CONCLUSIONS

The analysis of the sediment the C:N ratios indicated a strong correlation between the elemental composition of C and N. This also showed that the sludge/sediments were acting as a major sink for C and N. The C and N values were found to be significantly higher in the deeper areas than the shallow inlet regions. This showed that 60 % of the nutrients are terrestrial in origin. These parts mostly are silt laden which is the reason for low organic Carbon compared to the other parts of the lake. The quantity of C and N stored on the sediments in a daily basis was large which accounts to 9 t C and 2.9 t N. The north side of the lake was anthrpogenically more impacted than the other parts which is evident from the higher C/N ratio.

Therefore, proper wastewater management strategies should consider approaches to minimize indiscriminate sewage ingress and losses of nutrients from agricultural fields into the lake systems. The results indicated that, once nutrients are delivered into the lakes, a substantial part in taken up by biota which ultimately die, decompose and settles as sludge sediment in the lake bottom and with high turbulence created by high wind velocities and overflow of water during monsoon they are likely to be transported downstream without much attenuation in the lake bottoms. Future investigations that would account for nature of various pollutants entering the lake system, the lake bottom soil types, and nutrient loadings from all sources must be conducted to examine impact of the wastewater ingress on sediments at different levels. (Vegetated, non-vegetated, dredged, and non- dredged).

ACKNOWLEDGEMENT

The authors are grateful to Mr. Arun D.T. for assistance during sludge/sediment sampling in the field. We are grateful to the Ministry of Environment and Forests, Government of India for the infrastructure support. We are thankful to Centre for infrastructure, Sustainable Transport and Urban Planning [CiSTUP], Indian Institute of Science for funding this project.