Estimating nitrate, dissolved organic carbon and DOC fractions in forest floor leachates using ultraviolet absorbance spectra and multivariate analysis

Fluxes of dissolved organic carbon (DOC) in forested watersheds underlain by permafrost are likely to vary with changes in climatic regime that increase soil moisture and temperature. We examined the effects of temporal and spatial variations in soil temperature and moisture on DOC fluxes from the forest floor of contrasting north- and south-facing slopes in central Siberia. DOC fluxes increased throughout the growing season (JuneSeptember) on both slopes in 2002 and 2003. The most favorable combination of moisture content and temperature (deepest active soil layer) occurred in September, and we believe this was the primary driver of increased DOC concentrations and flux in autumn. Total DOC flux for JuneSeptember was 12.617.6 g C·m2 on the south-facing slope and 4.68.9 g C·m2 on the north-facing slope. DOC concentrations in forest floor leachates increased with increasing temperature on the north-facing slope, but were almost unaffected by temperature on the south-facing slope. Our results suggest that water input in midseason from melting of ice or precipitation events is the primary factor limiting DOC production. Significant positive correlations between amounts of precipitation and DOC flux were found on both slopes. Dilution of DOC concentrations by high precipitation volumes was observed only for the forest floor leachates collected from the north-facing slope. Our results suggest that global warming will result in increased DOC production in forest floors of permafrost regions, and that precipitation patterns will play an important role in determining the magnitude of these changes in DOC flux as well as its interannual variability. However, the longer-term response of soils and DOC flux to a warming climate will be driven by changes in vegetation and microbial communities as well as by the direct results of temperature and moisture conditions.

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Dissolved organic carbon in forest floor leachates: simple degradation products or humic substances?

The Science of The Total Environment ◽

10.1016/0048-9697(94)90549-5 ◽

1994 ◽

Vol 152 (1) ◽

pp. 37-47 ◽

Cited By ~ 77

Author(s):

Georg Guggenberger ◽

Wolfgang Zech

Keyword(s):

Organic Carbon ◽

Dissolved Organic Carbon ◽

Humic Substances ◽

Forest Floor ◽

Degradation Products ◽

Forest Floor Leachates

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Minimization of the Disinfection by-Product Precursors in Treated Waters Exposed to Ozone and Chlorine

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.884-885.91 ◽

2014 ◽

Vol 884-885 ◽

pp. 91-95

Author(s):

Shang Chao Yue ◽

Le Jun Zhao ◽

Xiu Duo Wang ◽

Qi Shan Wang ◽

Feng Hua He

Keyword(s):

Drinking Water ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Water Supply ◽

River Water ◽

Water Samples ◽

Full Scale ◽

Ultraviolet Absorbance ◽

Treatment Processes ◽

Removal Efficiencies

The objectives of this study were to investigate impact of preoxidation on disinfection by-product (DBP) precursors in drinking water via two different preoxidation methods. The full-scale study was conducted on surface river water in a water supply plant in Tianjin, China. Two treatment trains were performed, with prechlorination and preozonation as preoxidation methods, respectively. The water samples were collected on different stages along the treatment processes and analyzed by following organic parameters: dissolved organic carbon (DOC), UV254 and specific ultraviolet absorbance (SUVA). The results indicated that Train 2 with preozonation was more effective to reduce DBP precursors. Preozonation possessed an excellent ability in the removal of UV254 and SUVA, the removal efficiencies were 25.14% and 18.77%, respectively, comparing to the removal rates of 6.66% and 5.64% during prechlorination, separately.

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