Maldhure Atul, Rodge Anupama, Kothe Anjali, Nagarnaik Pranav, Khadse Gajanan, Bafana Amit, Kumar Mahesh, Labhasetwar Pawan
Water Technology and Management Division, CSIR-National Environmental Engineering Research Institute, Nagpur, 440020, India.
Health and Toxicity Cell, CSIR-National Environmental Engineering Research Institute, Nagpur, 440020, India.
Environ Monit Assess. 2023 Mar 30;195(4):524. doi: 10.1007/s10661-023-11068-1.
Lonar Lake is a highly saline inland water body created by a crater in Maharashtra, India. A rare occurrence of the colour change of lake water from green to brown and eventually to pinkish-red was observed in Lonar in June 2020. This phenomenon attracted the attention of researchers, academicians and interestingly legal fraternity to understand the causes of colour change. The literature studies coupled the phenomenon of colouration of water to three aspects: the presence of halophilic Halobacterium salinarum or an algal species of Dunaliella (Dunaliella salina) or oxidization of metals (Fe and Mn) present in water. A comprehensive study was done to understand and assess the change in the colour of Lonar Lake water. The green colour of the lake is primarily due to the dominance of chlorophyll-a pigment in the algae population. The stressed condition in June 2020 adversely affected the photosynthesis activity of Dunaliella sp. resulting in the red colouration of the species. This red colour of Dunaliella sp. is due to the formation of a pigment named carotenoid which is similar to that in halophilic bacteria. This pigment completely hides the green chloroplast, and water turns pinkish-red. This study describes detailed investigations of environmental and climatic parameters to determine possible causes of abiotic stress on the algae population of the lake. The major factors contributing to the stressed conditions are high dissolved solids, alkalinity and alkaline pH due to salts in the lake water due to evaporation losses and limited rainfall over the months. The study further verified whether the colour change is a cyclic event and predicted possible lake conditions for the event of colour change to occur in the future.
洛纳尔湖是印度马哈拉施特拉邦一个由火山口形成的高盐度内陆水体。2020年6月，人们在洛纳尔湖观察到湖水颜色罕见地从绿色变为棕色，最终变为粉红色。这一现象引起了研究人员、学者的关注，有趣的是，也引起了法律界人士的关注，他们想要了解颜色变化的原因。文献研究将水体变色现象与三个方面联系起来：嗜盐盐生盐杆菌或杜氏藻（盐生杜氏藻）的存在，或水中金属（铁和锰）的氧化。为了解和评估洛纳尔湖水颜色的变化，进行了一项全面的研究。湖水的绿色主要是由于藻类种群中叶绿素a色素占主导地位。2020年6月的压力状况对盐生杜氏藻的光合作用活动产生了不利影响，导致该物种呈现红色。盐生杜氏藻的这种红色是由于一种名为类胡萝卜素的色素形成，这种色素与嗜盐细菌中的色素相似。这种色素完全掩盖了绿色的叶绿体，水变成了粉红色。这项研究描述了对环境和气候参数的详细调查，以确定对湖泊藻类种群造成非生物胁迫的可能原因。造成压力状况的主要因素是由于湖水蒸发损失和数月降雨有限，湖水中盐分导致的高溶解固体、碱度和碱性pH值。该研究进一步验证了颜色变化是否是一个循环事件，并预测了未来颜色变化发生时湖泊可能的状况。
