Fluvial fluxes of water, suspended particulate matter, and nutrients and potential impacts on tropical coastal water Biogeochemistry: Oahu, Hawai‘i

Hoover, D. J.; MacKenzie, F. T.

Abstract:

Baseflow and storm runoff fluxes of water, suspended particulate matter (SPM), and nutrients (N and P) were assessed in conservation, urban, and agricultural streams discharging to coastal waters around the tropical island of Oahu, Hawai‘i. Despite unusually low storm frequency and intensity during the study, storms accounted for 8-77% (median 30%) of discharge, 57-99% (median 93%) of SPM fluxes, 11-79% (median 36%) of dissolved nutrient fluxes and 52-99% (median 85%) of particulate nutrient fluxes to coastal waters. Fluvial nutrient concentrations varied with hydrologic conditions and land use; land use also affected water and particulate fluxes at some sites. Reactive dissolved N:P ratios typically were ???16 (the ‘Redfield ratio‘ for marine phytoplankton), indicating that inputs could support new production by coastal phytoplankton, but uptake of dissolved nutrients is probably inefficient due to rapid dilution and export of fluvial dissolved inputs. Particulate N and P fluxes were similar to or larger than dissolved fluxes at all sites (median 49% of total nitrogen, range 22-82%; median 69% of total phosphorus, range 49-93%). Impacts of particulate nutrients on coastal ecosystems will depend on how efficiently SPM is retained in nearshore areas, and on the timing and degree of transformation to reactive dissolved forms. Nevertheless, the magnitude of particulate nutrient fluxes suggests that they represent a significant nutrient source for many coastal ecosystems over relatively long time scales (weeks-years), and that reductions in particulate nutrient loading actually may have negative impacts on some coastal ecosystems.

Genre:

Article

ProdID:

70037129

Citation Author:

Hoover, D. J.; MacKenzie, F. T.

Citation Contributing Office:

Citation Datum:

Citation Day:

Citation Edition:

Citation Editor:

Citation End Page:

570

Citation Issue:

Citation Keywords:

Citation Language:

English

Citation Larger Work Title:

Aquatic Geochemistry

Citation LatN:

Citation LatS:

Citation LonE:

Citation LonW:

Citation Month:

Citation No Pagination:

Citation Number Of Pages:

Citation Online Only Flag:

Citation Phsyical Description:

Citation Projection:

Citation Public Comments:

Citation Publisher:

Citation Series:

Citation Series Code:

Citation Series Number:

Citation Search Results Text:

Fluvial fluxes of water, suspended particulate matter, and nutrients and potential impacts on tropical coastal water Biogeochemistry: Oahu, Hawai‘i; 2009; Article; Journal; Aquatic Geochemistry; Hoover, D. J.; MacKenzie, F. T.