Study on the Pretreatment Technology of Phosphogypsum

The economic and effective pretreatment is a key to its recycling into useful building materials. The pretreatment such as washing, neutralizing with quick lime, grinding, floating, screening, calcination etc. have been studied. The effectiveness, problems and feasibility of pretreatment are analyzed. This paper presents the pretreatment principle of phosphogypsum utilization. If the phosphogypsum utilized is more than hundred thousand tones per year, the washing technology is recommended, otherwise, the technology of neutralizing with quick lime and grinding should be chosen.     

重金属污染土壤修复及其对作物效应

为了探讨不同的淋洗剂修复重金属污染的土壤效果,笔者研究利用水、石灰水、EDTA溶液、水+石灰水（即先用水淋洗后,再用石灰水淋洗）、水+石灰水+EDTA溶液（即先用水淋洗后,再用石灰水淋洗,最后用EDTA溶液淋洗）等5种淋洗方法处理尾矿重金属严重污染的土壤。结果表明：水、石灰水以及EDTA溶液等均能提取污染土壤中的重金属,其中EDTA提取的能力最强,水其次,而石灰水最弱;水稻、玉米、大豆和南瓜等4种作物在不经过修复的污染土壤上不能正常发芽生长,而在修复后的土壤上都能正常发芽,但水处理和EDTA溶液处理的土壤,种子发芽后很快死亡,而其他处理的作为仍可继续生长;石灰水或水+石灰水处理的土壤,作物生物量较高;在污染土壤上生长的作物均能吸收重金属,其中大豆和水稻吸收能力较强。这些结果表明,可以利用石灰来修复重金属尾矿污染的土壤,在修复的土壤上生长的大豆和水稻重金属含量较高,在作物布局上要尽量避免种植这2种作物。     

Long-term effects of lime and phosphogypsum application on tropical no-till soybean–oat–sorghum rotation and soil chemical properties

Root growth, nutrition and crop yield can be affected by soil chemical modifications caused by superficial limestone and phosphogypsum application in a no-till system. Using this approach, this study was conducted in southeastern Brazil, continuing an experiment that has been on-going since 2002 with the objective of evaluating the residual effects of the surface application of lime and phosphogypsum on the soil chemical characteristics and the root growth, nutrition and yield of soybean, black oat and sorghum in a dry winter region cultivated in 2008/2009 and 2009/2010. The experimental design was a randomized block with 4 replications. The treatments were applied in November 2004 and were as follows: original conditions, limestone application (2000 kg ha⁻¹), phosphogypsum application (2100 kg ha⁻¹), and limestone (2000 kg ha⁻¹) + phosphogypsum (2100 kg ha⁻¹) application. Superficial liming with or without phosphogypsum reduced the surface and subsurface soil acidity 5 years after application in the no-till system. The movement of Ca²⁺ and Mg²⁺ from the surface layer into the subsoil over time was evident. The phosphogypsum application associated with liming increased the Ca²⁺ levels throughout the soil profile. Liming maintained high levels of Mg²⁺ throughout the soil profile with or without phosphogypsum application. The organic matter content increased with liming with or without phosphogypsum, indicating that in the long term, these practices can increase the C accumulation. Phosphogypsum application had a residual effect on the SO₄-S levels, and high sulphate concentrations were observed in the subsoil after 5 years. Superficial liming improved crop nutrition and, when associated with phosphogypsum, increased Ca absorption by soybean and sorghum, as reflected in the increased yields of these crops.     

云南磷石膏堆存对区域水环境的影响研究

伴随着磷肥产量增加,磷石膏产排量对环境污染等问题愈加突出。为解决磷石膏堆放对环境造成的威胁和磷石膏的资源化利用,本研究通过对云南省磷矿资源主要集中地磷石膏堆场的实地调查、采样并结合模拟试验、建立预测模型等方法,明确磷石膏对区域水体环境介质存在的影响。结论如下：（1）不同堆存点磷石膏均呈酸性。滇池流域的磷石膏含磷量较高、抚仙湖流域的磷石膏含氟量较高。（2）通过地表径流试验,地表水总磷和氟化物的含量基本呈现随迁移距离增加而不断下降的趋势。并建立地表水污染物沿程迁移变化回归模型。地表径流中总磷和氟化物分别迁移至距堆场186.45 m和167.30 m外,可达到地表Ⅲ类水标准。（3）通过土柱淋溶试验,淋出液中总磷含量随淋溶次数的增加整体呈下降的趋势。不同土柱淋出液中氟含量呈现正相关的变化趋势,除个别土柱淋出液外,其他深度的淋出液氟含量在0.15～0.45 mg/L范围之内,可达到地下水的Ⅰ类至Ⅲ类标准。本研究为解决磷矿区乃至流域内磷石膏对水环境等造成的污染负荷问题,提供定量化的理论基础。     

磷石膏和有机肥对盐碱地糜子产量和叶片生理特性的影响

为探索磷石膏和有机肥对盐碱地糜子产量和叶片生理特性的影响,本试验以粘丰5号和内糜8号为试验材料,本研究以‘粘丰5号’和‘内糜8号’为试验材料,在大田条件下设置了4个处理,包括磷石膏（60 t/hm2）、有机肥（187.50 t/hm2）和磷石膏有机肥混合（60 t/hm2磷石膏+187.50 t/hm2有机肥）,以盐碱地未改良作为对照。结果表明：有机肥和磷石膏混合处理对两个糜子品种叶片糖分积累调控效果存在差异,对粘丰5号开花后14d的叶片蔗糖含量、可溶性糖含量促进效果较优,而对内糜8号开花后21d的叶片蔗糖含量、可溶性糖含量促进效果较优;粘丰5号整个测定时期叶片淀粉含量在磷石膏和有机肥混合处理、有机肥处理下基本上低于磷石膏处理,而内糜8号叶片淀粉含量在开花后7d~21d以磷石膏处理为最高,之后,以磷石膏处理为最低;开花后42d叶片可溶性蛋白含量在粘丰5号中以磷石膏有机肥混施处理最高,而在内糜8号中以单施有机肥处理为最高。三种盐碱地改良措施均能够增加糜子产量,其中以磷石膏和有机肥混合处理下的增加效果优于单施磷石膏和单施有机肥处理。     

Effect of surface treatments on soil crusting and infiltration

The effects of phosphogypsum and plant residue mulches on soil crusting and infiltration were studied on a Rhodic Paleustalf in Northern Natal, South Africa. Under field conditions infiltration rates were considerably higher than those obtained with a laboratory type rainfall simulator. Both ameliorants were effective in countering crust formation. Their effect continued over a growing season (4–5 months). Scanning electronmicrographs showed that under moist conditions microbial hyphae and residues were prominent in the surface crust. Extractable soil P built up to high levels in the phosphogypsum treated plots.     

A Modified Clean Production Technique of Recovering Calcium Phosphate for Gelatin Plant

A clean production technique, which can reduce wastewater pollution for gelatin plant in pH, suspended COD and Ca 2+ , has been proposed. Precipitated the lime from lime wastewater produced by lime process, then this alkali water without lime is added to another acidic wastewater produced by pickling process to e CaHPO 4. But in traditional technique, the lime wastewater with lime is added to pickling wastewater directly, little lime wastewater was consumed and large amount of lime wastewater, which contains high pH, high-suspended COD and high Ca, and is difficult to treat by biological treatment, is produced for gelatin plant. It is proved by the experiment that the final wastewater produced by the clean production technique has lower pH for the pickling wastewater consuming large amount of lime wastewater. It has lower COD for all the suspended COD and partial soluble COD being separated from the wastewater absorbed by CaHPO4 sedimentation, and that it has lower Ca for it is no longer the saturated lime solution.     

石灰配施有机物料对稻麦轮作土壤镉影响研究

研究旨在开展探究田间试验条件下铜陵市矿区附近镉重度污染农田土壤经石灰和有机物料修复后土壤镉形态的变化,为农田镉污染提供依据.通过水稻和小麦生长田间试验,研究生物有机肥、生物炭、生物肥3种有机物料与石灰配施对稻麦轮作土壤中镉形态变化的影响.研究结果显示:石灰配合有机物料施用后,小麦季土壤酸碱度范围为pH 4.72～5.3...     

田菁改良重度盐渍化土壤的效果分析

为评价田菁改良重度盐渍化土壤的效果,试验设置4个处理：（1）只种植田菁(T);（2）种植田菁,施用二铵450 kg/hm²(TA);（3）种植田菁,施用磷石膏2250 kg/hm²(TG);（4）不种植田菁的空白处理作对照(CK)。结果表明：施用磷石膏能够显著促进田菁生长(P<0.05),TG处理地上部、地下部生物量较T、TA处理分别增加了14.24%、24.77%和8.32%、12.39%,施用二铵对田菁生长的促进作用不显著。种植田菁能够显著降低重度盐渍化土壤含盐量、容重,提高土壤速效氮、速效钾、水溶性有机质(DOC)含量,及土壤大团聚体含量、平均重量直径(MWD)、总孔隙度(P<0.05),TG处理改良效果最大。相关分析表明,盐渍化土壤含盐量、Na⁺含量、DOC、有机质是维系盐渍化土壤结构的关键性状,降低土壤含盐量、Na⁺含量,提高DOC、有机质含量是盐渍化土壤改良方向。种植田菁,同时施用磷石膏是一种快速提升重度盐渍化土壤肥力的有效方法。     

石灰质量调查及添加量对糙皮侧耳熟料栽培的影响

石灰是食药用菌生产的重要辅料,研究旨在对当前食用菌栽培过程中使用的石灰辅料进行质量摸底,同时研究石灰在糙皮侧耳栽培中的最适添加量,达到精准指导糙皮侧耳和其他食用菌生产的目的.采用消化石灰物相分析法,对8份不同来源石灰的Ca(OH)2、CaO、CaCO3和MgO含量进行检测.同时选用7号石灰按不同比例添加至玉米芯培养料,...     

生物炭对强酸性茶园土壤酸度的改良效果研究

利用盆栽试验研究了施用石灰和不同用量生物炭对强酸性茶园土壤酸度的调控效果。结果表明：施用生物炭和石灰处理均可显著提高茶园土壤pH值。5~20 g/kg生物炭施用量处理土壤的pH值低于施用石灰处理,但当生物炭用量大于40 g/kg时土壤pH值显著高于石灰处理,说明在强酸性条件下,低用量生物炭处理在调节土壤pH值的效果不如石灰。施用生物炭处理土壤阳离子交换量比施用石灰处理提高了0.98%~8.67%,盐基饱和度提高0.85%~40.90%,土壤交换性钙、镁、钾和钠含量分别提高1.70%~11.36%、32.79%~80.52%、76.47%~1744.12%和4.93%~57.48%,说明施用生物黑炭比施用石灰可增强土壤对酸的缓冲性能。     

Chemical amelioration of surface crusting to reduce runoff and erosion on highly weathered soils

Because of the very low soil solution ionic strengths in highly weathered soils, clay particles can be readily dispersed under the impact of raindrops. The clay fraction of many soils is dispersible under the combined effects of mechanical disturbance and low electrolyte concentration. This clay dispersion results in fine particle segregation at the soil surface, with clay particles moving into and blocking soil pores resulting in the formation of a highly impervious crust which reduces infiltration. Because the clay is dispersed, the particles usually orient themselves in a laminar fashion as they settle. As a result, runoff is substantially increased, giving rise to soil erosion. The crusts formed in this manner often have very high strengths which prevent or substantially reduce crop emergence. The formation of such crusts can be prevented by the application of relatively low rates of by-product gypsum such as phosphogypsum on the soil surface which produces sufficient electrolyte in solution during raindrop impact to maintain the clay particles in a flocculated condition. The results of a number of experiments in which different soils were treated with phosphogypsum are discussed to illustrate the effects of electrolyte concentration, level of sodium and other factors on the formation of surface crusts and the consequent runoff and erosion. As a result of the application of phosphogypsum to the soil surface, a laminar orientation of clay particles at the surface is prevented, which allows a much greater proportion of the rainfall to enter the soil. Any crusts formed are thus much weaker and do not reduce seedling emergence. This type of crust formation can also be prevented by reducing raindrop impact through the use of mulches. This phenomenon occurs on many soils not normally considered to suffer from chemically-induced physical problems, which points to the importance of considering chemical as well as physical processes in the evaluation of potential runoff and erosion.     

石灰施用对酸性土壤养分状况和甘蔗生长的影响

土壤pH低,酸化严重是湛江蔗区甘蔗生产的产要限制因子之一。为了提高甘蔗产量,改善酸性 土壤障碍因素,采用土壤培养试验与甘蔗盆栽试验相结合,研究了施用石灰对酸性土壤养分状况和甘 蔗产量、糖分的影响。土壤培养试验结果表明：石灰施用量与供试酸性土壤pH、氮、钙、镁、硫、硅等有效 含量呈显著正相关,而与铁、锰的有效性呈显著负相关,说明通过合理施用石灰,可以显著提高土壤pH 和改善土壤各有效养分状况,从而提高酸性土壤生产力。桶栽试验结果也表明：在湛江蔗区强酸性土 壤上,合理施用石灰可以提高甘蔗产量和糖分,当每千克土壤施用石灰1.2 g,甘蔗产量和糖分分别比对 照提高14.2%和2.4%,当石灰施用过多,单位石灰增施量对蔗茎产量和糖分表现出负效。     

Field performance and molecular profiles of Mexican lime selections

The Mexican lime industry is interested in developing lime cultivars with improved characteristics for fresh and processing markets. The objective of this study was to determine the field performance and genetic molecular differences among four new Mexican lime [Citrus aurantifolia (Christm) Swingle] clonal selections compared to traditional thorny Mexican lime under the dry tropical conditions of Mexico. Tree growth, production, fruit quality, and molecular markers of the traditional thorny Mexican lime (MLT) cultivar were compared to the following lime selections: thornless Mexican lime (MLTS), seedless Mexican lime (MLS), ML 12-8, and ML 20-3. After 10 years of evaluation MLS showed the highest and MLTS the lowest tree growth. Most of the genotypes covered the soil surface area assigned to tree growth since they were 7 years old. Only the less vigorous MLTS required 9 years to cover the same space. MLT was the most productive selection (165 kg/tree/year, mean of 8 years of evaluation). MLS was the less productive (81 kg/tree in the same period of time). MLTS, ML 12-8, and ML 20-3 produced intermediate yields. Acidity and total soluble solids among the selections were very similar. However, MLS had the higher juice content and the lower seed number. The MLS selection is attractive for export market due to these characteristics. AFLP studies confirmed genetic differences among the five lime selections. Nevertheless, all five selections shared many bands as expected.     

AFLP data suggest a potential role for the low genetic diversity of acid lime (Citrus aurantifolia Swingle) in Oman in the outbreak of witches’ broom disease of lime

Acid lime (Citrus aurantifolia) is the fourth largest fruit crop in terms of cultivated area and production in Oman. However, over half a million lime trees were lost in Oman over the past 35?years due to witches?? broom disease of lime (WBDL) which is caused by Candidatus phytoplasma aurantifolia. This study was conducted to examine genetic diversity of acid lime in Oman. AFLP analysis of 143 acid lime samples from Oman, 2 from Brazil and one from Pakistan using 4 primer pair combinations produced 980 polymorphic loci (100?%) and 146 AFLP genotypes. Despite the long history of acid lime cultivation in Oman, populations of lime from different districts were found to have low levels of genetic diversity (0.0888?C0.2284). AMOVA analysis indicated the existence of high level of genetic differentiation (F _ST?=?0.271) among populations of acid lime from Oman and Brazil, which indicates that both populations have evolved independently for a considerably long period of time. On the other hand, AMOVA analysis showed that only 11?% of the genetic variation exists among populations from the 18 different districts in Oman. This suggests frequent exchange of acid lime planting material across geographical regions in Oman. Findings from this study suggest that the low level of genetic diversity of acid lime in Oman and frequent movement of acid lime planting material across districts are two main factors which contributed to the rapid spread and high susceptibility of acid limes to WBDL in the country.     

云南白菜根肿病有机防治技术的研究

选择高锰酸钾、石灰或草木灰、腐熟农家肥等有机投入品对根肿病的控制效果和施用方法进行了初步尝试。实验结果表明,有机肥、石灰、石灰水、高锰酸钾可以作为控制根肿病防治的物质,随着使用时间和使用方式的不同,对根肿病和蔬菜的产量的影响不同。石灰或草木灰塘施或对水浇施,腐熟农家肥和石灰或高锰酸钾配合使用对根肿病的发生均有较好的抑制作用;单施农家肥和高锰酸钾对根肿病控制效果不理想,用腐熟农家肥作底肥＋1%石灰水播种后浇塘＋1%石灰水三叶期浇根＋1%石灰水六叶期再浇根的组合模式可以有效地控制对根肿病的发生与危害。     

Study on the Lime Shape in the Essential System of Activated FA with Water Reducer

This paper studies the lime shape in the essential system of activated FA with water reducer.It shows that the water reducer has passive influence on activation of FA when lime is unslaked,and it will have positive influence when lime is slaked.A primary analysis has been done.     

旱地花生不同土壤类型植株钾素积累动态研究

为了对旱地花生科学施肥提供依据,在大田条件下,以砂姜黑土和棕壤为对象,研究了花生生育期内植株钾积累特性。结果表明：2种土壤类型花生植株根、茎、叶中钾积累量幼苗期都处于较低水平,二者差异不大;出苗后50天到成熟期,砂姜黑土花生根中钾积累量显著高于棕壤,而茎、叶钾积累量在出苗后60天明显低于棕壤。砂姜黑土花生籽仁中钾积累量比棕壤高60%。2种土壤类型花生整株钾积累符合Logistic方程,成熟期砂姜黑土整株钾积累量比棕壤高10%。棕壤花生茎、叶中钾转移到荚果的绝对量小于砂姜黑土,但其所占荚果钾积累比例高于砂姜黑土,进一步提高花生营养体钾素转化率是砂姜黑土花生高效施钾有效途径之一。     

磷石膏改良基质中Cd、Zn在蔬菜内的富集和迁移特征

为查明改良磷石膏是否可以用作耕地,选择白菜、上海青、叶用芥菜和菠菜在磷石膏改良基质上种植,分析Cd、Zn在4种蔬菜不同部位的富集和迁移特征。结果表明：4种蔬菜中Cd、Zn的含量范围分别为0.004~0.039、45.56~361.89 mg/kg,Cd可满足《农产品安全质量无公害蔬菜安全要求》,而Zn超过《农产品安全质量无公害蔬菜安全要求》。Cd、Zn在蔬菜中的总体分布规律均为：根＞茎＞叶,其富集系数分别为0.23~0.47、0.90~3.19,且Zn＞Cd,富集较强,表明Zn较Cd在蔬菜中的富集能力强,易被蔬菜吸收。Cd、Zn在蔬菜中的迁移率总体呈现为：地下部位＞地上部位。     

石灰对土壤重金属污染修复的研究进展

摘要：随着我国经济的快速发展,工农业导致包括重金属在内的大量污染物被排放到环境中,土壤环境污染日趋严峻。石灰由于其在土壤重金属污染修复方面具有成本低廉、操作简单、修复快速、效果明显等优势而受到越来越多的研究者关注,探讨石灰对土壤重金属污染修复效果及机理已成为当前研究的热点之一。系统地综述了国内外近些年来有关石灰对重金属污染土壤修复的研究进展,并重点阐述石灰对土壤重金属生物有效性的影响机理,以及石灰对重金属污染土壤的修复效果。研究表明,石灰对重金属的修复机理主要是通过改变土壤pH、土壤阳离子交换量CEC、土壤盐基饱和度BS、土壤氧化还原电位Eh等过程影响重金属在土壤中的吸附、沉淀、络合等。同时,石灰施用量、土壤pH、重金属污染程度、不同重金属种类以及土地利用类型等因素影响石灰的修复效果。因此,在实际修复过程中,为防止土壤出现板结现象,施用石灰过程中应考虑当地土壤的类型、石灰施用量、施用时期和施用方式等问题。研究旨在为探明石灰对重金属污染土壤改良修复的可行性提供理论支撑,并为实现重金属污染耕地达标生产及阻控提供科学依据。