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DRAGANA MUTAVDŽIĆ IVAN BRNARDIĆ MARIJA KAŠTELAN-MACAN 《Journal of environmental science and health. Part. B》2013,48(7):1085-1101
The purpose of this investigation was to determine the influence of humic acids (HA) and Ca-montmorillonite (CaM) on the solid-phase extraction (SPE) efficiency of atrazine, alachlor and α-cypermethrin from water samples at various pH-values. The nature and intensity of binding of the studied pesticides to CaM were determined by X-ray diffraction analysis and termogravimetric analysis (TGA) test. The studied pesticides eluted from discs were analysed by thin-layer chromatography (TLC). The effects of CaM and humic acid were generally pH-dependent and acted independently in extraction efficiency influence. Lower recovery of pesticides was observed at higher pH values when CaM was ≥0.1 g and was attributed to greater dispersion of clay, increased surface area and subsequent adsorption. Concentrations of dissolved organic carbon (DOC) in humic acid had less effect on the extraction efficiency when water was at pH 8 compared to water at pH 2, which was probably due to greater nonpolar interactions of the pesticides to the charge-neutralized humic acid molecule. 相似文献
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Stohlgren TJ Chong GW Schell LD Rimar KA Otsuki Y Lee M Kalkhan MA Villa CA 《Environmental management》2002,29(4):566-577
Basic information on where nonnative plant species have successfully invaded is lacking. We assessed the vulnerability of
22 vegetation types (25 sets of four plots in nine study areas) to nonnative plant invasions in the north–central United States.
In general, habitats with high native species richness were more heavily invaded than species-poor habitats, low-elevation
areas were more invaded than high-elevation areas, and riparian zones were more invaded than nearby upland sites. For the
100 1000-m2 plots (across all vegetation types), 50% of the variation in nonnative species richness was explained by longitude, latitude,
native plant species richness, soil total percentage nitrogen, and mean maximum July temperature (n = 100 plots; P < 0.001). At the vegetation-type scale (n = 25 sets of four 1000-m2 plots/type), 64% of the variation in nonnative species richness was explained by native plant species richness, elevation,
and October to June precipitation (P < 0.001). The foliar cover of nonnative species (log) was strongly positively correlated with the nonnative species richness at the
plot scale (r = 0.77, P < 0.001) and vegetation-type scale (r = 0.83, P < 0.001). We concluded that, at the vegetation-type and regional scales in the north–central United States, (1) vegetation types
rich in native species are often highly vulnerable to invasion by nonnative plant species; (2) where several nonnative species
become established, nonnative species cover can substantially increase; (3) the attributes that maintain high native plant
species richness (high light, water, nitrogen, and temperatures) also help maintain nonnative plant species richness; and
(4) more care must be taken to preserve native species diversity in highly vulnerable habitats. 相似文献
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