汉中地区水稻田氮元素污染调查研究

通过调查汉中地区水稻田的氮肥施用技术,包括氮肥品种与施用数量等,并结合水稻田实地采样和测定土壤与水体中氮元素含量,主要采取0~5 cm,5~10 cm,10~15 cm三个深度的土壤,测定其中可溶性氮的含量,分析结果找出水稻田氮元素含量变化原因。最后提出减少水稻田氮元素污染的治理措施。     

Denitrification in shallow groundwater in a coastal agricultural area in Japan

In a coastal agricultural area in the central part of Japan (Shizuoka), we found decreasing nitrate concentration with depth in a shallow groundwater, where the depth to water table varied between 0.6 and 1.2 m below ground surface. High nitrate concentrations (5–29 mg N L^–1) were often observed in the upper layer (0–2 m) of the groundwater, but the concentration decreased to less than 1 mg N L^–1 in the deeper layer. Ammonium was scarcely detected, and the concentration of dissolved oxygen was usually low (< 1 mgO₂ L^–1) in the groundwater. Nitrate in the groundwater often had very heavy nitrogen stable isotope ratios (>20{}). There was a negative relationship between nitrogen stable isotope ratio of nitrate and its concentration. When nitrate was injected into the groundwater with acetylene and bromide (a conservative tracer), nitrate concentration decreased to 20% of the initial level within 5 days, accompanied by the increase in nitrite and nitrous oxide concentration and a little change in bromide concentration. These results indicate that microbial denitrification plays a potential role in the decrease of nitrate in shallow groundwater at the study site.     

地下水硝酸盐污染来源分析及治理方法

地下水硝酸盐污染已日趋严重,已经在很大程度上影响了环境和人类的健康。系统地对硝酸盐污染的来源进行了介绍和分析,并且详细地阐述了要治理地下水硝酸盐的污染必须要从源头防止和局部治理两方面着手;同时也综合性地比较了各种治理方法的优缺点。最后综合分析得出结论。     

Nitrate contamination of groundwater: Measurement and prediction

Agriculture makes a significant contribution to the diffuse source contamination of surface and groundwater resources, particularly contributing to the NO ₃ ^- contamination of groundwater. Two approaches were adopted to evaluate management practices (within the context of the whole farming system) for their impacts on the environment : (1) measurement of the quality of groundwater under different farming systems, and (2) comparison of predictions of the impact of farming systems on water quality, obtained using whole farm N budgets, with measured values.The Ontario Farm Groundwater Quality Survey evaluated the rural groundwater quality in Ontario, with respect to common contaminants including NO ₃ ^- . Approximately 1300 domestic farm wells were sampled, and wells were drilled in some fields of farms involved in the study. NO ₃ ^- was present at concentrations above the maximum acceptable for drinking water (10 mg N 1^–1) in 14% of wells, including 7% of wells that also had unacceptable concentrations of coliform bacteria. Significant levels of NO ₃ ^- contamination were observed under most agricultural land use practices investigated.Calculation of N budgets was simplified by assuming that there was no net change in the N content of farm assets. The N inputs to agricultural systems considered were: purchases from off-farm suppliers, N₂ fixation and atmospheric deposition. Symbiotic N₂ fixation was estimated from empirical relationships between crop yield and N₂ fixed. The N outputs were in sales of plant and animal produce, gaseous and leaching losses. Gaseous loss was assumed to result only from volatilization of ammonia, estimated to be 39% of total manure N.We have identified one cash crop farming system where there was a true balance. The rotation included corn soybeans and wheat, with two years of soybean always being grown before corn. Many livestock farms, including two organic farms, gave large imbalances of N which might indicate that these operations were not in equilibrium.The relationship between measured and predicted values of NO ₃ ^- -N expected in the groundwater under the different management systems showed that the simplified N budget overestimated the NO ₃ ^- -N concentration by about one third. However, the budget approach appeared to identify farms where contamination was likely even if the actual amount was over estimated. Simplified budgets could therefore be used to compare the potential of different farming systems for causing environmental contamination.     

肥料中硝态氮、铵态氮、总氮的研究

研究仅含硝态氮、铵态氮的肥料,结果表明,用GB/T8572-2010《复混肥料中总氮含量的测定蒸馏后滴定法》检测含有硝态氮、铵态氮的肥料中铵态氮含量、硝态氮含量(差减法总氮含量-铵态氮含量=硝态氮含量)(标准GB/T8572-2010《复混肥料中总氮含量的测定蒸馏后滴定法》中没有体现总氮含量-铵态氮含量=硝态氮含量,这是根据铵态氮与硝态氮性质总结研究出来的)与标准NY/T1116-2014《肥料硝态氮、铵态氮、酰胺态氮含量的测定》单独检测铵态氮含量、硝态氮含量结果无显著性差异。GB/T8572-2010检测总氮含量与SN/T0736.5-2010《进出口化肥检验方法第5部分:氮含量的测定》检测总氮含量无显著性差异。     

The influence of nitrate reduction strategies on the temporal development of the nitrate pollution of soil and groundwater throughout Germany - a regionally differentiated case study

A GIS-based area-differentiating model has been used to analyze the nitrate pollution of soil and groundwater throughout Germany. The results of the calculations based on the model for the current situation show that a high potential for high nitrate pollution of the soil and groundwater (> 50 mg NO₃/l) is to be expected in all regions of Germany subject to intensive agricultural use. In order to achieve a sustainable use of water resources, effective strategies to reduce the nitrogen surpluses from agriculture must be developed and analyzed with respect to their spatial and temporal impact on the nitrate pollution of soil and groundwater, taking into consideration the various agricultural land usages as well as the different hydrological, hydrogeological and agricultural conditions.The effects of three different nitrate reduction strategies on the resulting N-surpluses and the nitrate concentration in the leachate were investigated: firstly, a stocking rate limitation, secondly, a limitation of both organic and mineral fertilizers and thirdly, a combination of three reduction measures consisting of a stocking rate limitation, an improvement of the nitrogen utilization factor by livestock and a higher utilization factor of nitrogen bound in organic fertilizers by crops. The analysis showed that separate application of each of these nitrogen reduction measures would only lower the nitrogen surpluses in a few regions. In order to achieve a considerable reduction of nitrate concentrations both in leachate from land under agricultural use and in the groundwater a combination of area-covering and regionally effective measures (scenario III) turned out to be most promising.     

中国硝酸盐资源开发利用现状及其前景展望

详细论述了我国硝酸盐资源概况以及资源开发与研究现状,同时对世界硝酸盐资源开发情况进行了综述.结合目前我国硝酸盐资源勘察程度、技术现有水平及市场需求,客观地分析了我国硝酸盐资源开发前景.     

Nitrogen budgets and environmental capacity in farm systems in a large-scale karst region, southern China

Field surplus nitrogen (N) and farm disposal N are major sources of water pollution in farming systems. These sources are estimated from N budgets in field and whole farms, which are associated with the production and consumption of food. This study was conducted to evaluate these two pollution sources in the steep mountainous karst region of Quibainong, Guangxi Province, southern China. The region is, characterized as an area of upland farms, due to the shallow soils and rapid water drainage through cracks in the limestone. Although field surplus N in 1960 was only 4.1 kg N ha^–1, current field surplus N ranged from 10.1 to 463 kg N ha^–1, with values above 50 kg N ha^–1 in farms along roads and less than 40 kg N ha^–1 in the farms away from roads. The results obtained in near-road farms were similar to those in a previous study of N budgets in China. There was a significant positive correlation between the field surplus N and N application rate, including when the previous data were incorporated. The proportion of manure to total N application decreased with increase of N application. Chemical fertilizer was applied in greater quantity in economically rich farms. Therefore, the increase of field surplus N in Quibainong may be caused by economic improvement. Although livestock and human excreta were stocked in manure barns, unused excreta N increased with the increase of N excreted. The unused excreta N also increased with the decrease of feed self-sufficiency, but was not related to N application rate. These facts indicate that livestock husbandry in Quibainong is related to economic status of farms, but independently of crop production.The N application rate of more than 160 kg N ha^–1 increased field surplus N to an extent greater than crop uptake N, and a N application rate of more than 185 kg N ha^–1 increased the potential nitrate-N concentration to more than 10 mg L^–1. Therefore, 160–185 kg N ha^–1 is suggested to be the environmental capacity to sustain optimal N cycling in Quibainong. The average value of excreta N produced on near-road farms in Quibainong was 171 kg N ha^–1. If excreta N was used evenly for crop cultivation without chemical fertilizer in whole fields, the optimal N cycling would be maintained.The survey conducted here using a questionnaire was effective in evaluating all kind of N flows in the farming systems.     

Nitrogen leaching and soil nitrate, nitrite, and ammonium levels under irrigated wheat in Northern Mexico

Nitrate (NO⁻¹ ₃) leaching from agricultural soils can represent a substantial loss of fertilizer nitrogen (N), but a large variation in losses has been reported. We report N leaching losses under four N fertilizer treatments and two farmer's fields in the Yaqui Valley, Mexico. In these irrigated wheat systems, farmers typically apply 250 kg N ha⁻¹ as anhydrous ammonia (knifed in) or urea(broadcast), with 75% applied directly before planting and 25% at the time of the first post-planting irrigation. Over two wheat seasons, we compared typical farmer's practices to alternatives that applied less N and more closely timed fertilizer application to plant demand. Field lysimeter measurements and predictions from a water transport simulation model (called NLOSS) were used to estimate the amount of N leached over the season. Approximately 5 and 2% of the applied N leached below the root zone with the typical farmer's practice in 1995–96 and 1997–98,respectively. The alternative treatments reduced N leaching losses by 60 to95% while producing comparable economic returns to the farmer. Leaching losses from the two farmer's fields were substantially higher (about 14and26% of the applied N). Our results indicate that the typical farmer's practice leads to relatively high N leaching losses, and that alternative practices synchronizing fertilizer application with crop demand can substantially reduce these losses. This revised version was published online in August 2006 with corrections to the Cover Date.     

离子色谱法和分光光度法测定井水中硝酸盐氮和亚硝酸盐氮的对比

文中对比研究了离子色谱法和光度法测定农村井水中硝酸盐氮和亚硝酸盐氮。离子色谱法和光度法测定硝酸盐氮的检出限、精密度、加标回收率分别为0.014 mg/L、1.4%~4.9%、94%~106%和0.030 mg/L、1.6%~6.7%、98%~105%;离子色谱法和光度法测定亚硝酸盐氮的检出限、精密度、加标回收率分别为0.002 mg/L、1.4%~4.4%、90%~102%和0.004 mg/L、0.7%~3.6%、92%~104%。试验结果表明,离子色谱法的检出限低,而两种方法的精密度、准确度、t值检验无显著性差异,两种方法均满足日常监测要求。离子色谱法具有样品前处理过程简单,测定过程快速且可实现多种离子同时检测等优点,更利于对井水水质的检测分析。     

从德国农业氮投入来认识中国氮污染的严重性及应采取的对策

为解决中国人多地少所带来巨大的粮食生产压力,近20年来,中国的氮肥消耗大幅度增加。2000年,中国氮肥消耗已占世界总氮肥消耗量的30%,氮肥用量超过225kg/hm2,在个别地区超过500kg/hm2,氮肥利用率仅为30%～40%,远低于发达国家70%～80%的水平,导致了环境污染。德国也曾经历为加速农业生产而大量使用氮肥,并带来环境污染这一发展阶段。20世纪80年代,德国开始制定一系列法规和政策减少氮肥使用,在氮肥消耗量下降的情况下,不但残留氮污染环境的问题得到有效遏制和缓解,而且粮食单产还继续保持增长势头。借鉴德国的发展经验,中国有必要制订相关法规和政策,通过大力提高氮肥利用率,以避免氮肥的过度使用。     

Nitrogen mineralization,nitrate leaching and crop growth following cultivation of a temporary leguminous pasture in autumn and winter

A field experiment was conducted to investigate the effect of timing and method of cultivation of a 3-year old ryegrass/white clover pasture on subsequent N mineralization, NO ₃ ^- -N leaching, and growth and N uptake of a wheat crop in the following season. The size of various N pools and decomposition of¹⁴C-labelled ryegrass material were also investigated. Cultivation method (mouldboard or chisel ploughing) generally had no significant effect on the accumulation of mineral N in the profile in the autumn or on the amount of NO ₃ ^- -N leached over winter.¹⁴C measurements suggested that initial decomposition rate of plant material was faster from May than March cultivation treatments. Despite this, overall net mineralization of organic N (of soil plus plant origin) increased with increasing fallow period between cultivation and leaching. The total amounts of mineral N accumulated in the soil profile before the start of leaching were 139, 119 and 22 kg N ha^–1 for the March, May and July cultivated soils respectively. Cumulative leaching losses over the trial calculated from soil solution samples were 78, 40 and 5 kg N ha^–1 for the March, May and July cultivated soils respectively. Differences in N mineralization over the season were generally not reflected by changes in amounts of potentially-mineralizable soil N (as measured by extraction or laboratory incubation) or levels of microbial biomass during the season. The amount of mineral N in the profile in spring increased with decreasing fallow period. This was reflected in an approximately 15% and 25% greater grain yield and N uptake respectively by the following wheat crop in plots cultivated in July rather than in March.     

贵州省磷酸盐工业的现状及可持续发展战略的研讨

阐述贵州省2002年底磷酸盐工业各品种的生产能力及2001年的实际产量;贵州省磷酸盐工业的技术水平及存在的问题。提出贵州省磷酸盐工业可持续发展的思路,2010年前达到的生产能力、主要原料供应方案、发展具体措施建议。     

地下水修复中纳米零价铁材料制备及应用综述

纳米零价铁（nZVI）具有较强的还原和吸附能力,能有效去除多种类型的污染物质,在地下水环境修复领域一直备受关注。但由于其易团聚和易钝化等缺陷,在实际应用过程中还存在着许多问题。本文综述了nZVI的常用制备方法,并对nZVI的常用改性方法进行归纳,分析各种改性方法起到的具体作用,指出改性过后的复合材料依然存在着的问题。在此基础上,阐述了改性nZVI在去除地下水中有机污染物和无机污染物的应用进展,总结了改性nZVI材料在去除过程中起到的具体作用和反应机制,并进一步归纳现阶段nZVI在地下水修复中的传输手段。根据已有研究成果,指出应改进现有制备方法实现nZVI的量产,在考虑nZVI生物毒性和材料再回收的前提下,合理使用多种改性方式实现nZVI的材料制备,选择符合污染场地实际情况的传输手段,从而提高nZVI在地下水污染修复中的使用寿命和对目标污染物的处理效果。     

双氧水生产节能减排的技术措施

结合作者的生产实践,对近年来双氧水生产方面节约能源、减少污染排放等采取的技术措施进行了分析和总结。主要有增设氢化液/工作液换热器,省略氧化液泵和磷酸泵,提高空气和氢气的利用率,合理处置氧化残液,氧化尾气节能回收,浓缩装置塔顶冷凝液回收利用等,对双氧水生产和装置设计工作有一定的参考价值。     

贵州省磷复肥工业的现状及应对入世之策

介绍贵州省目前磷复肥各品种的装置生产能力、实际产量、产品结构、技术水平。探讨应对入世之策 :加速技改 (按品种提出技改的重点内容 ) ,加速调整 ,形成经济规模等。     

国内土壤污染现状、特点和一些修复浅见

介绍了国内土壤污染现状及其特点,以及欧美等国对土壤修复概况,并对各种修复技术方法进行对比。现国内对此刚起步,无成熟经验,先选取几个土壤污染类型修复进行示范,待取得成功经验再推广。     

Kinetic and thermodynamic investigations of non-isothermal decomposition process of a commercial silver nitrate in an argon atmosphere used as the precursors for ultrasonic spray pyrolysis (USP): The mechanistic approach

The non-isothermal decomposition process of commercial silver nitrate used as the precursor for the USP procedure was investigated by simultaneous TGA–DTA measurements at different heating rates, in an argon atmosphere. Detailed kinetic and thermodynamic analyses, with special emphasis on the formation of a complete mechanistic scheme of the process were performed. It was found that the process under study can be described by the acceleratory power law kinetic model (P2), in the range of the extent of conversion (α) values (0.15 ≤ α ≤ 0.85), where the value of the apparent activation energy (E_a) can be considered as the constant (141.3 kJ mol⁻¹). The kinetic prediction analysis was shown that only the power law kinetic model (f(α) = 2α^1/2) gives the value of E_a which is consistent with the value obtained from the isothermal conditions. The critical temperature (T_c) of decomposition process was determined. The resulting value of T_c was in fairly good agreement with the starting temperature of thermal decomposition of silver oxide (Ag₂O). The thermodynamic functions of decomposition process are calculated by the activated complex theory and showed that the silver–oxygen bond secession can be interpreted as a “slow” stage of the decomposition process.     

Intermolecular Hydrogen Abstraction Reaction between Nitrogen Radicals in Purine Rings and Alkyl Ethers: A Highly Selective Method for the Synthesis of N‐9 Alkylated Purine Nucleoside Derivatives

A highly selective method for the synthesis of N‐9 alkylated purine nucleoside derivatives via an intermolecular hydrogen abstraction reaction between nitrogen radicals in purine rings and alkyl ethers was developed. Novel purine nucleoside derivatives were obtained with good to high yields in the presence of (diacetoxyiodo)benzene (DIB) and iodine in one‐step reaction.