Sewage fluxes and seasonal dynamics of physicochemical characteristics of the Bhagirathi-Hooghly River from the lower stretch of River Ganges, India

ABSTRACT

To understand the temporal variations of the physicochemical characteristics of the Bhagirathi-Hooghly River (BHR), three locations representing three districts of West Bengal were selected. The material fluxes from 34 drains during pre-monsoon season was quantified. The analysis of variance (ANOVA) revealed that no significant spatial variations were observed for the physicochemical parameters, whereas seasonal variations were significant. The mean discharge was found to be highest (247.2 × 10³ m³ d⁻¹) in the midstream drains. Highest mean concentrations of dissolved oxygen (DO) (7.35 mg L⁻¹) and nitrate (0.81 mg L ⁻¹) were observed during the post-monsoon season followed by the monsoon and pre-monsoon. According to the BIS, WHO and the European standard of water quality (pH, 6.5–8.5; Nitrate, 0–2.5 mg L⁻¹;DO, ≥5 mg L⁻¹), the results of the respective parameters revealed the BHR system is maintained at high to good water quality, meaning that the BHR system is slightly altered from its pristine environment. The mean concentrations of biological and chemical oxygen demands were found to be high during the monsoon season, revealing that a large quantity of refractory organic matter is transported to the eastern Bay of Bengal from the Ganges.

KEYWORDS:

• Anthropogenic runoff
• biological oxygen demand
• chemical oxygen demand
• factor analysis
• drains
• discharge

Acknowledgements

The authors thank the Secretary, Ministry of Environment Forest and Climate change (MoEF & CC), Government of India (GoI), and Chairman, Central Pollution Control Board (CPCB), MoEF & CC, GoI, for the financial support and for facilities provided during the study period. Thanks are also due to Dr Gregory Cooper, SOAS University of London, United Kingdom, for carrying out the necessary English modifications and the anonymous reviewers for the valuable suggestions to modify the earlier version of this manuscript. This study is a part of the comprehensive programme of MoEF & CC – CPCB under the National Ganga River Basin Authority.

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes on contributors

Vishnu Vardhan Kanuri is a Scientist-C in Central Pollution Control Board, Eastern Regional Directorate, Kolkata, India. He has completed PhD and MSc (Analytical Chemistry) from the Department of Inorganic and Analytical Chemistry, Andhra University, Visakhapatnam, India. His studies mainly focus on the air-water exchange of greenhouse gases and their impact on climate change, surface and marine water pollution. Currently he is working on the rejuvenation and surveillance of the River Ganges. His research interests are on water pollution management, carbon and nutrient biogeochemical cycles of marine, inland and surface waters.

Rita Saha is a Scientist-D in Central Pollution Control Board, Eastern Regional Directorate, Kolkata, India. She has completed PhD and MSc in Agriculture from the Department of Agriculture, Calcutta University, Kolkata, India. Currently engaged in the world bank project for rejuvenation and surveillance of the River Ganges. Her research interests are on abatement of air and water pollution.

Shiv Pratap Raghuvanshi is a Scientist-D in Central Pollution Control Board, Eastern Regional Directorate, Kolkata, India. He has MTech. in Environmental Sciences & Engineering and PhD in Environmental Engineering from Applied Mechanics Department, Indian Institute of Technology Delhi (IITD), India. His studies mainly focus on Energy-Environment interactions, Air & Water Pollution Management, Environmental regulations, Rejuvenation of River Ganga and its tributaries, Climate change Mitigation, Carbon dioxide emissions, control and carbon sequestration. His research interests are environmental regulations monitoring in industries, water pollution management, carbon sequestration, impact of climate change on surface water bodies, rejuvenation of the River Ganges and its tributaries and nutrient biogeochemistry of marine, inland and surface waters.

Ashwani Kumar Singh is a Research Associate in Central Pollution Control Board, India. He has served as a Project Associate in The Energy and Resources Institute (TERI), India. He was involved in teaching and supervising the BTech students. He has completed MTech in Biotechnology from Sardar Vallabhbhai Patel University of Agriculture and Technology, Meerut, Uttar Pradesh, India. His area of research and his expertise falls in the area of molecular biology and pollution studies of Inland and surface waters.

Bipasha D. Chakraborty is a Senior Research Fellow Central Pollution Control Board, Eastern Regional Directorate, Kolkata, India. She has completed MSc in Environmental Science from Calcutta University, Kolkata, West Bengal India. Her research interests are on volatile organic pollutants in air, water quality assessment of inland and surface waters.

Vaddem Kiran Kumar is a Research Associate in Central Pollution Control Board, Eastern Regional Directorate, Kolkata, India. He was involved in teaching and supervising both post graduate and undergraduate students. He has completed MTech in Biotechnology from Jawaharlal Nehru Technological University, Hyderabad, India and Masters in Microbiology from Kakatiya University, Warangal, India. He has qualified for ICAR-NET. His research interests are on microbial community structure and water quality assessment of Inland and surface waters.

S. C. Mohapatra is a Research Associate in Central Pollution Control Board, Eastern Regional Directorate, Kolkata, India. He previously worked as Functional Area Expert in Air Pollution Monitoring, Prevention &Control accredited by NABET (QCI), India. He has completed M.Tech. and M.Sc. in Environmental Science from Sambalpur University, Sambalpur, Odisha, India. His research interests are on Air pollution monitoring and modelling, water quality assessment of Inland and surface waters.

A. K. Vidyarthi is a Scientist-E & Additional Director in Central Pollution Control Board (CPCB), India. He is the Project Co-ordinator for the world bank program “Rejuvenation and Surveillance of the River Ganges”. He has completed Ph.D. from BITS Pilani, Rajasthan, India. His research interests are abatement of surface water pollution and development of Integrated Environmental Pollution Index for Industrial Clustures.

A. Sudhakar is a Scientist-E & Additional Director in Central Pollution Control Board (CPCB), India. He was an ex-Member Secretary of CPCB, India. He has completed ME from Delhi University, Delhi, India. His research interests are on abatement of air pollution, water quality assessment and rejuvenation of polluted rivers.

R. C. Saxena is an ex-Regional Director & Scientist-E in Central Pollution Control Board, Eastern Regional Directorate, Kolkata, India. He was worked on various aspects of air and water pollution management. He has completed MTech from Delhi University, Delhi, India.

ORCID

Vishnu Vardhan Kanuri http://orcid.org/0000-0001-7152-5486