ranging from 141 to 408, indicated that the lake water was unfit for drinking. In some seasons, such as the pre-monsoon period, the lake water was deemed unsuitable for irrigation due to high SAR values (18 ± 4 g/L, average ± standard deviation), consistently rising MH values exceeding 66 in all seasons and elevated sodium percentages surpassing 66% in both the pre-monsoon and monsoon seasons. The KR remained acceptable (averaging 0.8 to 2.5) in all seasons. Fish health in highly saline conditions was assessed using data from interviews, focus group discussions, and fish sampling (1684 fish from 10 sites). Results depicted that high salt contamination severely impacted fish length and weight. The study found low richness (Simpson's biodiversity: 0.697 and Shannon Weaver: 1.51) and evenness (Pielou's index: 0.48) among the fish populations. Since 1998, Manchar Lake has seen a decline in fish varieties from 32 to 23, with changes in fish species' feeding habits. To improve lake water quality, the study recommends diverting saline water to the sea before and after the monsoon season while utilizing freshwater from alternative sources to fill any water deficit.
巴基斯坦干旱地区最大的马钱子湖面临人为引起的盐度问题。本研究通过评估鱼类多样性和特征，调查了其对多方面生态系统服务的影响，包括作为饮用水和灌溉水的来源以及通过维持水生健康。对 21 个地点的 189 个水样的分析表明，主要离子的时空变化导致了湖水的盐度。本研究使用水质指数（WQI）、钠吸附比（SAR）、镁危害（MH）、钠百分比（Na%）和凯利比（KR）评估了水的适宜性用于饮用水和农业。WQI 范围从 141 到 408，表明湖水不适合饮用。在某些季节，如前季风期，由于 SAR 值较高（18 ± 4 g/L，平均值 ± 标准差），湖水不适宜灌溉，所有季节的 MH 值持续上升，均超过 66，前季风期和季风期的钠百分比均超过 66%。KR 在所有季节均保持在可接受范围内（平均为 0.8 至 2.5）。在高盐条件下，通过访谈、焦点小组讨论和鱼类采样（从 10 个地点采集的 1684 条鱼）获取的鱼类健康数据进行了评估。结果表明，高盐污染严重影响了鱼类的长度和重量。研究发现，鱼类种群的丰富度（辛普森多样性：0.697 和香农威弗：1.51）和均匀度（皮尔氏指数：0.48）较低。自 1998 年以来，马钱子湖的鱼类品种从 32 种减少到 23 种，鱼类物种的摄食习性发生了变化。为了改善湖水水质，研究建议在前季风期和后季风期将盐水引向大海，同时利用替代水源的淡水来填补任何水的不足。
