Evidence of elevation effect on stable isotopes of water along highlands of a humid tropical mountain belt (Western Ghats, India) experiencing monsoonal climate

Tripti, M.; Lambs, Luc; Moussa, Issam; Corenblit, Dov Jean-François

doi:10.1016/j.jhydrol.2019.03.086

Cited by 23 publications

(4 citation statements)

References 70 publications

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“…Furthermore, NH 4 concentrations varied among the coastal springs from 1 to 200 μmol L –1 , which indicates a point source of nitrogen affecting the springs, consistent with septic waste input. Stable isotopes of coastal spring water (δ 18 O, δD) plotted along the local meteoric water line (Figure C in the Supporting Information) indicated no secondary isotope effects such as evaporation and a signature comparable to precipitation during the South-West Monsoon season (May–August). , We therefore assume that groundwater sampled from coastal springs mainly recharged during storm events during the South-West Monsoon season . A rapid recharge during heavy rain events can flush pollutants and nutrients from the soil into groundwater, bypassing the soil filter, and may explain the elevated NO 3 , NH 4 , and DOC in CSW water.…”

Section: Results and Discussionmentioning

confidence: 88%

“…: δ 18 O NO3 = 7.00; δ 15 N NO3 = 9.54) are typical for septic waste and/or manure, 38 39 and a signature comparable to precipitation during the South-West Monsoon season (May−August). 40,41 We therefore assume that groundwater sampled from coastal springs mainly recharged during storm events during the South-West Monsoon season. 28 A rapid recharge during heavy rain events can flush pollutants and nutrients from the soil into groundwater, bypassing the soil filter, 37 and may explain the elevated NO 3 , NH 4 , and DOC in CSW water.…”

Section: ■ Introductionmentioning

confidence: 99%

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Tropical Beaches Attenuate Groundwater Nitrogen Pollution Flowing to the Ocean

Oehler

Ramasamy

George

et al. 2021

Environ. Sci. Technol.

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Tropical urbanized coastal regions are hotspots for the discharge of nutrient-enriched groundwater, which can affect sensitive coastal ecosystems. Here, we investigated how a beach modifies groundwater nutrient loads in southern India (Varkala Beach), using flux measurements and stable isotopes. Fresh groundwater was highly enriched in NO3 from sewage or manure. Submarine groundwater discharge and nearshore groundwater discharge were equally important contributors to coastal NO3 fluxes with 303 mmol NO3 m–1 day–1 in submarine and 334 mmol NO3 m–1 day–1 in nearshore groundwater discharge. However, N/P ratios in nearshore groundwater discharge were up to 3 orders of magnitude greater than that in submarine groundwater, which can promote harmful algae blooms. As groundwater flowed through the beach, N/P ratios decreased toward Redfield ratios due to the removal of 30–50% of NO3 due to denitrification and production of PO4 due to mineralization of organic matter. Overall, tropical beaches can be important natural biogeochemical reactors that attenuate nitrogen pollution and modify N/P ratios in submarine groundwater discharge.

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Section: Results and Discussionmentioning

confidence: 88%

Section: ■ Introductionmentioning

confidence: 99%

Tropical Beaches Attenuate Groundwater Nitrogen Pollution Flowing to the Ocean

Oehler

Ramasamy

George

et al. 2021

Environ. Sci. Technol.

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show abstract

“…Monthly or seasonal rainwater isotopic data are not available for the Nilgiri Plateau. The δD of surface and groundwater samples collected in the Nilgiri Plateau (Tripti et al, 2019) suggested −32‰, −45‰, and −53‰ as the mean annual δD rain for Region I, II, and III, respectively (See Supplemental Discussion, available online). The expected δD of rain at the sampling location (~2000 m a.s.l.)…”

Section: Methodsmentioning

confidence: 99%

Holocene precipitation hydrogen isotopic values on Nilgiri Plateau (southern India) suggest a combined effect of precipitation amount and transport paths

et al. 2023

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Paleoclimate investigations of the peat deposits in the Nilgiri Plateau, an important paleoclimate archive of India, are mainly restricted to the carbon isotope composition ((δ13C) of plant-derived materials and pollen studies. However, it is unclear whether these proxies reflect past variability in temperature or hydrology. Here, we report the hydrogen and carbon isotopic variability of n-alkanoic acid of chain length 28 (δDC28 and δ13CC28, respectively) and demonstrate that the peatland leaf wax hydrogen isotopes provide a sensitive record of past hydrology. The decoupling of δ13CC28 and δD of vegetation-corrected rain during the Holocene indicate that δD of the leaf wax compounds mainly respond to past hydrological variability whereas δ13C variations might reflect the temperature-controlled variability of C3 and C4 vegetation. Conforming with the other paleoclimate records from the region, the δDC28 variations showed a reducing precipitation trend since the early Holocene. However, a large amplitude of reconstructed δD of rain (~44‰) during the Holocene indicated changes in the moisture source and trajectory could be an additional factor contributing to the orbital-scale δD variability of proxies from the Indian region.

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“…Although many observations have confirmed the phenomenon of the altitude effect [13], counterexamples do exist and are sometimes termed the inverse altitude effect (IAE) [14,15]. There is currently a great deal of controversy regarding the spatial and temporal distribution of the IAE and the mechanism by which it occurs.…”

Section: Introductionmentioning

confidence: 99%

Satellite-Based Distribution of Inverse Altitude Effect of Global Water Vapor Isotopes: Potential Influences on Isotopes in Climate Proxies

Yang,

Xiao,

Wang

et al. 2023

Remote Sensing

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The widely-distributed altitude effect of stable isotopes in meteoric water, i.e., the negative correlation between stable hydrogen (or oxygen) isotope compositions and altitude, is the theoretical basis of isotope paleoaltimetry in climate proxies. However, as many recent local observations have indicated, the inverse altitude effect (IAE) in meteoric water does exist, and the regime controlling IAE is still unclear on a global scale. Based on a remote sensing product of the Infrared Atmospheric Sounding Interferometer (IASI), we examined the global frequency of IAE in water vapor isotopes, and the possible influences on isotopes in precipitation and climate proxies. According to the satellite-based δD values in water vapor at 2950 m and 4220 m above sea level, frequent IAEs are observed on a daily scale in North Africa, West and Central Asia, and North America, and IAEs are more likely to occur during the daytime than during the nighttime. We also converted water vapor δD to precipitation δD via equilibrium fractionation and then analyzed the potential presence of IAE in precipitation, which is more associated with climate proxies, and found that the spatial and temporal patterns of water vapor can be transferred to the precipitation. In addition, different thresholds of δD difference were also tested to understand the impact of random errors. The potential uncertainty of the changing isotope and altitude gradient should be considered in paleo-altitude reconstructions.

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Evidence of elevation effect on stable isotopes of water along highlands of a humid tropical mountain belt (Western Ghats, India) experiencing monsoonal climate

Cited by 23 publications

References 70 publications

Tropical Beaches Attenuate Groundwater Nitrogen Pollution Flowing to the Ocean

Tropical Beaches Attenuate Groundwater Nitrogen Pollution Flowing to the Ocean

Holocene precipitation hydrogen isotopic values on Nilgiri Plateau (southern India) suggest a combined effect of precipitation amount and transport paths

Satellite-Based Distribution of Inverse Altitude Effect of Global Water Vapor Isotopes: Potential Influences on Isotopes in Climate Proxies

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