RESUMO
Increasing concentrations of greenhouse gases in the atmosphere caused by human activities are the main cause of climate warming. Global warming is a severe challenge confronted by human society today. Reducing greenhouse gas emissions and increasing carbon sinks are the keys to addressing climate warming. Biochar addition is considered to be a promising way to reduce greenhouse gas emissions and increase carbon sinks, due to its unique physical, chemical, and biological properties. Therefore, it is of great significance to study the effects of biochar on soil greenhouse gas emissions to mitigate the greenhouse effect and achieve "carbon neutrality." The long-term and short-term effects of biochar on soil greenhouse gas emissions and their influencing mechanism were reviewed. It was found that the effects of biochar on soil greenhouse gas emissions varied with the types of biochar feedstock, pyrolysis temperature, application ratio, and soil and vegetable types. In addition, due to the different aging times and modes and cultivation methods, the mitigation effect of aged biochar on soil greenhouse gas could be enhanced or weakened or even disappeared. Further, based on the deficiencies of the previous research, the direction and focus of future research on the effects of biochar on soil greenhouse gas emissions were analyzed and prospected. It was proposed to strengthen simultaneous research on the effects of biochar on CO2, N2O, and CH4 emissions; reducing greenhouse gas emissions and carbon sequestration; different aging modes and cultivation methods of biochar; and revealing the influencing mechanism at the process level, through exploring the effects of biochar on soil carbon and nitrogen dynamics and tracing the source of greenhouse gases using 13C and 15N tracer technology.
RESUMO
OBJECTIVES: To study the characteristics of amino acid metabolism in preterm infants in Guangxi, China. METHODS: A retrospective analysis was performed on the medical data of 30 757 neonates who underwent the screening for inherited metabolic diseases and had negative results in Guangxi Neonatal Disease Screening Center from 2018 to 2020. Among these neonates, there were 28 611 normal full-term infants (control group) and 2 146 preterm infants (preterm birth group). According to gestational age, the preterm infants were further divided into four groups: very preterm (n=209), moderately preterm (n=307), and late preterm group (n=1 630). According to birth weight, they were divided into three groups: very low birth weight group (n=161), low birth weight group (n=1 085), and normal birth weight group (n=900). According to blood collection time, they were divided into three groups: 3-7 days group (n=1 664), 8-14 days group (n=314) and 15-28 days group (n=168). Tandem mass spectrometry was performed to measure the levels of 11 amino acids in dried blood spots, which were then compared between groups. RESULTS: After adjustment for confounding factors, there were significant differences in the levels of 11 amino acids among different gestational age groups (P<0.05), and significant differences were observed in the levels of the 11 amino acids between the control group and the various preterm groups (except for citrulline and methionine in the late preterm group). There were significant differences in the levels of 11 amino acids among different birth weight groups (P<0.05). Except for ornithine, there were significant differences in the levels of other amino acids among the different blood collection time groups (P<0.05). CONCLUSIONS: Gestational age, birth weight and blood collection time all affect amino acid metabolism in preterm infants in Guangxi, China. This provides a basis for the laboratory to establish the reference standard and clinical interpretation of blood amino acid levels in preterm infants, and to improve the nutritional metabolism of preterm infants.
