排序方式: 共有3条查询结果,搜索用时 0 毫秒
1
1.
G. Aldana M. Hernández S. Cram O. Arellano O. Morton 《Chemical Speciation and Bioavailability》2018,30(1):23-32
Trace metal species in the water column of a canal system forming a wetland filled with wastewater were analyzed to determine their correlation with metal accumulation in the gills of locally fished Oreochromis niloticus. The metal concentrations in the suspended particles and water dissolved were analyzed. The metal species were calculated using Windermere Humic Aqueous Model version VII showing that the high organic matter and major cation contents were important parameters. Also, the free ion metal concentration was expected to correlate with the organic matter aromaticity; however, organic compounds other than humic susbtances seem to be complexing the metals in the system. Additionally, no clear correlation could be found between metal accumulation in gills and any of the dissolved metal species. Nonetheless, certain trends could be seen between the calculated metal species and metal accumulation in the tilapia from the suspended particles. 相似文献
2.
Matthias Peichl Tim R. Moore M. Altaf Arain Mike Dalva David Brodkey Joshua McLaren 《Biogeochemistry》2007,86(1):1-17
We determined concentrations and fluxes of dissolved organic carbon (DOC) in precipitation, throughfall, forest floor and
mineral soil leachates from June 2004 to May 2006 across an age-sequence (2-, 15-, 30-, and 65-year-old) of white pine (Pinus strobus L.) forests in southern Ontario, Canada. Mean DOC concentration in precipitation, throughfall, leachates of forest floor,
Ah-horizon, and of mineral soil at 1 m depth ranged from ∼2 to 7, 9 to 18, 32 to 88, 20 to 66, and 2 to 3 mg DOC L−1, respectively, for all four stands from April (after snowmelt) through December. DOC concentration in forest floor leachates
was highest in early summer and positively correlated to stand age, aboveground biomass and forest floor carbon pools. DOC
fluxes via precipitation, throughfall, and leaching through forest floor and Ah-horizon between were in the range of ∼1 to
2, 2 to 4, 0.5 to 3.5, and 0.1 to 2 g DOC m−2, respectively. DOC export from the forest ecosystem during that period through infiltration and groundwater discharge was
estimated as ∼7, 4, 3, and 2 g DOC m−2 for the 2-, 15-, 30-, and 65-year-old sites, respectively, indicating a decrease with increasing stand age. Laboratory DOC
sorption studies showed that the null-point DOC concentration fell from values of 15 to 60 mg DOC L−1 at 0 to 5 cm to <15 mg DOC L−1 at 50 cm. Specific ultraviolet light absorption at 254 nm (SUVA254) increased from precipitation and throughfall to a maximum in forest floor and decreased with mineral soil depth. No age-related
pattern was observed for SUVA254 values. DOC concentration in forest floor soil solutions showed a positive exponential relationship with soil temperature,
and a negative exponential relationship with soil moisture at all four sites. Understanding the changes and controls of DOC
concentrations, chemistry, and fluxes at various stages of forest stand development is necessary to estimate and predict DOC
dynamics on a regional landscape level and to evaluate the effect of land-use change. 相似文献
3.
Impacts of drinking water pretreatments on the formation of nitrogenous disinfection by-products 总被引:5,自引:0,他引:5
The formation of disinfection by-products (DBPs), including both nitrogenous DBPs (N-DBPs) and carbonaceous DBPs (C-DBPs), was investigated by analyzing chlorinated water samples following the application of three pretreatment processes: (i) powdered activated carbon (PAC) adsorption; (ii) KMnO(4) oxidation and (iii) biological contact oxidation (BCO), coupled with conventional water treatment processes. PAC adsorption can remove effectively the precursors of chloroform (42.7%), dichloroacetonitrile (28.6%), dichloroacetamide (DCAcAm) (27.2%) and trichloronitromethane (35.7%), which were higher than that pretreated by KMnO(4) oxidation and/or BCO process. The removal efficiency of dissolved organic carbon by BCO process (76.5%)--was superior to that by PAC adsorption (69.9%) and KMnO(4) oxidation (61.4%). However, BCO increased the dissolved organic nitrogen (DON) concentration which caused more N-DBPs to be formed during subsequent chlorination. Soluble microbial products including numerous DON compounds were produced in the BCO process and were observed to play an essential role in the formation of DCAcAm in particular. 相似文献
1