溶解性有机质及磷石膏对香溪河消落带土壤镉释放的影响
Influence of Dissolved Organic Matter and Phosphogypsum on the Release of Cadmium in the Soil of the Water Level Fluctuating Zone of the Xiangxi River
胡爽 1江梦含 2张俊杰 1邱霖萱 2杜容山 3刘婷 1李鑫怡 1席颖 2胥焘1
作者信息
- 1. 三峡大学三峡库区生态环境教育部工程研究中心,湖北宜昌 443002;三峡大学生物与制药学院,湖北宜昌 443002
- 2. 三峡大学三峡库区生态环境教育部工程研究中心,湖北宜昌 443002;三峡大学水利与环境学院,湖北宜昌 443002
- 3. 三峡大学三峡库区生态环境教育部工程研究中心,湖北宜昌 443002;宜昌市环境保护监测站,湖北宜昌 443002
- 折叠
摘要
为探究磷石膏和溶解性有机质(DOM)对香溪河消落带土壤中镉(Cd)释放的影响,选择狗牙根(Cynodon dactylon)作为外源DOM,进行室内模拟淹水浸出实验,研究了在落干和淹水两种环境下,狗牙根和磷石膏对土壤理化性质、DOM含量和性质以及重金属释放的影响.结果表明:在实验初期,狗牙根与磷石膏共同添加降低了土壤pH值,增加了土壤速效磷和可溶性硫酸盐(SO4-)的含量,促进Cd向间隙水释放,但抑制了 Cd向上覆水的迁移;随着培养时间延长,DOM中的蛋白组分转变为微生物腐殖质组分,腐殖质化程度增强,落干和淹水状态下各组间隙水中Cd浓度均降低,DOM作为硫酸盐还原菌的碳源,起到了固定Cd的作用.Cd浓度与pH值、SUVA254(芳香性指数)、HIX(腐殖质化程度)负相关,与DOC、Mn、SO42-、速效磷含量正相关.磷石膏的添加降低了土壤pH值,H+增加,Cd2+活性增强,同时磷石膏中的SO42-对锰氧化物起到还原作用,锰氧化物所结合的Cd被解离,促进了 Cd的释放.狗牙根腐解过程中释放的DOM在实验初期促进土壤中的Cd向间隙水溶出,而在实验末期,DOM参与SO42-的还原,促进Cd2+转为CdS沉淀而被固定在土壤中.
Abstract
This research aims to examine the impact of dissolved organic matter(DOM)and phosphogypsum on the release of cadmium(Cd)in the soil of the water level fluctuating zone(WLFZ)in the Xiangxi River.It focuses on soil samples collected from the WLFZ of the Xiangxi River,with particular attention given to the role of Cynodon dactylon as an external source of DOM.Indoor simulated flooding leaching experiments were carried out to reveal the effects of DOM and phosphogypsum on soil physicochemical properties,DOM characteristics,and heavy metal release under both drying and flooding environments.The results showed that at the initial stage of the experiment,the addition of Cynodon dactylon and phosphogypsum decreased the soil pH value,increased the content of available phosphorus and SO42-,promoted the release of Cd into pore water,but inhibited the migration of Cd into the overlying water.With the extension of culture time,the protein components in DOM were transformed into microbial humus components,leading to an increasing degree of humification(HIX).The Cd concentration in the pore water of all groups decreased under both drying and flooding conditions.DOM,acting as a carbon source for sulfate-reducing bacteria,played a role in immobilizing Cd.The Cd content was negatively correlated with pH,SUVA254(aromatic structure)and HIX,and positively correlated with DOC,Mn,SO42-and available phosphorus content.In each treatment,the addition of phosphogypsum decreased soil pH value,increased H+,and enhanced Cd2+activity.SO42-in phosphogypsum played a reducing role in manganese oxides,leading to the dissociation of Cd bound to manganese oxides and consequently promoting the release of Cd.At the beginning of the experiment,DOM was released during Cynodon dactylon decomposition promoted the release of Cd from soil to pore water;at the end of the experiment,DOM participated in the reduction of SO42-,facilitating the conversion of Cd2+to CdS precipitation and subsequent fixation in the soil.
关键词
消落带/溶解性有机质/磷石膏/镉/迁移Key words
water level fluctuating zone/dissolved organic matter/phosphogypsum/cadmium/transfer引用本文复制引用
基金项目
国家自然科学基金(42177397)
国家自然科学基金(42107441)
湖北省创新群体滚动项目(2015CFA021)
出版年
2024
NETL
NSTL
万方数据