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1.
PLoS One ; 15(6): e0228364, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32484823

RESUMO

Nitrogen transformation in soil is a complex process and the soil microbial population can regulate the potential for N mineralization, nitrification and denitrification. Here we show that agricultural soils under standard agricultural N-management are consistently characterized by a high presence of gene copies for some of the key biological activities related to the N-cycle. This led to a strong NO3- reduction (75%) passing from the soil surface (15.38 ± 11.36 g N-NO3 kg-1 on average) to the 1 m deep layer (3.92 ± 4.42 g N-NO3 kg-1 on average), and ensured low nitrate presence in the deepest layer. Under these circumstances the other soil properties play a minor role in reducing soil nitrate presence in soil. However, with excessive N fertilization, the abundance of bacterial gene copies is not sufficient to explain N leaching in soil and other factors, i.e. soil texture and rainfall, become more important in controlling these aspects.


Assuntos
Amônia/análise , Fertilizantes , Regulação da Expressão Gênica/efeitos dos fármacos , Minerais/farmacologia , Nitratos/análise , Ciclo do Nitrogênio/genética , Solo/química , Dosagem de Genes/efeitos dos fármacos , Ciclo do Nitrogênio/efeitos dos fármacos
2.
Sci Total Environ ; 526: 116-26, 2015 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-25925189

RESUMO

Mesophilic anaerobic digestion (MAD) produces renewable energy, but it also plays a role in reducing the impact of digestates, both by reducing odor and pathogen content. Ten full-scale biogas plants characterized by different plant designs (e.g. single digesters, parallel or serial digesters), plant powers (ranging from 180 to 999 kWe), hydraulic retention time (HRT) (ranging between 20 to 70 days) and feed mixes were monitored and odors and pathogens were observed in both ingestates and digestates. Results obtained indicated that MAD reduced odors (OU) from, on average, OUingestate=99,106±149,173 OU m(-2) h(-1) (n=15) to OU digestate=1106±771 OU m(-2) h(-1) (n=15). Pathogens were also reduced during MAD both because of ammonia production during the process and competition for substrate between pathogens and indigenous microflora, i.e. Enterobacteriaceae from 6.85∗10(3)±1.8∗10(1) to 1.82∗10(1)±3.82∗10(1); fecal Coliform from 1.82∗10(4)±9.09 to 2.45∗10(1)±3.8∗10(1); Escherichia coli from 8.72∗10(3)±2.4∗10(1) to 1.8∗10(1)±2.94∗10(1); Clostridium perfringens from 6.4∗10(4)±7.7 to 5.2∗10(3)±8.1 (all data are expressed as CFU g(-1) ww). Plants showed different abilities to reduce pathogen indicators, depending on the pH value and toxic ammonia content.


Assuntos
Poluição do Ar/prevenção & controle , Odorantes/análise , Esgotos/microbiologia , Eliminação de Resíduos Líquidos/métodos , Poluição do Ar/análise , Anaerobiose , Biocombustíveis , Fenômenos Biológicos , Reatores Biológicos , Temperatura
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