Impact of river discharge on the coastal water pH and pCO2 levels during the Indian Ocean Dipole (IOD) years in the western Bay of Bengal

Sarma, V. V. S. S.; Paul, Y.S.; Vani, D Gayatri; Murty, V. S. N.

doi:10.1016/j.csr.2015.07.015

Cited by 32 publications

(5 citation statements)

References 35 publications

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“…On the other hand, the results in Table 4 show a significant positive correlation between pH and NDVI in winter (r = 0.99, p = 0.01), which is consistent with the phenomenon that the growth of NDVI usually means the improvement of water quality, especially in the acidified rivers [53,58]. Unfortunately, this study does not observe the significant correlations between pH and urban lands, river discharge and road salting, which are usually considered to be the factors affecting river acidification [13,[59][60][61]. The reasons for this may include: (1) The period of the observed data is probably insufficient;…”

Section: Reasons For the Trends Of River Phsupporting

confidence: 80%

Are UK Rivers Getting Saltier and More Alkaline?

Jiang

et al. 2022

Water

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River salinisation and alkalinisation have become one of the major environmental problems threatening the safety of global freshwater resources. With the accelerated climate change and aggravating anthropogenic influences, it is important to identify the trends and causes of river salinisation and alkalinisation so that better mitigation measures could be taken. This study has focused on the UK rivers because there has been insufficient investigation on this topic. To understand the salinisation and alkalinisation trends and causes of rivers in the UK over the past 20 years from a vertical (analysis of each river) and horizontal (comparison of all rivers) perspective, this study uses the Theil-Sen regression and Mann-Kendall test to deal with the trends of conductivity (proxy on salinisation) and pH (proxy on alkalinisation), obtains outliers of conductivity and pH by boxplot, and calculates the Pearson’s and the Kendall’s Tau correlation coefficients (α = 0.05) between the water quality data and the potential factors (potential road salting, normalized difference vegetation index (NDVI), river discharge, agricultural and urban lands). The results show that the UK rivers are becoming more alkaline with a median pH increase of 0.05 to 0.40, but less salty with a median conductivity decrease of 0.06 to 0.11 mS/cm. And the changes in conductivity and pH have seasonality and regionality, which shows that there are usually greater changes in trends and medians of them in winter or through reaches with more anthropogenic disturbance. Furthermore, from a vertical perspective, the conductivity of more than 50% of rivers in this study is negatively correlated with NDVI and river discharge, and positively correlated with potential road salting, and the pH of that is positively correlated with agricultural lands. While from a horizontal perspective, NDVI and agricultural lands are positively correlated with pH, and potential road salting and urban lands are positively correlated with conductivity. Therefore, road salting, urbanisation, agricultural lands, river discharge and vegetation cover can be considered to affect river salinisation and alkalinisation in the UK.

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Section: Reasons For the Trends Of River Phsupporting

confidence: 80%

Are UK Rivers Getting Saltier and More Alkaline?

Jiang

et al. 2022

Water

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“…This would lead to ballast of organic matter to the depth with limited oxidation in the water column (Ittekkot et al, ). Under enhanced river discharge scenario in future, coastal upwelling may be weakened due to increased stratification caused by river discharge (Masood et al, ; Mirza et al, ; Sarma et al, ). Even under increase in river discharge scenario, nutrients may not be added to BoB as river‐borne nutrients are consumed within the few kilometers from the coast (Krishna et al, ; Sarma et al, ).…”

Section: Discussionmentioning

confidence: 99%

Ventilation of Oxygen to Oxygen Minimum Zone Due to Anticyclonic Eddies in the Bay of Bengal

Sridevi

Bhaskar²

2018

JGR Biogeosciences

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Intense oxygen minimum zone (OMZ) occurs in the middepth of the Eastern Tropical Pacific (ETP), Arabian Sea (AS), and Bay of Bengal (BoB). However, the occurrence of anammox/denitrification was reported only in the ETP and AS and its absence in the BoB is attributed to presence of traces of dissolved oxygen (DO). Anticyclonic eddies (ACEs) supply high-nutrient, organic-rich, and oxygen-poor waters from the coastal upwelling regions leading to strengthening of OMZ in the offshore of AS and ETP. In the absence of western boundary upwelling, we hypothesize that the ACEs supply DO-rich water leading to weakening of OMZ in the BoB. Six ACEs were sampled by bio-argo floats and measured in situ hydrography and DO. All sampled eddies were formed in the eastern BoB, close to Andaman Sea, and moved toward west. Warm and DO-rich waters were observed in the core of OMZ (150-300 m), influenced by ACEs, by 0.5-1.46°C and 3.2-6.5 μM, respectively, than no eddy region in the BoB. Based on the mean lifetime of ACE, the rate of ventilation in the 100-300 m was estimated to be 0.07 ± 0.02 μmol/L/day, which is 3 to 4 times higher than bacterial respiration rates (0.02 μmol/L/day). Concerns of OMZ intensification leading to denitrification/anammox conditions in the BoB have been expressed, but with several ACEs forming in time and space in the BoB the denitrification occurrence is unlikely.SARMA AND UDAYA BHASKAR 2145

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“…High-resolution monitoring conducted in other Indian estuaries and adjacent coastal water bodies have revealed that decreased river discharge would create conditions for algal blooms that can 475 lead to hypoxic conditions, biodiversity reduction, and decreased fish harvests (Sarma et al, 2009(Sarma et al, , 2010(Sarma et al, , 2011Bharathi, 2015). In addition, decreased river discharge can enhance coastal upwelling, leading to further increase in pCO2 levels and acidification in the adjacent coastal waters (Sarma et al, 2015).…”

Section: Effects Of Increasing Water Pollution In Asian River Systemsmentioning

confidence: 99%

Reviews and syntheses: Anthropogenic perturbations to carbon fluxes in Asian river systems: Concepts, emerging trends, and research challenges

Park¹,

Nayna²,

Begum³

et al. 2018

Preprint

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Abstract. Human activities are drastically altering water and material flows in river systems across Asia. These anthropogenic perturbations have rarely been linked to the carbon (C) fluxes of Asian rivers that may account for up to 40-20 50% of the global fluxes. The primary object of this review was to provide a conceptual framework for assessing human impacts on Asian river C fluxes, along with a latest update on anthropogenic alterations of riverine C fluxes, focusing on the impacts of water pollution and river impoundments on CO2 outgassing from the rivers draining South, Southeast, and East Asian regions that account for the largest fraction of river discharge and C exports from Asia and Oceania. Recent booms in dam construction across Asia have created a host of environmental problems; yet only a small number of studies have 25 explicitly investigated altered rates of greenhouse gas (GHG) emissions and organic C transport. There have been contrasting reports on impoundment effects: decreases in GHG emissions in the reservoirs exhibiting enhanced primary production vs. increased emissions from the flooded vegetation and soils in the early years following dam construction or from the impounded river reaches and downstream estuaries during the monsoon period. These contrasting results suggest that the rates of metabolic processes in the impounded and downstream reaches can greatly vary longitudinally over time, as 30 a combined result of diel shifts in the balance between autotrophy and heterotrophy, seasonal fluctuations between the dry and monsoon periods, and a long-term change from a leaky post-construction phase to a gradual C sink. Rapid pace of urbanization across southern and eastern Asian regions has dramatically increased municipal water withdrawal, generating annually 120.2 km 3 of wastewater in 24 countries, which comprises 38.6% of the global municipal wastewater production disproportionately affect the receiving river water, particularly downstream of rapidly expanding metropolitan areas, including eutrophication, increases in the amount and lability of organic C, and pulse emissions of CO2 and other greenhouse gases (GHGs). As reviewed for three representative rivers (the Ganges, Mekong, and Yellow River), the lower reaches of these rivers and their polluted tributaries tend to exhibit higher levels of organic C and the partial pressure of CO2 (pCO2) than the eutrophic reservoirs and less impacted upstream reaches. More field measurements of pCO2, together with accurate 40 flux calculations based on river-specific model parameters, are urgently required to provide more accurate estimates of GHG emissions from the Asian rivers that are now underrepresented in the global C budgets. Researchers working on individual river systems need to be linked to collaborative research networks to facilitate global synthesis of local field data. These synthesis efforts, combined with conceptual and mathematical models, will contribute to a better understanding of how anthropogenic perturbations in rapidly urb...

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Impact of river discharge on the coastal water pH and pCO2 levels during the Indian Ocean Dipole (IOD) years in the western Bay of Bengal

Cited by 32 publications

References 35 publications

Are UK Rivers Getting Saltier and More Alkaline?

Are UK Rivers Getting Saltier and More Alkaline?

Ventilation of Oxygen to Oxygen Minimum Zone Due to Anticyclonic Eddies in the Bay of Bengal

Reviews and syntheses: Anthropogenic perturbations to carbon fluxes in Asian river systems: Concepts, emerging trends, and research challenges

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