典型小流域农田土壤Cd形态分布及纳米羟基磷灰石阻控效果

Spatial variation of agricultural soil Cd species and the nanohydroxyapatite resistance control in a typical small watershed

沿浏阳铁山河流域采集6个土壤样品(S1~S6),分析其Cd含量及形态空间差异特征,并结合室内淹水模拟实验,研究淹水条件下纳米羟基磷灰石添加量对不同样品Cd有效性与形态转化的影响。结果表明,从流域上游到下游,土壤总镉含量分别为1.14、1.37、1.98、7.44、7.45、6. 99 mg·kg-1,有效态Cd所占百分比依次为51.75%、40.15%、39.39%、16.40%、28.86%、29.76%,总量与有效态Cd的空间差异均非常明显,而有效态Cd所占百分比与土壤p H呈显著负相关。淹水可降低土壤Cd的有效性,且随着淹水时间延长,土壤有效态Cd逐渐向残渣态转化。添加纳米羟基磷灰石可明显降低土壤有效Cd含量,且随着添加量增加,阻控效果越好。当添加量为5%时,阻控效果最佳;与对照相比,S1~S6有效Cd含量分别降低了77.97%、83.64%、82.05%、77.87%、74.88%、73.56%。研究结果可为矿区小流域农业安全生产的分区管理和重金属污染治理提供数据支持与科学参考。

Six soil samples were collected from Tieshan watershed,a typical mining small agricultural watershed in Liuyang City,which were used to analyze spatial variation of soil Cd content and its species.Effects of various nanohydroxyapatite addition doses on soil Cd availability and form transformation were examined using indoor flooding simulation experiment.Results showed that total Cd content in soils was 1.14,1.37,1.98,7.44,7.45 and 6.99 mg·kg-1 from upstream to downstream of the watershed,with the percentage of available Cd being 51.75%,40.15%,39.39%,16.40%,28.86%and 29.76%,respectively.Spatial variation of soil total Cd and available Cd contents was highly significant in the watershed.The percentage of available Cd had significant negative correlation with soil pH.Flooding significantly decreased soil available Cd content.More available Cd transformed into the residual state with extension of flooding time.Soil available Cd content was decreased greatly with addition of nanohydroxyapatite,the effects of which were better with the increasing dose,being best at 5%.Compared with flooding alone,soil available Cd decreased by 77.97%,83.64%,82.05%,77.87%,74.88%and 73.56%in samples collected from sites S1-S6,respectively.The results can provide scientific reference for district management of safe agricultural production and control of heavy metal pollution in watershed scale of mining area in China.