Chemical weathering, river geochemistry and atmospheric carbon fluxes from volcanic and ultramafic regions on Luzon Island, the Philippines

Schopka, H. H.; Derry, Louis A.; Arcilla, Carlo A.

doi:10.1016/j.gca.2010.11.014

Cited by 97 publications

(82 citation statements)

References 60 publications

(78 reference statements)

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“…Weathering rates of volcanic islands are high as measured in stream fluxes (Louvat and Allègre, 1997;Dessert et al, 2003;Rad et al, 2007;Schopka et al, 2011), but the results of this study and of Rad et al (2007) imply weathering rates derived only from stream fluxes will substantially underestimate the total CO 2 consumption in these settings. Groundwater geochemical fluxes range from being roughly equal to the stream fluxes on Kaua'i and O'ahu (Table 2 and Li, 1988) to more than an order of magnitude greater on Hawai'i (Table 2).…”

Section: Dessert Et Al (2003) Investigated Chemical Weathering Fluxementioning

confidence: 73%

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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: Dessert Et Al (2003) Investigated Chemical Weathering Fluxementioning

confidence: 73%

“…Methods for sampling and chemical analyses are described in Schopka et al (2011). Briefly, filtered samples were analyzed for DSi by molybdate blue spectrophotometry (Mortlock and Froelich, 1989).…”

Section: Chemistrymentioning

confidence: 99%

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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“…However, our volcanic database is strongly weighted towards rivers draining the Philippine island arc volcanics (Schopka et al, 2011), that comprise 79 of our 180 data. Of these, those rivers with W > 200 t km -2 yr -1 drain unconsolidated pyroclastic deposits from the Mt.…”

Section: Role Of Lithologymentioning

confidence: 99%

“…Les sols alpins sont produits plus lentement que les bassins versants correspondants ne s'érodent (ce qui suggère l'existence d'un autre processus d'érosion fournissant des sédiments aux rivières, mais n'ayant pas lieu dans les sols), alors que les sols des montagnes San Gabriel ont des taux de production du sol qui dépassent les taux de dénudation à l'échelle du bassin versant. (Schopka et al, 2011). This data is shown in white as most of the Philippine catchments with weathering rates > 200 t km -2 yr -1 are from rivers draining unconsolidated pyroclastic deposits from the eruption of Mt.…”

Section: Figure 2 Chemical Weathering Rate Vs Erosion Rate For Regounclassified

“…Data are from multiple sources (Dessert et al, 2001;Dessert et al, 2009;Gaillardet et al, 2011;Goldsmith et al, 2010;Goldsmith et al, 2008;Hartmann and Moosdorf, 2011;Jones et al, 2010;Louvat and Allegre, 1998;Louvat et al, 2008;Lyons et al, 2005;Pokrovsky et al, 2005;Schopka et al, 2011). 9 Same as (7) but omitting the 79 samples from the Philippines that were heavily weighted in the volcanic dataset due to their large number (Schopka et al, 2011). Some of these rivers drain unconsolidated volcanic ash.…”

mentioning

confidence: 99%

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Soils as pacemakers and limiters of global silicate weathering

Dixon

Blanckenburg

2012

Comptes Rendus. Géoscience

130

154

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The weathering and erosion processes that produce and destroy regolith are widely recognized to be positively correlated across diverse landscapes. However, conceptual and numerical models predict some limits to this relationship that remain largely untested. Using new global data compilations of soil production and weathering rates from cosmogenic nuclides and silicate weathering fluxes from global rivers, we show that the weatheringerosion relationship is capped by certain 'speed limits'. We estimate a soil production speed limit of between 320 to 450 t km -2 y -1 and the associated weathering rate speed limit of roughly 150 t km -2 y -1. These limits appear to be valid for a range of lithologies, and also extend to mountain belts, where soil cover is not continuous and erosion rates outpace soil production. We argue that the presence of soil and regolith is a requirement for high weathering fluxes from a landscape, and that rapidly eroding, active mountain belts are not the most efficient sites for weathering. . Ces limites semblent être valides pour une large gamme de roches-mères, et s'appliquent aussi aux zones montagneuses, où les sols ne recouvrent pas toute la surface et où les taux d'érosion dépassent ceux de la production du sol. Nous avançons que la présence d'un sol est un prérequis pour qu'un paysage exporte de fort flux d'altération, et que les chaînes de montagne actives présentant de forts taux d'érosion ne sont pas les sites les plus efficaces pour l'altération.

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Growth of the Maritime Continent and its possible contribution to recurring Ice Ages

Molnár

Cronin

2015

Paleoceanography

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The areal extent of the Maritime Continent (the islands of Indonesia and surrounding region) has grown larger by~60% since 5 Ma. We argue that this growth might have altered global climate in two ways that would have contributed to making recurring Ice Ages possible. First, because rainfall over the islands of the Maritime Continent not only is heavier than that over the adjacent ocean but also correlates with the strength of the Walker Circulation, the growth of the Maritime Continent since 5 Ma may have contributed to the cooling of the eastern tropical Pacific since that time. Scaling relationships between the strength of the Walker Circulation and rainfall over the islands of the Maritime Continent and between sea surface temperature (SST) of the eastern tropical Pacific and the strength of easterly wind stress suggest that the increase in areal extent of islands would lead to a drop in that SST of 0.75°C. Although only a fraction of the 3-4°C decrease in SSTs between the eastern and western tropical Pacific, the growth of the Maritime Continent may have strengthened the Walker Circulation, increased the east-west temperature gradient across the Pacific and thereby enabled ice sheets to wax and wane over Canada since 3 Ma. Second, because the weathering of basaltic rock under warm, moist conditions extracts CO 2 from the atmosphere more rapidly than weathering of other rock or of basalt under cooler or drier conditions, the increase in weathering due to increasing area of basalt in the Maritime Continent may have drawn down enough CO 2 from the atmosphere to affect global temperatures. Simple calculations suggest that increased weathering of basalt might have lowered global temperatures by 0.25°C, possibly important for the overall cooling.

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Chemical weathering, river geochemistry and atmospheric carbon fluxes from volcanic and ultramafic regions on Luzon Island, the Philippines

Cited by 97 publications

References 60 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

Soils as pacemakers and limiters of global silicate weathering

Growth of the Maritime Continent and its possible contribution to recurring Ice Ages

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