抗生素在土壤中的吸附行为研究进展

抗生素是人类与动植物疾病防治中被广泛使用的抑菌或杀菌药物,由于其不能完全被机体吸收转化,大部分以原形或代谢物的形式经不同途径进入土壤环境,导致土壤微环境破坏,最终影响人类健康。本文通过文献查阅,综合近几年的研究现状,分析土壤矿物质、有机质、土壤溶液及土壤生物对抗生素吸附作用的机理,探究土壤矿物质、有机质、土壤溶液及土壤生物对抗生素吸附性能的影响,并对抗生素在土壤中的吸附行为进行了展望,以期为土壤中抗生素污染防治提供理论依据。     

土壤中抗生素的环境行为及分布特征研究进展

抗生素被广泛应用于治疗和控制人类及其他动物的细菌感染性疾病,并且可以作为饲料添加剂或生长促进剂用于禽畜养殖。大量抗生素通过有机肥施用、污水灌溉等途径持续进入土壤,导致土壤环境中抗生素种类不断增加、含量逐年增高。抗生素污染会对土壤中微生物、动物、植物等产生直接或间接的影响,诱导耐药菌株及抗性基因的产生,并且抗生素还可以被植物吸收,通过食物链影响人类健康。本文系统介绍了近20年来土壤中抗生素的相关研究,并着重就土壤中抗生素的来源归趋、环境行为以及时空分布情况进行了总结。研究认为土壤中抗生素的环境行为受抗生素种类和土壤性质的强烈影响,并且土壤中抗生素的时空分布与其环境行为和人类活动密切相关。     

铬在土壤中的吸附解吸研究进展

对铬在土壤中的吸附解吸研究进行了综述,土壤中铬的吸附解吸机理包括非专性吸附(离子交换吸附)、专性吸附以及物理表面吸附,分别对pH、氧化还原电位、土壤组分(土壤矿物和有机质)、竞争离子以及离子强度等因素对铬吸附解吸的影响作了论述。文章进一步描述了土壤中铬吸附解吸的数学模型Freundlich方程、Langmuir方程、一级动力学模型、金属-腐殖酸模型(one-sitemodel)和表面络合模型-扩散层模型(DLM)等的研究情况,并对今后的研究方向进行了探讨。     

金霉素在不同耕作土壤中的吸附－解吸行为

用批平衡吸附试验研究了金霉素在河南封丘潮土、南京黄棕壤、常熟水稻土和江西鹰潭红壤4种土壤中的吸附行为。结果表明,金霉素的土壤吸附-解吸行为均可用Freundlich模型和Langmuir模型进行良好的线性拟合。其Kf值差异较大,分别为潮土1135Lkg-1,黄棕壤1250Lkg-1,水稻土2618Lkg-1和红壤4315Lkg-1,显示金霉素在4种土壤中的吸附行为存在较大的差异。此外,金霉素在4种土壤上的解吸过程存在明显的滞后现象。研究还表明4种土壤中金霉素的吸附参数Kf值与土壤pH呈显著负相关。     

土壤镉吸附的研究进展

综述了土壤镉吸附的机理和土壤pH、有机质含量、粘粒矿物类型及含量、土壤溶液中竞争性阳离子、共存阴离子、土壤温度等土壤性质对土壤镉吸附的影响；总结了土壤镉的吸附量随土壤pH增加、温度升高及有机质、铁锰氧化物和粘土矿物含量增加而增加的机理；竞争性阳离子的存在抑制镉的吸附，土壤溶液中共存阴离子对镉吸附的影响取决于阴离子种类和土壤类型。     

土壤对病毒的吸附行为及其在环境净化中的作用

病毒在土壤上的吸附行为在很大程度上决定着其对饮用水的污染威胁。通过一次平衡法实验,比较研究噬菌体MS2和X174在6种不同性质土壤上的吸附行为的差别,同时阐述土壤中本身存在的微生物对土壤吸附行为的影响。总体趋势为土壤对X174的吸附能力高于对MS2的吸附能力;红黏土对病毒的吸附能力最强,而沙质潮土最弱;土壤中本身存在的微生物对土壤吸附病毒的影响依不同类型的土壤和病毒而异,除了红黏土外,灭菌土壤显著增加其对MS2的吸附;但对X174来说,灭菌后显著降低其在红黏土上的吸附,其他5种土壤的灭菌处理对X174的吸附行为没有显著影响。说明红黏土或与红黏土类似性质的材料在净化被病毒污染的水域时可能是一比较理想的病毒吸附剂;而在沙质潮土地区,病毒通过被土壤吸附而达到过滤净化的可能性则比较小。土壤中可能存在某一种或一类特殊微生物,它们可能可以控制病毒在土壤中的吸附行为,因而进一步研究其机理十分必要。     

兽药抗生素在土壤环境中的行为

兽药抗生素的环境暴露问题逐渐受到人们的极大关注。但是,以往的少数相关研究仅仅报道了某些兽药抗生素在水体环境和底泥中的存在,其中涉及土壤体系的则更少。同时,对兽药抗生素在土壤中的暴露途径和迁移、转化等了解较少。某些兽药抗生素如土霉素等,在环境中的持久性较强,对生物和环境可能存在着潜在的威胁。本文回顾了某些兽药抗生素在土壤体系(包括底泥)中的环境行为。     

邻苯二甲酸和水杨酸在可变电荷土壤中的吸附行为

研究了2种低分子量有机酸邻苯二甲酸和水杨酸在2种代表性可变电荷土壤红壤和砖红壤中的吸附行为。结果表明,可变电荷土壤对有机酸的吸附容量较大,对邻苯二甲酸的吸附亲和力大于对水杨酸的亲和力,在砖红壤中2种有机酸的吸附量大于在红壤中的,这与土壤的游离铁、铝氧化物的含量一致。土壤氧化铁在有机酸吸附中起着重要作用,粘土矿物如高岭石对有机酸的吸附量很小。有机酸的吸附涉及专性吸附和静电吸附2种机制,并以前者为主。当pH小于4.5时,pH的改变对有机酸的吸附影响不大;当pH大于4.5时,有机酸的吸附量随pH的增加而减小。     

挥发性氯代烃在土壤中的吸附行为研究进展

挥发性氯代烃(Volatile chlorinated hydrocarbons,VCHs)是工业污染场地的常见污染物,在非饱和带存在于土壤气相、水相、固相或以高密度非水相液体(Dense non-aqueous phase liquids,DNAPL)的形式存在,形成一个动态平衡系统。土壤对VCHs的吸附不仅影响土壤中的污染物浓度,而且极大地影响VCHs的迁移转化行为。根据VCHs在土壤中的吸附机制,可以对土壤中的VCHs浓度进行预测,优化各种模型参数,指导污染修复及管理工作。本文总结了VCHs在非饱和带土壤中的相间分配特征,吸附机制及其影响因素,特别探讨了土壤有机碳、矿物及水分对吸附的影响,提出了当前研究中存在的问题,并对将来研究进行了展望。     

离子交换树脂膜吸附土壤养分的动力学研究

采用从英国进口的离子交换树脂膜和室内埋置法研究了取自河北玉田县的 4个土壤吸附土壤磷、钾、钙、镁和锰的动力学。结果表明 ,在 0 .5～ 2 4h的吸附时间内 ,随着提取时间的延长 ,树脂膜吸附的土壤磷、钙量和锰量显著增加 ,而吸附的钾量减少。     

Boron sorption isotherm: A method to estimate boron fertilizer requirement

Abstract

The boron sorption isotherm method of soil testing may provide an estimate of the fertilizer required to bring the soil to an optimum boron level. Data from the boron isotherm experiment suggests that at low concentrations a plot of added boron vs equilibrium solution boron will be linear. The boron concentration at which this plot becomes linear will depend on the characteristics of the soil tested. The data, from this and other studies, suggest that 0.5 ppm boron in the equilibrium solution should be the approximate upper limit of boron concentration where this relationship is linear. Since boron added is linear with respect to boron in equilibrium solution, boron fertilizer required to adjust the equilibrium solution concentration can be calculated from the least squares regression equation of these two variables. This fertilizer requirement can only be determined when the optimum level of boron in equilibrium solution is known. Thus, further study is needed to establish this optimum level for all plant species.     

多氯联苯同系物在水稻土中的吸附行为比较

土壤是事关农产品生产环境质量安全的重要环境介质,同时因持久性有毒污染物多氯联苯(polychlorinated biphenyls,PCBs)在世界范围内普遍检出而备受科学界与政府关注。Ren等首次在中国范围内调查了52个采样点处表层土壤中的PCBs浓度,在其所有采样点处的PCBs平均浓度为     

Competitive sorption of microbial metabolites on an iron oxide mineral

A large fraction of soil organic matter (SOM) is composed of small molecules of microbial origin. However, the biotic and abiotic cycling of these nutrients is poorly understood and is a critical component of the global carbon cycle. Although there are many factors controlling the accessibility of SOM to microbes, sorption to mineral surfaces is among the most significant. Here, we investigated the competitive sorption of a complex pool of microbial metabolites on ferrihydrite, an iron oxide mineral, using a lysate prepared from a soil bacterium, Pseudomonas stutzeri RCH2. After a 24-h incubation with a range of mineral concentrations, more than half of the metabolites showed significant decreases in solution concentration. Phosphate-containing metabolites showed the greatest degree of sorption followed by dicarboxylates and metabolites containing both nitrogen and an aromatic moiety. Similar trends were observed when comparing sorption of metabolites with an equimolar metabolite mixture rather than a bacterial lysate. Interestingly, ectoine, lysine, two disaccharides and uracil were found not to sorb and may be more bioavailable in iron oxide-rich soils. Additionally, the highest-sorbing metabolites were examined for their ability to mobilize mineral-sorbed phosphate. All phosphate-containing metabolites tested and glutathione released phosphate from the mineral surface within 30 min of metabolite addition. These findings of preferential sorption behavior within a complex pool of microbial metabolites may provide insight into the cycling of SOM and specific nutrient availability. Finally, the release of highly-sorptive metabolites may be an underexplored mechanism utilized by microbial communities to gain access to limited environmental nutrients.     

滇池宝象河流域土壤磷的累积及吸附特征研究

磷是导致湖泊水体富营养化的主要污染物质。本文对滇池宝象河流域稀疏林地、坡耕地、平地耕地及大棚土壤的0～5cm、5～10cm、10～20cm层土壤全磷、有效磷、磷固定量及磷吸持指数(PSI)等指标进行了测定或计算,并就磷的累积与分布特征、吸附特征等进行了评价。结果表明:流域表层土壤的全磷、Olsen-P和水溶性磷均有明显的累积,尤以大棚土壤磷的累积效应最为明显(平均值分别为1·67gkg-1、75·9mgkg-1和27·7mgkg-1),且Olsen-P和水溶性磷的含量在耕层各层次上表现为从上往下依次降低的趋势。吸附特征方面,表层土壤的磷固定量在68·4～351·2mgkg-1之间,不同土地利用类型不同土壤层次间的土壤磷固定量无显著差异;而土壤的PSI值以上游稀疏林地和坡耕地土壤中的显著较高,根据PSI值低于30的比例,推测出中上游平地耕地和下游大棚区土壤磷素存在着较大的潜在流失风险。     

The effect of soil type on phosphorus sorption capacity and desorption dynamics in Irish grassland soils

Abstract. The phosphorus (P) sorption and desorption dynamics of eleven major agricultural grassland soil types in Ireland were examined using laboratory techniques, so that soils vulnerable to P loss might be identified. Desorption of P from soil using the iron-oxide paper strip test (Pfeo), water extractable P (Pw) and calcium chloride extractable P (Pcacl₂) depended on soil P status in all soils. However, soil types with high organic matter levels (OM), namely peat soils (%OM >30), had lower Pfeo and Pw but higher Pcacl₂ values compared to mineral soils at similar soil test P levels. Phosphorus sorption capacity remaining (PSCr) was measured using a single addition of P to soils and used to calculate total P sorption capacities (PSCt) and degree of P saturation (DPS). Phosphorus sorption capacities correlated negatively with % OM in soils indicating that OM may inhibit P sorption from solution to soil. High organic matter soils exhibited low P sorption capacities and poor P reserves (total P, oxalate extractable P) compared to mineral soils. Low P sorption capacities (PSCt) in peat soils were attributed to OM, which blocked or eliminated sorption sites with organic acids, therefore, P remained in the soil solution phase (Pcacl₂). In this work, peat and high organic matter soils exhibited P sorption and desorption characteristics which suggest that these soils may not be suitable for heavy applications of manure or fertilizer P owing to their low capacities for P sorption and storage.     

Dissolved organic matter enhances the sorption of atrazine by soil

The influence of dissolved organic matter (DOM) on the sorption of atrazine (2-chloro-4-ethylamino-6-isopylamino-1,3,5-triazine) by ten soils was investigated. Batch sorption isotherm techniques were used to evaluate the important physiochemical properties of soil determining the sorption of atrazine in the presence of DOM. The sorption of atrazine as a representative of nonionic organic contaminants (NOCs) by soil with and without DOM could be well described by the Linear and Freundlich models. The n values of the Freundlich model were generally near to 1, indicating that linear partitioning was the major mechanism of atrazine sorption by soil samples. The apparent distribution coefficient, value, for atrazine sorption in the presence of DOM initially increased and decreased thereafter as the DOM concentration increased in the equilibrium solution. DOM at relatively lower concentrations significantly enhanced the sorption of atrazine by soil, while it inhibited the atrazine sorption at higher concentrations. For all the soil samples, the maximum of was 1.1~3.1 times higher than its corresponding K _d value for the control (without DOM). The maximum enhancement of the distribution coefficient () in the presence of DOM was negatively correlated with the content of soil organic carbon (SOC) and positively correlated with the clay content. The critical concentration of DOM, below which DOM would enhance atrazine sorption, was negatively correlated with SOC. The influence of DOM on atrazine sorption could be approximately considered as the net effect of the cumulative sorption and association of atrazine with DOM in solution. Results of this study provide an insight into the retention and mobility of a NOC in the soil environment.     

Adsorption of dissolved organic carbon to mineral soils: A comparison of four isotherm approaches

The partitioning of dissolved organic carbon (DOC) within mineral soils is primarily controlled by adsorption to soil particle surfaces. We compare the theoretical limitations and modeling accuracy of four isotherm approaches to describe DOC partitioning to soil surfaces. We use 52 mineral soil samples to create linear initial mass (IM), non-linear, and Langmuir isotherms, all relating the initial solution concentration (X_i) to the amount of DOC adsorbed or released from soil surfaces. The Langmuir isotherm is also used with final concentration (X_f). The IM isotherm failed to meet theoretical assumptions and provided poor fits to experimental data. The non-linear and Langmuir X_i approaches had good fits to experimental data, and the Langmuir X_i approach had the most robust estimates of desorption capacity. Both Langmuir X_i and X_f isotherms hold the advantage of estimating the maximum adsorption capacity, yet the X_f isotherm is a better reflection of adsorption processes.     

Effects of long-term manure applications on the occurrence of antibiotics and antibiotic resistance genes (ARGs) in paddy soils: Evidence from four field experiments in south of China

Most studies of the effects of manure amendment on the occurrence of antibiotics and antibiotic resistance genes (ARGs) in soil employ the investigation of grab samples or short-term laboratory studies. However, the effects of long-term manure applications on antibiotics, ARGs and their vertical distribution in paddy soil in field experiments are lacking. We assessed the concentrations of antibiotics, ARGs and their vertical distribution in paddy soil receiving long-term manure applications in four field experiments. High concentrations of tetracyclines were detected in most manured soils, while sulfonamides were not detectable. Long-term manure amendments generally increased the antibiotic concentrations and ARGs abundances in the paddy soil over decades. However, in some sites such significant trends of ARGs could not be observed. The abundance of ARGs was statistically correlated with antibiotics and soil properties including pH and soil organic matter (SOM), indicating their importance in the selection of resistance genes. Tetracyclines could be detected in soil at different depths and the concentrations of tetracyclines and abundance of ARGs generally decreased with increasing soil depths.