ABSTRACT:Arsenic is a ubiquitous element in the environment and occurs naturally in both organic and inorganic forms. Under aerobic condition, the dominant form of arsenic in waters is arsenate, which is highly mobile and toxic. Arsenic poisoning from drinking water remains a serious world health issue. There are various standard methods for arsenic removal from drinking waters (coagulation, sorption, ion-exchange reactions or methods of reverse osmosis) and alternative methods, such as biosorption. Biosorption of arsenic from natural and model waters by native or chemically modified (with urea or ferric oxyhydroxides) plant biomass prepared from sawdust of Picea abies was studied. The kinetic of the adsorption process fitted well the pseudo second order adsorption model and equilibrium was achieved after 2 h. The results showed that biosorption was well described by both Langmuir and Freundlich isotherms. The maximum biosorption capacity of the sawdust modified with ferric oxyhydroxides, evaluated by Langmuir adsorption model, was 9.259 mg/g, while the biosorption capacity of unmodified biosorbent or biosorbent modified with urea was negligible. The adsorption capacity is comparable to results published by other authors, suggesting that the prepared chemically modified biosorbent has potential in remediation of contaminated waters.
The quantification of arsenic biovolatilization by microscopic filamentous fungi Aspergillus clavatus, A. niger, Trichoderma viride and Penicillium glabrum under laboratory conditions is discussed in this article. The fungi were cultivated on a liquid medium enriched with inorganic arsenic in pentavalent form (H 3 AsO 4 ). Filamentous fungi volatilized 0.010 mg to 0.067 mg and 0.093 mg to 0.262 mg of arsenic from cultivation systems enriched with 0.25 mg (5 mg.l −1 of arsenic in culture media) and 1.00 mg of arsenic (20 mg.l −1 of arsenic in culture media), respectively. These results represent the loss of arsenic after a 30-day cultivation from cultivation systems. The production of volatile arsenic derivatives by the A. niger and A. clavatus strains was also determined by hourly sorption using the sorbent Anasorb (CSC) on the 29th day of cultivation.
A strong windstorm in November 2004 resulted in a huge blown-down spruce forest area in the southern part of the Tatra National Park in the Western Carpathians in Slovakia, Central Europe. The aim of this work is to study the vegetation composition of spruce forest at differently managed sites four years after this disturbance. Four study areas were selected for this purpose: (i) an area where the fallen trees were extracted and new seedlings were planted; (ii) an area, which was hit by a forest fire after the extraction; (iii) an area where no active management was applied; (iv) a reference forest unaffected by such disturbance. A total of 100 plots were selected, 25 of each area type. The result of DCA and CCA analyses consistently indicated that after this short period the non-extracted and extracted areas are currently most similar to the reference forest area, while the fire affected area differed. A one-way ANOVA comparing species cover for the different plot sizes indicated some significant differences between the extracted and non-extracted plots. The abundance of certain species commonly occurring in spruce forests, such as Dyopteris carthusiana agg., Vaccinium myrtillus and Avenella flexuosa, correlated weli with the non-extracted plots, compared to the extracted plots. Coverage of these species was lowest on burned plots. The lowest Shannon-Wiener’s diversity values were recorded in burned plots. This was most likely a consequence of mono-dominant competitive species spread, (mainly Chamerion angustifolium) which profited from the altered ecological conditions following the fire. Although some differences were also registered in the Shannon-Wiener diversity index between the remaining research plots, however these were not statistically significant. The most important results of our investigations include the extensive influence of fire disturbance on vegetation. Study revealed that the wind-disturbed area is able to regenerate sufficiently without human intervention
Arsenic removal from aqueous solutions by biomass of two fungal strains, Aspergillus niger and Neosartorya fischeri, was assessed. The biosorption capacity of fungal biomass was studied within the As(V) concentration range of approximately 0.2 to 5.0 mg L(-1) at two different pH values (pH 5 and 7). With increasing initial arsenic concentration, the biosorption capacity of both fungal strains increased almost linearly and achieved the sorption capacity of 0.317 and 0.124 mg g(-1) for biomass of N. fischeri and A. niger, respectively. The effect of biomass treatment with FeCl3 and HCI on As(III) and As(V) uptake was also studied. The optimum biosorption pH as well as the effect ofbiomass treatment was found to be dependent on the fungal strain used. Treatment with FeCl3 and HCl did not result in any significant increase in arsenic uptake. To the contrary, treatment with ferric oxyhydroxide was found to be very effective and virtually 100% of the arsenic was removed from the samples of contaminated natural water.
The biosorption of cadmium and arsenic from aqueous solutions onto the unmodified compact biomass of microscopic filamentous fungus Aspergillus clavatus DESM. was studied in the concentration range of 0.25 -100 mg.l -1 . The experimental biosorption results for arsenic and cadmium followed well the Freundlich equilibrium sorption model.
The use of pesticides in agricultural practices raises concerns considering the toxic effects they generate in the environment; thus, their sustainable application in crop production remains a challenge. One of the frequently addressed issues regarding their application includes the development of a sustainable and ecofriendly approach for their degradation. Since the filamentous fungi can bioremediate various xenobiotics owing to their efficient and versatile enzymatic machinery, this review has addressed their performance in the biodegradation of organochlorine and organophosphorus pesticides. It is focused particularly on fungal strains belonging to the genera Aspergillus and Penicillium, since both are ubiquitous in the environment, and often abundant in soils contaminated with xenobiotics. Most of the recent reviews on microbial biodegradation of pesticides focus primarily on bacteria, and the soil filamentous fungi are mentioned only marginally there. Therefore, in this review, we have attempted to demonstrate and highlight the exceptional potential of aspergilli and penicillia in degrading the organochlorine and organophosphorus pesticides (e.g., endosulfan, lindane, chlorpyrifos, and methyl parathion). These biologically active xenobiotics have been degraded by fungi into various metabolites efficaciously, or these are completely mineralized within a few days. Since they have demonstrated high rates of degradation activity, as well as high tolerance to pesticides, most of the Aspergillus and Penicillium species strains listed in this review are excellent candidates for the remediation of pesticide-contaminated soils.
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