Renato de Aragão Ribeiro Rodrigues

EMISSÕES DE ÓXIDO NITROSO E METANO DO SOLO EM ÁREAS DE RECUPERAÇÃO DE PASTAGENS NA AMAZÔNIA MATOGROSSENSE

This study evaluates the chemical processes responsible for the nitrous oxide (N2O) and methane (CH4) fluxes in the managed pasture (PM) and unmanaged pasture (PNM). In addition, the impact of nitrogen fertilization on the N2O and CH4 fluxes was assessed. The experiments were conducted on three farms in Alta Floresta city in the state of Mato Grosso. Both regular and intensive samples were collected from PM, PNM, and forest areas for each of the properties. The gases were sampled using static chambers in the morning. Higher N2O fluxes were recorded in the PMs, whereas the CH4 fluxes showed no influence of nitrogen fertilization in both regular and intensive samples. Low fertilizer levels resulted in low N2O emissions.

Fluxos de óxido nitroso em solos com cobertura de Floresta Ombrófila Densa Montana na Serra dos Órgãos, Rio de Janeiro

Soil fluxes of N2O were determined over one year in montane tropical rainforest of southeastern Brazil with average annual rainfall of 2.8 m. Annual mean (± standard deviation) and median N2O fluxes were 3.0 ± 1.4 and 2.7 µg N m-2 h-1, respectively, is 5-10 times lower than mean values reported in literature for tropical rainforest soils in the Amazon basin. N2O fluxes varied spatially and seasonally, were about twice as high during summer as in winter, and significantly influenced by both monthly precipitation and soil temperature.

Short-term effect of Eucalyptus plantations on soil microbial communities and soil-atmosphere methane and nitrous oxide exchange

Soil greenhouse gas (GHG) emissions are a significant environmental problem resulting from microbially-mediated nitrogen (N) and carbon (C) cycling. This study aimed to investigate the impact of Eucalyptus plantations on the structure and function of a soil microbial community, and how resulting alterations may be linked to GHG fluxes. We sampled and monitored two adjacent Eucalyptus plantations—a recently logged site that harbored new seedlings and an adult plantation—and compared them to a site hosting native vegetation. We used 16S rRNA gene sequencing and qPCR amplifications of key nitrogen and methane cycle genes to characterize microbial structure and functional gene abundance and compared our data with soil parameters and GHG fluxes. Both microbial community attributes were significantly affected by land use and logging of Eucalyptus plantations. The genes nosZ and archaeal amoA were significantly more abundant in native forest than in either young or old Eucalyptus plantations. Statistical analyses suggest that land use type has a greater impact on microbial community structure and functional gene abundance than Eucalyptus rotation. There was no correlation between GHG fluxes and shifts in microbial community, suggesting that microbial community structure and functional gene abundance are not the main drivers of GHG fluxes in this system.

Deposições atmosféricas úmida, seca e total de nitrogênio inorgânico dissolvido no Estado do Rio de Janeiro.

As entradas atmosfericas de nitrogenio reativo (Nr) nos ecossistemas terrestres tem aumentado drasticamente nas ultimas cinco decadas em decorrencia das atividades humanas. As deposicoes atmosfericas desempenham importante papel na remocao de Nr atmosferico e representa uma ferramenta util para o acesso ao nivel de poluicao do ar. A presente revisao discute o aporte atmosferico do nitrogenio inorgânico (NH4 + + NO3 -) no estado do Rio Janeiro (RJ), assim como suas principais fontes antropicas. Os fluxos de deposicao total de nitrogenio inorgânico amostrados com coletores automaticos de deposicao umida (chuva) e seca (particulas sedimentaveis) e com coletores de deposicao total foram compilados de estudos realizados em areas oceânicas (n = 2), costeiras urbanas (n = 2) e de Floresta Atlântica montana (n = 7) no estado do RJ. Os fluxos de deposicao do nitrogenio inorgânico variaram de 4,3 a 17 kg N ha-1 ano-1, com os menores valores encontrados no macico do Itatiaia e na Ilha Grande (4,3 e 4,6 kg N ha-1 ano-1, respectivamente) e os maiores na Serra dos Orgaos (8,2-17 kg N ha-1 ano-1). A deposicao umida representou a principal via de remocao de nitrogenio inorgânico da atmosfera, compreendendo 83-94% do NH4 + e 57-95% do NO3 - depositados. Este trabalho e de grande relevância para o entendimento dos padroes de deposicao atmosferica do nitrogenio inorgânico no RJ.

STRUCTURAL LEAF CHANGES IN TREES AROUND A SUBWAY AIR DUCT

Varios artigos vem mostrando que os sistemas de metro causam impactos na qualidade do ar, atraves da emissao de material particulado. No entanto, nao ha informacoes disponiveis sobre o efeito desse impacto na vegetacao. Folhas de arvores de tres especies diferentes localizadas do lado da saida de dutos de um metro no Rio de Janeiro, Brasil, se mostraram mais assimetricas do que as de arvores localizadas do lado da entrada. Essas folhas tambem apresentaram alteracoes na camada de cera epicuticular e no conteudo de clorofila.