Loss of carbofuran from rice paddy water: chemical and physical factors.

The loss of carbofuran was studied from rice paddy water treated with a granular formulation of the insecticide, and from ponds filled with drainage from the paddy. The average half-life (t 1/2) for carbofuran loss was 57 hr. Controlled experiments indicated that pH was the predominating factor governing carbofuran loss from water in the environment studied. The loss due to hydrolysis was over 700 times more rapid at pH (t 1/2 = 1.2 hr.) than at pH (t 1/2 = 864 hr.) in buffered deionized water. The average pH of the rice paddy was 8, but diurnal fluctuations of 7 to 9.5 are common in similar environments. Impurities in the water, sunlight, and temperature influence the rate of carbofuran loss but not nearly so much as pH. There was no evidence for significant loss due to evaporation or oxidation. The results have important implications for the duration of the insecticide's activity and the effect on fish within or downstream from treated paddies.     

Residues of carbosulfan and its metabolites carbofuran and 3-hydroxy carbofuran in rice field ecosystem in China

The fate of carbosulfan (seed treatment dry powder) was studied in rice field ecosystem, and a simple and reliable analytical method was developed for determination of carbosulfan, carbofuran, and 3-hydroxyl carbofuran in brown rice, rice straw, paddy water, and soil. The target compounds were extracted using acetonitrile or dichloromethane, cleaned up on acidic alumina or florisil solid phase extraction (SPE) cartridge, and analyzed by gas chromatography. The average recoveries of carbosulfan, carbofuran and 3-hydroxy carbofuran in brown rice, rice straw, paddy water, and soil ranged from 72.71% to 105.07%, with relative standard deviations of 2.00–8.80%. The limits of quantitation (LOQs) of carbosulfan, carbofuran and 3-hydroxy carbofuran in the samples (brown rice, rice straw, paddy water and soil) were 0.011, 0.0091, 0.014, 0.010 mg kg^?1, 0.016, 0.019, 0.025, 0.013 mg kg^?1, and 0.031, 0.039, 0.035, 0.036 mg kg^?1, respectively. The trials results showed that the half-lives of carbosulfan, carbofuran and 3-hydroxy carbofuran in rice straw were 4.0, 2.6 days, 3.9, 6.0 days, and 5.8, 7.0 days in Zhejiang and Hunan, respectively. Carbosulfan, carbofuran and 3-hydroxy carbofuran were detected in soils. Carbosulfan and 3-hydroxy carbofuran were almost undetectable in paddy water. Carbofuran was detected in paddy water. The final residues of carbosulfan, carbofuran and 3-hydroxy carbofuran in brown rice were lower than 0.05 mg kg^?1, which were lower than 0.5 mg kg^?1 (MRL of carbosulfan) or 0.1 mg kg^?1 (MRL of carbofuran). Therefore, a dosage of 420 g active ingredient per 100 kg seed was recommended, which could be considered as safe to human beings and animals. These would contribute to provide the scientific basis of using this insecticide.     

Accelerated degradation of carbofuran in standing water from carbofuran‐retreated Azolla plots

Abstract

Carbofuran (2, 3‐dihydro‐2, 2‐dimethyl‐7‐benzofuranyl N‐methylcarbamate) was mixed with standing water from six flooded Azolla (a fern harboring a nitrogen fixing alga, Anabaena azollae) plots that had been regularly treated with carbofuran before. The insecticide completely disappeared in 5 to 10 days when mixed with water from three of the six plots. The enrichment culture, prepared by further additions of carbofuran to the standing water from an Azolla plot, degraded bendiocarb (2, 2‐dimethyl‐l, 3‐benzidioxol‐4‐yl‐N‐methylcarbamate), carbofuran and carbosulfan [2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl (di‐n‐butyl‐aoinosulfenyl) methyl‐carbamate ] in that order. Enrichment culture, upon sterilization by autoclavlng, lost its ability to degrade carbofuran. Evidently, accelerated degradation of carbofuran in standing water from retreated Azolla plots was mediated by microorganisms.     

Residues of carbofuran and its two carbamate metabolites in field‐treated rutabaga 1

Abstract

Carbofuran was applied over seeded rutabaga cv. York and residues (corrected for recovery) of carbofuran, 3‐hydroxy‐ and 3‐ketocarbofuran in the harvested roots averaged 0.15, 0.23 and 0.07 ppm in peel and 0.09, 0.14 and 0.05 ppm in pulp, respectively. Samples were extracted by hot acid digestion, partitioned in methylene chloride and cleaned up on Florisil. The 3‐hydroxy‐carbofuran was ethoxylated and the compounds were converted into their dinitrophenyl ethers and analysed by electron capture gas chromatography using 3% OV‐3 column.     

Use pattern of pesticides and their predicted mobility into shallow groundwater and surface water bodies of paddy lands in Mahaweli river basin in Sri Lanka

Pesticides applied on agricultural lands reach groundwater by leaching, and move to offsite water bodies by direct runoff, erosion and spray drift. Therefore, an assessment of the mobility of pesticides in water resources is important to safeguard such resources. Mobility of pesticides on agricultural lands of Mahaweli river basin in Sri Lanka has not been reported to date. In this context, the mobility potential of 32 pesticides on surface water and groundwater was assessed by widely used pesticide risk indicators, such as Attenuation Factor (AF) index and the Pesticide Impact Rating Index (PIRI) with some modifications. Four surface water bodies having greater than 20% land use of the catchment under agriculture, and shallow groundwater table at 3.0 m depth were selected for the risk assessment. According to AF, carbofuran, quinclorac and thiamethoxam are three most leachable pesticides having AF values 1.44 × 10^?2, 1.87 × 10^?3 and 5.70 × 10^?4, respectively. Using PIRI, offsite movement of pesticides by direct runoff was found to be greater than with the erosion of soil particles for the study area. Carbofuran and quinclorac are most mobile pesticides by direct runoff with runoff fractions of 0.01 and 0.08, respectively, at the studied area. Thiamethoxam and novaluron are the most mobile pesticides by erosion with erosion factions of 1.02 × 10^?4 and 1.05 × 10^?4, respectively. Expected pesticide residue levels in both surface and groundwater were predicted to remain below the USEPA health advisory levels, except for carbofuran, indicating that pesticide pollution is unlikely to exceed the available health guidelines in the Mahaweli river basin in Sri Lanka.     

添加给水厂残泥对稻田土壤中毒死蜱环境赋存及厌氧降解的影响

给水厂残泥(WTR)是给水厂混凝过程产生的安全废弃物,是一种高效低廉的毒死蜱吸附材料。为评估将WTR作为吸附材料添加于土壤中缓解毒死蜱危害的可行性,探究了添加WTR对稻田土壤中毒死蜱环境赋存、厌氧降解及其代谢产物TCP形成的影响。实验结果表明:毒死蜱首要厌氧降解途径是快速水解为TCP,添加WTR显著降低了土壤中毒死蜱与TCP的生物有效性(P<0.05)。72 d厌氧培养时间内,未添加WTR土壤中高达79%的毒死蜱主要以生物可利用态存在;在WTR添加土壤中,72%～95%的毒死蜱以稳定的残渣态存在,但毒死蜱在土壤中的降解速度因此减慢,TCP生成量随之减少。在未添加WTR土壤中,92%以上的TCP以水溶态为主,添加WTR可有效减少其水溶态所占比例,WTR添加量为10%时,其水溶态含量降至47%。随着WTR添加量增加,毒死蜱与TCP由土壤向上覆水迁移的量显著减少(P<0.05)。未添加WTR的土壤水溶液体系上覆水中毒死蜱和TCP浓度分别高达537 μg·L-1和1 750 μg·L-1,添加2%WTR可使其最高浓度分别降低50%。在厌氧滞水的稻田土壤中,WTR主要金属元素(Fe、Al和Mn)稳定性强,二次污染风险较低。综合以上研究结果,WTR适于作为土壤添加物应用于毒死蜱与TCP污染控制。     

5种浮床植物对宁夏引黄灌区稻田退水中氮磷的去除效果

为了探索植物浮床技术应用和农业面源污染防治的有效措施,采用稻田退水沟渠原位实验,研究了美人蕉(Canna indica)、千屈菜(Lythrum salicaria)、黄菖蒲(Iris pseudacorus)、空心菜(Ipomoea aquatica)、水稻(Oryza sativa)5种不同浮床植物对退水中氮、磷的去除效果。结果表明,在稻田退水中生长4个月后,5种浮床植物生物量均大幅度增加。其中,美人蕉生物增长量最大,为97.2 g·株⁻¹,其次为千屈菜达到81.3 g·株⁻¹;空心菜成活率最高,达到91.67%,美人蕉其次,为87.50%,而水稻成活率最低,仅为60.71%;千屈菜茎叶和根系的氮含量最高,分别达到0.85%和0.65%;美人蕉茎叶、根系的磷含量最高,分别达到0.15%、0.17%;空心菜氮吸收量最高,达到14 239.46 mg·m⁻²,美人蕉其次,为10 798.00 mg·m⁻²;水稻磷吸收量最高,达到407.11 mg·m⁻²,空心菜其次,为374.41 mg·m⁻²;空心菜对稻田退水中总氮(TN)去除率最高,达到85.88%,其次为美人蕉,为81.67%;空心菜总磷(TP)去除率最高,达到80.32%,其次为水稻,达到72.86%。根据上述实验结果,推荐浮床空心菜和美人蕉作为宁夏引黄灌区农田排水沟水质改善的主要植物。     

Observations on the influence of water and soil pH on the persistence of insecticides

Abstract

The pH‐disappearance rate profiles were determined at ca. 25°C for 24 insecticides at 4 or 5 pH values over the range 4.5 to 8.0 in sterile phosphate buffers prepared in water‐ethanol (99: 1 v/v). Half‐lives measured at pH 8 were generally smaller than at lower pH values. Changes in half lives between pH 8.0 and 4.5 were largest (>1000x) for the aryl carbamates, carbofuran and carbaryl, the oxime carbamate, oxamyl, and the organophosphorus insecticide, trichlorfon. In contrast, half lives of phorate, terbufos, heptachlor, fensulfothion and aldicarb were affected only slightly by pH changes. Under the experimental conditions described half lives at pH8 varied from 1–2 days for trichlorfon and oxamyl to >1 year for fensulfothion and cyper‐methrin. Insecticide persistence on alumina (acid, neutral and basic), mineral soils amended with aluminum sulfate or calcium hydroxide to different pH values and four natural soils of different pH was examined. No correlation was observed between the measured pH of these solids and the rate of disappearance of selected insecticides applied to them. These observations demonstrate the difficulty of extrapolating the pH dependent disappearance behaviour observed in homogeneous solution to partially solid heterogeneous systems such as soil.     

Effects of rapeseed residue on lead and cadmium availability and uptake by rice plants in heavy metal contaminated paddy soil

Rapeseed (Brassica napus L.) has been cultivated for biodiesel production worldwide. Winter rapeseed is commonly grown in the southern part of Korea under a rice-rapeseed double cropping system. In this study, a greenhouse pot experiment was conducted to assess the effects of rapeseed residue applied as a green manure alone or in combinations with mineral N fertilizer on Cd and Pb speciation in the contaminated paddy soil and their availability to rice plant (Oryza sativa L.). The changes in soil chemical and biological properties in response to the addition of rapeseed residue were also evaluated. Specifically, the following four treatments were evaluated: 100% mineral N fertilizer (N100) as a control, 70% mineral N fertilizer + rapeseed residue (N70 + R), 30% mineral N fertilizer + rapeseed residue (N30 + R) and rapeseed residue alone (R). The electrical conductivity and exchangeable cations of the rice paddy soil subjected to the R treatment or in combinations with mineral N fertilizer treatment, N70 + R and N30 + R, were higher than those in soils subjected to the N100 treatment. However, the soil pH value with the R treatment (pH 6.3) was lower than that with N100 treatment (pH 6.9). Use of rapeseed residue as a green manure led to an increase in soil organic matter (SOM) and enhanced the microbial populations in the soil. Sequential extraction also revealed that the addition of rapeseed residue decreased the easily accessible fraction of Cd by 5-14% and Pb by 30-39% through the transformation into less accessible fractions, thereby reducing metal availability to the rice plant. Overall, the incorporation of rapeseed residue into the metal contaminated rice paddy soils may sustain SOM, improve the soil chemical and biological properties, and decrease the heavy metal phytoavailability.     

Evaluation of photolysis and hydrolysis of pyraclostrobin in aqueous solutions and its degradation products in paddy water

This study evaluated the hydrolysis and photolysis kinetics of pyraclostrobin in an aqueous solution using ultra-high-performance liquid chromatography–photodiode array detection and identified the resulting metabolites of pyraclostrobin by hydrolysis and photolysis in paddy water using high-resolution mass spectrometry coupled with liquid chromatography. The effect of solution pH, metal ions and surfactants on the hydrolysis of pyraclostrobin was explored. The hydrolysis half-lives of pyraclostrobin were 23.1–115.5?days and were stable in buffer solution at pH 5.0. The degradation rate of pyraclostrobin in an aqueous solution under sunlight was slower than that under UV photolysis reaction. The half-lives of pyraclostrobin in a buffer solution at pH 5.0, 7.0, 9.0 and in paddy water were less than 12?h under the two light irradiation types. The metabolites of the two processes were identified and compared to further understand the mechanisms underlying hydrolysis and photolysis of pyraclostrobin in natural water. The extracted ions obtained from paddy water were automatically annotated by Compound Discoverer software with manual confirmation of their fragments. Two metabolites were detected and identified in the pyraclostrobin hydrolysis, whereas three metabolites were detected and identified in the photolysis in paddy water.     

复配钝化剂对稻田重金属有效性及其水稻吸收的影响

针对红壤稻米中重金属Cd超标的问题,通过筛选钝化剂并将其复配用于大田实验,以研究复配钝化剂对土壤有效态重金属(Cd、Pb和Cu)及水稻吸收重金属的影响及其作用机理。室内筛选实验表明,在11种无机和有机钝化剂中,海泡石、生石灰和聚丙烯酰胺对土壤重金属钝化效果较好,使有效态Cd、Pb和Cu分别降低了32.4% ~ 89.2%、19.5% ~ 99.1%和49.4% ~ 92.4%,并将它们确定为复配钝化剂的成分。大田实验结果表明,生石灰、聚丙烯酰胺和海泡石复配对土壤中重金属钝化效果最佳,使有效态Cd、Pb和Cu分别降低了28.6%、20.2%和23.5%(p<0.05),其钝化机制为离子交换和络合作用。而且,该复配钝化剂对土壤化学性质影响最小。复配钝化剂使稻米中Cd的质量分数降低了21.7% ~ 93.1%(p<0.05)。另外,复配钝化剂对土壤微生物丰度和多样性没有显著影响。考虑到土壤的安全性和稳定性,推荐将生石灰、聚丙烯酰胺和海泡石复配钝化剂用于降低红壤稻米对Cd的吸收以确保粮食安全生产。本研究结果可为重金属污染红壤稻田的安全利用提供参考。     

The influence of pH and organic matter content in paddy soil on heavy metal availability and their uptake by rice plants

The experiments were done to investigate the effect of soil pH and organic matter content on EDTA-extractable heavy metal contents in soils and heavy metal concentrations in rice straw and grains. EDTA-extractable Cr contents in soils and concentrations in rice tissues were negatively correlated with soil pH, but positively correlated with organic matter content. The combination of soil pH and organic matter content would produce the more precise regression models for estimation of EDTA-Cu, Pb and Zn contents in soils, demonstrating the distinct effect of the two factors on the availability of these heavy metals in soils. Soil pH greatly affected heavy metal concentrations in rice plants. Furthermore, inclusion of other soil properties in the stepwise regression analysis improved the regression models for predicting straw Fe and grain Zn concentrations, indicating that other soil properties should be taken into consideration for precise predicting of heavy metal concentrations in rice plants.     

Partitioning of arsenic in soil-crop systems irrigated using groundwater: a case study of rice paddy soils in southwestern Taiwan

The accumulation of As in rice due to groundwater irrigation in paddy fields represents a serious health hazard in South and Southeast Asia. In Taiwan, the fate of As in long-term irrigated paddy fields is poorly understood. Groundwater, surface soil, and rice samples were collected from a paddy field that was irrigated with As-containing groundwater in southwestern Taiwan. The purpose of this study is to elucidate the source and sink of As in the paddy field by comparing the As fractions in the soils that were obtained by a sequential extraction procedure (SEP) with the As uptake of rice. The risks associated with eating rice from the field can thus be better understood. The concentration of As in groundwater varied with time throughout the growing seasons of rice, but always exceeded the permitted maximum (10 μg L⁻¹) for drinking water by the WHO. The As concentration increased with the concentration of Fe in the groundwater, supporting the claim that a large amount of As was concentrated in the Fe flocs collected from the internal wall of the groundwater pump. The results of the SEP revealed that As bound with amorphous and crystalline hydrous oxides exhibited high availability in the soils. The root of rice accumulated the largest amount of As, followed by the straw, husk, and grain. Although the As concentration in the rice grain was less than 1.0 mg kg⁻¹, the estimated intake level was close to the maximum tolerable daily intake of As, as specified by the WHO.     

石灰对稻米吸收Cd的影响及施用风险的区域调查与田间实验

通过区域调查与田间实验相结合的方法探讨施用石灰对土壤-水稻系统镉(Cd)污染的控制效果和潜在风险.区域调查结果显示,研究区稻米Cd超标率高达72.6％;石灰处理可降低21.1％的土壤Cd活性和9.7％的稻米Cd超标率,并小幅提升土壤pH,但存在不确定性.田间实验结果显示,经石灰处理后,稻米Cd含量从0.26 mg·kg...     

Photolytic and photocatalytic degradation of quinclorac in ultrapure and paddy field water: identification of transformation products and pathways

Quinclorac (QNC) is an effective but rather persistent herbicide commonly used in rice production. This herbicide presents a mean persistence in the environment so its residues are considered of environmental relevance. However, few studies have been conducted to investigate its environmental behavior and degradation. In the present work, direct photolysis and TiO₂ photocatalysis of the target compound in ultrapure and paddy field water were investigated. After 10 h photolysis in ultrapure water, the concentration of QNC declined 26% and 54% at 250 and 700 W m⁻², respectively. However, the amount of quinclorac in paddy field water remained almost constant under the same irradiation conditions. QNC dissipated completely after 40 min of TiO₂ photocatalysis in ultrapure water, whereas 130 min were necessary to degrade 98% of the initial concentration in paddy field water.Possible QNC photolytic and photocatalytic degradation pathways are proposed after structure elucidation of the main transformation products, through liquid chromatography-electrospray ionization-quadrupole time-of-flight mass spectrometry and exact mass measurements. Pyridine ring hydroxylation at C-9 followed by ring opening and/or oxidative dechlorination were the key steps of QNC degradation.     

改性火山岩滤料去除矿井水中铁锰离子影响因素研究

以改性火山岩滤料作为除铁除锰的滤料,通过对模拟矿井水的过滤试验,研究了滤速、pH值、滤层厚度及铁锰离子浓度对其除铁除锰效率的影响。结果表明：改性火山岩滤料能实现模拟矿井水中Mn²⁺的100%去除,效果明显优于未改性火山岩;最为合理的过滤滤速为7～8 m/h;除铁除锰的过程主要发生在滤层厚度为90 cm的上部滤层中;随着铁锰浓度的升高,改性火山岩滤料除铁的效率变化很小,除锰效率呈快速、线性降低;中性或偏碱性的环境有利于改性火山岩滤料充分发挥高效吸附去除能力。     

根施钙镁磷肥与叶喷硅/硒联合调控水稻镉吸收

南方水稻镉（Cd）污染是我国当前面临的主要环境问题之一。以中稻丰两优1号为材料,采用大田小区实验,研究了根区施加钙镁磷肥（P1：1 800 kg·hm-2、P2：3 000 kg·hm-2）、叶面喷施硅/硒（LS：2.0 mmol·L-1 Na2SiO3、LX：25 μmol·L-1 Na2SeO3、LSX：1.0 mmol·L-1 Na2SiO3+12.5 μmol·L-1 Na2SeO3）以及根区与叶面联合处理（P1LS、P1LX、P1LSX、P2LS、P2LX、P2LSX）下水稻对Cd的吸收。结果表明：1）根施钙镁磷肥显著降低了土壤有效态Cd含量（p1、P2较对照分别降低16.1%和29.5%;单独的根施钙镁磷肥或叶喷硅/硒处理后,稻米Cd含量较对照均显著降低（p1 40.8%、P2 57.2%、LS 42.3%、LX 35.0%、LSX 39.2%;根施钙镁磷肥与叶喷硅/硒联合调控对降低稻米Cd含量表现出显著的协同效应（p值显著性）,其中P1LS、P1LX和P1LSX较单独的P1分别降低了61.2%、59.5%和68.2%,P2LS、P2LX和P2LSX较单独的P2分别降低了75.0%、54.2%和75.7%。2）Cd从秸秆向籽粒转运系数（SS）大于从根向秸秆转运系数（RS）,根区与叶面联合处理明显降低RS和SS,并有显著的协同效应（p1与Si/Se联合,RS和SS平均降低了7.4%和22.0%,P2与Si/Se联合,RS和SS平均降低了16.0%和19.6%。3）从食品安全来说,单独的根施钙镁磷肥或叶喷硅/硒,大米Cd含量多数超标（国标0.2 mg·kg-1）,而根区与叶面联合处理几乎都能实现Cd含量不超标,其中降幅最大的为P2LS 和P2LSX,稻米Cd含量不到0.09 mg·kg-1。因此,根施钙镁磷肥与叶喷硅/硒联合处理可显著降低水稻Cd吸收、保障稻米质量安全。     

污泥水解酸化过程中污染物的释出及其影响因素研究

为了回收利用污泥中的有机物、氮和磷,研究了将厌氧污泥接种到吸附了污染物质的剩余污泥中,对污泥水解酸化的促进以及污泥中微生物所摄取污染物质的释出规律;揭示了厌氧条件下发酵时间、污泥量、pH和热处理对污染物释出的影响。结果表明,接种24 h后污染物被大量释放出来;在发酵时间为24 h条件下,污染物释出量与污泥质量成正比;吸附了污染物的剩余污泥相对含量越高,释磷量越大;污泥厌氧发酵时,碱性条件下有机物和正磷酸盐的释出量大于酸性条件,加碱调高pH可有效促进氨氮的释出;对吸附了污染物的剩余污泥进行短时热处理可有效缩短其厌氧发酵时污染物的释出时间。结果表明,控制污泥厌氧水解发酵条件可以促进污染物的释出,有利于下一步的回收。     

池塘养殖水体pH、营养盐、叶绿素a及3种磺胺类抗生素分布特征及其相关性分析

为了解农村池塘养殖水体的水质情况,分析了湖北宜东平原34个农村分散养殖鱼塘水体中pH、叶绿素a、总氮(TN)、总磷(TP)及3种磺胺类抗生素(SAs,即磺胺二甲嘧啶、磺胺甲噁唑及磺胺异噁唑),并讨论了它们之间的相关性.结果表明,所监测鱼塘水体pH值差异较小,范围为7.26~8.96,但鱼塘之间的TN、TP及叶绿素a含量差别大,其含量范围分别为0.074~47.185 mg/L、0.007~1.311 mg/L及4~421 μg/L.其中有85.29%的鱼塘水体TN含量劣于地表水V类标准,17.65%TP劣于V类,只有3个鱼塘的叶绿素a含量小于10 μg/L,水体富营养化严重.鱼塘水中3种SAs的浓度范围为23~828 ng/L,其检出率顺序为磺胺异噁唑(47%)> 磺胺甲噁唑(18%)> 磺胺二甲嘧啶(6%).对所考察因子的相关性研究表明,鱼塘养殖水体的pH、TN及TP无相关,但磺胺二甲嘧啶与TN/TP呈显著正相关(r=0.345,P=0.05).叶绿素a与水体中TN及TP的关系呈较好的幂指数函数关系,而且TP为浮游植物的生长限制因子.     

稻壳沸石的合成及其对氨氮的吸附/脱附动力学

以稻壳为原料采用水热合成法制备了沸石,运用XRD、SEM和BET技术表征了合成沸石的结构特性。通过静态实验,研究了合成沸石对氨氮的吸附和脱附机理。结果表明：延长水热合成的晶化时间有利于合成沸石晶核的形成,合成沸石比表面积为28.418 m2·g-1,平均孔径为31.1 nm,孔体积为0.22 m3·g-1,属NaP型微介孔吸附材料。伪二级吸附动力学模型更适合描述合成沸石对氨氮的吸附过程,由伪二级吸附动力学模型拟合得到的平衡吸附量与实测值相差在1.0%以内。颗粒内扩散速率是由膜扩散和内扩散共同控制,颗粒内扩散速率常数kp随初始浓度的增加而提高。MNaOH/ANMNaOH/AN的增大,温度对脱附的促进作用变得越来越小,当MNaOH/AN>1.21时,氨氮的脱附率可达92.1%。伪二级脱附动力学模型的拟合结果优于伪一级,碱当量高于临界值之后对提高合成沸石脱附氨氮的效果不大。