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Stream dissolved organic matter bioavailability and composition in watersheds underlain with discontinuous permafrost 总被引:1,自引:0,他引:1
Kelly L. Balcarczyk Jeremy B. JonesJr. Rudolf Jaffé Nagamitsu Maie 《Biogeochemistry》2009,94(3):255-270
We examined the impact of permafrost on dissolved organic matter (DOM) composition in Caribou-Poker Creeks Research Watershed
(CPCRW), a watershed underlain with discontinuous permafrost, in interior Alaska. We analyzed long term data from watersheds
underlain with varying degrees of permafrost, sampled springs and thermokarsts, used fluorescence spectroscopy, and measured
the bioavailabity of dissolved organic carbon (DOC). Permafrost driven patterns in hydrology and vegetation influenced DOM
patterns in streams, with the stream draining the high permafrost watershed having higher DOC and dissolved organic nitrogen
(DON) concentrations, higher DOC:DON and greater specific ultraviolet absorbance (SUVA) than the streams draining the low
and medium permafrost watersheds. Streams, springs and thermokarsts exhibited a wide range of DOC and DON concentrations (1.5–37.5 mgC/L
and 0.14–1.26 mgN/L, respectively), DOC:DON (7.1–42.8) and SUVA (1.5–4.7 L mgC−1 m−1). All sites had a high proportion of humic components, a low proportion of protein components, and a low fluorescence index
value (1.3–1.4), generally consistent with terrestrially derived DOM. Principal component analysis revealed distinct groups
in our fluorescence data determined by diagenetic processing and DOM source. The proportion of bioavailable DOC ranged from
2 to 35%, with the proportion of tyrosine- and tryptophan-like fluorophores in the DOM being a major predictor of DOC loss
(p < 0.05, R
2 = 0.99). Our results indicate that the degradation of permafrost in CPCRW will result in a decrease in DOC and DON concentrations,
a decline in DOC:DON, and a reduction in SUVA, possibly accompanied by a change in the proportion of bioavailable DOC. 相似文献
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Sebastian Wetterich Ulrike Herzschuh Hanno Meyer Lyudmila Pestryakova Birgit Plessen C. M. Larry Lopez Lutz Schirrmeister 《Hydrobiologia》2008,614(1):171-195
Taxonomical and geochemical investigations on freshwater ostracods from 15 waters in Central and Northeast (NE) Yakutia have
been undertaken in order to estimate their potential usefulness in palaeoenvironmental reconstructions based on regional fossil
records. Higher variability in environmental factors such as pH, electrical conductivity, and ionic content was observed in
thermokarst-affected lakes in Central Yakutia than in NE Yakutia lakes. Species diversity of freshwater ostracods reached
up to eight taxa per lake, mostly dominated by Candona weltneri Hartwig 1899, in Central Yakutia, whereas in NE Yakutian waters the diversity was lower and Candona muelleri jakutica Pietrzeniuk 1977 or Fabaeformiscandona inaequivalvis (Sars 1898) had highest frequencies. Coupled analyses of stable isotopes (δ18O, δ13C) and element ratios (Sr/Ca, Mg/Ca) were performed on both host waters and ostracod calcite, aiming to estimate the modern
relationships. Correlations between host waters and ostracod calcite of single species were found for δ18O, δ13C and Sr/Ca and Mg/Ca ratios. The relationships between δ18O, Mg/Ca and Sr/Ca ratios and electrical conductivity (salinity) as an expression of solute concentrations in the waters mainly
controlled by evaporation are more complicated but evident, and may be useful in future interpretation of geochemical data
from fossil Siberian ostracods.
Handling editor: K. Martens 相似文献
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