Hidden erosion on volcanic islands

Rad, Sétareh; Allègre, Claude J.; Louvat, Pascale

doi:10.1016/j.epsl.2007.07.019

Cited by 119 publications

(83 citation statements)

References 26 publications

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“…For example, SGD from the island of Hawai'i has a temperature of ~19-21°C (Johnson et al, 2008;Peterson et al, 2009), andConrad et al (1997) showed that groundwater in deep drill holes on the east flank of Kilauea volcano is the same temperature from sea level down to ~500 m below sea level -~20-25°C. The results from Rad et al (2007) are therefore not directly comparable with our work. Conrad et al (1997) do report much higher temperatures deeper in the drillholes, but our sampling did not tap any of this water.…”

Section: Water Chemistry and Chemical Fluxescontrasting

confidence: 55%

“…Such sources probably enhance the silica and bicarbonate fluxes delivered to the oceans in SGD but the island-wide impact is probably modest. Rad et al (2007) found that groundwater fluxes accounted for 45 to 70% of the total HCO 3 -fluxes from the three studied islands, and 65 -95% of cation fluxes. For the two islands for which Rad et al (2007) report dissolved silica values, 45 -80% of the silica flux was via groundwater.…”

Section: Water Chemistry and Chemical Fluxesmentioning

confidence: 99%

“…Rad et al (2007) found that groundwater fluxes accounted for 45 to 70% of the total HCO 3 -fluxes from the three studied islands, and 65 -95% of cation fluxes. For the two islands for which Rad et al (2007) report dissolved silica values, 45 -80% of the silica flux was via groundwater. No uncertainties were calculated, but given the reconaissance nature of the sampling and water balance data they are probably large.…”

Section: Water Chemistry and Chemical Fluxesmentioning

confidence: 99%

“…In other words, chemical weathering fluxes transported to the oceans via groundwater are up to an order of magnitude larger than via surface water. Rad et al (2007) also estimated the chemical weathering flux carried as groundwater discharge from two islands in the Lesser Antilles volcanic arc and the hotspot Reunion Island. They used stream discharge data and island-wide estimates of evapo-transpiration to estimate ground water infiltration.…”

Section: Water Chemistry and Chemical Fluxesmentioning

confidence: 99%

“…Street et al (2008) used multiple chemical tracers (salinity, dissolved silica and Ra-isotopes) to quantify SGD in several locations in Hawai'i, Johnson et al (2008) used thermal infrared imagery to demonstrate the presence of large, cold freshwater plumes along the west coast of the island of Hawai'i and Peterson et al (2009) quantified the discharge via these plumes using salinity and Ra-isotopes. SGD is not only an important pathway for the delivery of water from land to ocean; it also transports significant amounts of dissolved solids from weathering on land directly to the global ocean (Rad et al, 2007;Georg et al, 2009).…”

Section: Introductionmentioning

confidence: 99%

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Chemical weathering fluxes from volcanic islands and the importance of groundwater: The Hawaiian example

Schopka

Derry

2012

Earth and Planetary Science Letters

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We investigated the products and rates of chemical weathering on the Hawaiian Islands, sampling streams on Kaua'i and both streams and groundwater wells on the island of Hawai'i. Dissolved silica was used to investigate the flowpaths of water drained into streams. We found that flowpaths exert a major control on the observed chemical weathering rates. A strong link exists between the degree of landscape dissection and flowpaths of water through the landscape, with streams in undissected landscapes receiving water mainly from surface runoff and streams in highly dissected landscapes receiving a considerable fraction of their water from groundwater (springs and/or seepage). Total alkalinity in Hawaiian streams and groundwater is produced exclusively by silicate chemical weathering. We find that fluxes of total alkalinity (often called "CO 2 consumption rate" in the geochemical literature), from the islands are lower than those observed in basaltic regions elsewhere. Groundwater is, overall, the major transport vector for products of chemical weathering from the Hawaiian Islands. On the youngest and largest island, submarine groundwater discharge (SGD) transports more than an order of magnitude more solutes to the ocean than surface water and on the youngest part of the youngest island, SGD is the only link between the terrestrial weathering system and the ocean. These results suggest that groundwater, and particularly SGD, needs to be included in geochemical weathering budgets of volcanic islands.

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Section: Water Chemistry and Chemical Fluxescontrasting

confidence: 55%

Section: Water Chemistry and Chemical Fluxesmentioning

confidence: 99%

Section: Water Chemistry and Chemical Fluxesmentioning

confidence: 99%

Section: Water Chemistry and Chemical Fluxesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Chemical weathering fluxes from volcanic islands and the importance of groundwater: The Hawaiian example

Schopka

Derry

2012

Earth and Planetary Science Letters

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Sea level and climate forcing of the Sr isotope composition of lateMioceneMediterranean marine basins

Schildgen

Cosentino

Frijia

et al. 2014

Geochem Geophys Geosyst

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Sr isotope records from marginal marine basins track the mixing between seawater and local continental runoff, potentially recording the effects of sea level, tectonic, and climate forcing in marine fossils and sediments. Sr/ 86 Sr analyses from the astronomically tuned Lower Evaporites in the central Apennines (Italy) allow us to explore the effect of glacio-eustatic sea level and precipitation changes on 87 Sr/ 86 Sr. Most variation in our data can be explained by changes in sea level, with greatest negative excursions from global seawater values occurring during relative sea level lowstands, which generally coincided with arid conditions in the Mediterranean realm. We suggest that this greater sensitivity to lowered sea level compared with higher runoff could relate to the inverse relationship between Sr concentration and river discharge. Variations in the residence time of groundwater within the karst terrain of the circum-Mediterranean region during arid and wet phases may help to explain the single (robust) occurrence of a negative excursion during a sea level highstand, but this explanation remains speculative without more detailed paleoclimatic data for the region.

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Field estimates of groundwater circulation depths in two mountainous watersheds in the western U.S. and the effect of deep circulation on solute concentrations in streamflow

Frisbee

Tolley

Wilson

2017

Water Resources Research

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Estimates of groundwater circulation depths based on field data are lacking. These data are critical to inform and refine hydrogeologic models of mountainous watersheds, and to quantify depth and time dependencies of weathering processes in watersheds. Here we test two competing hypotheses on the role of geology and geologic setting in deep groundwater circulation and the role of deep groundwater in the geochemical evolution of streams and springs. We test these hypotheses in two mountainous watersheds that have distinctly different geologic settings (one crystalline, metamorphic bedrock and the other volcanic bedrock). Estimated circulation depths for springs in both watersheds range from 0.6 to 1.6 km and may be as great as 2.5 km. These estimated groundwater circulation depths are much deeper than commonly modeled depths suggesting that we may be forcing groundwater flow paths too shallow in models. In addition, the spatial relationships of groundwater circulation depths are different between the two watersheds. Groundwater circulation depths in the crystalline bedrock watershed increase with decreasing elevation indicative of topography‐driven groundwater flow. This relationship is not present in the volcanic bedrock watershed suggesting that both the source of fracturing (tectonic versus volcanic) and increased primary porosity in the volcanic bedrock play a role in deep groundwater circulation. The results from the crystalline bedrock watershed also indicate that relatively deep groundwater circulation can occur at local scales in headwater drainages less than 9.0 km2 and at larger fractions than commonly perceived. Deep groundwater is a primary control on streamflow processes and solute concentrations in both watersheds.

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Hidden erosion on volcanic islands

Cited by 119 publications

References 26 publications

Chemical weathering fluxes from volcanic islands and the importance of groundwater: The Hawaiian example

Chemical weathering fluxes from volcanic islands and the importance of groundwater: The Hawaiian example

Sea level and climate forcing of the Sr isotope composition of lateMioceneMediterranean marine basins

Field estimates of groundwater circulation depths in two mountainous watersheds in the western U.S. and the effect of deep circulation on solute concentrations in streamflow

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