TY - JOUR
T1 - An environmental magnetic record of heavy metal pollution in Vembanad lagoon, southwest coast of India
AU - Narayana, A. C.
AU - Ismaiel, M.
AU - Priju, C. P.
N1 - Funding Information:
The first author (ACN) thanks Department of Ocean Development for funding through a research project (No. DOD/11-MRDF/4/2/UNI/97(P-6) dt.27.3.2001 ) when the author was with Cochin University of Science & Technology. ACN also acknowledges his student Late S. Shyju, who died in road accident, for his innovative efforts and help rendered in collecting the core samples. CPP thanks CSIR for JRF and Senior Research Fellowships and the Cochin University for facilities. Authors thank Prof. R. Shankar, Department of Marine Geology, Mangalore University, India, for the facilities extended for measuring the magnetic parameters.
Publisher Copyright:
© 2021 Elsevier Ltd
PY - 2021/6
Y1 - 2021/6
N2 - Magnetic signature of the iron-bearing minerals archived in sediments is sensitive to change in environment and therefore, studied to reconstruct the signals linked with environmental processes. In the present work, we have analyzed 11 sediment cores from Vembanad lagoon, southwest coast of India, to estimate the magnetic fluctuations associated with environmental processes. Down-core variation in magnetic susceptibility and anhysteretic, isothermal and saturation isothermal remnant magnetization and S and H-ratios have been interpreted to map the degree and spatial distribution of anthropogenic pollution in and around the lagoon. Downcore variation of magnetic susceptibility of Vembanad lagoon sediments varies from 10 to 100 × 10−8 m3/ kg. The top layers of sediment samples from river mouth regions (Periyar and Muvattupuzha rivers) show higher susceptibility values and incidentally these samples are of coarse sized. The subtle variations in SIRM/χlf ratios suggest that there are magnetic grain size differences in the samples. The SIRM and χlf relation suggests that dominant magnetic grain size in sediments. The low ARM/χlf ratios suggest a relatively higher ferrimagnetic contribution and coarser magnetite grain size. Rock magnetism data reveal that the coarse magnetic grain size is affecting the pollution of Vembanad lagoon. We also analyzed downcore variability of metal concentrations such as Fe, Mn, Cu, Zn, Ni and Cr, and all these metals exhibit higher concentrations in the top layers of the cores. Our study suggests that higher values of magnetic parameters and metal concentrations are due to various anthropogenic sources.
AB - Magnetic signature of the iron-bearing minerals archived in sediments is sensitive to change in environment and therefore, studied to reconstruct the signals linked with environmental processes. In the present work, we have analyzed 11 sediment cores from Vembanad lagoon, southwest coast of India, to estimate the magnetic fluctuations associated with environmental processes. Down-core variation in magnetic susceptibility and anhysteretic, isothermal and saturation isothermal remnant magnetization and S and H-ratios have been interpreted to map the degree and spatial distribution of anthropogenic pollution in and around the lagoon. Downcore variation of magnetic susceptibility of Vembanad lagoon sediments varies from 10 to 100 × 10−8 m3/ kg. The top layers of sediment samples from river mouth regions (Periyar and Muvattupuzha rivers) show higher susceptibility values and incidentally these samples are of coarse sized. The subtle variations in SIRM/χlf ratios suggest that there are magnetic grain size differences in the samples. The SIRM and χlf relation suggests that dominant magnetic grain size in sediments. The low ARM/χlf ratios suggest a relatively higher ferrimagnetic contribution and coarser magnetite grain size. Rock magnetism data reveal that the coarse magnetic grain size is affecting the pollution of Vembanad lagoon. We also analyzed downcore variability of metal concentrations such as Fe, Mn, Cu, Zn, Ni and Cr, and all these metals exhibit higher concentrations in the top layers of the cores. Our study suggests that higher values of magnetic parameters and metal concentrations are due to various anthropogenic sources.
KW - Coastal sediments
KW - Environmental magnetism
KW - Heavy metals
KW - Southwest coast of India
KW - Vembanad lagoon
UR - http://www.scopus.com/inward/record.url?scp=85104347446&partnerID=8YFLogxK
U2 - 10.1016/j.marpolbul.2021.112344
DO - 10.1016/j.marpolbul.2021.112344
M3 - Article
C2 - 33887598
AN - SCOPUS:85104347446
SN - 0025-326X
VL - 167
JO - Marine Pollution Bulletin
JF - Marine Pollution Bulletin
M1 - 112344
ER -