Chemistry of bulk precipitation in southwestern Viti Levu, Fiji

Abstract

JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact support@jstor.org.Cambridge University Press is collaborating with JSTOR to digitize, preserve and extend access to Journal of Tropical Ecology.http://www.jstor.org ABSTRACT. The amounts and chemical composition of bulk precipitation were investigated over a continuous 21-mo period (January 1990 to September 1991) at four sites along an East-West transect perpendicular to the coast of Southwest Viti Levu, Fiji. Measured rainfall totals in 1990 ranged fiom 1796 mm at the coastal Korokula station to 2113 mm at the inland Tulasewa station, which is somewhat higher than the long-term average of 1707 mm at a reference weather station located in the centre of the study area. The first 9 mo of 1991 were relatively dry (range 1027-1533 mm) with a total of 1157 mm at the reference site as compared to a long-term avcrage of 1330 mm. Concentrationis of all investigated constituents in bulk rainfall were low, except during the passage of cyclone Sina due to the deposition of large amiiounts of, especially, chloride, sodium and sulphate in sea spray. Concentrations of sodium and magnesium could be explained fully by maritime contributions to the rainfall coimipositioin at all sites. Maritime contributions to the concentrations of calcium, sulphate and potassium accounted for 10-40% of the total, whereas bicarbonate, ammonium, nitrate, silicon, aluminium, iron and manganese werc derived exclusively from terrestrial sources. The annual atmospheric nutrient deposition rates were low by pantropical standards, particularly when the contribution of cyclone Sina was excluded. Annual totals (in kg ha-') ranged from 2.4-8.8 for nitrogeni, 0.4-1.1 for phosphorus, 2.3-4.9 for potassium, 1.4-1.9 for calcium and from 1.1-1.3 for magnesium. The inclusion of the contribution by the cyclone more than doubled the dcposition of potassium, calcium and magnesiumll, although values still remained well within the range reported for humiiid tropical areas. The estimated atmospheric deposition of nutrients over a typical rotation period (16 y) was sufficient to balance losses in harvested Pinus caribaea logs (stemwood plus bark) of potassium, calciumil and magnesium, but not of nitrogen and, probably, phosphorus. Nutrient losses associated with the harivestinig of stemwood alone were compensated entirely by the atmospheric inputs.

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

“…If [Cl À ] tot,i < 200 lM, all Cl À is assumed to come from atmospheric deposition. The value of [Cl À ] rain = 200 lM derives from the assumption that rainfall in the region has an average chloride concentration of 100 lM (Eklund et al, 1997;Waterloo et al, 1997;Fujita et al, 2000;Kyoung Lee et al, 2000) and the evapotranspiration factor is around 2. Inputs from Cl À bearing minerals such as amphiboles are believed to be minor and in any case are not well constrained by our data.…”

Precipitation partitioning and related nutrient fluxes in a subtropical forest in Okinawa, Japan

“…The reason for the high value of stemflow at our site could be related to the crown morphology of the dominant species, C. sieboldii, which has inclined branches and concave shaped leaves. In addition, wind speed [23] and very high rainfall [43] can also affect the stemflow rate. On Okinawa, windstorms, particularly typhoon events, are very frequent and this may be an important cause of the high fraction of stemflow.…”

“…In addition, typhoons are frequent. Typhoon events can bring a large amount of rainfall with high concentrations of Na and Cl to the island [13,22,43]. Comparing the chemistry of precipitation and runoff at 47 forested sites in the whole of Japan, Iwatsubo et al [20] found that concentrations of Cl and Na in rainfall and runoff were significantly and negatively correlated to distance from the sea.…”

Evaporation from Pinus caribaea plantations on former grassland soils under maritime tropical conditions

“…Although the work in 1990-1991 was conducted during a period for which the rainfall distribution resembled the longterm average at Nabou [Waterloo, 1994], the simulations were carried out using climatic data collected at the more inland site of Tulasewa. Rainfall in southwestern Viti Levu shows a high interannual variation (864-2983 mm yr -• at Nadi) and increases with distance from the coast (from 1796 mm near the coast to 2113 mm at Tulasewa in 1990 [Waterloo et al, 1997]). The annual transpiration of the grass may vary considerably with rainfall and the length of the dry and wet seasons [Riou, 1984], as these particularly affect the magnitude of the LAI (Figure 8).…”