Bioavailability of bound residue derived from 14C-labeled chlorsulfuron in soil and its mechanism of phytotoxicity

The bioavailability of bound residue(BR) derived from ^14C-labeled chlorsulfuron in soil and effect of the main components of the BR on growth of rape( brassica napus) and rice( Oryza sativa L. ) were investigated. The results showed that the BR with the concentration of 0.28 and 0.56 nmol/g air-dried soil, which was calculated by special radioactivity of ^14C-labeled chlorsulfuron parent compound, resulted in significant depression effect on growth of rape seedling. It was assured that the main components(2-amino-4-methoxyl-6-methyl-1,3,5-triazine, 2-amino-4-hydroxyl-6-methyl-1,3,5-triazine, and 2-chloro-benzenesul-fonamide) of the BR did not inhibit the growth of rape and rice. LC-MS analysis demonstrated that the parent compound previously bound to the soil matrix could be again released and transformed into methanol-extractable residue during the course of rape growth. It was concluded that the molecular leading to the phytotoxicity to rape and rice in the BR is still the parent compound.     

Bound 14 C-metsulfuron-methyl residue in soils

Bound residue(BR) of ^14 C-metsulfuron-methyl (^14 C-BR) in seven kinds of soil was significantly negative-related to soil pH and positive-related to the clay content during the initial 20 d of incubation, but only was significantly negative-related to soil pH after 30 d incubation. Again, the soil pH was found to be the dominant factor affecting BR formation from ,4 C-metsulfuron-methyl among the basic properties(soil pH, clay, OM and CEC etc. ) of soil. The maximum content of ^14C-BR in the 7 soils accounted for 19.3% -52.6% of applied amount. In addition, the composition of the ,4 C-BR in fluvio marine yellow loamy(S7) at the 90 d of incubation was identified using the coupling technique of LC-MS and isotope tracing method. The results showed that the^14 C-[2-amino-4-hydroxyl-6-methyl-1 3, 5]-triazine, ^14 C-[2-amino-4-methoxy-6-methyl-1, 3, 5]-tdazine and ^14 C-metsulfuron-methyl parent compound constituted the main components of the BR derived from ^14 C-metsulfuron-methyl in the S7. The relative percentage of the three compounds accounted for 41.4%, 35.8% and 19.3% of total recovery radioactivity, respectively. The results also indicated that a non-radioactive component, 2-methylformate-benzenesulfonyl-isocyanate, one of the degraded products of metsulfuron-methyl in soil, was also found to be one of the components of the BR. The parent compound in BR can well explain the phytotoxic effect on substitution crops caused by the BR derived from metsulfuron-methyl in soil.     

根际土壤中汞甲基化与去甲基化作用双同位素示踪研究

根际环境特殊的理化性质可能显著促进汞(Hg)的甲基化.为证实上述假设,本研究采集了三峡库区消落带狗牙根根际土和非根际土,分别测定了根际土与非根际土中总汞(THg)和甲基汞(MeHg)含量及主要理化性质,并采用双同位素示踪法(~(199)Hg~(2+)和Me~(201)Hg)进行室内模拟培养实验,探究其Hg的甲基化与去甲基化速率.结果表明,根际土壤中的Fe~(2+)、Mn~(2+)、有机质含量、过氧化氢酶活性显著高于非根际土(p0.05),MeHg含量、细菌、真菌数极显著大于非根际土(p0.01);根际土壤中MeHg的含量与Mn~(2+)、SO_4~(2-)、有机质含量存在显著正相关性(p0.05),与过氧化氢酶活性、细菌、真菌数存在显著正相关性(p0.01);根际土壤中Hg甲基化、去甲基化速率、净甲基化潜力均显著大于非根际土(p0.05),有菌根际土的甲基化与去甲基化速率显著大于无菌根际土(p0.05).本研究证实了根际是Hg发生甲基化的一个活跃区域,其中,微生物在根际土壤中Hg的甲基化与去甲基化过程中均起着主要作用.     

Dynamic response of chlorsulfuron herbicide to nitrogen mineralization and the ratio of microbial biomass nitrogen to nitrogen mineralization in the soil

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14C-甲磺隆在土壤中的可提态残留、结合态残留和矿化

在实验室培养条件下,从质量平衡角度,研究了¹⁴C-甲磺隆在7种土壤中形成结合残留(¹⁴C-BR)、可提态残留(¹⁴C-ER)以及矿化为¹⁴CO₂的规律;同时对¹⁴C-BR的主要影响因子及其在腐殖质中的分布规律进行了研究.结果表明:①¹⁴C-甲磺隆在土壤中形成的¹⁴C-ER,其含量与土壤pH呈显著正相关.甲磺隆母体化合物在7种土壤中 的半减期为13.3～66.6d,降解速率常数λ(d-1)与pH呈显著负相关.②¹⁴C-甲磺隆在7种土壤中形成的¹⁴C-BR,其含量在培养初期的20d内,与土壤pH呈显著负相关且与土壤粘粒含量呈显著正相关;而培养20d后,¹⁴C-BR的含量只与土壤pH呈显著负相关.pH是¹⁴C-甲磺隆在土壤中形成BR的主要影响因子.¹⁴C-甲磺隆在7种土壤中的¹⁴C-BR的最大值约为引入量的19.3%～52.6%.③在整个培养试验过程中,7种土壤中的¹⁴C-BR主要分布在富啡酸和胡敏素中,但其分布在胡敏酸中的相对百分比较小.因此,在¹⁴C-甲磺隆形成BR的过程中,富啡酸的作用＞胡敏素>胡敏酸.④在整个培养试验期间(180d),¹⁴C-甲磺隆在7种土壤中通过三嗪杂环开环矿化为¹⁴CO₂的量约占引入量的12.9%～27.0%,其在碱性土壤中更难被矿化为¹⁴CO₂.     

沼渣协同硫酸亚铁修复Cr(Ⅵ)污染土壤

通过稳定化实验、连续提取实验及植物毒性实验,研究了沼渣对硫酸亚铁稳定化Cr （Ⅵ）污染土壤的促进效果与机制.结果表明,沼渣协同硫酸亚铁对土壤中Cr （VI）有良好的稳定化效果.最佳的修复条件为：n（Fe）/n（Cr）=3∶1,含水率为35%,沼渣投加量为4.5%,反应时间为12 d,此时Cr （VI）稳定化效率为99.85%,残余六价铬含量为1.49 mg·kg^-1,满足《土壤环境质量建设用地土壤污染风险管控标准》（GB 36600—2018）第二类用地筛选值5.7 mg·kg^-1的限值要求.由连续提取实验结果可知,沼渣+硫酸亚铁稳定化处理后酸溶态铬含量显著降低,而可还原态、可氧化态和残渣态铬含量明显增加.风险分析进一步表明,沼渣+硫酸亚铁稳定化处理后铬的风险等级由非常高风险降至低风险.植物毒性分析可知,沼渣+硫酸亚铁稳定化处理植物毒性显著降低.微生物多样性和群落结构分析可知,沼渣+硫酸亚铁稳定化处理后土壤中细菌群落的丰度和多样性均明显增加.     

土壤中多环芳烃的稳定碳同位素特征及其对污染源示踪意义

分析了天津市不同功能区土壤中多环芳烃的稳定碳同位素组成特征、土壤中菲、甲基菲、荧葸和芘的δ^13C值范围分别为-29．5‰～-23．2‰、-39．8‰～-23．4‰、-27．2％～-23．6‰和-28．1‰～-22．6‰,不同功能区稳定碳同位素组成的差异反映了PAHs来源的差异．稳定碳同位素组成特征表明,在研究区内,化石燃料燃烧产物的干-湿沉降是土壤PAHs的最主要来源之一,其它可能的来源有污水携带的油污、农作物茎杆及薪柴不完全燃烧产物等．就具体地点而言,土壤PAHs以二元混合输入为主,据此,运用稳定碳同位素组成的二元复合数值模型对不同来源PAHs的相对贡献率进行了估算     

不同有机物料对黑土腐殖质元素组成及结构的影响

 利用元素分析仪及红外光谱仪研究施用不同有机物料对黑土腐殖质元素组成及结构影响的差异性.结果表明:与对照(CK)相比,有机物料施用5a后,黑土胡敏酸(HA)中C、H含量均显著降低,并以木本处理作用最显著.除动物粪便处理HA中N含量与CK相等外,其余有机处理N含量均显著高于CK,施用动物残体则使HA中O含量显著降低.施用草本残体可以提高富里酸(FA)中N含量.动物残体使FA中H含量显著降低.施用草本残体、木本残体使FA中C含量升高,O含量影响降低.有机物的施用使铁结合胡敏素(HMi)中C、H含量下降而使O含量上升,并以草本处理作用最显著,同时草本处理也使HMi中N含量降低.与CK相比,施用动物粪便、木本残体提高了粘粒结合胡敏素(HMc)中C、N含量而降低了O含量,有机物料施用5a后均使黑土HMc中H含量降低,且各处理之间差异显著.与CK相比,有机物料施用五年后均使HA及FA脂族性减弱,并以草本残体处理影响最明显.对于HMc,施用有机物料有利于提高其脂族性,同时使芳香C=C振动减弱,并且以木本处理影响最明显.有机物料施用5a后使HMi的羟基含量及碳水化合物减少,而使其脂族性提高.试验结果证实,不同有机物料处理对黑土腐殖质各组分特征的影响有明显差异.     

水淹频率增加对闽江口湿地土壤有机碳及其活性组分的影响

研究河口湿地土壤有机碳及其活性组分对水淹频率的响应,对认识海平面上升背景下湿地土壤碳循环具有重要意义.本文以闽江河口湿地为研究区,测定了区内6、7和8月高潮滩(偶尔水淹,H样地)和中潮滩(频繁水淹,M样地)表层土壤有机碳(SOC)及其活性组分-微生物生物量碳(MBC)、易氧化有机碳(EOC)及可溶性有机碳(DOC)的含量,并进一步通过原位培养方法(H样地植物-土壤移动到M样地进行培养)分析了水淹频率增加对SOC及其活性组分的影响.结果表明:H样地SOC、EOC、MBC和DOC含量平均值分别为45.11 g·kg-1、30.21 g·kg-1、385.29 mg·kg-1和749.98 mg·kg-1,总体显著高于而M样地SOC、EOC、MBC和DOC含量(p0.05),高出的比例分别为161.81%、136.2%、200.6%和710.86%;野外培养90 d后,SOC和EOC均无显著变化,而MBC和DOC随培养时间延长,影响逐渐增大,90 d培养后,两者均显著下降,下降比例分别为28.21%和93.84%;此外,SOC及其活性组分在一定程度上受到土壤理化性质的影响,除EOC外,SOC、MBC和DOC均与p H、TN和TP呈显著相关(p0.01).这些结果表明,在较长时间尺度,水淹频率可以直接影响SOC及其活性组分,也可能通过影响p H、TN和TP等因子,间接影响SOC及其活性组分.     

Amplification of plasmid DNA bound on soil colloidal particles and clay minerals by the polymerase chain reaction

Polymerase chain reaction(PCR)was used to amplify a 600-base pair(bp)sequence of plasmid pGEX-2T DNA bound on soil colloidal particles from Brown soil(Alfisol)and Red soil(Ultisol),and three different minerals(goethite,kaolinite,montmorillonite). DNA bound on soil colloids,kaolinite,and montmorillonite was not amplified when the complexes were used directly but amplification occurred when the soil colloid or kaolinite-DNA complex was diluted,10- and 20-fold.The montmorillonite-DNA complex required at least 100-fold dilution before amplification could be detected.DNA bound on goethile was amplified irrespective of whether the complex was used directly,or diluted 10- and 20-fold.The amplification of mineral-bound plasmid DNA by PCR is,therefore,markedly influenced by the type and concentration of minerals used.This information is of fundamental importance to soil molecular microbial ecology with particular reference to monitoring the fate of genetically engineered microorganisms and their recombinant DNA in soil environments.     

转Bt基因克螟稻秸杆对淹水土壤细菌群落的影响

在实验室条件下通过秸杆还土试验比较了克螟稻Bt基因表达最高期秸杆和同一时期亲本稻秸杆的添加对淹水土壤可培养厌氧细菌数量和细菌群落组成的影响 .结果表明 ,与亲本对照相比 ,培养初期克螟稻秸杆的添加对淹水土壤厌氧发酵性细菌、产氢产乙酸细菌、反硝化细菌和产甲烷细菌的数量产生了显著性影响 ,但培养后期这种显著性差异基本消失 .PCR 变性梯度凝胶电泳 (DGGE)指纹图谱和主成份分析 (PCA)结果表明 ,两种秸杆处理土壤细菌群落组成在培养的第 3周和第 5周达到显著性差异 ,随着培养时间的延伸 ,两种秸杆处理土壤间细菌群落组成的差异逐渐减小 .到培养的第 1 1周 ,两种秸杆处理土壤间细菌群落组成的差异基本消失 .尽管如此 ,在培养的整个过程中 ,秸杆处理土壤中可培养厌氧性细菌数量和土壤细菌群落的组成均与纯土对照存在显著性差异 .试验结果表明 ,在实验室培养的条件下 ,没有观察到转Bt基因克螟稻秸杆对淹水土壤微生物明显的长期负面影响     

Simultaneous elution of polycyclic aromatic hydrocarbons and heavy metals from contaminated soil by two amino acids derived from β-cyclodextrins

Two highly water-soluble amino acids,which derived from β-CDs,i.e.,glutamic acid-β-cyclodextrin (GluCD) and ethylene-diamineβ-cyclodextrin (EDCD),were synthesized and were examined for their effect on solubilization of anthracene (ANT),complexation of cadmium (Cd2+),and elution removal of ANT and Cd2+ in soil.The results showed that GluCD and EDCD were powerful complexant for ANT and Cd2+.In the presence of 10 g/L GluCD and EDCD,the solubilization of ANT increased by 47.04 and 23.85 times compared to the control,respectively.GluCD resulted in approximately 90% complexation of Cd2+ while 70% complexation was observed for EDCD.Simultaneously,GluCD and EDCD could greatly enhance the elution removal of ANT and Cd 2+ from soil.GluCD resulted in the highest elution efficiency of ANT and Cd2+.With the addition of 10 g/L GluCD,53.5% of ANT and 85.6% of Cd2+ were eluted,respectively.The ANT had a negligible effect on the Cd2+ removal due to different complexing sites of ANT and Cd2+,while Cd2+ enhanced the ANT removal under the addition of GluCD because Cd2+ neutralized the-COOH group of GluCD.Adversely,the removal of ANT was decreased with Cd2+ under the addition of EDCD,this was due to the fact that Cd2+ enhanced the polarity of EDCD molecule and inhibited the complexation between ANT and EDCD.The study suggested that GluCD could be preferred and be successfully applied to remediation of heavy metals or organic compounds in contaminated soil.     

青藏高原东麓贡嘎山东坡土壤中Pb的来源解析

选择青藏高原东麓典型山地——贡嘎山(东坡),根据不同海拔梯度(海拔2 000~4 500 m)差异设置8个采样点,根据土壤发育情况分别采集O层(有机层)、A层(矿物质层)和C层(母质层)样品,分析土壤中w(Pb)的海拔分布特征,并利用FA-MLR(因子回归分析)法、地球化学指标法和Pb同位素三元混合模型定量判识表层土壤中Pb的来源. 结果表明:①各层土壤中w(Pb)表现为O层〔(41.73±4.38)mg/kg〕>A层〔(30.47±2.17)mg/kg〕>C层〔(23.04±1.50)mg/kg〕(P<0.05). 随着海拔的增加,O层和A层中w(Pb)总体呈升高—降低—升高趋势;C层中w(Pb)随着海拔的变化无显著差异,表明贡嘎山东坡土壤中w(Pb)的地球化学背景值基本一致. ②各层土壤中206Pb/207Pb表现为O层208Pb/206Pb表现为O层>A层>C层. ③Pb同位素三元混合模型结果显示,表层(O层和A层)土壤中Pb可能受到化石燃料燃烧和矿物开采及金属冶炼活动的影响;根据FA-MLR法、地球化学指标法和Pb同位素三元混合模型这3种方法,得到O层中污染Pb所占比例分别达到84.9%、66.0%和63.7%,A层中分别为56.6%、27.8%和44.9%;在海拔分布上,Pb的污染在海拔2 770 m以下主要归因于当地化石燃料的燃烧,而在林线(约3 700 m)以上则来自矿物开采及金属冶炼活动.      

江苏洋口港地区地下水的环境同位素组成及其形成演化研究

江苏洋口港地区是江苏沿海开发重点建设的深水港区,水质优良的地下水是港区经济社会发展的重要基础.本研究利用近期获得的钻孔剖面地层对比数据资料,沿水文径流剖面分层采集水样,通过识别地表水、各含水层地下水的环境同位素(δD、δ~(18)O、~3H、~(14)C)组成指纹特征,以揭示研究区地下水的形成演化规律.结果表明,研究区浅层地下水主要来源于现代大气降水的入渗补给,大气降水在补给地下水过程中经历了明显的蒸发过程;研究区深层地下水的放射性~(14)C年龄主要为15000~26000 a,其稳定同位素δ~(18)O、δD值比现代降水低,是晚更新世末次冰期(大理冰期)的盛冰期降水入渗补给.地下水含水层的氘、氧、碳同位素分布具有明显的呈层性,随着地下水埋藏深度增加,地下水中的δD、δ~(18)O值呈下降趋势.浅层地下水与地表水水力联系紧密,可更新能力较强;深层地下水径流缓慢,总体上处于封闭-半封闭状态,可更新能力弱.江苏沿海平原天然地下水流动是自晚更新世末期以来,伴随着冰退、海平面上升而调整到目前的模式.末次盛冰期以来的自然地理及地质发展史,决定着研究区第四系地下水流系统的演变格局,现代人类活动加强了浅层与深层地下水之间的水力联系.研究在高强度开发地下水条件下的区域水文循环特征,可为沿海地区地下水演变机理和调控研究提供技术支持.     

柠檬酸对污染棕壤中镉的去除优化及结合形态影响

针对农田土壤重金属污染,研究了有机酸对土壤中镉的去除条件优化及结合形态的影响,旨在发展一种环境友好、可原位且永久去除土壤中镉(Cd)的淋溶暗排联合净化方法.采用环境友好型淋溶剂柠檬酸,通过批试验确定淋溶最佳参数(柠檬酸浓度、固液比、淋溶次数、淋溶时间和淋溶方式).同时,将自行设计的淋溶瓶和淋溶暗排箱用于批试验最优化参数...     

油田区土壤石油烃组分残留特性研究

为了揭示石油开采区土壤石油烃组成及残留特性,探讨石油污染物的来源与风化程度,采集了胜利油田孤岛和河口采油区共5口油井周边土壤样品及原油样品,利用气相色谱-质谱联用仪(GC-MS)分析原油及土壤样品中的链烷烃(正烷烃+姥鲛烷+植烷)及多环芳烃(polycyclic aromatic hydrocarbons,PAHs)共51种石油烃单体的含量.结果表明,与原油相比,油田区土壤总提取物中链烷烃与PAHs所占的比例明显偏低;土壤石油烃的组分构成与原油相比,链烷烃中碳数小于12的正烷烃比例明显降低,而高碳数正烷烃比例增加.选择正十八烷/植烷作为指示土壤风化程度的标志,利用主成分分析(principal component analysis,PCA)法分析其与土壤中各石油烃组分的关系,结果显示碳数大于33的正烷烃与中环芳香烃具有高残留性.利用主成分分析综合分析用于土壤石油烃来源识别的4个指标,结果表明,土壤中的石油烃具有明显的原油"指纹".研究结果为油田土壤污染特性的认识提供了依据与基础.     

Determination of arsenic in grain and soil by hydride nondispersive atomic fluorescence method

Quantity of trace arsenic in grain and soil was determined by hydride nondispersive atomic fluorescence method.Optimum conditions of measurement were selected in the experiment including the pH of the medium, reductive agent, the concentration and flowing velocity of KBH4, rate of carrier gas and atomized temperature. The reference sample of rice C was determined and the linear relationship of the calibration curve was plotted, indicating that the method was highly precise. In the experiment of recovery rate, the method was quite satisfactory.Based on the determination of hundreds of samples, it is proved that atomic fluorescence method is rapid, sensitive and low in interference. It is very efficient on determination of trace arsenic in soils and grains, especially in grains.     

雪玉洞表土有机氯农药的分布及来源研究

为研究有机氯农药(OCPs)在重庆丰都雪玉洞表土中的水平分布趋势、组成特征和来源,采用气相色谱-微池电子捕获检测器(GC-μECD)分析了10个代表性表层土样中18种OCPs.结果表明,研究区表层土壤中18种OCPs除o,p'-DDD、ε-HCH、艾氏剂和狄氏剂外均有不同程度的检出,其中,HCH、DDT、七氯和甲氧滴滴涕的检出率高达100%,是主要的污染物.土壤中总有机氯农药的含量范围为1.24~750.56 ng·g^-1,平均值为79.57 ng·g^-1.DDTs和HCHs可能分别来自于工业DDTs和林丹的非法使用,并且近期可能有新的输入.通过相关分析得出,研究区10个采样点有机氯农药基本具有相同的来源,并且土壤有机碳是影响有机氯农药分布的重要因素.对比中国的土壤质量标准(GB15618-95)发现,研究区土壤中HCHs和DDTs的残留均处于较低水平.由于岩溶地区地表土层厚度分布不连续,且地下岩溶形态较为发育,有机氯农药可能通过裂隙或落水洞进入地下河系统,对洞穴滴水和地下河水造成潜在的污染风险.     

名山河流域水稻土组分对微团聚体吸附-解吸铜的影响

以名山河流域典型的水稻土为例,利用模拟-培养试验和选择溶解法,研究各土壤组分对原土和不同粒径微团聚体吸附解吸Cu2+能力的影响.结果表明,去除土壤组分前后的原土和不同粒径微团聚体对Cu2+的吸附均用Langmuir方程拟合效果最佳,原土和不同粒径微团聚体对Cu2+的吸附能力大小顺序为:0.002mm2.000～0.250mm原土0.053～0.002mm0.250～0.053mm.与未去除土壤组分的原土相比,去除土壤组分的原土和微团聚体对Cu2+的吸附量均有所减小,尤其以去除有机质后对Cu2+吸附量的减小最为显著,在0.002mm微团聚体中减小值高达44.50%±2.77%,0.250～0.053mm微团聚体中Cu2+吸附量减小值最低,为37.68%±3.11%.经不同处理后原土和各粒径微团聚体吸附量减少的顺序为:去有机质去游离氧化铁去无定形氧化铁.去除各土壤组分后,原土和各粒径微团聚体对Cu2+的专性吸附降低,非专性吸附显著上升,降低了原土和各粒径微团聚体对Cu2+污染的缓冲能力,同时显示了各土壤组分在专性吸附中的重要性.     

基于稳定同位素与多元素的土壤铅污染源解析

以杭州市富阳区典型工矿企业附近农田为研究对象,基于单因子指数法及内梅罗指数法对土壤重金属污染状况进行了评价,并采用稳定同位素与多元素特征指纹结合多元统计定量解析研究区内农田土壤重金属铅污染的来源,建立基于铅稳定同位素与多元素特征指纹结合主成分-聚类分析的农田土壤铅污染源解析技术.结果 表明:研究区域内电镀厂和冼矿场附近...