Effect of phosphate fertiliser type on the accumulation and plant availability of cadmium in grassland soils

Cadmium (Cd), a potentially toxic heavy metal for humans and animals, accumulates in the liver and kidneys of older animals grazing New Zealand and Australian pastoral soils. Phosphorus (P) fertiliser is the major input of Cd into these farming systems. A study was conducted to evaluate the effects, over 10 years, of annual application (30 kg P ha^–1 yr^–1) of four forms of P fertilisers having different solubilities and Cd contents [41, 32, 10 and 5 g Cd g^–1 for North Carolina phosphate rock (NCPR), single superphosphate (SSP), diammonium phosphate (DAP) made from low Cd phosphate rocks and Jordan phosphate rock (JPR) respectively] on soil and herbage Cd concentrations. Ten years of fertiliser application caused a marked increase in surface soil Cd concentrations. Total soil Cd was significantly higher in SSP and NCPR treatments compared to control (no P fertiliser), JPR and DAP treatments in the 0–30 and 30–75 mm soil depths. Plant-available Cd (0.01 M CaCl₂ extractable Cd) was higher in SSP treatments than in control and other fertiliser treatments. Chemical analysis of herbage samples showed that there was no significant difference in Cd concentration in pasture grasses between treatments in the second year of the trial but in the eighth and tenth year, plots fertilised with SSP and NCPR had significantly higher Cd in pasture grasses in most of the seasonal cuts compared to control, JPR and DAP. Cadmium recovery by both grasses and clover was less than 5% of Cd applied in fertiliser. Clover Cd concentration and yield were much lower than those for grass and therefore its contribution to pasture Cd uptake was very low (< 7%). A strong seasonal effect on grass Cd concentration, which is inversely related to pasture growth rate, was observed in all three sampling years — Cd concentration was highest during autumn and lowest in spring. Total Cd contents of the fertilisers and their rate of dissolution rather than soil pH [pH (H₂O) at 30–75 mm depth of 5.39, 5.20, 5.11 and 5.36 for NCPR, SSP, DAP and JPR treatments respectively]influenced soil and herbage Cd. These results showed that the use of P fertilisers with low Cd contents will reduce herbage Cd levels and has the potential of reducing Cd levels in grazing animals and their products.     

Use of electroultrafiltration (EUF) method for investigating the behaviour of phosphate fertilizers in tropical soils

The solubility of superphosphate and rock phosphate was studied in six soils differing widely in pH, clay content, and type of clay minerals. Soils were incubated with increasing amounts of phosphate fertilizer for 1, 4, 12, and 24 weeks at 60% maximum water capacity and then extracted by means of electroultrafiltration (EUF). In the acid soils (pH-H₂ O: 4.3 to 5.6) the phosphate quantities extracted did not differ much between fertilizer types. In the neutral soils (pH-H₂ O: 6.6 to 6.9) 2 to 10 times as much was extracted from the superphosphate treatments as from the rock phosphate treatments. A fractionated EUF extraction (change of extraction time and voltage) showed that in the acid soils, rock phosphate was more soluble than superphosphate, but in neutral soils the opposite was true. In five of the six soils investigated the solubility of superphosphate declined during an incubation period of 24 weeks, whereas the solubility of rock phosphate showed no clear trend in relation to the time of incubation.

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Zusammenfassung Die Lölichkeit von Superphosphat und Rohphosphat wurde in 6 Böden untersucht, die sich beachtlich in ihrem pH-Wert, in ihrem Tongehalt und in ihren Tonmineraltypen unterschieden. Die Böden wurden mit steigenden Phosphatmengen für die Dauer von 1, 4, 12, und 24 Wochen bei 60% der maximalen Wasserkapazität inkubiert und dann mittels Elektroultrafiltration (EUF) extrahiert. In den sauren Böden (pH-H₂O): 4.3 bis 5.6) unterschieden sich die Phosphatmengen nicht wesentlich, die von den beiden Phosphatdüngemitteln extrahiert wurden. In den neutralen Böden (pH-H₂ O: 6.6 bis 6.9) wurde von den Superphosphatvarianten 2 bis 10 fach mehr Phosphat extrahiert als von den Rohphosphatvarianten. Eine fractionierte EUF-Extraktion (Änderung der Desorptionszeit und der Spannung) zeigte, daß in den sauren Böden das Rohphosphat besser löslich war als das Superphosphat; in den neutralen Böden wurde die umgekehrte Beziehung gefunden. In 5 von den 6 untersuchten Böden nahm die Löslichkeit des Superphosphates im Verlaufe der 24 wöchigen Inkubationsdauer ab. Die Löslichkeit des Rohphosphates zeigte keinen klaren Trend in Abhängigkeit von der Inkubationsdauer.

     

含磷洗涤剂对环境的影响及监管建议

分别从水体、动植物及人类三方面详细阐述了污水排放的含磷有机物对环境造成的危害,并且参照国外的经验提出了治理污染的具体建议。     

高水溶性磷酸二铵生产技术开发

介绍高水溶性磷酸二铵生产原理及生产技术。通过研究浓磷酸沉降过程,采用特殊的强制性渣酸分离技术除去酸中金属离子络合物((Fe,Al)_3KH_(14)(PO_4)_8·4H_2O)淤渣;同时,根据洗涤工段磷铵料浆特性,调节洗涤系统磷酸加入量及磷酸二铵料浆pH值,并采用强制性渣浆分离技术除去磷铵料浆中金属离子络合物沉淀,提高磷酸二铵产品水溶磷含量。对产品养分进行理论计算,产品w(总养分)为65.23%。600 kt/a高水溶性磷酸二铵生产装置投产以来,生产装置运行平稳,产品m(P_2O_(5水溶))/m(P_2O_(5有效))均值高达92.26%。     

入世后高浓度磷肥中镉的问题

入世后 ,TBT协议所形成的技术贸易壁垒将影响我国磷肥进出口贸易 ,讨论高浓度磷肥中放射性元素镉的分布、除去方法 ;针对磷肥中潜在镉的污染问题 ,建议利用 TBT协议建立必要的技术壁垒。     

湖北白果坪磷矿镉地球化学特征及研究意义

通过对白果坪磷矿床中镉地球化学特征的研究,探讨了对磷块岩矿床中镉的表生地球化学作用过程研究的意义.白果坪磷矿风化磷矿中的镉含量较原生磷矿镉含量高近一倍,表明在地表氧化环境下,镉元素在酸性水溶液的作用下被氧化淋滤发生了明显迁移.镉在磷块岩中的赋存状态为类质同象和吸附态,在风化磷矿石中以吸附态为主.研究镉元素在表生风化作用下的活化-迁移-沉淀富集机理可以为防治磷矿山开采中可能产生的镉污染提供对策.     

The effect of long-term phosphatic fertiliser applications on the amounts and forms of cadmium in soils under pasture in New Zealand

This paper presents the results of an investigation into the rate of Cd accumulation and changes in forms of Cd in a soil that has been subjected to long-term superphosphate fertiliser application. Results indicate that there had been a significant accumulation of Cd in the soil during the past 44 years. On the high fertiliser treatment (376 kg superphosphate ha^-1 yr^-1), Cd was estimated to have accumulated at a rate of 7.8 g ha^-1 yr^-1. During the course of the trial, there was an increase in the proportion of Cd associated with exchangeable and soil organic matter fractions on the fertilised plots, which was related to a corresponding increase in soil organic carbon levels. Results also indicate that although there was a large proportion of added Cd associated with the organic fraction, the concentration of applied Cd occurring in the residual fraction was also substantial (i.e >25% of added Cd). In addition, an investigation into the effects of residence time of Cd in the soil indicated that there was a redistribution of Cd into less soluble forms with time (i.e. residual Cd), along with a decrease in total soil Cd concentrations. There was also evidence of movement of Cd down the soil profile in this irrigated soil. The implications of these results for Cd phytoavailability are discussed.     

微波辐射制备复合吸附剂对磷酸根的吸附性

用微波辐射制备无机复合吸附剂。将该吸附剂进行含磷废水的吸附试验，研究了静态吸附的动力学、热力学和再生条件。结果表明：该吸附剂对磷酸根的吸附符合一级反应动力学；平衡浓度与吸附容量符合Freundlich吸附等温线。失活的吸附剂在低的碱性溶液中很容易再生，解吸率可达98％，活化率为99％。     

特殊形貌磷酸镉铵的室温固相合成

为了丰富微孔材料磷酸镉的研究内容以及探讨其形貌控制的方法,报道使用简单的室温固相法合成制备了新颖的、具有特殊形貌的磷酸镉铵(NH4)CdPO4.H2O,并对该样品进行了比较全面的表征测试。研究结果表明,在模板剂的帮助下可以制备具有规整矩形片状形貌的磷酸镉铵,其长和宽在0.8—1.5μm范围内。该粒径尺寸明显大于由XRD估算的平均粒径(56 nm),表明该样品为多晶态颗粒。并初步探讨了模板剂对该磷酸盐形貌的控制机理。磷酸镉铵的形貌控制研究为今后进一步深入探究其性能,特别是吸附性能,奠定了相应的实验基础。     

ZnAl类水滑石制备温度对吸附剩余污泥脱水液中磷酸根的影响

A group of Zn-Al layered double hydroxides (LDHs) were synthesized at different temperatures from 25–90 °C in order to investigate the influence of synthesis temperature on characteristics of the LDHs and their phosphate adsorption behaviour. The results reveal that an increase in the synthesis temperature generally improves the specific surface area of the sample and the phos-phate adsorption capacity. The significantly enhanced crystallinity of the Zn-Al-30, synthesized at 30 °C, leads to a remarkable de-crease in the specific surface area and consequently a poor phosphate adsorption capacity. It is suggested that the surface adsorption plays an important role in the phosphate uptake by the Zn-Al LDHs. Zn-Al-70 presents a relatively higher crystallinity and a lower specific surface area, compared with Zn-Al-60 and Zn-Al-80, but the highest phosphate adsorption capacity, indicating that surface adsorption is only one of the pathways for phosphate removal. The phosphate adsorption by the Zn-Al follows a pseudo-second-order kinetic equation. The adsorption isotherms fit Langmuir models, and the maximum adsorption capacities of the Zn-Al-25, Zn-Al-50 and Zn-Al-70 are estimated to be 17.82, 21.01 and 27.10 mg&#8226;g&#61485;1 adsorbent, respectively.     

纳米钛酸锶钡粉体制备及其对水中Cd2+吸附行为

采用草酸盐化学共沉淀法制备了草酸氧钛锶钡前驱体,通过905℃高温煅烧,制得了高纯纳米钛酸锶钡,并利用SEM、TEM、FT-IR和XRD对其进行了表征;并将该粉体应用于水中重金属镉离子的吸附.结果表明：该法合成的钛酸锶钡粉体为球形,钙钛矿结构,平均粒径为36 nm.对水中的镉离子具有较强的吸附能力,其吸附量与介质的pH值有密切关系,吸附动力学符合Langmuir和Bangham速率方程所描述的规律;吸附等温线较好地符合Langmuir和Freundlich等温方程,吸附行为是自发的、放热的物理吸附过程.     

煤气化渣对磷酸根的吸附与解吸性能研究

煤气化渣是煤化工领域的一种固废,其大量排放对自然环境造成很大压力,对其进行资源化利用尤为重要。本研究基于煤气化渣结构特殊、比表面积较大的特点,研究了不同吸附条件对煤气化渣吸附磷酸根的影响,同时研究了煤气化渣对磷酸根的解吸及再吸附特性。结果表明,煤气化渣对磷酸根的吸附符合Langmuir等温吸附模型和拟二级动力学反应模型。在pH=7、投料量为2.5 g/L、温度为30 ℃、时间为480 min的条件下,其Langmuir饱和吸附量达到3.998 4 mg/g。此外,煤气化渣对磷酸根还具有较好的解吸效率和再吸附能力。研究表明煤气化渣具有作为磷肥缓释剂的潜力。     

The isotherm,kinetic and thermodynamic studies of the cadmium uptake by colpomenia sinuosa

ABSTRACT

A number of isotherm models were studied and modeled for colpomenia sinuosa. The experimental data were fitted among the 12 biosorption kinetic models. Thermodynamic studies indicated a spontaneous and endothermic process. The morphology of the biosorption process was revealed by Fourier transfer infrared (FT-IR) analysis and scanning electron microscope (SEM). The isotherm and kinetic parameters were compared with other microorganisms.     

Effectiveness of partially acidulated phosphate rock as a source to plants in calcareous soils

In a series of greenhouse experiments granulated phosphate fertilizers prepared by mixing triple superphosphate with phosphate rock and partially acidulated phosphate rock, ranging in their content of water souble P from 95 to 17 per cent of total P were applied to neutral and slightly alkaline (pH 6.9–7.8), sandy loam to clay soils ranging in calcium carbonate content from 2 to 35 percent. Dry matter yield of clover, alfalfa, millet or maize were obtained, P uptake determined and sodium bicarbonate extractable P in soil measured. In one field experiment triple superphosphate was compared to mixture of triple superphosphate and phosphate rock on maize. X ray difraction on one triple superphosphate — phosphate rock mixture and on one partially acidulated phosphate rock showed that both fertilizers contain mainly monocalcium phosphate and fluorapatite. After incubation in soil the dicalcium phosphate content rose and the monocalcium phosphate disappeared.Parameters received in greenhouse experiments and in the field indicate that phosphate fertilizers composed of superphosphate and up to 50 percent phosphate rock are as efficient source of P to plants on calcareous and slightly alkaline soils as superphosphate. If this indication would be proven in extensive field experimentation it would lead to savings in acid consumption and in fertilizer manufacturing plant capacity for calcareous soils.     

木素稀硝酸氧化及其与磷酸钙作用的研究

研究了造纸黑液木素稀硝酸氧化法制备活性氧化木素的适宜条件。结果表明,当磷酸含量为4.0%,木素与稀硝酸的质量配比为1∶10,可得到腐殖酸含量达46%的氧化木素。研究了氧化木素和氨化氧化木素对3种磷酸钙的溶解性的影响,讨论并合理地解释了反应机理。     

A comparison of sequential extraction procedures for measuring phosphate rock residues in soils

Laboratory studies have been undertaken to evaluate sequential extraction procedures to measure phosphate rock (PR) residues in a range of temperate (New Zealand) and tropical (Indonesian) soils. The amounts of soil and PR-P were measured by using a sequential procedure which involved pre-extraction with either 1M NaCl or 0.5M NaCl/TEA (pH 7), followed by 1M NaOH and mineral acids. The acids included varying concentrations of HCl or H₂SO₄ (0.5–4M) and a tri-acid mixture of HCl, HNO₃ and HClO₄ (5:5:7). Amounts of PR residues in the soil were estimated from increases in amounts of the acid-extractable P (acid-P) or Ca (acid-Ca) in the PR-treated over untreated soil.Amounts of PR-P residues (measured by HCl-P) in New Zealand soils varying in pH and Ca levels were completely recovered (±5%) when the soils were pre-extracted with 0.5M NaCl/TEA, rather than 1M NaCl (or no pre-extraction). Pre-extraction of acid soil/PR mixtures with 1M NaCl caused dissolution of PR during the extraction. Although the HCl-Ca also estimated the amount of PR residues well, particularly after a 0.5M NaCl/TEA pre-extraction, this method was less sensitive than the HCl-P method, particularly in the soils with high native Ca saturation.In contrast to the high recovery obtained from the New Zealand soils, the recovery of the PR-P residues in the Indonesian soils in the HCl extracts following the 0.5M NaCl/TEA and 1M NaOH extractions were low ranging from 62 to 86%. Although increasing the concentration of HCl (upto 4M) did not cause any improvement in the recovery of PR-P, extraction with H₂SO₄ achieved complete recovery of PR-P. For all soils, a sequential extraction involving 0.5M NaCl/TEA-1M NaOH-0.5M H₂SO₄ is recommended for measuring PR residues in pairs of PR-treated and untreated field or laboratory incubated soils.     

常压微波消解-原子吸收光谱法测定磷矿中铅、镉、汞

采用常压微波消解法前处理磷矿样品,使用GGX-9型原子吸收光谱仪测定磷矿中铅、镉、汞含量,铅、镉、汞检出限分别为0.009 3、0.012 0、0.011 0μg/g,加标回收率分别为100.06%～100.18%、99.73%～100.18%、99.51%～100.63%,3种元素的相对标准偏差均在1%左右。     

Differential influence of soil pH on the availability of partially sulphuric and phosphoric acidulated phosphate rocks II. Chemical and scanning elecronmicroscopic studies

Part I of this study showed that the plant availability of P from a reactive phosphate rock (PR), North Carolina PR, partially acidulated with phosphoric acid (Phos-PAPR) increased with decreasing soil pH from pH 6.1 to 5.1, whereas availability from a blend of similarly reactive PRs partially acidulated with sulphuric acid (SA-PAPR) changed little. The present study was carried out to explain the above results. Phosphate sorption maximum of soil as a function of soil pH was determined. Soil samples obtained at the completion of the pot experiment [5] were analysed for inorganic P fractions, and the amounts of PR dissolved from the PAPRs were determined. A leaching study, simulating pot experiment conditions, was conducted to determine the changes in the chemical composition and the spatial distribution of P, S and Ca in the fertilizer residues. The properties of the PAPRs were further characterised by sequential extraction of the fertilizers. Phosphate sorption isotherms indicated a smaller amount of P in solution at lower pH values, which suggested reduced P availability with decreasing soil pH. Dissolution of the residual PR-P was generally greater in Phos-PAPR treatment than in PR applied directly or in the SA-PAPR treatment. PR-P dissolution in Phos-PAPR increased with decreasing pH but not in SA-PAPR. Chemical, electron microprobe, X-ray micro-analysis and X-ray powder diffraction studies of the fertilizer residues obtained from the leaching and sequential extraction experiments showed rapid dissolution of the Ca(H₂PO₄)₂ phase of the fertilizers but the CaSO₄.XH₂O persisting as a cementing phase between the PR particles. The CaSO₄.XH₂O which intially existed mostly in an anhydrous form changed to gypsum. It was concluded that the dissolution of PR-P in the SA-PAPR was impeded by the presence of CaSO₄.XH₂O acting as a physical barrier and also by providing higher Ca in solution than that would exist in a saturated solution of the apatites. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effect of citrate and tartrate on phosphate adsorption by amorphous ferric hydroxide

Curves for P adsorption by ferric hydroxide in the presence of citrate and tartrate were prepared. From the curves, it appeared as though tartrate at 10^–4 M has no effect on P adsorption up to 750µmol P g^–1 ferric hydroxide adsorbed. However, observation of flocculation patterns show that even when the curves are identical, there is a difference in the way P is adsorbed in the presence of tartrate and citrate in terms of the type of site that is attacked.Assessment of phosphate - citrate competition using³²P and¹⁴C showed that citrate is less readily adsorbed by ferric hydroxide than tartrate and that citrate dissolves adsorption sites more readily than tartrate.The implications of this study are that root exudates containing a greater amount of tartrate would cause more efficient use of added P by plants since tartrate occupies the high affinity sites and therefore reduces phosphate fixation. Plants which produce root exudates high in citrate content would be able to utilize more fixed P than plants which produce exudates lower in citrate content because citrate dissolves sites at which P is held.     

磷在土壤中的固定机制和磷肥的高效利用

磷肥当季利用率只有10%～25%,通过系统分析文献研究进展表明,磷肥低效利用的主要原因是土壤对磷的固定,固定方式包括吸附固定和化学反应固定。土壤对磷的固定取决于土壤中碳酸钙、铁铝氧化物、土壤粘粒的含量以及土壤中磷的初始浓度,在施肥初期发生大量的吸附固定,持续数小时至数十小时,后期逐渐转化为化学反应固定,使有效态磷转化为无效态磷,持续数月乃至数年。磷肥在土壤中的固定动力学可用Elovich方程描述。要减弱土壤对磷的固定,需要降低土壤中水溶性磷的浓度。本文结合文献中报道的嵊县红壤对磷的固定规律和油菜对磷的吸收特性,定量分析了磷在土壤中的释放、固定、吸收过程,通过建立模型计算得出,与单施普通磷肥相比,混施普通磷肥和包膜磷肥可大幅度降低施肥量和提高磷的当季利用率。