有机酸对污染土壤中镉释放的影响

There is limited information on the release behavior of heavy metals from natural soils by organic acids. Thus, cadmium release, due to two organic acids (tartrate and citrate) that are common in the rhizosphere, from soils polluted by metal smelters or tailings and soils artificially contaminated by adding Cd were analyzed. The presence of tartrate or citrate at a low concentration (≤ 6 mmol L^-1 for tartrate and ≤ 0.5 mmol L^-1 for citrate) inhibited Cd release, whereas the presence of organic acids in high concentrations (≥ 2 mmol L^-1 for citrate and ≥ 15 mmol L^-1 for tartrate) apparently promoted Cd release. Under the same conditions, the Cd release in naturally polluted soils was less than that of artificially contaminated soils. Additionally, as the initial pH rose from 2 to 8 in the presence of citrate, a sequential valley and then peak appeared in the Cd release curve, while in the presence of tartrate the Cd release steadily decreased. In addition, Cd release was clearly enhanced as the electrolyte concentration of KNO₃ or KCl increased in the presence of 2 mmol L^-1 tartrate. Moreover, a higher desorption of Cd was shown with the KCl electrolyte compared to KNO₃ for the same concentration levels. This implied that the bioavailability of heavy metals could be promoted with the addition of suitable types and concentrations of organic acids as well as reasonable field conditions.     

土壤中铅的积累及污染的农业防治

本文叙述了铅在土壤 分布和积累规律，土壤对铅的吸附特性及土壤中铅的形态和生物有效性，同时还阐述了土壤中铅的过量积累对土壤生物活性的影响及防治土壤铅污染的苦干农业措施。     

土壤中重金属复合污染的表征

综述土壤中重金属复合污染的表征方法的研究进展,目的在于为农业生态环境中重金属污染的研究和防治提供参考。     

温度对硼在土壤中吸附－解吸动力学的影响

The effect of temperature on the properties of boron adsorption-desorption in brown-red soil,yellowbrown soil and calcareous alluvial soil of Hubei Province was investigated with the mobile displacement technique.The experimental data of B adsorption-desorption amounts and reaction time at 25 and 40℃ were fitted by the zero-order,first-order and parabolic diffusion kinetic equations.The adsorption process was in conformity with the parabolic diffusion law at both the temperatures,and the values of rate constant of the parabolic diffusion equation in B adsorption were 0.138,0.124 and 0.105 mg kg^-1 min^-1/2 at 25℃,and 0.147,0.146and 0.135mg kg^-1 min^1/2 at 40℃ for the brown-red soil,yellow-brown soil,and calcareous alluvial soil,respectively,The relationship between amount of B desorption and reaction time could be well described by the first-order kinetic equation,and the corresponding values of rate constant were 0.0422,0.0563 and 0.0384min^-1 at 25℃,and 0.0408,0.0423 and 0.0401min^-1 at 40℃ for the brown-red soil,the yellow-brown soil and the calcareous alluvial soil,respectively.Therefore,the desorption process of B might be related to the amount of B adsorbed in soil,The higher th temperature,the lower the amount of B adsorption of the same soil in the same reaction time,The values of the apparent activation energy of B adsorption in the three soils calculated with the rate constants of parabolic diffusion equation were 3.27,8.44 and 12.99 kJ mol^-1,respectively,based on the experimental data of B adsorption amounts and reaction time at and 40℃.     

温室土壤硅素释放动力学特征的研究

施硅可以促进园艺作物生长、提高其抗逆性和改善果实品质,但关于温室土壤硅素供应特征及其影响因素、合理调控土壤硅素肥力的研究却鲜有报道。采用淹水培养试验与化验分析结合的方法,研究温室土壤的硅素释放特征及其影响因素。结果表明,幂函数方程y=kxm能很好地描述土壤硅素的累积释放特征,方程参数k(硅素初始释放量)、m(硅素释放速率系数)、km(初始释放速率)受土壤pH和有机质的显著影响,均与土壤pH、有机质含量呈极显著的直线正相关关系;此外,参数k和km还分别与土壤游离氧化铁含量呈显著的指数和幂函数正相关关系。应用释放动力学方程求得的100天硅素累积释放量与土壤pH、有机质含量分别呈极显著的指数和直线正相关关系,但多元逐步回归分析结果表明硅素累积释放量与土壤有机质含量关系更为密切。应用释放动力学方程及其参数评价温室土壤的供硅能力具有可行性,值得进一步深入研究。     

乙草胺对土壤脲酶动力学特征的影响

采用室内模拟试验方法,以典型棕壤为供试土壤,研究不同浓度乙草胺对土壤脲酶活性和酶动力学参数的影响。结果表明,不同浓度乙草胺能显著抑制土壤脲酶活性,并在培养的第3～6 d达到最大抑制;利用模型 y=c/(1+bx)和y=c(1+ax)/(1+bx) 对不同浓度乙草胺与土壤酶活性的关系进行拟合,证明模型y=c/(1+bx)拟合效果较好,表明乙草胺除草剂对土壤脲酶的抑制作用为完全抑制,而脲酶ED50 为13.12～75.76 mg/kg;乙草胺的施入使土壤脲酶Vmax值降低,Km值则保持不变,属于典型的非竞争性抑制。     

离子强度及pH对不同类型土壤中胶体释放的影响

采用实验室土柱纵向淋溶法,研究了离子强度及pH变化对常熟乌栅土原状、扰动土柱以及东北黑土、江西红壤扰动土柱土壤胶体释放的影响。结果表明离子强度变化对我国不同类型土壤胶体释放影响不同：淋洗液电解质为NaCl时,对于常熟乌栅土以及东北黑土,离子强度减小促进胶体的释放,反之抑制胶体的释放;对于江西红壤,离子强度变化对土壤胶体释放则不产生影响。淋洗液电解质为CaCl2条件下,土壤胶体的释放量低于淋洗液为NaCl,且离子强度变化对三种土壤胶体的释放均不产生明显影响。相同条件下,常熟乌栅土及东北黑土胶体释放量远远大于江西红壤,pH变化则对上述类型土壤胶体释放的影响不明显。研究结果有助于进一步阐明水化学条件的变化对我国不同类型土壤胶体释放的影响规律。     

低分子量有机酸对土壤磷释放动力学的影响

模拟植物在缺磷条件下,根系所分泌的有机酸种类和数量,用流动法研究了柠檬酸,苹果酸,草酸和酒石酸对土壤磷释放的影响。结果表明：有机酸能明显促进土壤中磷的释放,不同有机酸对石灰性土壤活化能力大小的次序为草酸≥柠檬酸〉苹果酸〉酒石酸;而对酸性土壤磷的释放量与Ｆｅ＋Ａｌ释放量之间呈极 相关,有机酸活化土壤磷能力大小的次序为柠檬酸〉草酸〉酒石酸〉苹果酸。     

金属污染土壤的植物修复

本文就金属污染土壤的植物吸取、植物稳定、植物挥发这三种植物修复技术国际研究与发展的态势作一描述，以进一步推动我国在土壤生物修复这一世界科学前沿领域的研究。     

砂质土壤pH对中性缓释复合肥养分释放特性的影响研究

采用连续恒温培养研究了30℃条件下砂质酸性、中性土壤对2种不同剂型中性缓释复合肥养分释放特性的影响.研究结果表明,中性缓释复合肥的养分累积量、拟合动力学方程参数b值及养分平均释放相对百分率的变化趋势,受砂质土壤pH的影响基本一致.随砂质土壤pH升高,两种中性缓释复合肥氮素和磷素释放速率、累积量和相对百分率变大;砂质土壤pH降低,中性缓释复合肥钾素释放速率、累积量和相对百分率变大.两个中性缓释复合肥的养分释放速率对于砂质土壤pH变化响应一致,均表现为SRF1(有机无机型)＜SRF2(无机型).     

Tween 80对DDTs污染场地土壤的增溶洗脱效果研究

以苏南某滴滴涕类化合物（DDTs）污染场地土壤为研究对象,进行实验室批量洗脱试验,研究了环境友好型表面活性剂Tween 80对土壤中DDTs的增溶洗脱效果及其影响因素。结果表明,Tween 80显著地增加了DDTs表观溶解度,在临界胶束浓度（CMC）以上对DDTs的增溶曲线呈指数衰减函数关系,DDTs各组分洗脱量顺序为4,4′-DDT〉4,4′-DDD〉2,4′-DDD〉2,4′-DDT。Tween 80的浓度、洗脱次数及土壤吸附作用共同影响其对DDTs的洗脱效果。去离子水能有效去除土壤中残留Tween 80,Tween 80解吸附率最高可达72.66%,大大降低了Tween 80二次污染土壤的风险。Tween 80增溶和去离子水解吸附联合过程对DDTs洗脱效果产生显著的协同作用。10 000 mg·L^-1浓度条件下Tween 80对DDTs的去除率最高为72%,其次为8 000 mg·L^-1 的Tween 80水溶液,去除率为66.72%。采用8 000 mg·L^-1的Tween 80溶液进行土壤洗涤处理,结合其他修复技术,可能会是修复DDTs污染土壤的有效技术方案之一。     

不同种植年限设施菜田土壤无机磷组分的累积和释放特征

[目的]探明设施栽培条件下土壤磷素随种植年限的变化规律,揭示温室土壤无机磷积累和淋溶损失的主体成分,为设施农业合理施用磷肥和可持续发展提供依据.[方法]采集了辽宁省铁岭县(2～28 a)和海城市(2～33 a)不同种植年限的设施土壤,以土壤全磷、有效磷、无机磷组分含量的变化及磷素释放曲线为切入点,分析了设施栽培条件下土...     

缓释复合肥料对酸性菜园土壤微生物数量特征的影响

采用盆栽试验研究缓释复合肥料（SRF）对酸性菜园土壤微生物数量特征的影响。两次测定（35d和45d）结果表明,在各处理中,SRF处理土壤微生物量碳（SMBC）含量、细菌和放线菌数量均为最高,其中SMBC达到显著;SRF处理微生物量氮（SMBN）含量显著高于普通复合肥（CCF）处理（分别提高25.8%和38.6%）,真菌数量低于包膜缓释肥（CRF）处理,高于CCF处理;与施用普通复合肥（CCF）处理相比,SRF能够显著提高白菜产量（分别提高16.4%和13.9%）,而与包膜肥料CRF处理无显著差异。     

有机化工污染场地修复后的再利用风险评价

为检验污染土壤修复工程的效果,判断修复土地再利用的生态与环境风险,用人体健康风险评价法,依据土壤污染物进入人体的主要途径及可测量的参数,通过评估一块被有机物污染的场地修复前后的风险,度量了不同土地利用方式下多种土壤污染物经各种途径进入并危害人体健康的风险值及总风险。结果表明,不同土地利用方式下,苯、硝基苯、苯胺的总非致癌风险分别由修复工程实施前的4.42～46.10降低到修复后的2.50×10-3～2.61×10-2,总致癌风险则分别由3.06×10-6～7.41×10-6降低到4.75×10-7～1.19×10-6,修复后的土地适宜作为商业服务或工业用地。     

Effect of Soil Properties on Boron Adsorption and Release in Arid and Semi-Arid Benchmark Soils

The adsorption isotherms indicated that the adsorption of boron (B) increased with its increasing concentration in the equilibrium solution. The Langmuir adsorption isotherm was curvilinear and it was significant when the curves were resolved into two linear parts. The maximum value of adsorption maxima (b1) was observed to be 7.968 mg B kg^?1 in Garhi baghi soil and the bonding energy (k) constant was maximum at 0.509 L mg^?1 in Jodhpur ramana soil. The Langmuir isotherm best explains the adsorption phenomenon at low concentrations of the adsorbent, which of course was different for different soils. There was significant correlation between b1 and clay (r = 0.905**), organic matter contents (r = 0.734*), and cation exchange capacity (CEC; r = 0.995**) of soils. A linear relationship was observed in all the soils at all concentration ranges between 0 and 100 mg B L^?1, indicating that boron adsorption data conform to the Freundlich equation. Soils that have a higher affinity for boron adsorption, like Garhi baghi, tended to desorb less amount of boron, that is, 43.54%, whereas Ballowal saunkhari desorbed 48.00%, Jodhpur ramana 48.42%, and Naura soil 58.88% of the adsorbed boron. Boron desorption by these soils is positively and significantly correlated with the sand content (r = 0.714**) and negatively with clay content (r = ?0.502*) and CEC (r = ?0.623**). The maximum value of 37.59 mg kg^?1 for desorption maxima (Dm) was observed in Garhi baghi soil and also a constant related to B mobility (Kd) was found to be maximum in Garhi baghi (0.222 L kg^?1) soil Note: *P<0.05; ^**P<0.01.     

棕壤和蛭石对外源钾的固定和释放特征

在外源钾施入量为2800mgkg-1条件下,供试耕地棕壤的固钾容量高达1450mgkg-1。在试验条件下,棕壤对钾素的固定量随外源钾施入量的增加而增加。蛭石对钾素的固定量具有随外源钾的施入量增加而呈线性增大的规律,其中0.3mm~0.1mm粒级蛭石对于钾素的固定量要高于1mm~0.3mm和<0.1mm两粒级蛭石对钾素的固定量。蛭石和棕壤对外源钾的固定率表现为随固钾量的增加而趋于降低的规律,但钾素释放量却随之提高。     

膨润土和沸石在镉污染土壤治理中的应用

采用通过盆栽试验,研究了膨润土和沸石对镉污染土壤的治理效果。结果表明,施加膨润土后不同污染程度土壤的交换态、碳酸盐结合态镉的质量分数都有所下降,铁锰氧化物结合态、有机结合态和残渣态镉的质量分数则有所上升。沸石和膨润土对轻度、中度镉污染土壤都表现出钝化作用,对重度镉污染土壤,膨润土对镉的钝化效果明显,而沸石却起到了激活镉的作用。在不同程度镉污染土壤上,膨润土可增加乌塌菜的生物量,并可抑制其对镉的吸收,降低乌塌菜植株体内镉的浓度,对乌塌菜的生长具有显著的促进作用。沸石对轻度和中度镉污染土壤均可降低乌塌菜植株体内镉的浓度,促进乌塌菜的生长并增加其生物量;对重度镉污染土壤,沸石对乌塌菜的生长影响较小,乌塌菜植株体内镉的积累显著增加。     

膨润土和沸石在镉污染土壤治理中的应用

采用通过盆栽试验,研究了膨润土和沸石对镉污染土壤的治理效果。结果表明,施加膨润土后不同污染程度土壤的交换态、碳酸盐结合态镉的质量分数都有所下降,铁锰氧化物结合态、有机结合态和残渣态镉的质量分数则有所上升。沸石和膨润土对轻度、中度镉污染土壤都表现出钝化作用,对重度镉污染土壤,膨润土对镉的钝化效果明显,而沸石却起到了激活镉的作用。在不同程度镉污染土壤上,膨润土可增加乌塌菜的生物量,并可抑制其对镉的吸收,降低乌塌菜植株体内镉的浓度,对乌塌菜的生长具有显著的促进作用。沸石对轻度和中度镉污染土壤均可降低乌塌菜植株体内镉的浓度,促进乌塌菜的生长并增加其生物量;对重度镉污染土壤,沸石对乌塌菜的生长影响较小,乌塌菜植株体内镉的积累显著增加。     

Release Kinetics of Some Nutrients from a Sandy Loam Soil Treated with Different Organic Amendments

ABSTRACT

An incubation study was undertaken to examine the periodic release of some macronutrients and micronutrients in a sandy loam treated with different organic amendments (farmyard manure, mushroom compost, poultry manure, vermicompost, biogas slurry, and biochar of Lantana weed) added @ 15 t ha^?1 for 120 d through entrapment of released nutrients on ion exchange resins. Among organic amendments, the highest total contents were recorded for Ca, Mg, and S in farmyard manure, for K, Fe, and Mn in mushroom compost, for P, Zn, and Cu in biogas slurry, for B in biochar. The highest average release was recorded for P, Zn, Mn, and B from poultry manure, for Cu from biogas slurry, for Fe from vermicompost, for Ca, Mg, and S from mushroom compost, and for K from farmyard manure. The kinetics of mineralization and release of these nutrients conformed well to the zero-order kinetics and also to a power function equation. The initial release amount and release rate coefficient estimated by the power function equations were correlated significantly to the general properties of organic amendments and also to the type of C species present in organic amendment. Organic amendments having relatively higher content of water soluble C or fulvic or humic acids are likely to release nutrients through an early mineralization/solubilization from soil reserve.