The seasonal distribution and pollution potential of dissolved heavy metals and nutrients in subterranean estuaries in southern India

N K Vishnudattan; Douglas R Tait; S Bijoy Nandan; E H Aravind; D S Suresh Babu; P R Jayachandran

doi:10.1016/j.marpolbul.2023.115339

The seasonal distribution and pollution potential of dissolved heavy metals and nutrients in subterranean estuaries in southern India

Mar Pollut Bull. 2023 Sep;194(Pt B):115339. doi: 10.1016/j.marpolbul.2023.115339. Epub 2023 Jul 28.

Authors

N K Vishnudattan¹, Douglas R Tait², S Bijoy Nandan³, E H Aravind¹, D S Suresh Babu⁴, P R Jayachandran⁵

Affiliations

¹ Department of Marine Biology, Microbiology & Biochemistry, School of Marine Sciences, Cochin University of Science & Technology, Fine Arts Avenue, Cochin 682016, Kerala, India.
² Faculty of Science and Engineering, Southern Cross University, Lismore, NSW 2480, Australia.
³ Department of Marine Biology, Microbiology & Biochemistry, School of Marine Sciences, Cochin University of Science & Technology, Fine Arts Avenue, Cochin 682016, Kerala, India. Electronic address: bijoynandan@yahoo.co.in.
⁴ National Centre for Earth Sciences Studies, Akkulam, Thiruvananthapuram 695031, Kerala, India.
⁵ Applied Research Center for Environment and Marine Studies (ARC-EMS), Research Institute, King Fahd University of Petroleum & Minerals (KFUPM), Dhahran 31261, Saudi Arabia.

PMID: 37517279
DOI: 10.1016/j.marpolbul.2023.115339

Abstract

In order to better understand the distribution pattern, pollution degree and the submarine groundwater discharge (SGD) of dissolved heavy metals, 15 subterranean estuaries (STEs) along southwest Indian coast were sampled over three contrasting seasons. The average concentration of metals were ranked as, pre-monsoon > monsoon > post-monsoon with 3 to 12-fold higher groundwater metal concentrations than the adjacent seawater. Average SGD derived essential metal fluxes were five times higher than the toxic metal fluxes of which Fe and Zn together contributed >90 %. Using the Single Factor Contamination Index, the majority of sites were minimally contaminated with only two sites indicating moderate ecological risk due to As. Higher fluxes of Fe, Cu and Zn were likely a result of rising anthropogenic activities. The SGD derived nutrient fluxes were an important source of DIP for primary production in coastal waters and represented 30 % and 44 % of the DIN and DIP inputs respectively.

Keywords: Groundwater; Kerala coast; Nutrients; SGD; Toxic metals.

MeSH terms

Environmental Monitoring
Estuaries
Groundwater*
India
Metals, Heavy*
Nutrients
Seasons
Seawater

Substances

Metals, Heavy