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1.
Environ Monit Assess ; 186(6): 3743-53, 2014 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-24504670

RESUMO

There is worldwide concern over the increase use of nanoparticles (NPs) and their ecotoxicological effect. It is not known if the annual production of tons of industrial nanoparticles (NPs) has the potential to impact terrestrial microbial communities, which are so necessary for ecosystem functioning. Here, we have examined the consequences of adding the NPs particularly the metal oxide (CuO, ZnO) on CH4 oxidation activity in vertisol and the abundance of heterotrophs, methane oxidizers, and ammonium oxidizers. Soil samples collected from the agricultural field located at Madhya Pradesh, India, were incubated with either CuO and ZnO NPs or ionic heavy metals (CuCl2, ZnCl2) separately at 0, 10, and 20 µg g(-1) soil. CH4 oxidation activity in the soil samples was estimated at 60 and 100 % moisture holding capacity (MHC) in order to link soil moisture regime with impact of NPs. NPs amended to soil were highly toxic for the microbial-mediated CH4 oxidation, compared with the ionic form. The trend of inhibition was Zn 20 > Zn 10 > Cu 20 > Cu 10. NPs delayed the lag phase of CH4 oxidation to a maximum of 4-fold and also decreased the apparent rate constant k up to 50 % over control. ANOVA and Pearson correlation analysis (α = 0.01) revealed significant impact of NPs on the CH4 oxidation activity and microbial abundance (p < 0.0001, and high F statistics). Principal component analysis (PCA) revealed that PC1 (metal concentration) rendered 76.06 % of the total variance, while 18.17 % of variance accounted by second component (MHC). Biplot indicated negative impact of NPs on CH4 oxidation and microbial abundance. Our result also confirmed that higher soil moisture regime alleviates toxicity of NPs and opens new avenues of research to manage ecotoxicity and environmental hazard of NPs.


Assuntos
Cobre/química , Metano/análise , Nanopartículas/química , Poluentes do Solo/química , Solo/química , Óxido de Zinco/química , Agricultura , Cobre/análise , Índia , Metano/química , Nanopartículas/análise , Oxirredução , Poluentes do Solo/análise , Óxido de Zinco/análise
2.
Bioresour Technol ; 98(7): 1474-81, 2007 May.
Artigo em Inglês | MEDLINE | ID: mdl-17067794

RESUMO

Integrated use of inorganic fertilizer N and well decomposed cattle manure (CM) or 30-35 days old Parthenium (Parthenium hysterophorus L.), a weed grown off site as green manure (GM) under repeated applications of fertilizer P and urea N for eight years in a rice (Oriza sativa L.)-wheat (Triticum estivum L.) sequence was studied on transformation of fertilizer P applied to soil at the National Research Center for Weed Science, Jabalpur, India. Based on the results, it appeared that, repeated applications of 52 kg super-phosphate P resulted in a marked increase in Olsen P linearly with time. Conjunctive use of urea fertilizer N with organic manure resulted in a larger increase in Olsen P in the Vertisol. Studies further revealed that the greater accumulation of fertilizer P applied in excess to crop removal occurred in inorganic P in the plots receiving only fertilizer N. However, plots receiving fertilizer N along with organic manures led to P accumulation predominantly in organic forms. The study suggests that these two pools of P acted as a sink when fertilizer P was applied in excess to crop removal and are bio-chemically active. The Olsen P status after 8 cycles of rice-wheat crops revealed that the average amount of fertilizer P required after adjusting for crop uptake to increase Olsen P by 1 mg kg(-1) soil was 7.2 kg Pha(-1) in the plots receiving only fertilizer N. Whereas, application of 5t FYM or 6t GM reduced it to 4.6 kg Pha(-1). The plots receiving manure always maintained a greater concentration of Olsen P. The application of CM or GM with fertilizer N enriched short-term inorganic P as well as long-term organic P fertility. After eight years, larger concentrations of organic P in the subsurface layer (16-30 cm), compared to initial values, indicates downward movement of P in organic forms.


Assuntos
Agricultura/métodos , Oryza/metabolismo , Fósforo/farmacocinética , Triticum/metabolismo , Asteraceae , Disponibilidade Biológica , Fertilizantes , Índia , Esterco , Nitrogênio , Solo/análise , Fatores de Tempo
3.
Bioresour Technol ; 87(3): 279-88, 2003 May.
Artigo em Inglês | MEDLINE | ID: mdl-12507868

RESUMO

Laboratory pot experiments were run to study the effects of added zinc (Zn) with and without farmyard manure (FYM) and phosphorus (P) on Zn transformations in two Alfisols, together with Zn uptake by wheat plants grown up to 60 days. In the first experiment the treatments included four levels of Zn (0, 3.75, 7.5 and 15 mgkg(-1) soil) and two levels of FYM (0 and 10 tha(-1)), and in the second experiment five levels of P (0, 20, 40, 80 and 160 mgkg(-1) soil) and one level of Zn (7.5 mgkg(-1) soil). The soils were sequentially fractionated into water-soluble plus exchangeable (CA-Zn), inorganically bound (AAC-Zn), organically bound (PYR-Zn), oxide bound (OX-Zn) and residual (RES-Zn) forms. The effect of added FYM was more evident on the OX-Zn fraction and the percentage utilization of Zn by wheat was the greatest with the addition of FYM alone at the rate of 10 tha(-1) (1.95-2.38%) in comparison to other treatment combinations. Among the levels, application of 7.5 mg Zn kg(-1) soil showed the maximum increase in different fractions of soil Zn and significantly increased the Zn utilization by wheat (0.87-1.17%) as compared to other Zn levels (0.58-0.88%). On an average, about 85% of the added Zn was recovered in different fractions in Zn treated pots. However, the recovery per cent of the added Zn was significantly higher at Zn level 7.5 (95%) mgkg(-1) soil than at 3.75 (87%) and 15 (73%) mg Zn kg(-1) soil levels. Phosphorus additions up to 40 mgkg(-1) soil increased the plant-available Zn in soils whereas at higher P levels plant-available forms decreased with a concominant increase in the inert forms. At 160 mg P kg(-1) soil, the P effect was more pronounced in the shoot than in the root, suggesting that a higher P level inhibits Zn translocation from root to upper plant parts. Path analysis showed that the organically (PYR-Zn) and inorganically bound (AAC-Zn) Zn fractions were the predominant fractions that influenced the Zn availability to plants.


Assuntos
Esterco , Fósforo/química , Poluentes do Solo/metabolismo , Zinco/metabolismo , Disponibilidade Biológica , Biotransformação , Raízes de Plantas , Triticum/química , Zinco/química
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