In:
Limnology and Oceanography, Wiley, Vol. 49, No. 5 ( 2004-09), p. 1503-1511
Abstract:
Anthropogenic nitrogen (N) often causes coastal eutrophication, yet little is known about the fate and retention of effluent N in coastal waters and, hence, about the system’s ability to assimilate excess N loads. We used the spatial distribution of stable N isotope ratios and algal pigments in sedimentary organic matter from a Baltic bay receiving tertiary‐treated effluent to evaluate the extent of effects and the role of nearshore marine environments as sinks of anthropogenic N. Surface sediments (0–2 cm and 2–4 cm) exhibited a pronounced spatial gradient of δ 15 N, with the most elevated values (~8‰) near the outfall; values decreased linearly to values of ;4‰ outside the bay. Sedimentary pigment concentrations were consistent with water‐column data and showed that phytoplankton biomass was elevated in the inner reaches of the bay. In particular, diatoms were heavily labeled (δ 15 N ~ 10‰), reached maximum abundance near the effluent outfall, and were likely the main mechanism delivering effluent N to the sediments. Sediments within the bay removed ~5–11% of wastewater N inputs, with 50% of the sequestered effluent N buried in the basin nearest to the outfall. Magnitudes of N removal by sediments (23–26 x 10 4 kg N yr −1 ) were less than those estimated for denitrification (30–60 x 10 4 kg N yr −1 ), but they were substantially greater than biological uptake by macroalgae (~2 x 10 4 kg N yr −1 ). Taken together, these patterns demonstrate the idea that coastal sediments can be effective sinks of wastewater N, even after 30 yr of effluent input.
Type of Medium:
Online Resource
ISSN:
0024-3590
,
1939-5590
DOI:
10.4319/lo.2004.49.5.1503
Language:
English
Publisher:
Wiley
Publication Date:
2004
detail.hit.zdb_id:
2033191-5
detail.hit.zdb_id:
412737-7
SSG:
12
SSG:
14
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