Heavy metal accumulation in a flow restricted, tropical estuary

Balachandran, K.K.; Raj, C.M. Lalu; Nair, M.; Joseph, T.; Sheeba, P.; Venugopal, P. Dilip

doi:10.1016/j.ecss.2005.06.013

Cited by 119 publications

(63 citation statements)

References 18 publications

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“…The monsoon-derived alluvium accumulates in the estuary during postmonsoon, whereas silting environment prevails during the pre-monsoon [15,16]. The natural and anthropogenic factors influencing the geochemistry of sediments in the Cochin backwaters and the adjacent coast have been reported [2,17]. Many studies have assessed the environmental changes caused by anthropogenic input of nutrients and other materials in this estuarine system, albeit, systematic study over a region covering tidal cycles are not yet reported.…”

Section: Introductionmentioning

confidence: 99%

“…Reclamations over the past several decades have resulted in considerable shrinkage of the Cochin backwaters [13]. The hydraulic barriers constructed to prevent saline incursion into the upstream agricultural fields imposed flow-restrictions and increased sedimentation in the estuary [2,6,14]. The monsoon-derived alluvium accumulates in the estuary during postmonsoon, whereas silting environment prevails during the pre-monsoon [15,16].…”

Section: Introductionmentioning

confidence: 99%

“…Cochin backwaters, one of the largest tropical estuaries of India (256 km 2 ), are facing gross pollution problems following the release of untreated effluents from industries (0.104 x 10 6 m 3 d −1 ) and domestic sectors (0.26 x 10 3 m 3 d −1 ) [12]. Reclamations over the past several decades have resulted in considerable shrinkage of the Cochin backwaters [13].…”

Section: Introductionmentioning

confidence: 99%

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Fresh Water Influence on Nutrient Stoichiometry in a Tropical Estuary, Southwest Coast of India

Martin¹,

Vijay²,

Laluraj³

et al. 2007

Appl Ecol Env Res

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Abstract. Cochin backwaters, a micro tidal estuary, undergo a characteristic transformation from a riverdominated system during summer monsoon to a tide-dominant system during pre-monsoon season. The present study observes that as the river flow weakens after monsoon, the flushing of the estuary diminishes and the nitrogen and phosphorous loadings through anthropogenic activities (industries) and sediment re-suspension alter the nutrient stoichiometry substantially. The increased tidal activity during pre-monsoon changes the estuary into a vertically mixed, eutrophic and flow-restricted system supporting an enhanced organic production. This implies that monsoon-induced hydrology plays an important role in regulating the nutrients, secondary production and even the migrant fauna of the estuary. The system is delicately poised, as continuous release of pollutants including nutrients into this estuary would suppress fish and shell fish production, where only pollution tolerant species can exist.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Fresh Water Influence on Nutrient Stoichiometry in a Tropical Estuary, Southwest Coast of India

Martin¹,

Vijay²,

Laluraj³

et al. 2007

Appl Ecol Env Res

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“…The high organic enrichment in sediment in the Cochin and Neendakara harbour region in the present observation could be a sign of environmental deterioration. The nutrient delivery from industries, aggravated by the complex circulation and weak flushing had led to an increased production and settling of organic matter in the estuarine transect especially at Cochin transect [52,53].…”

Section: Discussionmentioning

confidence: 99%

“…Thus the industrial complex consisting of fertilizer, refinery, smelters, etc., discharging their effluents through run off via Periyar River to the Cochin transect might be responsible for the accumulation of heavy metals in sediments. Further, the reduced flushing in Cochin harbour Balachandran et al, [52] could increase the organically rich domestic sewage, leading to settlement of particles in the bottom. The positive significant correlations between sediment Pb and Cd indicated the enrichment of these metals and adsorption onto ferromanganese oxides precipitated in the sediment [55].…”

Section: Cochinmentioning

confidence: 99%

Heavy Metal Contamination and Risk Assessment in the Marine Environment of Arabian Sea, along the Southwest Coast of India

S¹,

Muduli²,

Vardhan³

et al. 2012

CHEMISTRY

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Marine ecosystem is being threatened by the discharge of untreated sewage wastes and industrial effluents which ultimately affects the sustainability of living resources and public health. These wastes carry enormous level of toxicants especially the heavy metals have the tendency to accumulate into the basic food chain and move up through the higher trophic level and results in negative impact on the marine resources thus causing economic loss. In this regard, to ascertain the level of heavy metals in water, particulate, zooplankton (Zn, Mn, Pb, Cu, Cd and Hg) and in sediment (Pb, Al, Cd and Hg) along southern Kerala coast, India has been evaluated during early 2006. The heavy metal concentrations followed the hierarchy; Zn>Mn>Pb>Cu>Cd>Hg; Pb>Zn>Mn>Cu>Cd>Hg; Zn>Pb>Mn>Cu>Cd>Hg and Pb>Al>Cd>Hg in seawater, particulate matter, zooplankton and sediment respectively. The results revealed that in all the transacts (except Cochin) the heavy metal concentrations are below the threshold levels associated with the toxicological effects and the regulatory limits. Metal enrichments were observed close to the major urban areas of coastal waters, mostly associated with large scale industrialization. Enrichment factor, geoaccumulation index and pollution load index were calculated to evaluate the heavy metal threats along the coastal sediment. It revealed minor to moderately severe enrichment of Cd, Pb and Hg in the industrial zones of the coastal stretches especially at Cochin. A comparison with sediment quality guideline quotient indicated that there may be probability of ecotoxicological threats to the benthic community along Cochin transect.

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Evolution to decay of upwelling and associated biogeochemistry over the southeastern Arabian Sea shelf

et al. 2016

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Observations along 10 shelf transects in 2012 near 10°N in the southeastern Arabian Sea revealed the usual warm oligotrophic conditions during the winter monsoon and upwelling of oxygen-deficient, nutrient-rich cool water during the summer monsoon (SM). By changing an oligotrophic to a nutrient-replete condition, the upwelling is the major process that regulates the biogeochemistry of this shelf. Its onset is perceptible at 100 m depth between January and March. The upwelling reaches the surface layer in May and intensifies during June-July but withdraws completely and abruptly by October. Despite the nutrient injection, the primary production during SM, integrated for euphotic zone, is comparable to that during the preceding spring intermonsoon (SIM). Again, as usual, the high oxygen demand coupled with low concentration in the upwelled subsurface waters causes severe oxygen depletion below the shallow pycnocline. The oxygen concentrations/saturations of 2012 on the midshelf are similar from those of mid-1958 to early 1960, except for marginally higher values during the peak upwelling period due to relatively weak upwelling in 2012. This implies little anthropogenic influence on coastal hypoxia unlike many other coastal regions. In 2012, the inner shelf system shifted from net autotrophy in SIM to net heterotrophy in SM but on an annual basis it was net autotrophic (gross primary production to community respiration ratio, GPP/R:1.11 ± 0.84) as organic production exceeded consumption.

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Heavy metal accumulation in a flow restricted, tropical estuary

Cited by 119 publications

References 18 publications

Fresh Water Influence on Nutrient Stoichiometry in a Tropical Estuary, Southwest Coast of India

Fresh Water Influence on Nutrient Stoichiometry in a Tropical Estuary, Southwest Coast of India

Heavy Metal Contamination and Risk Assessment in the Marine Environment of Arabian Sea, along the Southwest Coast of India

Evolution to decay of upwelling and associated biogeochemistry over the southeastern Arabian Sea shelf

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