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Identifying sources of nitrogen to Hanalei Bay, Kauai, utilizing the nitrogen isotope signature of macroalgae

Environmental Science and Technology

By:
, , , , , and
DOI: 10.1021/es0700449

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Abstract

Sewage effluent, storm runoff, discharge from polluted rivers, and inputs of groundwater have all been suggested as potential sources of land derived nutrients into Hanalei Bay, Kauai. We determined the nitrogen isotopic signatures (??15N) of different nitrate sources to Hanalei Bay along with the isotopic signature recorded by 11 species of macroalgal collected in the Bay. The macroalgae integrate the isotopic signatures of the nitrate sources over time, thus these data along with the nitrate to dissolved inorganic phosphate molar ratios (N:P) of the macroalgae were used to determine the major nitrate source to the bay ecosystem and which of the macro-nutrients is limiting algae growth, respectively. Relatively low ??15N values (average -0.5???) were observed in all algae collected throughout the Bay; implicating fertilizer, rather than domestic sewage, as an important external source of nitrogen to the coastal water around Hanalei. The N:P ratio in the algae compared to the ratio in the Bay waters imply that the Hanalei Bay coastal ecosystem is nitrogen limited and thus, increased nitrogen input may potentially impactthis coastal ecosystem and specifically the coral reefs in the Bay. Identifying the major source of nutrient loading to the Bay is important for risk assessment and potential remediation plans. ?? 2007 American Chemical Society.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Identifying sources of nitrogen to Hanalei Bay, Kauai, utilizing the nitrogen isotope signature of macroalgae
Series title:
Environmental Science and Technology
DOI:
10.1021/es0700449
Volume
41
Issue:
15
Year Published:
2007
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Environmental Science and Technology
First page:
5217
Last page:
5223