Chemosphere ( IF 5.778 ) Pub Date : 2021-02-15 , DOI: 10.1016/j.chemosphere.2021.129987 Penggang Pei; Tao Sun; Yingming Xu; Yuebing Sun
In order to get insight into the distribution characteristics of mercury (Hg) and organic carbon in soil aggregates, and the diversity and composition of soil microbial community under different farmland–use types (soil form three adjacent cultivation systems, i.e., corn, vegetable, and rice fields, named as CFS, VFS, and RFS), a field investigation close to Wanshan Hg mining area was conducted. Results indicated that soil total Hg (0–20 cm) presented in decreasing order of RFS (5.27 mg kg−1) > VFS (4.32 mg kg−1) > CFS (2.21 mg kg−1), implying soils from rice field with higher ability of Hg accumulation. Soil aggregate–associated Hg and organic carbon enriched with the decrease of particle size under all farmland–use types, with the maximum at microaggregates (<0.053 mm). Due to the mass ratio of soil aggregates fraction, soil aggregate–associated Hg and organic carbon mainly distributed in >2 mm particles for RFS, whereas 0.25–2 mm particles for CFS and VFS. Furthermore, 16S rRNA results revealed the obvious differences in RFS and dry land soils (CFS and VFS), such as the observed species and unique OUTs, Shannon index, relative abundance at phylum and genus, which implied the diversity and composition of soil microbial community were greatly affected by farmland–use types. Spearman correlation and RDA results suggested farmland–use types, pH and total Hg were main drives for differences in soil microbial community. These findings provide evidence that farmland–use type is an important factor that affects soil total Hg accumulation, soil aggregate–associated Hg and organic carbon distribution, as well as the indigenous microbial community profiles.
为了深入了解汞（Hg）和有机碳在土壤团聚体中的分布特征，以及不同农田利用类型（土壤形成三个相邻的耕作系统，即玉米，蔬菜，稻田（分别称为CFS，VFS和RFS），在靠近万山汞矿区的地方进行了田间调查。结果表明，土壤总Hg（0–20 cm）以RFS（5.27 mg kg -1）> VFS（4.32 mg kg -1）> CFS（2.21 mg kg -1）的降序排列。），表明稻田土壤中的Hg积累能力更高。在所有农田使用类型下，与土壤团聚体相关的汞和有机碳随着粒径的减小而富集，在微团聚体中最大（<0.053 mm）。由于土壤团粒部分的质量比，与土壤团粒相关的汞和有机碳主要分布在RFS中大于2 mm的颗粒中，而CFS和VFS则为0.25-2 mm。此外，16S rRNA结果揭示了RFS和旱地土壤（CFS和VFS）的明显差异，例如观察到的物种和独特的OUT，香农指数，门和属的相对丰度，这暗示了土壤微生物群落的多样性和组成。受到农田用途类型的极大影响。Spearman相关性和RDA结果表明耕地使用类型，pH和总汞是土壤微生物群落差异的主要驱动力。这些发现提供了证据，证明耕地的使用类型是影响土壤总Hg积累，土壤团聚相关Hg和有机碳分布以及土著微生物群落概况的重要因素。