 |
| Titel |
Nutrient dynamics in tropical rivers, lagoons, and coastal ecosystems of eastern Hainan Island, South China Sea |
| VerfasserIn |
R. H. Li, S. M. Liu, Y. W. Li, G. L. Zhang, J. L. Ren, J. Zhang |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 2 ; Nr. 11, no. 2 (2014-01-30), S.481-506 |
| Datensatznummer |
250117155
|
| Publikation (Nr.) |
 copernicus.org/bg-11-481-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| Nutrient dynamics based on field observations made along the eastern Hainan
Island during the period 2006–2009 were investigated to understand nutrient
biogeochemical processes, and to provide an overview of human perturbations
of coastal ecosystems in this tropical region. The rivers showed seasonal
variations in nutrient concentrations, with enrichment of dissolved inorganic
nitrogen and dissolved silicate, and depletion of PO43−. High
riverine concentrations of nitrate mainly originated from agricultural
fertilizer inputs. The DIN : PO43− ratios ranged from 37 to 1063,
suggesting preferential depletion of PO43− relative to nitrogen in
rivers. Chemical weathering in the drainage area might explain the high
levels of dissolved silicate. Aquaculture ponds contained high concentrations
of NH4+ and dissolved organic nitrogen. The particulate phosphorus
concentrations in the study area were lower than those reported for estuaries
worldwide. The particulate silicate levels in rivers and lagoons were
lower than the global average level. Nutrient biogeochemistry in coastal
areas was affected by human activities (e.g., aquaculture, agriculture), and
by natural phenomena including typhoons. The nutrient concentrations in
coastal waters were low because of dispersion of land-derived nutrients in
the sea. Nutrient budgets were built based on a steady-state box model, which
showed that riverine fluxes are magnified by estuarine processes (e.g.,
regeneration, desorption) in estuaries and Laoyehai Lagoon, but not in
Xiaohai Lagoon. Riverine and groundwater inputs were the major sources of
nutrients to Xiaohai and Laoyehai lagoons, respectively, and riverine inputs
and aquaculture effluents were the major sources for the eastern coast of
Hainan Island. Nutrient inputs to the coastal ecosystem increased with
typhoon-induced runoff of rainwater, elucidating the important influence of
typhoons
on small tropical rivers. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|