Dissolved carbon and silica fluxes from Kali, Sharavati and Sita-Swarna rivers, Southwestern India

Nishitha, D'Souza; Akshitha, Vignesh; Kumar, Arun; Amrish, Vadakkeveedu Narayan; Praveenkumarreddy, Yerabham; Khare, Neloy; Udayashankar, H N; Manjunatha, B.R.; Balakrishna, Keshava

doi:10.1016/j.jenvman.2021.112273

Cited by 8 publications

(5 citation statements)

References 36 publications

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“…This compensates the removal of DSi by diatom uptake and causes less deviation from the TDL. Such non-conservative behavior of DSi in estuaries has been widely reported (Bell 1984;Amann et al 2014;Akshitha et al 2021).…”

Section: Mixing Behaviormentioning

confidence: 53%

Spatio-temporal variation of major ion chemistry and nutrient stoichiometry in a tropical monsoonal estuary: insight into biogeochemical processes

Akhtar

Equeenuddin

2023

Environ Earth Sci

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Major ions and nutrient chemistry of surface water from the Devi river estuary, eastern India has been studied in order to understand the governing biogeochemical processes. Concentration of Na, K, Ca, Mg, Cl, SO 4 and PO 4 increases towards higher salinity; however, NO 3 and dissolved silica (DSi) decreases from upper to lower estuary. All major ions, except NO 3 and DSi, show the highest and lowest concentration in summer and monsoon season respectively. Increased surface runoff has resulted in the highest concentration of NO 3 and DSi in the monsoon period. The Na, Cl, SO 4 , NO 3 and PO 4 ions show conservative mixing behavior in the estuary throughout the year. Non-conservative behavior of DSi is attributed to the combined process of mineral weathering and biological removal by diatoms. Enrichment and depletion of Ca and Mg in the estuary is owed to carbonate mineral precipitation and dissolution processes. Decreasing carbonate saturation indices (SI) with reducing pH accompanied by lowering of DO% suggests the in uence of organic matter degradation on the carbonate precipitation and/or dissolution potential. Nutrient stoichiometric ratios -NO 3 :PO 4 , DSi:PO 4 and DSi:NO 3 -are found to vary spatially and seasonally as a result of differences in geochemical processes prevailing in the fresh-and marine-water environment. A prominent PO 4 limitation is observed in the upper estuary during summer and winter. However, this limitation reduces towards the lower estuary owing to precipitation of Fesulphide under the in uence of higher salinity. In contrast, the in ux of PO 4 -limited freshwater into the estuary controls the nutrient limitation in the monsoon season. The spatial variation of chlorophyll concentration in the estuary is in accordance to the nutrient stoichiometric ratios. Thus, this study emphasizes on the role of unique biogeochemical processes in controlling the spatial and seasonal distribution of major ions and nutrient stoichiometry in a tropical estuarine system.

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Section: Mixing Behaviormentioning

confidence: 53%

Spatio-temporal variation of major ion chemistry and nutrient stoichiometry in a tropical monsoonal estuary: insight into biogeochemical processes

Akhtar

Equeenuddin

2023

Environ Earth Sci

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“…Table 1 shows the descriptive statistics of surface water samples collected along the salinity gradients in the Swarna, Sharavati and Kali estuaries. During the study period, salinity varied from 0.02 to 31.50 ppt during post-monsoon and (Nishitha et al 2021). Furthermore, dissolved trace metals analysed from Swarna, Sharavati and Kali estuaries showed significant spatiotemporal variations along the salinity gradients.…”

Section: Resultsmentioning

confidence: 97%

“…However, the PP bottles (250-ml capacity) used for trace metal collection were acid washed with 0.2 N Suprapur® nitric acid. The details of the sampling methods adopted can be found in the earlier work (Nishitha et al, 2021). Later in the field, at each location before collecting the sample, the bottles were rinsed thrice with the seawater.…”

Section: Methodsmentioning

confidence: 99%

“…Fig. 1 Map showing the sampling points along the salinity gradient of Sita-Swarna, Sharavati and Kali estuaries (Nishitha et al, 2021) Furthermore, the water samples for trace metal determination were filtered immediately using 0.22-m pore-size Nuclepore filter paper. Immediately after the filtration, the water samples were transferred to a PP grade bottles which were soaked overnight in 0.2 N Suprapur® nitric acid.…”

Section: Methodsmentioning

confidence: 99%

“…Similarly, the river Sharavati originates in Ambutheertha and spreads across two districts of Karnataka, Shimoga and Uttara Kannada. The river flows for 128 km and discharges 324 m 3 /sec annually to the Arabian Sea (Amrish et al, 2021). River Kali, the longest perennial river of coastal Karnataka (length184 km), has an annual discharge of 210 m 3 /sec to the Arabian Sea.…”

Section: Study Areamentioning

confidence: 99%

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Risk assessment and spatio-temporal distribution of dissolved trace metals in Swarna, Sharavati and Kali estuaries, South-West Coast of India

Nishitha

Sudheer

Kumar

et al. 2022

Environ Sci Pollut Res

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Trace metals act as a limiting nutrient and prerequisite for primary productivity in marine environments. The distribution of metals in dissolved phase along the salinity gradients of Swarna, Sharavati and Kali estuaries in southwestern India, during post and pre-monsoon seasons, were studied. We have investigated the behaviour of trace metals in the estuarine environment and their extent of impact on human health and ecosystem. The study revealed, non-conservative behaviour of dissolved Mn, Fe, Ni, Cd and Co in the estuaries. Whereas Cu behaved non-conservatively in post-monsoon and conservatively in pre-monsoon seasons. Risk assessment studies revealed that higher chronic daily intake (CDI) in humans, through dermal pathway, in Swarna and Sharavati estuaries during post-monsoon, whereas it was during pre-monsoon season in the Kali estuary. Hazard Index values for the studied metals in adults and children are below risk thresholds, though children are more prone to health risk through the dermal pathway.

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Study of trace metal contamination and ecological risk assessment in the sediments of a tropical river estuary, Southwestern India

Nishitha

Amrish

Kumar

et al. 2022

Environ Monit Assess

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The present study aims to assess the extent of trace metal pollution in the sediments of Sita-Swarna estuary, west coast of India, and investigate their possible ecological risk on the aquatic environment. The sediment cores were analyzed for sand, silt, clay, organic carbon, and trace metals (Al, Fe, Mn, As, Cd, Co, Zn, Pb, Ni, Cr, and Cu) at 2-cm intervals. The study revealed that sediments have deposited in relatively violent to very violent hydrodynamic energy conditions. Factor analysis indicated that the metal distribution is mainly controlled by Fe–Mn oxyhydroxides and organic carbon. Further, the geochemical approach, pollution indices, and statistical evaluation revealed moderate pollution in the catchment. From an ecotoxicological perspective, the estimated risk index (RI) value was found to less than 150, indicating low risk for aquatic life. Thus, this baseline study would help to adopt strategies in pollution control and protect the fragile marine environment.

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Dissolved carbon and silica fluxes from Kali, Sharavati and Sita-Swarna rivers, Southwestern India

Cited by 8 publications

References 36 publications

Spatio-temporal variation of major ion chemistry and nutrient stoichiometry in a tropical monsoonal estuary: insight into biogeochemical processes

Spatio-temporal variation of major ion chemistry and nutrient stoichiometry in a tropical monsoonal estuary: insight into biogeochemical processes

Risk assessment and spatio-temporal distribution of dissolved trace metals in Swarna, Sharavati and Kali estuaries, South-West Coast of India

Study of trace metal contamination and ecological risk assessment in the sediments of a tropical river estuary, Southwestern India

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