Implications of sugarcane straw removal for soil greenhouse gas emissions in Sao Paulo State, Brazil

The use of sugarcane straw is a promising option to enhance bioenergy production. But the implications of straw removal for soil greenhouse gas (GHG) emission are not yet fully understood due to scarcity of studies under Brazilian conditions. Four field experiments were designed to assess soil N2O and CH4 emissions derived from nitrogen (N) fertilization under scenarios of sugarcane straw removal in Sao Paulo state, Brazil. Our focus was also to derive the direct N2O emission factor (EF) that represents the regional conditions of sugarcane production, taking into account the data obtained from this study and those from the literature. In each field study, four straw removal rates (no removal (NR); low removal (LR)-removal of 5 Mg ha(-1); high removal (HR)-removal of 10 Mg ha(-1); and total removal (TR)-removal of 15 Mg ha(-1)) were arranged in a randomized block design. This study shows a clear evidence that CH4 fluxes are very low for all assessed sites regardless of straw removal rates, indicating a predominance of CH4 consumption by the soil. Cumulative N2O emissions ranged from 0.20 to 4.09 kg ha(-1) year(-1) and were significantly affected by straw removal in two sites, indicating that straw removal reduces N2O emissions. The average direct N2O EFs obtained from this study and from the literature were 0.28, 0.44, 0.70, and 0.56% for TR, HR, LR, and NR treatments, respectively, which are consistently lower than the EF of 1% suggested by the IPCC. Based on our regional-specific EF (Tier 2), the direct N2O emissions derived from N fertilization under scenarios of straw removal showed a reduction of at least 50% in relation to IPCC approach. Our findings are a step forward in providing regional-specific data to reduce the high level of uncertainty concerning N2O emission assessments of sugarcane ethanol in Brazil, but further studies are needed to evaluate how straw removal for bioenergy production and the associated changes in soil organic carbon stocks affect the GHG balance of sugarcane124843857CAPES - Coordenação de Aperfeiçoamento de Pessoal e Nível SuperiorCNPQ - Conselho Nacional de Desenvolvimento Científico e TecnológicoFAPESP – Fundação de Amparo à Pesquisa Do Estado De São Paulosem informação310478/2017-02017/02299-4; 2014/20593-9; 2018/20793-9LCG and LCZ are grateful to the Brazilian Federal Agency for Support and Evaluation of Graduate Education – (CAPES) for providing doctoral fellowships. BGO thanks the São Paulo Research Foundation – FAPESP for providing the research grant (no. 2017/02299-4). HC is supported by grants from National Council for Scientific and Technological Development - CNPq (310478/2017-0) and FAPESP (2014/20593-9 and 2018/20793-9). We would like to thank LNBR’s group of technicians for all the support provided for field and laboratory activities, and the mills management for the experimental sites and the logistics support during the fieldwork.This research was financially supported by the Sugarcane Renewable Electricity project — SUCRE/PNUD (grant number BRA/10/G31

ERICA: prevalências de hipertensão arterial e obesidade em adolescentes brasileiros

OBJECTIVE:To estimate the prevalence of arterial hypertension and obesity and the population attributable fraction of hypertension that is due to obesity in Brazilian adolescents. METHODS: Data from participants in the Brazilian Study of Cardiovascular Risks in Adolescents (ERICA), which was the first national school-based, cross-section study performed in Brazil were evaluated. The sample was divided into 32 geographical strata and clusters from 32 schools and classes, with regional and national representation. Obesity was classified using the body mass index according to age and sex. Arterial hypertension was defined when the average systolic or diastolic blood pressure was greater than or equal to the 95th percentile of the reference curve. Prevalences and 95% confidence intervals (95%CI) of arterial hypertension and obesity, both on a national basis and in the macro-regions of Brazil, were estimated by sex and age group, as were the fractions of hypertension attributable to obesity in the population. RESULTS:We evaluated 73,399 students, 55.4% female, with an average age of 14.7 years (SD = 1.6). The prevalence of hypertension was 9.6% (95%CI 9.0-10.3); with the lowest being in the North, 8.4% (95%CI 7.7-9.2) and Northeast regions, 8.4% (95%CI 7.6-9.2), and the highest being in the South, 12.5% (95%CI 11.0-14.2). The prevalence of obesity was 8.4% (95%CI 7.9-8.9), which was lower in the North region and higher in the South region. The prevalences of arterial hypertension and obesity were higher in males. Obese adolescents presented a higher prevalence of hypertension, 28.4% (95%CI 25.5-31.2), than overweight adolescents, 15.4% (95%CI 17.0-13.8), or eutrophic adolescents, 6.3% (95%CI 5.6-7.0). The fraction of hypertension attributable to obesity was 17.8%. CONCLUSIONS:ERICA was the first nationally representative Brazilian study providing prevalence estimates of hypertension in adolescents. Regional and sex differences were observed. The study indicates that the control of obesity would lower the prevalence of hypertension among Brazilian adolescents by 1/5. DESCRIPTORS:Adolescent. Obesity, epidemiology. Hypertension, epidemiology. Cross-Sectional Studies.OBJETIVO: Estimar as prevalências de hipertensão arterial e obesidade e a fração atribuível populacional de hipertensão arterial devida à obesidade em adolescentes brasileiros. MÉTODOS: Foram avaliados dados dos participantes do Estudo de Riscos Cardiovasculares em Adolescentes, estudo seccional l nacional de base escolar. A amostra foi dividida em 32 estratos geográficos e conglomerados de escolas e turmas, com representatividade nacional, macrorregional e de capitais. Obesidade foi classificada pelo índice de massa corporal segundo idade e sexo. Considerou-se hipertensão arterial a média da pressão arterial sistólica ou diastólica maior ou igual ao percentil 95 da curva de referência. Foram estimadas prevalências e intervalos de confiança de 95% (IC95%) de hipertensão arterial e de obesidade, nacionais e nas macrorregiões do País, por sexo e grupo etário, assim como as frações de hipertensão atribuíveis à obesidade na população. RESULTADOS: Foram avaliados 73.399 estudantes, 55,4% do sexo feminino, com média de idade 14,7 anos (DP = 1,6). A prevalência de hipertensão arterial foi 9,6% (IC95% 9,0-10,3); sendo as mais baixas observadas nas regiões Norte, 8,4% (IC95% 7,7-9,2) e Nordeste, 8,4% (IC95% 7,6-9,2) e a mais alta na região Sul, 12,5% (IC95% 11,0-14,2). A prevalência de obesidade foi 8,4% (IC95% 7,9-8,9), mais baixa na região Norte e mais alta na Sul. As prevalências de hipertensão arterial e obesidade foram maiores no sexo masculino. Adolescentes com obesidade tiveram prevalência de hipertensão arterial mais elevada, 28,4% (IC95% 25,5-31,2), do que aqueles com sobrepeso, 15,4% (IC95% 13,8-17,0), ou eutróficos, 6,3% (IC95% 5,6-7,0). A fração de hipertensão arterial atribuível à obesidade foi de 17,8%. CONCLUSÕES: O ERICA foi o primeiro estudo brasileiro com representatividade nacional a estimar a prevalência de hipertensão arterial aferida em adolescentes. A fração da prevalência de hipertensão arterial atribuível à obesidade mostrou que cerca de 1/5 dos hipertensos poderiam não ser hipertensos se não fossem obesos. DESCRITORES: Adolescente. Obesidade, epidemiologia. Hipertensão, epidemiologia. Prevalência. Estudo Transversal