秸秆还田对镉污染农田土壤中镉生物有效性的影响

通过温室盆栽试验和土壤培养试验,研究了重金属镉污染水稻土和人为模拟镉污染土壤上不同种类和不同量的作物秸秆还田后,土壤中可提取态镉的动态变化规律以及对白菜生长和吸收重金属镉的影响。结果表明,秸秆还田显著提高了2种镉污染土壤的pH值。镉污染水稻土上还田玉米和菜豆秸秆显著提高了土壤中醋酸铵提取态镉和DTPA提取态镉含量,秸秆还田后2周时醋酸铵提取态镉含量增加了17%~33%,随时间延长,土壤中可提取态镉增加变的不明显。模拟镉污染土壤上还田玉米和菜豆秸秆对土壤中醋酸铵提取态镉和DTPA提取态镉含量影响不明显。镉污染水稻土上秸秆还田量2%时显著降低了白菜体内镉含量,还田菜豆秸秆和玉米秸秆白菜体内镉含量分别降低了18%和27%。还田玉米秸秆影响了白菜生长,降低了白菜的产量;模拟镉污染土壤上还田菜豆秸秆对白菜生长和镉含量影响不明显,但还田2%玉米秸秆降低了白菜生物量,增加了白菜镉含量。     

油菜连作及施用堆肥对土壤镉赋存形态和生物有效性的影响

通过温室土培盆栽试验,研究了重金属镉污染土壤上连作油菜及施用堆肥对土壤中镉赋存形态及生物有效性的影响。结果表明：（1）在油菜连作体系下,施用堆肥显著降低油菜地上部镉含量。施用堆肥改变了土壤镉赋存形态,显著降低土壤易溶态和碳酸盐结合态镉含量而增加土壤铁锰氧化物结合态镉含量,从而降低土壤镉的生物有效性。（2）在相同堆肥处理下,种植两茬油菜后的土壤易溶态和碳酸盐结合态镉含量与不种植油菜的处理相比显著降低;而土壤硫化物及有机结合态镉含量较对照有所上升,种植油菜对土壤铁锰氧化物结合态镉和残渣态含量影响不显著,但是不同积累镉能力油菜朱苍花籽和川油Ⅱ-93之间对土壤镉形态的影响差异不显著。     

氮肥对油菜根-土界面镉迁移及镉组分变化特征的影响

利用盆栽试验研究了不同形态氮肥对镉污染土壤油菜根土-界面pH、油菜生长、镉迁移及镉组分变化特征的影响.结果表明,不同形态的氮对油菜地上部Cd积累有显著的影响,施用铵态氮肥可以显著提高油菜地上部Cd含量,而施用硝态氮肥则对地上部Cd含量没有明显的影响.铵态氮肥能显著降低油菜根际pH,使得油菜根际残渣态、碳酸盐态和铁锰结合态Cd强烈活化,促使这三种形态Cd向交换态转换,从而增加了Cd的生物有效性.     

钝化剂对铅锌尾矿砂中重金属的固化作用

铅锌尾矿砂重金属含量高,对环境危害大。为了减缓铅锌尾矿砂的重金属污染风险,采用室内培养实验方法,在铅锌尾矿砂中添加油菜秸秆、芒草秸秆、水稻秸秆、石灰和磷酸一铵等钝化剂,并通过DTPA及Tessier连续提取铅、锌、镉的化学形态,评价钝化剂对铅、锌、镉的移动性和生物有效性的影响。结果表明,油菜秸秆、芒草秸秆、水稻秸秆、石灰和磷酸一铵均显著地降低Cd的生物有效性及其迁移能力;磷酸一铵、油菜秸秆均能有效地降低尾矿砂中Pb的生物有效性及其迁移能力,尤其是磷酸一铵有极显著的效果;油菜秸秆、芒草秸秆、水稻秸秆和磷酸一铵均能有效地降低尾矿砂中Zn的生物有效性及其迁移能力。尾矿砂中DTPA态Cd、Zn与交换态、碳酸盐结合态Cd、Zn极显著正相关,DTPA态Pb与碳酸盐结合态Pb极显著正相关。从Pb、Cd、Zn生物有效态含量的减少方面考虑,油菜秸秆和磷酸一铵是较好的铅锌尾矿砂原位钝化剂。     

不同惰性有机碳物料对土壤镉赋存形态和生物有效性的影响

通过温室盆栽试验和土壤培养试验,研究镉污染土壤和模拟镉污染土壤中加入草炭、活性碳和风化煤3种物料对土壤镉赋存形态和生物有效性的影响,探讨其作为重金属镉污染土壤修复剂的可行性。研究结果表明：3种有机碳物料均降低了土壤pH值,镉污染土壤加入不同惰性有机碳修复剂后,土壤中醋酸铵提取态Cd含量和DTPA提取态Cd含量变化不明显。在模拟Cd污染土壤上则不同,加入不同惰性有机碳修复剂后土壤中醋酸铵提取态Cd含量和DTPA提取态Cd含量均明显降低,降低幅度以风化煤最高,且随加入时间延长降低幅度增加。土壤中加入风化煤和草炭可显著增加土壤中轻组有机质含量,风化煤对土壤中镉有较强富集作用。两种土壤镉赋存形态均为酸提取态〉可还原态〉可氧化态,镉污染土壤加入有机物料后酸提取态镉含量无显著性变化,可还原态镉草炭和活性碳处理显著降低,草炭处理可氧化态镉也显著降低,模拟镉污染土壤加入有机物料后,酸提取态镉风化煤处理显著性降低,可还原态镉活性碳处理显著提高,可氧化态镉无显著性变化。在镉污染土壤上,3种有机碳物料对玉米生长没有显著影响,但增加了玉米体内镉含量;风化煤处理显著降低了白菜生物量,增加了白菜体内镉含量。模拟镉污染土壤上3种有机碳物料对白菜和玉米的生长和体内镉含量均没有显著影响。     

长期秸秆还田对德阳地区稻田土壤镉赋存形态的影响

明确长期秸秆还田对稻田土壤Cd污染阻控或促进效应,有利于制定针对性的农田Cd污染治理措施,对保障粮食安全生产具有重要意义。以四川省德阳市旌阳区Cd污染稻田为研究对象,通过田间实地调查与采样分析,探讨了秸秆还田不同年限(0 a、1 a、4 a、8 a)对农田土壤Cd赋存形态及其生物有效性的影响。结果表明,研究区稻田土壤Cd形态含量分布为:残渣态铁锰氧化物结合态有机结合态碳酸盐结合态可交换态;秸秆还田(4 a以上)显著增加了土壤有机质含量,进而促进了稻田耕作层(0~20 cm)土壤有机结合态Cd含量水平显著上升(以秸秆还田4 a,其含量增加了45%为最高),对土壤可交换态Cd含量略有增加效应;土壤p H则随秸秆还田年限的延长呈先升高后缓慢下降趋势,主要影响土壤碳酸盐结合态Cd含量水平的变化。从土壤Cd形态的生物利用性角度评价,随秸秆还田年限延长(1~4 a),能减轻稻田耕作层(0~20 cm)土壤有效态Cd的分配,促进其向潜在态Cd转移;而对犁底层(20~40 cm)土壤Cd形态的生物有效利用性的影响未达显著水平。总体来看,秸秆还田(1~4 a)提高了土壤有机质含量,显著增加了耕作层(0~20 cm)土壤有机结合态Cd含量水平,促进了耕作层(0~20 cm)稻田土壤Cd由有效态向潜在态转化,降低稻田土壤Cd污染状况;持续长期的秸秆还田(连续秸秆还田8 a以上),则可能因土壤p H下降而促进土壤Cd由潜在态向有效态转化,增加稻田土壤Cd的生物吸收累积效率。     

生物黑炭对玉米苗期根际土壤氮素形态及相关微生物的影响

生物黑炭被作为土壤改良剂应用逐渐被认可,但其应用机制特别是生物黑炭对氮素形态和根际微生物的影响机理尚不明确,影响其推广。本文采用盆栽试验,研究了玉米和水稻秸秆烧制的生物黑炭按不同量施入土壤后,对玉米苗期株高、生物量和根际土壤氮素形态及相关微生物的影响。结果表明,施入60 g·kg-1玉米黑炭和40~60 g·kg-1水稻黑炭均对玉米苗期株高有显著(P0.05)降低作用,其中水稻黑炭的降低效果更为明显;分别施入60 g·kg-1玉米黑炭和20~60 g·kg-1水稻黑炭后,玉米植株地上部生物量均显著降低。施入60 g·kg-1玉米黑炭后根际土壤含水量和微生物量氮显著提高。随两种生物黑炭施入量的不断增加,玉米苗期根际土壤全氮、硝态氮含量以及固氮作用强度也显著增加,且均在60 g·kg-1施用量下达最大值。施用40 g·kg-1玉米黑炭可显著提高玉米苗期根际土壤氨态氮含量。同时,施用两种生物黑炭后,均不同程度地抑制了玉米根际土壤中细菌总体数量,促进了固氮菌和纤维素降解菌的生长,其中施入60 g·kg-1玉米黑炭的效果最为明显。综上,玉米和水稻秸秆生物黑炭的适量施用,可以促进玉米根际土壤氮素的循环转化,影响相关微生物的群落结构,且与水稻秸秆相比,玉米秸秆生物黑炭的施用效果更加明显。本文针对作物生长、土壤氮素形态及相关微生物数量3个方面研究生物黑炭施入土壤对氮有效性的影响,能够更全面、更准确地将生物黑炭如何影响土壤氮素转化展现出来,促进生物黑炭的深入开发利用,对黑土肥力保护具有一定意义。     

不同有机肥对镉污染土壤镉形态及小麦抗性的影响

为了探讨有机肥钝化修复镉污染土壤对小麦生理抗性及小麦体内镉含量的响应,通过盆栽试验研究了不同有机肥对镉污染土壤Cd形态、小麦体内脯氨酸、丙二醛及小麦各部位镉含量的影响。结果表明:在镉污染土壤上施用有机肥后土壤可交换态Cd与碳酸盐结合态Cd含量有所下降,铁锰氧化物结合态Cd、有机结合态Cd和残留态Cd含量有所增加。施用羊粪、鸡粪的处理SH、CHSM、CMSL、CL。施用猪粪的处理PMPHPL。施用有机肥后小麦体内脯氨酸、丙二醛含量和小麦各部位Cd含量显著下降,施用羊粪、鸡粪的处理随施肥量的增加小麦体内脯氨酸、丙二醛含量和Cd含量明显降低,施用猪粪的PM处理的小麦脯氨酸、丙二醛含量和小麦根、茎、叶、籽粒中的Cd含量显著低于其他处理,其综合效果猪粪羊粪鸡粪。有机肥可通过改变污染土壤中的重金属形态而降低其生物有效性,可用于重金属污染土壤修复。     

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。     

施用生物炭和石灰对土壤镉形态转化的影响

通过室内培养试验,比较石灰、生物炭及生物炭和石灰配施3种改良剂作用下镉污染草甸土中土壤镉各形态转化以及pH的影响。结果表明,土壤添加生物炭培养60d,土壤pH呈随时间增加逐渐增加的趋势,而添加石灰和生物炭与石灰配施处理,土壤pH呈现先增加至最大值而后缓缓降低趋于稳定的趋势,但均显著高于对照。各改良剂的施用均显著降低土壤可交换态Cd含量,与CK处理相比,添加生物炭、石灰和生物炭石灰混合改良剂后,土壤可交换态Cd含量分别降低8.6%~13.7%,17.8%~21.7%和18.4%~23.3%。相关分析结果表明,土壤可交换态Cd含量与土壤pH之间均存在极显著的负相关关系(R2=0.74)。土壤添加改良剂后,显著降低土壤可交换态Cd比例,增加碳酸盐结合态、铁锰氧化物结合态、有机结合态和残渣态Cd比例,从而降低土壤重金属的生物有效性。     

不同钝化剂配施硫酸锌对石灰性土壤中镉生物有效性的影响研究

为了降低轻度镉（Cd）污染土壤中Cd的生物有效性以确保农产品安全,以低吸收豆类蔬菜（豇豆）作为供试植物,通过田间试验研究了在轻度Cd污染（Cd1.5mg·kg-1）石灰性土壤中施加赤泥、油菜秸秆、玉米秸秆、赤泥＋油菜秸秆等钝化处理并配施硫酸锌肥料对土壤中Cd的生物有效性的影响。结果表明,与对照相比,不同钝化处理可显著（P〈0.05）降低豇豆豆角中Cd浓度和土壤中可溶态Cd浓度;钝化处理条件下豇豆豆角中Cd浓度降低了27%（玉米秸秆）~83%（赤泥＋油菜秸秆）。在施加钝化剂的基础上,配施硫酸锌肥料可进一步降低豇豆对Cd的吸收,各钝化处理在配施锌肥后,豇豆豆角中Cd平均浓度与未施锌肥相比降低了27%。对不同作物秸秆而言,富含巯基的油菜秸秆比富含纤维素的玉米秸秆钝化效果好。由此可见,在轻度Cd污染的石灰性土壤中,无机钝化剂赤泥和富含巯基的油菜秸秆复合使用是一种高效且环境友好的钝化手段。同时,合理施用锌肥可能会进一步降低作物对Cd的吸收。     

Cadmium accumulation and partitioning in Ocimum basilicum as influenced by the application of various potassium fertilizers

Potassium (K) is one of the major essential nutrient elements whose application of organic or nano-chelate-fertilizers has received increased attention recently. Cadmium (Cd) contamination in agricultural soils and environment is increasing due to the over-application of Cd-containing phosphate fertilizers. But few studies have been carried out on the environmental influences of K-nano-chelate fertilizers especially on Cd-polluted soils. Therefore, the effects of K-fertilizer application in different rates (0, 100 and 200 mg kg^?1 soil) and forms (KCl, K₂SO₄ and K-nano-chelate) on Cd content and partitioning in Ocimum basilicum grown on an artificially Cd-contaminated calcareous soil (with 40 mg Cd kg^?1 soil) were studied under greenhouse conditions. Cadmium decreased shoot dry weight (SDW), but did not affect root dry weight (RDW) and no consistent trend was observed with applied K. Cadmium increased shoot and root Cd concentration or uptake. KCl and K₂SO₄ increased shoot Cd concentration compared to that of control, whereas K-nano-chelate did not affect it. In Cd-treated soils the mean value of Cd translocation factor (ratio of Cd concentration in shoots to that of roots) decreased by 60% as compared to that of the control. Application of 100 mg K-K₂SO₄ and 100 and 200 mg K-nano-chelate increased the Cd translocation factor by 49, 59 and 112% in Cd-treated soils, respectively. In Cd-treated soils, greater amounts of Cd accumulated in roots. K-nano-chelate could mitigate the adverse effect of Cd on SDW and Cd accumulation in plants grown on Cd-polluted soils, so the risk of Cd entrance to the food chain is reduced (however, in Cd-untreated soils, K-nano-chelate increased the Cd translocation factor higher than other K sources). In Cd-polluted soils KCl was the most inappropriate fertilizer that may intensify Cd accumulation in plants. However, it may be useful in the phytoremediation of Cd-polluted soils.     

Distribution and Availability of Heavy Metals in Raw and Acidulated Phosphate Rock–Amended Soils

Abstract

The effectiveness of the application of raw (PR‐1), and partially acidulated phosphate rock (PR), at 25% (PR‐25) and at 50% (PR‐50), was investigated to reduce extractability and plant uptake of Pb, Cd, Cu, Ni, and Zn in three calciorthids soils.Furthermore, the effects of soil treatments on metal extractability were evaluated by sequential extraction. Similarly, such effects were assessed on the phytoavailability of metals of maize (Zea mays L.) through a pot experiment. Water‐soluble and exchangeable metal fractions (the bioavailable fractions) were influenced distinctively by PR treatments and soil properties. In addition, decrease of soluble and exchangeable metal fractions was compensated by an increase in metal extracted from other fractions. Most bioavailable soil metals correlated significantly with their associated level in plant tissue. Finally, plant metal uptake decreased with PR treatments, suggesting that PR application was likely to be effective in controlling metal immobilization in these soils.     

Effect of humic acid amendment on cadmium bioavailability and accumulation by pak choi (Brassica rapa ssp. chinensis L.) to alleviate dietary toxicity risk

Cadmium (Cd) contamination in soil and its movement into food chain through vegetable dietary poses a risk to human health. A pot experiment was conducted to investigate the effect of humic acid (HA) and two cultivars of Brassica rapa ssp. chinensis L. (pak choi) with differing Cd accumulation abilities on Cd accumulation in different Cd contaminated Ferralsol, Histosol and Luvisol soils. The results showed that HA significantly increased soil pH and cation exchange capacity in Ferralsol (acidic) and Histosol (neutral) soils. HA was more effective in Ferralsol and Histosol soil in reducing bioavailable Cd and its accumulation in both cultivars. Low and high Cd accumulating cultivars combined with HA effectively reduced shoot Cd concentration by 7–34% and 19–35% in Histosol soil, whereas 22–34% and 11–26% in Ferralsol soil, respectively. However, no such reduction was observed for Cd accumulation and bioavailability in Cd-contaminated Luvisol (alkaline) soil. Application of HA enhanced shoot dry biomass in both cultivars grown in Histosol and Ferralsol soils. Therefore, the HA amendment combination with low Cd accumulating cultivars of pak choi could be an effective method for phytostabilization and reduce health risks associated with consuming this vegetable grown in Cd-contaminated acidic and neutral pH soils.     

在积累镉油菜后茬种植白菜可否减少其对镉的吸收?

Rapeseed (Brassica campestris L.), a Cd-accumulating crop, is effective in reducing plant-available Cd from soil. A pot experiment was conducted to test the hypothesis that the Cd uptake by Chinese cabbage (Brassica pekinensis Rupr.) grown in rotation with rapeseed would be reduced due to the efficient removal of bioavailable Cd from soil solution by the rapeseed crops. The Cd removal by shoot for the rapeseed cultivar Zhucang Huazi ranged from 0.24% to 0.99% in natural Cd-contaminated soil (soil A) and from 0.63% to 1.23% in artificial Cd-contaminated soil (soil B) during the growth period of 4–7 weeks; whereas that for the rapeseed cultivar Chuanyou II-93 ranged from 0.25% to 0.66% and from 0.38% to 1.02%, respectively. Chinese cabbage grown in the pots with soil A for five weeks after harvesting rapeseed exhibited a significantly lower Cd concentration compared to that grown in the control pots (uncropped with rapeseed). However, the rotation of rapeseed did not lower the Cd concentration of Chinese cabbage on soil B. Although an increase of Cd uptake was observed in the rapeseed cultivars with growth time, and the decrease of soil NH 4 OAc-extractable Cd was found only in the natural rather than artificial Cd-contaminated soil.     

解钾细菌与黏土矿物协同促进玉米生长提高土壤养分有效性

为了揭示解钾细菌在西北矿区浅埋古河道土壤中对植物生长和土壤养分利用的影响,通过日光温室短期盆栽的方式,以不同黏土矿物配比的人工培土为基质模拟古河道不同质地土壤,以西北地区常见农作物玉米为宿主,研究解钾细菌在人工培土基质中的微生物数量变化规律,以及二者协同作用对玉米生长和矿质养分吸收的影响。结果表明:1)土壤黏土矿物含量增大有利于提高土壤解钾细菌数量,促进微生物活性。当黏土矿物质量分数为68%,速效钾质量分数约170 mg/kg时,解钾细菌数量最大;2)玉米地上部分干质量、根冠比、根系活力随黏土矿物含量增大而增大,以解钾细菌作用下黏土矿物质量分数68%的玉米生长效果最佳;3)在解钾细菌作用下,植物氮磷钾积累量和土壤养分利用的最佳土壤黏土矿物质量分数为45%、68%和75%,土壤钾素、氮素和磷素最大利用率分别达到65%、53%和17%;4)解钾细菌在土壤钾素含量低时促进土壤磷素吸收,土壤钾素过量时,促进土壤氮磷钾的吸收,提高土壤养分利用率。因此,土壤黏土矿物与解钾细菌相互作用,而且积极影响植物生长和土壤养分的吸收利用,这对进一步探寻适合矿区浅埋古河道土壤的微生物复垦技术,深入改良和开发矿区退化土壤具有重要意义。     

镉修复土壤中磷酸盐对镉的形态转化和植物吸收的影响

Phosphate was found to have neither influence on Cd transformation nor effect on plant Cd uptake in three Cd-amended upland soils.However,on submerged red earth,high phosphate dressing inhibited the transformation of Cd from exchangeable fraction to other lower-available ones.Cadmium uptake by rice plants increased simultaneously with increasing phosphate supply though plant resistance to Cd also increased at high phosphate level.Application of phosphate as an amendment for Cd-contaminated soil was therefore not recommended in view of the increasing influx of Cd into food chain especially on flooded soils.