南方丘陵区土壤重金属含量、来源及潜在生态风险评价

为了探究南方丘陵区土壤重金属污染特征及生态风险状况,选择南方某省丘陵区作为研究区,利用2017年采集的60个点位的土壤样品,采用单因子污染指数（P_i）、内梅罗综合污染指数（P_综）和潜在生态风险指数（RI）评估As、Cd、Cr、Cu、Hg、Ni、Pb和Zn这8种重金属含量特征和潜在生态风险程度,并利用正定矩阵因子分解模型（PMF）解析其污染来源.结果表明：①研究区8种重金属元素的含量均有超标,内梅罗综合污染指数显示,研究区呈现轻度、中度和重度污染所占的比例分别为63%、8%和2%,无污染和轻微污染的样点占27%,因此基本处于轻度污染;②综合潜在生态风险指数表明,土壤重金属RI为39.58~224.15,低等和中等生态风险的样点所占的比例为73.33%和25%,而重度生态风险的样点所占比例为1.67%,该样点生态风险程度虽然最高,但重金属含量低于该省土壤元素背景值;③通过PMF模型得到6个污染源：自然源、农业活动源、铜矿采选和交通运输组成的混合源、工业活动源、交通源和生活垃圾排放源,贡献率依次为24.8%、17.7%、17.7%、17.6%、12.0%和10.2%.     

复垦红壤中牧草根际微生物群落功能多样性

通过盆栽试验研究了浙江省诸暨铜矿区复垦红壤牧草根际微生物生物量及群落功能多样性的变化.结果表明,种植不同牧草使矿区土壤根际微生物生物量碳发生了显著的变化,其影响大小因矿区土壤污染程度而异.无污染和轻度污染土壤根际微生物生物量碳变化表现为黑麦草+三叶草>三叶草>黑麦草>未种植土壤,处理间差异均达显著水平(P<0.05),重度污染环境下各处理间差异不明显.Biolog数据分析显示,种植不同牧草的矿区土壤根际微生物群落结构和功能多样性也发生了相应改变,根际土壤微生物群落代谢剖面(AWCD)均显著高于未种植牧草土壤,处理间差异达极显著水平(P<0.001).典型变量分析揭示了不同牧草根际微生物群落利用碳源种类和数量存在明显差异.     

改性土壤对模拟含油废水中油的吸附

研究季铵盐阳离子表面活性剂四甲基铵离子 ( TMA)和十六烷基三甲基铵离子 ( HDTMA)改性的土壤 (黑土、黄棕壤、红壤 )对水中油的吸附作用 .结果表明 :改性土壤和未改性土壤均可吸附水中的油 ,但改性土壤对水中油的吸附能力明显高于未改性土壤 .改性土壤吸附油能力的顺序依次为 :1 CEC- HDTMA黑土 >1 CEC-HDTMA黄棕壤 >1 CEC- HDTMA红壤 >1 CEC-TMA黑土 >1 CEC-TMA黄棕壤 >1 CEC- TMA红壤 .未改性土壤和 HDTMA改性土壤对油的吸附通过分配来进行 ,吸附等温线可由 Henry方程表示 ,得出 logK_SOM为 2.69,logK_HDTMA为 3.35;TMA改性土壤对油的吸附符合 Langmuir方程 ,其对油的饱和吸附量分别为 1150 mg/kg( TMA黑土 ) ,751 mg/kg( TMA黄棕壤 ) ,172 mg/kg( TMA红壤 )     

Extractable atrazine and its metabolites in agricultural soils from the temperate humid zone

Extractable atrazine and its metabolites (hydroxyatrazine, deethylatrazine and deisopropylatrazine) were evaluated in agricultural soils from the temperate humid zone (Galicia, NW Spain) under laboratory conditions. The experiment was performed with five soils with different properties (organic C, soil texture and atrazine application history), both unamended and treated with atrazine at field application rate. Measurements of the atrazine compounds were made at different time intervals (1, 3, 6, 9 and 12 weeks) during a 3-month incubation period. Results showed that only hydroxyatrazine was detected in the extractable fraction of the unamended soils, with values remaining relatively constant throughout the incubation period. Atrazine addition notably increased the concentration of the parent compound and its degradation products; deisopropylatrazine and hydroxyatrazine were the main metabolites detected in the extractable fraction of the treated soils, whereas deethylatrazine was not detected. After 7 days incubation, values of total extractable residues, expressed as percentage of initially added atrazine, ranged from 75 to 86% (25–68% of atrazine, 7–11% of hydroxyatrazine and 9–57% of deisopropylatrazine). The values decreased rapidly during the first 3 weeks of incubation, showing values of 2–8% in soils with higher atrazine application and from 28 to 30% in soils with lower application history. At the end of the incubation, 2–8% of total extractable residues were still detected (0–4% of atrazine, 2–3% of hydroxyatrazine and 0–2% of deisopropylatrazine), indicating a residual effect of atrazine addition. These variations in the extractable fraction indicated that most added atrazine was rapidly degraded, especially in soils with higher application history.     

构建土壤生态筛选基准的技术关键及方法学概述

土壤生态筛选基准是指为了对陆地生物及关键的土壤生态功能提供适当保护而制定的土壤中污染物的浓度限值,污染物浓度超过此值,需对土壤采取进一步的风险评价行动或污染控制措施.论文综述了当前国际上土壤生态筛选基准的发展现状,系统阐述了制定土壤生态筛选基准的方法学及4个基本步骤:数据收集、适用数据的选择、基于效应的数据外推与阈值估算和筛选值的最终确立,并对构建适于我国使用的土壤生态筛选基准时可能会遇到的关键问题进行了讨论.     

新农药硫肟醚在土壤中的降解

在实验室条件下对新农药硫肟醚[o-(3-苯氧苄基)-2-甲硫基-1-(4-氯苯基)丙基酮肟醚]在不同地区土壤中的降解动态进行了研究.结果表明,硫肟醚在土壤中的降解遵循一级动力学方程.硫肟醚在非灭菌与灭菌长沙粉砂质黏土中的降解速率常数(k)分别为8.106×10^-3和1.630×10^-3,半衰期分别为85.5d和425.2d,微生物对硫肟醚在土壤中的降解具有显著的影响.硫肟醚在3种土壤中的降解速率大小依次为湖南永州重黏土>甘肃天水黏土>辽宁沈阳粉砂质黏土,其降解半衰期分别为46.1,63.8,70.0d,降解速率常数分别为1.503×10^-2,1.087×10^-2,9.904×10^-3.根据国内农药在土壤中的残留期划分标准,硫肟醚属于较易降解类农药.     

泉州市不同功能区土壤铅同位素组成及其来源分析

为查明泉州市土壤铅的污染来源,采集了泉州市不同功能区表层(O～20cm)土壤及城市环境污染端元(燃煤尘、汽车尾气尘、污泥)样品.采用ICP-MS测定土壤Pb含量,用热电质谱仪测定各样品的铅同位素组成.分析结果表明,泉州市不同功能区表层土壤已受到一定程度铅污染;泉州市土壤铅同位素208 Pb/(207+206)Pb和206Pb/207 Pb比值变化较大,分别为1.0769～ 1.1486和1.1150～1.2142;泉州市区各端元组分铅同位素组成差别比较大,可以有效示踪和鉴别泉州市区环境铅的污染来源.运用铅同位素示踪技术追踪土壤铅的污染来源结果表明,泉州市区土壤总铅同位素和可溶相铅同位素组成变化较大,土壤中铅来源较为复杂.交通繁忙区土壤铅污染主要来源于汽车尾气排放,农业区土壤铅主要来源于城市污泥与当地土壤背景,商业区土壤铅主要来源于城市污泥与燃煤尘及其煤渣的排放,居民区土壤铅污染主要受城市污泥与汽车尾气排放影响.     

安徽庐江潜在富硒土壤硒生物有效性及其影响因素

为研究潜在富硒土壤硒生物有效性,采集安徽庐江潜在富硒地区64组水稻及对应根系土壤样品,分析土壤理化性质、土壤养分、全硒、不同形态硒及大米硒含量,采用线性回归法探究土壤硒生物有效性的影响因素.结果表明,大米硒含量（记作Se_rice,下同）为0.037~0.120 mg/kg,土壤全硒含量（记作Se_tot,下同）为0.260~1.177 mg/kg,土壤硒以腐殖酸态硒（15.5%~44.7%）、强有机态硒（12.5%~53.3%）和残渣态硒（8.1%~68.5%）为主.土壤有效硫、有效磷通过提高强有机态、腐殖酸态和浸提性硒含量并促进水稻籽实（大米）对硒的吸收,而土壤阳离子交换量（cation exchange capacity,CEC）、速效钾、全铁和全锰通过降低水稻生物可利用态硒含量（包括水溶态、腐殖酸态、强有机态和浸提性硒）抑制水稻籽实（大米）对硒的吸收.Se_tot与Se_rice显著正相关（R=0.616,P < 0.01）,非残渣态硒含量与有机质含量之比（记作NRE-Se/OM）与Se_rice相关性最强（R=0.774,P < 0.01）.土壤NRE-Se/OM、有效硫、有效铁、全锰构建的多元逐步线性对数回归模型可解释水稻籽实（大米）吸收硒的76.0%的方差.因此引入变量NRE-Se/OM,并结合土壤有效硫、有效铁和全锰能有效评价和预测研究区土壤硒生物有效性.      

Adsorption characteristic of bensulfuron-methyl at variable added Pb^2＋ concentrations on paddy soils

The combined pollution of heavy metal Pb²⁺ and bensulfuron-methyl (BSM), originating from chemical herbicides, in agroecological environments has become commonplace in southern China. The adsorption of BSM on three paddy soils in the presence of Pb²⁺ was examined using high-performance liquid chromatograph (HPLC). Results indicated that adsorption of BSM could accurately be described by a Freundlich isotherm equation with correlation constant (R) > 0.98, irrespective of the presence of spiked Pb²⁺. Of the various factors influencing BSM sorption, soil pH appeared to be the most influential. The constant K_f of Freundlich isotherm equation tended to increase with increasing Pb²⁺ concentration in soil which indicated that the spiked of Pb²⁺ in paddy soils would promote the sorption of BSM. ΔG^θ of BSM in three paddy soils was less than 40 kJ/mol in all treatments, indicating the adsorption of BSM is mainly physical in nature. The elution of soil dissolved organic matter (DOM) enhanced the adsorption of BSM in paddy soils. The mechanisms involved in the promotion effects of the spiked Pb²⁺ on BSM adsorption might be the modified surface characteristics of paddy soil solids due to the soil acidification and the increase of soil organic matter concentration because of DOM binding.     

持续淹水和干湿交替预培养对2种水稻土中Cd形态分配及高丹草Cd吸收的影响

采用盆栽试验的方法,研究了前期持续淹水和干湿交替预培养对2种水稻土———太湖地区黄泥土、江西鹰潭红壤性水稻土中外源Cd形态分配及高丹草吸收Cd的影响.结果表明,在5mg·kg^-1和10mg·kg^-1外源Cd处理下,与干湿交替预培养比较,持续淹水预培养后黄泥土中MgCl₂提取态Cd分别由21.8%、28.5%下降为8.0%、16.9%,而NH₂OH.HCl提取态Cd由17.7%、17.3%升高为28.1%、37.5%;红壤性水稻土NaAc提取态Cd由20.8%、29.6%下降为11.6%、12.6%.回归分析表明,MgCl₂提取态Cd与高丹草Cd吸收量呈显著负相关关系.长期淹水预培养显著降低高丹草对黄泥土Cd的吸收.