Bahir Dar University, Department of Biology, P.O.Box 79, Bahir Dar, Ethiopia.
ScientificWorldJournal. 2022 Sep 27;2022:7317702. doi: 10.1155/2022/7317702. eCollection 2022.
Freshwater lakes are important sources of water for domestic, agricultural, and industrial uses. Lake Tana offers a range of ecosystem services to the surrounding communities. However, this lake is facing deterioration in water quality due to pollution caused by anthropogenic influences. Therefore, regular monitoring of key water quality parameters is critical to understanding the water quality status of the lake. This study aimed to assess the seasonal fluctuation of water quality of the Southern Gulf of Lake Tana using indicator bacteria and some physicochemical parameters. A total of 48 water samples were collected in dry and wet seasons from eight sites in the study area. Total coliforms (TC), faecal coliforms (FC), and some physicochemical parameters (pH, temperature, turbidity, electrical conductivity, total dissolved solids, dissolved oxygen, biochemical oxygen demand, ammonium, nitrate, and phosphate) were determined following standard methods. The results revealed that coliform counts were above the permissible level set by Ethiopian Standards and varied significantly among sites ( < 0.05). FC counts ranged from 1 to 1600 MPN/100 ml (with the lowest and highest mean value of 1 at site 8 to 1076.5 ± 3.1 at site 4) and again TC counts ranged from 1 to 1600 MPN/100 ml (with a mean value of 4.8 ± 1.81 at site 6 to 1600 at site 4 and site 8). The findings also confirmed that the highest counts of coliforms were observed during the wet season. The high counts are attributed to the discharge of human excreta and animal wastes during the rainy season from the different anthropogenic activities near the Gulf. Significant variations in most of the physicochemical parameters were also observed between sites and seasons. FC and biochemical oxygen demand (BOD in most sites did not meet the EPA standard for surface water. Corrective measures are highly recommended for anthropogenic activities driving high pollution loads in the lake.
淡水湖泊是家庭、农业和工业用水的重要水源。塔纳湖为周边社区提供了一系列生态系统服务。然而，由于人为影响造成的污染，这个湖泊的水质正在恶化。因此，定期监测关键水质参数对于了解湖泊的水质状况至关重要。本研究旨在使用指示菌和一些理化参数评估塔纳湖南部海湾的水质季节性波动。在研究区域的八个地点，在旱季和雨季共采集了 48 个水样。总大肠菌群（TC）、粪大肠菌群（FC）和一些理化参数（pH 值、温度、浊度、电导率、总溶解固体、溶解氧、生化需氧量、氨、硝酸盐和磷酸盐）按照标准方法进行了测定。结果表明，大肠菌群计数超过了埃塞俄比亚标准规定的允许水平，且各站点之间差异显著（<0.05）。FC 计数范围为 1 至 1600 MPN/100 ml（最低和最高平均值分别为 1，位于 8 号站点，最高值为 1076.5 ± 3.1，位于 4 号站点），TC 计数范围也为 1 至 1600 MPN/100 ml（6 号站点的平均值为 4.8 ± 1.81，而 4 号站点和 8 号站点的最高值为 1600）。研究结果还证实，在雨季期间观察到大肠菌群的最高计数。高计数归因于雨季期间来自海湾附近不同人为活动的人类排泄物和动物废物的排放。大多数站点的理化参数也存在显著差异。大多数站点的 FC 和生化需氧量（BOD）都不符合 EPA 地表水标准。强烈建议对导致湖泊高污染负荷的人为活动采取纠正措施。
