垃圾堆肥对铬污染土壤的修复机理研究

运用二次通用旋转组合试验设计,通过模拟土培试验,研究垃圾堆肥对铬污染土训中有效铬含量的影响,铬的形态变化。结果表明,垃圾堆肥可显著减少铬污染土壤中有效铬含量,垃圾堆肥主要是促进水溶志铬向结晶形沉淀态铬转化;垃圾堆肥用于修复铬污染土壤是安全的。     

石灰和海泡石对镉污染土壤的修复效应与机理研究

研究了稻作和旱作两种种植制度下,施用石灰、海泡石及两种改良剂配施对镉污染土壤pH值、土壤镉形态变化及作物对镉的吸收等的影响.结果表明,施用改良剂使稻作条件下的土壤pH提高0.3～1.8个单位,旱作条件下土壤pH提高幅度为0.3～2.0个单位:两种种植制度下,作物有效性较高的酸提取态镉含量显著减少,而作物有效性较低的可还原态和残渣态镉含量显著增加,进而引起了水稻和萝卜对镉的吸收量降低.其中以石灰和海泡石配施的效果最好,单施海泡石次之,单施石灰效果最差,且各处理均随改良剂用量的增加效果增强,虽然,施用改良剂可以有效降低土壤中镉的作物有效性,但对水稻产量和生物量及镉在水稻和萝卜两种作物地上部分的分配规律均没有明显的影响.     

MgAl-LDHs磁性颗粒对镉污染农田土壤的减量修复研究

本研究以不同巯基改性的镁铝层状双金属氢氧化物(MgAl-LDHs)为原材料制备了四种毫米级磁性颗粒修复材料,并开展了对土壤中镉(Cd)去除效果的对比试验,考察MgAl-LDHs磁性颗粒修复材料的投加量和作用时间对Cd去除效果的影响,探讨了修复材料对三种实际污染农田土壤(Cd总量在0.73~0.86 mg/kg之间)中Cd的去除效果与机制。结果表明,以泰克莱尔MgAl-LDHs为原材料制得磁粒MgAl-LDHs-C对Cd的去除效果最好。确定磁粒MgAl-LDHs-C与土壤的最佳投加质量比为1:10,最适作用时间为3 h,在此条件下,浙江台州土壤DTPA提取态Cd含量由0.56 mg/kg下降至0.30 mg/kg;控制m(土):V(液)为1:2,反应温度为25 ℃,振荡频率为180 r/min,按照最优选投加量和作用时间分别向江苏太仓、甘肃白银和浙江台州污染农田土壤中施用MgAl-LDHs-C,三种土壤中Cd总量去除率分别达到26.0%、23.8%和34.7%。对土壤Cd的形态分析结果表明,MgAl-LDHs-C可以显著降低土壤可交换态、可还原态、可氧化态Cd的含量。本研究所制备的MgAl-LDHs-C材料具有良好的土壤Cd去除能力,可为Cd污染农田土壤的减量修复提供科学依据。     

磷灰石等改良剂对重金属铜镉污染土壤的田间修复研究

通过田间小区试验,研究了磷灰石、石灰、木炭、猪粪、铁粉5种改良剂对Cu、Cd复合污染土壤的改良效果。结果表明,石灰、磷灰石、木炭、猪粪降低了土壤溶液中重金属Cu、Cd的含量,提高了土壤溶液的pH,但改良效果随着时间的推移不断降低。磷灰石、石灰、木炭的加入显著降低了有效态Cu含量,但对有效态Cd含量影响较小。与猪粪相比,磷灰石、石灰、木炭显著增加了黑麦草生物量,提高了对重金属Cu、Cd的吸收能力,对该污染土壤的修复具有实践应用价值。     

2种菌联合修复农田土壤镉污染的研究

采用盆栽试验,运用BCR四步法、火焰原子吸收法和稀释涂布平板法等方法,研究了沼泽红假单胞菌(Rhodopseudanonas palustris)和枯草芽孢杆菌(Bacillus subtilis)联合作用对修复农田土壤重金属镉污染盆栽种植小白菜(Brassica campestris L. ssp.chinensis Makino)的效果及安全性,旨在探讨降低土壤镉生物有效性的有效途径,为新型生物菌肥研究提供理论依据。结果表明,沼泽红假单胞菌、枯草芽孢杆菌单独作用以及联合作用均能使农田土壤中镉的固定态增加,降低农田土壤中镉的生物有效性,联合菌处理组镉的生物有效性降低最显著,为32.70%,均对农田土壤中微生物各生理类群数量有显著性影响(P0.05),其中,细菌的数量达到10~5 CFU/g;均显著降低了小白菜根、茎中镉含量,联合菌处理组根、茎中镉的去除率分别达到58.06%～71.37%和73.66%～76.70%;均增加了小白菜株高、茎鲜重、叶绿素a、b的含量和叶绿素a/b的比值,联合菌处理组小白菜的生物量增加18.13%～69.55%。研究结果说明,沼泽红假单胞菌和枯草芽孢杆菌联合作用,对农田土壤镉污染的修复效果显著,且促进了小白菜的生长,具有修复农田土壤重金属污染的潜力。     

不同改良剂对镉污染土壤中小白菜吸收镉的影响

采用盆栽试验, 研究了施用石灰、钙镁磷肥、泥炭、碱渣4种土壤改良剂对外加镉污染的赤红壤上小白菜产量、镉吸收量、土壤有效态镉及pH的影响。结果表明: 外加1 mg·kg^-1和5 mg·kg^-1镉对小白菜生物量无显著影响, 且1 mg·kg^-1镉对小白菜生长有一定的促进作用; 施用改良剂对镉污染土壤上小白菜无显著增产效果。施用4种改良剂均能降低小白菜地上部镉含量, 作用效果为石灰≈泥炭>碱渣>钙镁磷肥。不同改良剂对小白菜根部镉含量影响不同, 泥炭和石灰在所有镉浓度下、钙镁磷肥在0和1 mg·kg^-1镉浓度下可显著降低根部镉含量, 而碱渣无明显作用, 种植两茬规律一致。土壤有效态镉含量与pH呈显著负相关; 施用石灰、碱渣、钙镁磷肥使土壤pH显著升高, 有效态镉含量显著降低, 从而降低小白菜对镉的吸收; 泥炭可显著提高土壤pH, 虽降低土壤有效态镉作用效果不显著, 但显著降低小白菜体内镉含量, 这可能与土壤中形成难以被植物吸收的镉有机结合物有关。两茬蔬菜种植结果显示, 施用后期改良剂对镉污染的抑制效果也较明显。     

镉污染稻田土壤调理剂效果研究

为了验证土壤调理剂对降低稻米镉含量和提高水稻产量的作用,于2018年7月-11月进行了该产品在水稻上的田间试验.结果表明:与不施土壤调理剂的对照相比,施用土壤调理剂能改善水稻多项经济性状,水稻株高、有效穗、穗长、穗总粒数、穗实粒数、结实率和千粒重均有所增加.根据水稻产量构成性状计算的理论产量看,稻谷增产率在11.1％-...     

石灰与生物炭配施对不同浓度镉污染土壤修复

通过室内培养试验,研究生物炭与石灰不同用量配施对镉污染土壤pH和镉赋存形态的影响。结果表明,生物炭与石灰配施能够明显提高污染土壤pH,且随着施入量的增加pH提升效果显著。随着石灰和生物炭配施用量的增加,土壤交换态镉降低比例逐渐增大。培养60天后,镉污染浓度为5mg/kg的土壤交换态镉含量同对照处理相比依次减少36.80%,49.12%和57.38%;而土壤镉污染浓度为20mg/kg的土壤交换态镉含量较对照相比分别降低29.27%,31.68%和39.03%。2个浓度中土壤碳酸盐结合态镉、铁锰氧化物结合态镉和有机结合态镉均有所增加,残渣态镉虽有所增加,但在不同浓度之间存在差异。总体来看,本试验用量条件下,石灰和生物炭配施对污染浓度为5mg/kg的土壤镉钝化效果优于污染浓度为20mg/kg的土壤。     

影响土壤中镉的植物有效性的因素及镉污染土壤的植物修复

阐述了镉的来源及其对人类的危害,并对影响土壤中镉的植物有效性的土壤因素中的pH、氧化还原电位(Eh)、有机物质、营养物质浓度对镉的植物有效性的作用作了详细的阐述。此外对其它如EDTA、淤泥等对土壤中镉的植物有效性的影响和镉污染土壤的植物修复等方面也进行了综述,并对镉污染土壤的修复治理与趋势进行了展望。     

盐基离子 (NO3-、SO42-、SiO32-) 对小白菜铬污染毒性的调控机制

通过水培试验,探讨了主要盐基离子(NO3-、SO42-、SiO32-)对小白菜Cr(Ⅵ)污染毒性的调控作用,结果表明:①Cr对小白菜有极强的致毒能力,可有效抑制小白菜生长、Fe养分吸收和小白菜叶片硝酸还原酶活性,故妨碍碳氮代谢进而降低小白菜产量品质;②适度提高NO3--N浓度可有效缓减Cr对小白菜吸收Fe和硝酸还原酶活性的抑制毒性,并刺激小白菜生长,但NO3-同时也有协同促进小白菜吸收Cr的明显效果:③适当提高SO42-浓度能有效抑制小白菜对Cr吸收,并提高小白菜硝酸还原酶活性,但过高SO42-浓度有一定盐胁迫毒害效应,会影响其对降低小白菜Cr生物毒性的作用效果;④SiO32-对小白菜吸收Cr有较强的抑制作用,但这种作用未起到缓减小白菜Cr生理毒性的明显效果.试验结果表明,适当控制营养液NO3-浓度是抑制小白菜Cr吸收的关键,针对不同的Cr污染水平来调节NO3-、SO42-、SiO32-浓度配比,是抑制小白菜吸收Cr的有效技术措施.     

低量施氮对小青菜生长和氮素损失的影响

采用田间试验和微区试验相结合,研究了低量施氮对小青菜(Brassica.chinensis)产量、氮肥利用率和氮素损失的影响,其中氮素总损失用15N示踪法测定,氨挥发用通气密闭室法测定,反硝化损失用乙炔抑制-原状土柱培养法测定,不加乙炔测定N2O排放。结果表明,施用氮肥显著增加了小青菜的产量和吸氮量,在75和150kg/hm2氮肥水平下,氮肥利用率分别为46.8%和39.4%。由于试验地土壤pH低(5.38),各处理的氨挥发均很低且差异不大,施用氮肥没有增加氨挥发。试验地土壤反硝化损失和N2O排放量较高,分别为N4.34kg/hm2/sup和N2.65kg/hm2,施用氮肥没有增加反硝化损失和N2O排放,表明氮源不是反硝化作用的限制因子。在N75和150kg/hm2两个施氮水平下,氮素回收率分别为103%和91.3%,并且土壤残留氮主要累积在020cm土层,表明肥料氮损失很少,这与氨挥发、反硝化损失较低的结果相吻合。     

重金属污染对水稻田土壤硫酸盐还原菌种群数量及其活性的影响

在实验室条件下,采用重金属Cd2+、As5+、Cu2+、Pb2+和Cr3+处理黄松稻田土壤、紫色稻田土壤和红壤稻田土,28d后分析重金属污染对水稻田土壤的硫酸盐还原菌(SRB)种群数量和硫酸盐还原活性(SRA)的影响。结果表明,在每千克干土中加入200mgPb2+时,对稻田土壤的SRB种群数量和SRA有促进作用;当加入的Cd2+、As5+、Cu2+、Pb2+和Cr3+每千克干土分别超过1.0、30、500、400和200mg时,对稻田土壤SRB种群数量和SRA有明显抑制作用。随着加入量的增加,重金属对水稻田土壤的SRB种群数量和SRA的抑制作用越来越强,水稻田土壤通过自身来恢复SRB种群数量和SRA所需的时间也越长。同一种重金属元素对不同土壤的SRB种群数量和SRA抑制的污染临界值也有差异。     

Phytoremediation of selenium‐contaminated soils: the efficiency of different cropping systems

Field experiments were conducted at two locations in the seleniferous region of northwestern India from 2001 to 2006 to evaluate the efficiency of four cropping systems in removing Se from contaminated soil containing 2843–4345 μg Se per kg in the surface layer (0–15 cm). Rapeseed (Brassica napus) followed by arhar (Cajanus cajan), sunn hemp (Crotalaria juncea) or cotton (Gossypium arboretum) and wheat (Triticum aestivum) followed by rice (Oryza sativa) were the four cropping systems. The total biomass generated by Brassica‐based systems ranged from 16 to 21 t/ha when harvested at maturity. Corresponding values for a wheat–rice sequence were 22–26 t/ha. Among the different crops at both the experimental sites, the highest Se content was recorded in leaves (157–209 mg/kg), grains (64–201 mg/kg) and stems (42–93 mg/kg) of Brassica and the lowest in the shoots (10–27 mg/kg), grains (5–13 mg/kg) and straw (13–20 mg/kg) of the rice crop. Except for S and P, concentrations of other nutrients (Zn, Cu, Mn and Fe) were not significantly affected by variations in the Se content of plants. Significant correlation coefficients were observed between Se and S (r = 0.838, P ≤ 0.001), Se and P (r = 0.817, P ≤ 0.001) at the peak flowering stage (n = 16), and r = 0.743, P ≤ 0.001 and r = 0.498, P ≤ 0.05, respectively, at the maturity stage (n = 16). Total Se removal through harvested biomass of rapeseed‐based cropping sequences varied from 716 to 1374 g/ha/yr at peak flowering and 736–949 g/ha/yr at the maturity stage. Corresponding values for a wheat–rice system were 435–492 and 370–517 g/ha/yr, respectively. The amount of Se recycled through leaf senescence ranged from 255 to 500 g/ha/yr for Brassica‐based cropping systems. In the wheat–rice system, Se addition through irrigation varied from 170 to 243 g/ha/yr and was three to four times more than that added in Brassica‐based systems. On completion of the phytoremediation experiments at site I, Se removal through harvested biomass at maturity was 1.7–5.1% of total Se in the soil down to a depth of 120 cm and 4.8–13.2% at site II. Analysis showed that Se losses under different crop rotations were 18.5–24.5% at site I and 21–33% at site II of total soil Se. Thus, at both sites 16–20% of total Se lost from the soil was unexplained. Results show that Brassica‐based cropping systems lead to significant reductions in Se capital of contaminated soil over 2–3 years. Although a long‐term commitment is required, adoption of Brassica‐based systems as a regular agricultural practice must lead to sustainable management of seleniferous soils.     

硫酸根硫和单质硫对青菜硫素营养的影响

为探究施用硫酸根硫(SO₄^2--S)和单质硫(S⁰-S)对土壤有效硫含量及青菜硫素营养的影响,以矮脚黄青菜品种为材料,采用小区试验,分析不同类型硫肥(硫酸钾和硫磺粉)处理对供试土壤pH值、土壤有效硫含量、青菜产量及硫素营养含量的影响。结果表明,施用硫酸钾(SO₄^2--S)和硫磺粉(S⁰-S)均降低了弱碱性土壤pH值,增加了土壤有效硫含量,且施用SO₄^2--S的影响较S⁰-S更明显。施用SO■-S和S⁰-S均可有效提高青菜株高、可食部分干重和含硫量,均在106 g·m^-2处理水平下达到最大值,且施用SO₄^2--S的提升作用优于S⁰-S。53 g·m^-2SO₄^2--S处理水平下,与对照相比,青菜可食部分硝酸盐含量下降了38...     

不同土壤对Cr吸附的动力学特征

该文采用振荡平衡法比较了来自中国15 个省区16 种土壤对Cr（VI）的吸附及其动力学特性,并探讨了土壤pH值、阳离子交换量、黏粒含量和有机质对Cr（VI）吸附及其动力学参数的影响。结果表明：具有较低土壤pH值和较高物理黏粒含量的土壤对Cr（VI）具有较大的表观吸附量,而土壤阳离子交换量和有机质因素对土壤Cr（VI）的表观吸附量影响较小。酸性土壤对Cr（VI）吸附能力较强,可以采用一级动力学方程和抛物线方程描述Cr（VI）在酸性土壤中的动力学行为,且土壤的表观吸附速率和平衡时的吸附量与土壤的pH值呈显著（p＜0.05）负相关关系,而与物理黏粒含量呈显著（p＜0.01）正相关关系;而碱性土壤对Cr（VI）吸附能力较小,很难用动力学方程描述其吸附动力学特性。可见,土壤pH值不仅影响土壤对Cr（VI）的表观吸附量,并且对Cr（VI）表观吸附动力学特征产生了较大影响。     

广东大宝山矿区土壤重金属污染

Soil contamination in the vicinity of the Dabaoshan Mine, Guangdong Province, China, was studied through determi- nation of total concentrations and chemical speciation of the toxic metals, Cu, Zn, Cd, and Pb, using inductively coupled plasma mass spectrometry. The results showed that over the past decades, the environmental pollution was caused by a combination of Cu, Zn, Cd, and Pb, with tailings and acid mine drainage being the main pollution sources affecting soils. Significantly higher levels （P ≤ 0.05） of Cu, Zn, Cd, and Pb were found in the tailings as compared with paddy, garden, and control soils, with averages of 1486, 2516, 6.42, and 429 mg kg^-1, respectively. These metals were continuously dispersed downstream from the tallings and waste waters, and therefore their concentrations in the paddy soils were as high as 567, 1 140, 2.48, and 191 mg kg^-1, respectively, being significantly higher （P ≤ 0.05） as compared with those in the garden soils. The results of sequential extraction of the above metals from all the soil types showed that the residual fraction was the dominant form. However, the amounts of metals that were bound to Fe-Mn oxides and organic matter were relatively higher than those bound to carbonates or those that existed in exchangeable forms. As metals could be transformed from an inert state to an active state, the potential environmental risk due to these metals would increase with time.     

施硅对小白菜吸收累积和迁移重金属铬的影响

蔬菜品质越来越引起全社会的关注,如何预防和治理重金属对蔬菜产品的污染是目前需要迫切解决的环境问题。通过模拟铬污染土壤施硅的盆栽试验,探讨硅、铬在土壤-蔬菜作物系统间的迁移、转化特性,为研究通过施硅调控蔬菜重金属污染提供依据。研究结果表明:(1)在不同铬水平胁迫下,硅在小白菜体内的积累量不同,根吸收硅的量不同;总的趋势是在试验的各个铬污染水平,一定的施硅量均可提高小白菜地上部的硅含量。(2)铬的各污染处理均有随施硅量的提高而降低小白菜铬积累量的趋势,说明施硅可有效抑制小白菜对铬的吸收。(3)硅的施入,可抑制根吸收的铬进一步运输到地上部,因而减轻了小白菜可食部分受铬污染的程度,在高浓度铬污染处理下,小白菜根中的铬较难运转到茎部;而运输到茎部的铬却易于向叶部转移。(4)硅的加入降低了小白菜各部位对铬的富集能力,从而降低了重金属铬对小白菜的污染。     

Dichromate Digestion–Spectrophotometric Procedure for Determination of Soil Microbial Biomass Carbon in Association with Fumigation–Extraction

A dichromate digestion and spectrophotometric procedure is proposed for estimating soil microbial biomass carbon (C) in association with fumigation–extraction. The recommended procedure uses a volume (1.6 ml) of 0.5 M potassium sulfate (K₂SO₄) soil extracts and oxidant solution (dichromate–sulfuric acid, 2.4 mL), mixed with a volume (4 mL) for digestion at 140 °C for 30 min. The digested solution is then directly read for absorbance at 350 nm using a spectrophotometer, and the C in the digested soil extracts is measured against glucose standards. The K_EC (indicating the extractable part of microbial biomass C after fumigation) value is estimated as 0.33 for the proposed method. There are good correlations between soil microbial biomass C measured by the proposed method, the dichromate digestion titration, and oven oxidation by total organic C (TOC) analytical method. This method is a simple, rapid, and economical procedure associated with fumigation–extraction for biomass C analysis.