稻田耕层土壤黑碳分布特征及影响因素

Characteristics of topsoil black carbon distribution and influencing factors of paddy

为探究我国稻田土壤黑碳含量分布特征及其影响因素,本研究采用苯多羧酸法(Benzene polycarboxylic acid,BPCA)对稻田耕层土壤黑碳(Black carbon,BC)含量及稳定性进行测定与分析,以完善国内农田土壤黑碳研究,并为农业可持续发展提供理论依据.结果表明:(1)黑碳含量为(0.70±0.08)^(4.57±1.63)g·kg-1,平均值为(1.63±0.18)g·kg-1;黑碳储量为(1.55±0.18)^(6.18±2.39)t·h m-2,平均值为(2.71±0.27)t·hm-2.(2)黑碳含量排序:西南区>东北区>华南区>华东区>华北区>西北区,黑碳储量排序:西南区>东北区>华北区>华南区>华东区>西北区.(3)在苯多羧酸含量特征方面,西南区表现为苯四甲酸(∑tetracarboxylic acids,B4CAs)>苯六甲酸(mellitic acid,B6CA)>苯五甲酸(benzenepentacarboxylic acid,B5CA)>苯三甲酸(∑tricarboxylic acids,B3CAs),华北区表现为B6CA>B4CAs>B5CA>B3CAs,其它耕作区表现为B6CA>B5CA>B4CAs>B3CAs.B5CA/B6CA、B6CA/B4CAs分别为(0.73±0.06)^(0.98±0.18)、(1.07±0.14)^(1.38±0.10),平均值分别为(0.92±0.02)、(1.23±0.03).研究发现,稻田土壤黑碳分布特征是人为因素、黑碳结构特性及环境因素等综合作用的结果.土壤黑碳主要来自稻田作物燃烧,并且黑碳含量与pH及容重间的相关性不显著,而与土壤有机碳、黏粒呈显著正相关.

To improve the research of soil black carbon （BC） of paddy in China and support theoretical basis for agricultural sustainable development, the characteristics of topsoil BC distribution and influencing factors of paddy in China were determined using benzene polycarboxylic acids （ BPCAs ） as markers. Paddy soils were sampled from 6 different regions in China （Northeast China, North China, East China, South China, Northwest China, Southwest China）, taken by horizon down to 15 cm depth and tested for soil BC and degree of condensation. The results showed that BC contents ranged from （0.70±0.08） to （4.57±1.63） g.kg^-1 , with average of （1.63±0.18） g.kg^-l , which were in the order of Southwest China〉Northeast China〉South China〉East China〉North China〉Northwest China. Paddy soils accumulated BC were ranged from （1.55±0.18） to （6.18±2.39） t·hm^-2, with average of （2.71±0.27） t·hm-2, which were in the order of Southwest China〉Northeast China〉North China〉South China〉East China〉Northwest China. And BPCAs patterns showed that ∑tetracarboxylie acids （B4CAs） 〉mellitic acid （B6CA） 〉benzenepentacarboxylic acid （B5CA） 〉 ∑ tricarboxylie acids （B3CAs） in Southwest China, moreover, B6CA〉B4CAs〉B5CA〉B3CAs in North China, furthermore, B6CA〉B5CA〉B4CAs〉B3CAs in other regions. B5CA/B6CA was ranged from （0.73±0.06） to （0.98±0.18）, with average of （0.92±0.02）. B6CA/B4CAs was ranged from （1.07±0.14） to （ 1.38±0.10）, with average of （1.23 ± O. 03）. We concluded that BC accumulation was affected by paddy management, BC structural properties and environmental factors. Burned crop residues were a major source for BC in paddy topsoil in China. BC was correlated with pH, bulk density not significantly, however, was significantly and positively correlated with soil organic carbon and clay concentration.