Uptake of Cd,Pb, U,and Zn by plants in floodplain pollution hotspots contributes to secondary contamination

Environmental Science and Pollution Research - Willows, woody plants of genus Salix common in floodplains of temperate regions, act as plant pumps and translocate the Cd and Zn in the soil profiles...     

Interactions of sodium azide with triazine herbicides: effect on sorption to soils

Sodium azide (NaN(3)) is one of the biocides commonly used to inhibit microbial growth during sorption experiments. However, a few reports have suggested that NaN(3) can react with the analyte of interest. In this study, the interactions of NaN(3) with triazine herbicides were investigated and the effect of atrazine transformation on its sorption to soil was evaluated. The concentration of atrazine in the presence of NaN(3) decreased significantly over period of time. After 14 days, only 38% of the initial atrazine concentration (10 mg l(-1)) was detected in a solution containing 1,000 mg l(-1) NaN(3) at pH 5.5. The magnitude and the rate of atrazine transformation increased with increase in NaN(3) load and with decrease in pH. In contrast to atrazine behavior, the concentrations of prometon and ametryn did not change during the experiment. GC/MS analysis indicated that the chlorine atom of atrazine is replaced by the azide group yielding 2-azido-4-(ethylamino)-6-(isopropylamino)-s-triazine. Atrazine transformation by NaN(3) significantly affected sorption of herbicide to soil. The presence of NaN(3) affects indirectly the sorption of atrazine due to competitive effect of its derivative. Our results demonstrated that the application of NaN(3) as a biocide in sorption-desorption experiments must be carefully evaluated. This issue is vital for sorption experiments conducted over long periods of time or/and with concentration of NaN(3) higher than 100 mg l(-1).     

Synthesis of substituted cyclodextrins

Environmental Chemistry Letters - Cyclodextrins are naturally occurring, non-toxic and biodegradable cyclic oligosaccharides. The main feature of cyclodextrins is the ability to encapsulate...     

Long-term dynamics of biomass production, soil chemical properties and plant species composition of alluvial grassland after the cessation of fertilizer application in the Czech Republic

The resilience, the ability of an ecosystem to recover after termination of perturbation, of highly productive Alopecurus grassland was investigated after the cessation of the following long-term fertilizer treatments applied under a two- or three-cut management regime: unfertilized control, PK, N₁₀₀PK, N₂₀₀PK, N₃₀₀PK and N₄₀₀PK. Annual application rates of pure nutrients per hectare were 0–400 kg for N, 40 kg for P and 100 kg for K. The dynamics of biomass production were measured for 16 years and the effect of former fertilizer treatments on soil chemical properties, biomass chemical properties, plant species composition and species richness were investigated 16 years after the last application of fertilizers. It was concluded that 16 years was not long enough to achieve resilience in plant-available soil P and K concentrations, N/P ratios in the plant biomass or plant species composition, but that it was long enough to achieve resilience in species richness. In the case of biomass production the effect of former fertilizer treatments was apparent in 10 of the 16 seasons investigated, indicating that resilience in biomass production must be evaluated using data from more than 1 vegetation season. The results of the study stress the necessity for long-term research because of high year-to-year variability in biomass production as well as long-term after-effects of fertilizer treatments in alluvial grassland.     

Uniparental disomy in fetuses diagnosed with balanced Robertsonian translocations: risk estimate

Forty-two fetuses with non-homologous Robertsonian translocations were analyzed for uniparental disomy (UPD). One fetus with a de novo translocation t(13q;14q) had maternal isodisomy of chromosome 14. In a summary of the published data (including the present study), 315 cases were analyzed for UPD after prenatal diagnosis of balanced Robertsonian translocations, of these two fetuses had UPD, giving a risk estimate of 0.65% (CI 0.2–2.3). This risk justifies the recommendation of UPD analysis in fetuses diagnosed prenatally with Robertsonian translocations, with the emphasis on the chromosomes known to contain imprinted genes, such as 14 and 15. We also discuss the possibility of UPD in offspring of Robertsonian translocation carriers with normal karyotype. Based on the risk for UPD in fetuses with Robertsonian translocation we suggest to test these fetuses for UPD and to do so on amniocytes rather than chorionic villi when the risk for unbalanced karyotype is ∼1%, comparable to the risk for UPD. Copyright © 2002 John Wiley & Sons, Ltd.     

Mesoscale meteorological modelling for Hong Kong-application of the MC2 model

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Carbon exchange between ecosystems and atmosphere in the Czech Republic is affected by climate factors

By comparing five ecosystem types in the Czech Republic over several years, we recorded the highest carbon sequestration potential in an evergreen Norway spruce forest (100%) and an agroecosystem (65%), followed by European beech forest (25%) and a wetland ecosystem (20%). Because of a massive ecosystem respiration, the final carbon gain of the grassland was negative. Climate was shown to be an important factor of carbon uptake by ecosystems: by varying the growing season length (a 22-d longer season in 2005 than in 2007 increased carbon sink by 13%) or by the effect of short- term synoptic situations (e.g. summer hot and dry days reduced net carbon storage by 58% relative to hot and wet days). Carbon uptake is strongly affected by the ontogeny and a production strategy which is demonstrated by the comparison of seasonal course of carbon uptake between coniferous (Norway spruce) and deciduous (European beech) stands.