Source identification of Organic Matter using C/N Ratio in freshwater lakes of Kashmir Valley, Western Himalaya, India

作者：Lone Aasif Mohmad; Shah Rayees Ahmad; Achyuthan Hema^*; Rafiq Mohammd

来源：Himalayan Geology, 2018, 39(1): 101-114.

• Freshwater lakes
• Lake catchments
• Lake bed sediments
• Natural and anthropogenic nutrient inputs
• Organic matter source

Assessing the organic matter (OM) content, its source and the nutrient loading in lake sediments helps limnologists to maintain the desired trophic status of lakes. The present study aims at investigating the spatial distribution and source of OM, CaCO3 content, total nitrogen (TN) and carbon to nitrogen (C/N ratio) in the lake sediments of three freshwater (Manasbal, Wular and Anchar) lakes, from Kashmir valley, India. In all these lakes, finer sediment fractions (silt and clay) are dominant. Low to moderate C/N ratio in the lake sediments of Manasbal (15.00), Wular (11.86) and Anchar (12.32) suggest a combination of in situ phytoplanktons (macrophytes) and external sources such as domestic effluents and agricultural runoff as the major contributors of OM. The TN content (<3%) suggests nitrogen deficient lake systems and its distribution in the sediments is influenced by the presence of mixed OM sources. High C/N ratio and a positive correlation of OM with coarser fractions indicate high terrestrial input in Manasbal Lake sediments. Principal component analysis (PCA) suggest that primary in situ productivity within the lakes, terrestrial input from catchment watershed and anthropogenic activities occurring along the lake margins control the deposition and distribution of OM, TN, sediment grain size and CaCO3 content. This study highlights that these lakes are dynamic ecosystems with large amount of OM contributed by terrestrial sources. Hence, different measures need to be implemented and continuously monitored to assess and quantify the extent of in situ and terrestrial OM loading in these lakes.

• 出版日期2018