脱硫石膏对稻田CH4释放及其功能微生物种群的影响

为探究脱硫石膏对温室气体CH_4排放及其功能微生物种群的影响,采用静态暗箱/气相色谱法,高通量测序和荧光定量PCR技术,研究了FGDG0(0 t·hm~(-2))、FGDG1(2 t·hm~(-2))、FGDG2(4 t·hm~(-2))、FGDG3(8 t·hm~(-2))、FGDG4(16 t·hm~(-2))这5个施加脱硫石膏处理下CH_4排放特征、稻田细菌群落结构及产甲烷菌和甲烷氧化菌丰度的变化.结果表明施加脱硫石膏后,土壤p H显著提高(P0.05),土壤氧化还原电位、有机质、速效钾含量增加,但处理间无显著差异(P0.05);稻田CH_4平均排放通量随着脱硫石膏用量增加而降低,且FGDG1FGDG2FGDG3FGDG4,较对照分别减少31.56%、57.30%、83.60%、90.66%;与对照相比,FGDG1、FGDG2处理增加了土壤细菌丰富度和多样性,但用量超过4 t·hm~(-2)后,细菌丰富度和多样性逐渐降低;与对照相比,稻田土壤硫酸盐还原菌属相对丰度显著提高6.98%~13.56%,甲烷氧化菌pmo A基因丰度增加0.3%~6.2%,产甲烷菌mrc A基因丰度显著下降2.4%~15.8%,且丰度比(pmo A/mcr A)随着脱硫石膏用量增加而增大;相关性分析表明,CH_4平均排放通量与土壤中硫酸盐还原菌属相对丰度呈显著负相关,与产甲烷菌mcr A基因丰度呈显著正相关,与pmo A/mcr A比呈显著负相关.综上,脱硫石膏能够提高稻田土壤细菌群落多样性,抑制稻田CH_4排放.

Effects of Gypsum on CH4 Emission and Functional Microbial Communities in Paddy Soil

In this study, the effects of gypsum (FGD) on CH₄ emission and functional microbial community in paddy soil were identified under five treatments, including FGDG₀(0 t·hm^-2), FGDG₁(2 t·hm^-2), FGDG₂(4 t·hm^-2), FGDG₃(8 t·hm^-2), and FGDG₄(16 t·hm^-2). The methane flux was determined using static chamber and chromatography. Bacterial community structure and its effect on soil bacterial community structure, and the abundance of methanogenic and methanotrophs were measured via high-throughput sequencing and quantitative PCR. The results showed that after treatment with desulfurated gypsum, pH of the soil increased significantly (P<0.05). Redox potential, organic carbon, and available potassium content increased, with no significant difference (P>0.05). The average emission flux of CH₄ reduced with the increase of desulfurated gypsum content, following the following trend:FGDG₁ > FGDG₂ > FGDG₃ > FGDG₄. They decreased by 31.56%, 57.30%, 83.60%, and 90.66%, respectively, compared with the control. Compared with the control, FGDG₁ and FGDG₂ increased the richness and variety of soil bacteria. However, when the application amount exceeds 4 t·hm^-2, the richness and variety of soil bacteria decrease. Compared with the control, the relative abundance of sulfate-reducing bacteria in paddy soil increased significantly by 6.98%-13.56%. The abundance of the methane-oxidizing bacteria pmoA gene increased by 0.3%-6.2%. The abundance of the methanogen gene, mrcA decreased significantly by 2.4%-15.8%, while the abundance ratio (pmoA/mcrA)increased with the increase of the amount of desulfurated gypsum. Correlation analysis showed that the average emission of CH₄ was markedly negatively correlated with the relative abundance of the sulfate-reducing bacteria and pmoA/mcrA percentage in soil, and significantly positively correlated with methanogenic gene, mcrA. In summary, desulfurated gypsum can improve the diversity of bacterial communities and reduce the emission of CH₄ in the paddy soils.