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。     

降雨条件下农田土壤中磷的迁移规律

研究农田土壤中不同深度处的磷元素含量在多次降雨后的变化规律.[方法]通过三次人工降雨,分别从不同土壤深度处取出土样,进行测定分析,找出磷元素含量随土壤深度变化以及降雨量变化的变化趋势.[结果]第一,降雨后磷含量随土壤深度增加而逐渐减少,这一规律主要体现在30cm以上的土壤层;第二,30cm土壤层以上,同深度的土壤P含量随着降雨次数的增加的而减少.[结论]选择科学合理的磷肥施用量,同时控制农田土壤水的排出.     

浑善达克沙地沙尘气溶胶的化学元素组成及含量

利用2001年4月下旬到5月上旬内蒙古桑根达莱和北京站的近地面大气气溶胶采样及其化学元素分析资料,比较分析了晴天、一般沙尘天及沙尘暴天颗粒化学元素在PM2.5,PM2.5-10,PMl0-中的相对含量.结果表明,颗粒化学元素质量浓度总和随着沙尘浓度增大而普遍增大,但其在PM中相对含量的变化并不相同于绝对含量增长.在扬沙或浮尘天气,表面粘附作用导致粗颗粒富集一定的污染元素,而在沙尘暴期间,受强天气过程影响大量污染元素被输送到下游区域.沙尘气溶胶中部分细颗粒来自富含Al,Ca,Fe等矿质元素的土壤,粗颗粒主要来自富含Si元素的沙粒.Na元素主要来自土壤而非沙地.     

绿地系统对径流污染物净化机理的研究

采用城市绿地和降雨系统模拟装置,研究绿地系统对径流污染物的净化机理。研究表明,模拟绿地对径流污染物的削减和污染物总量的控制有较好作用。降雨期间绿地系统对径流污染物中化学需氧量、氨氮、硝酸盐氮及总磷的去除率为32.1%-49.9%;污染物的去除主要靠土壤和植物根系的截留、吸附和吸收作用,通过分析,发现土壤对氨氮及总磷的吸附反应在常温下较易进行,对硝酸盐氮的吸附反应在常温下较难进行。降雨后微生物开始降解吸附于土壤颗粒表面和植物根系的污染物,5-8d土壤中微生物数量达到最大值,14-17d土壤污染物含量基本降到降雨前水平,土壤得到再生。     

不同施肥处理对设施农业土壤主要阴离子含量的影响

该试验选择具有16年棚龄的北方大棚,选用腐植酸、沸石为主要材料,通过测土施肥的试验方法,研究设施农业次生盐渍土的阴离子含量状况。结果表明：施用无机肥料可以快速增加土壤表层0～20cm的阴离子盐分含量,但对20cm以下土壤阴离子影响不明显。测土配方施肥处理、测土配方施肥＋腐植酸处理、测土配方施肥＋沸石处理、测土配方施肥＋腐植酸＋沸石处理与农民常规施肥相比,在降低土壤盐分含量方面效果显著,各处理均能有效降低土壤的盐分离子NO3^-、SO4^2-、Cl^-、HCO3^的含量水平。     

施肥对土壤环境中砷污染的影响

通过盆栽试验研究了不同施肥处理与外源砷污染对土壤肥力及砷形态的影响。结果表明,在同一砷浓度处理条件下,与空白处理相比,有机肥+化肥处理土壤有效磷和速效钾含量增加量最多,分别增加了1.29倍~26.75倍、0.44倍~2.14倍,对土壤全氮和有机质的影响不大,同一砷浓度下土壤中各种砷的形态差异不大(P0.05);在同一施肥处理下,随着外源砷浓度的增加,土壤有效磷呈显著增加的趋势,土壤全氮和有机质的含量差异不显著;土壤总砷含量呈现显著增加的趋势,外源砷质量分数从0mg/kg~100mg/kg,土壤总砷含量平均显著增加了81.8mg/kg,土壤可交换态砷和碳酸盐结合态砷在外源砷加入量为10mg/kg时含量最低。     

中外腐植酸文摘

一、含腐植酸水溶肥料对生长期水稻不同部位镉含量的影响 研究了不同水平含腐植酸水溶肥料处理对湖北大冶土壤pH和生长期水稻各部位镉含量的影响.采集湖北大冶水稻试验区土壤及抽穗期和灌浆期的水稻根部,穗部,叶片,茎部10、20、30 cm等,分别测定土壤酸碱度和水稻各部位样品中的镉含量.结果表明:与对照区(常规施肥)相比,施用...     

氟磺胺草醚在土壤中的淋溶及其影响因素

[目的]研究氟磺胺草醚在土壤中的淋溶规律及不同因素的影响。[方法]采用自行设计的淋溶柱模拟环境条件,通过高效液相色谱仪检测分析氟磺胺草醚在土壤中的淋溶特性。[结果]土壤含水量10%、降雨量100 mm、降雨速度23~25滴/min条件下,表土中添加高剂量氟磺胺草醚150 mg/kg,淋溶深度可达30~35 cm;淋溶土壤有机质含量7.4%时,淋溶深度可达20~25 cm;高土壤含水量20%时,土壤淋溶深度超过35 cm;同一时间内降雨量高达140 mm时,土壤淋溶深度超过35 cm;淋溶柱表层分别添加氟磺胺草醚水剂(SL)、乳油(EC)和微乳剂(ME),结果显示水溶性较大的水剂表现出较强的淋溶特性。[结论]氟磺胺草醚淋溶深度与土壤的吸附性和渗透性有关,增加土壤吸附性,减少土壤渗透性,农药向土壤下层运行的速度降低,土壤淋溶作用减弱。     

淋滤作用下朱仙庄煤矸石中重金属的迁移研究

为探寻煤矸石中重金属在其下方土壤中的迁移规律,以宿州朱仙庄煤矿区一矸石堆下方土壤为研究对象,采用粉末压片、X射线荧光光谱法测定土壤样品中Cu、Zn、Ni等多种元素。结果表明:该地区重金属元素主要集中累积在0 cm处的土壤表层上,0 cm以下增减趋势具有一定的波动性;各元素中,Cu元素最易受到影响;在土壤剖面上,重金属迁移至沉积层(30～50 cm)后,含量变化明显。该地区Co、Cr、Mn元素在土壤不同层位上的含量变化特征显著。     

腐植酸对设施土壤的养分、盐分及番茄产量和品质的影响研究

试验选择具有10年棚龄的北方大棚,在不同施肥条件下,分别对土壤养分、盐分及番茄产量和品质等进行了研究,具体对因处理不同而引起的土壤养分与水溶性盐分含量、盐基离子组成的变化以及番茄的维生素C（Vc）含量和含糖量等进行了分析。结果表明,腐植酸含有多种物质,它的施用可以提高土壤有机质含量,并且能增加土壤速效态P、K的含量,降低土壤电导率。施用复混肥的土壤电导率增加37％,而施用腐植酸可以使土壤电导率降低10．4％。土壤盐基离子含量的增加,主要是由水溶性NH4^＋、K^＋、Ca^2＋、Mg^2＋含量的增加引起的。腐植酸由于含有各种官能团,可以有效抑制土壤中水溶性K^＋、Ca^2＋、Mg^2＋等盐基离子的增加,进而降低土壤的电导率。腐植酸对番茄的产量和品质也都有显著的影响,能使番茄增产36．5％,并明显提高番茄的VC含量和含糖量。     

Phenolic acid content of soils from wheat-no till,wheat-conventional till,and fallow-conventional till soybean cropping systems

Soil core (0–2.5 and/or 0–10 cm) samples were taken from wheat no till, wheat-conventional till, and fallow-conventional till soybean cropping systems from July to October of 1989 and extracted with water in an autoclave. The soil extracts were analyzed for seven common phenolic acids (p-coumaric, vanillic,p-hydroxybenzoic, syringic, caffeic, ferulic, and sinapic; in order of importance) by high-performance liquid chromatography. The highest concentration observed was 4 g/g soil forp-coumaric acid. Folin & Ciocalteu's phenol reagent was used to determine total phenolic acid content. Total phenolic acid content of 0- to 2.5-cm core samples was approximately 34% higher than that of the 0- to 10-cm core samples. Phenolic acid content of 0- to 2.5-cm core samples from wheat-no till systems was significantly higher than those from all other cropping systems. Individual phenolic acids and total phenolic acid content of soils were highly correlated. The last two observations were confirmed by principal component analysis. The concentrations were confirmed by principal component analysis, tions of individual phenolic acids extracted from soil samples were related to soil pH, water content of soil samples, total soil carbon, and total soil nitrogen. Indirect evidence suggested that phenolic acids recovered by the water-autoclave procedure used came primarily from bound forms in the soil samples.The use of trade names in this publication does not imply endorsement by the North Carolina Agricultural Research Service of products named, nor criticism of similar ones not mentioned.     

Nitrate leaching and soil moisture prediction with the LEACHM model

The LEACHM model developed by Wagenet and Hutson [1989] was used to predict the mineral nitrogen and water content in the soil under a winter wheat crop from February to April in two years and three locations. The model grossly overestimated soil water content, probably due to the bad fitting of the assumed water retentivity function to the experimental data at high water contents, and to the presence of a relatively shallow water table (1.0–1.5m). Measured soil hydraulic conductivity varied with water content in a different manner than predicted by the model. By assuming a sandy or gravelly soil layer between the bottom of the measured soil profile and the water table, prediction of soil water content improved considerably. Simulation showed that, under the experimental conditions studied, soil mineral nitrogen varied mainly due to the fertilizer additions, mineralization and denitrification. Nitrogen uptake by plants and leaching were small. Low values of nitrate leaching were predicted by the model because of low drainage. Large differences between predicted and observed values in the mineral nitrogen in the soil occurred in some cases, both in the total amount and its profile distribution.     

紫外分光光度法测定水质总氮影响因素分析

总氮是衡量水体富营养化程度的重要指标之一。测定水和废水中总氮的方法通常采用碱性过硫酸钾氧化-紫外分光光度法（GB1894—1989）。但是依据该方法在实际测定水质总氮含量时,空白值经常较高、样品总氮测定值不在该方法规定的上下限范围内和同一样品总氮测定值波动较大。针对出现的上述问题进行分析,找出影响因素,提出改进的建议。从以下几个方面来分析其影响因素：实验用水、碱性过硫酸钾、消解时间、分析室环境条件、玻璃器皿的洗涤、波长定位准确性和氨氮值高于总氮值。     

风化煤腐植酸对土壤理化性状的影响

以潮土和棕壤土为研究对象,通过添加不同量未活化和活化的风化煤腐植酸,对比研究了2种腐植酸对土壤肥力和理化性状的影响。试验结果表明：单施未活化的风化煤腐植酸和活化的风化煤腐植酸对土壤中全氮含量无明显效果,但可以活化和释放土壤中难溶性磷、矿物态钾、缓效性钾,使其转化成速效磷和速效钾;施用3个月后,2种土壤中速效磷、速效钾、阳离子交换量、水稳性团聚体均有不同程度的增加。其中,碱活化的风化煤腐植酸对土壤理化性状具有良好的影响,可使2种土壤中的速效磷含量、速效钾含量、阳离子交换量、水稳性团聚体数量分别增加24.80-130.87 mg/kg、43.01-113.19 mg/kg、8.87-9.49 cmol/kg、8.01%-18.84%。     

Simulating water and nitrogen behaviour in soils cropped with winter wheat

The SWATNIT model [26], predicting water and nitrogen transport in cropped soils, was evaluated on experimental data of winter wheat for different N treatments. The experiments were monitored at three different locations on different soil types in the Netherlands. Crop growth was simulated using the SUCROS model [11] which was integrated in the SWATNIT model. Both water and nitrogen stress were incorporated. Except for the soil hydraulic properties, all model parameters were taken from literature. The model performance was evaluated on its capability to predict soil moisture profiles, nitrate and ammonia profiles, the time course of simulated total dry matter production and LAI; and crop N-uptake. Results for the simulations of the soil moisture profile indicate that the soil hydraulic properties did not reflect the actual physical behaviour of the soil with respect to soil moisture. Good agreement is found between the measured and simulated nitrate and ammonia profiles. The simulation of the nitrate content of the top layer at Bouwing was improved by increasing the NH ₄ ⁺ -N-distribution coefficient thereby improving the simulation of the NH ₄ ⁺ -N-content in this layer. Deviations between simulated and measured nitrate concentrations also occurred in the bottom layers (60–100 cm) of the soil profile. The phreatic ground water might influence the nitrate concentrations in the bottom layers. Concerning crop growth modelling, improvements are needed with respect to the partitioning of total dry matter production over the different plant organs in function of the stress, the calculation of the nitrogen stress and the total nitrogen uptake of the crop through a better estimate of the N-demand of the different plant organs.     

Hydrophobic recovery of repeatedly plasma-treated silicone rubber. Part 2. A comparison of the hydrophobic recovery in air,water, or liquid nitrogen

Surfaces of medical grade silicone rubber (Q7-4750, Dow Corning) were modified by repeated (six times) RF plasma treatments using various discharge gases: oxygen, argon, carbon dioxide, and ammonia. The treated samples were stored for a period of 3 months in ambient air, water, or liquid nitrogen. Subsequently, the temporal behavior of the effects of the plasma treatment on the physicochemical surface properties of the silicone rubber was investigated using water contact angle measurements and X-ray photoelectron spectroscopy (XPS). Hydrophobic recovery during 3 months storage in ambient air was considerable and nearly complete for all four plasmas used. Hydrophobic recovery was almost completely suppressed during storage in liquid nitrogen, and only a minor increase of around 10° in advancing water contact angle was observed for all four plasma treatments. Also during storage of treated samples in water, hydrophobic recovery was minimal and initiated again by returning the treated samples to ambient air. XPS analyses showed that argon, carbon dioxide, and ammonia plasma-treated silicone rubber all had increased carbon percentages at the expense of oxygen and silicon after storage in water, or in liquid nitrogen, compared with after storage in ambient air. Interestingly, the carbon content of oxygen plasma-treated silicone rubber decreased during storage in water, or in liquid nitrogen, compared with storage in ambient air, while its oxygen and silicon percentages increased.     

黄山市浅层地下水中氮污染的研究

通过对新安江(黄山段)浅层地下水17个采样点水样的采集,用碱性过硫酸钾消解紫外分光光度法测定水中总氮含量。结果表明,黄山市浅层地下水总氮含量严重超标的有1个,超标的有9个,符合标准的7个。其最主要的污染源是生活污水、养殖废水及工业污水不达标排放造成这部分水域总氮含量超标。另外一个原因是浅层地下水更新周期较长导致总氮积累的结果。     

N2O and NO emissions from grassland soils after the application of cattle and swine excreta

N₂O and NO fluxes from grassland soil after the application of cattle and swine excreta were measured by a closed chamber method in the autumn and winter of 1994 to 1995. Fresh excrement and urine were spread on the grassland experimental plots and these gas fluxes were measured one or two times a week. In the autumn experiment, N₂O and NO fluxes began to increase several days after the application, the NO flux reaching a maximum after 16 days. In the winter experiment, N₂O and NO fluxes began to increase 45 days after the application and reached a maximum after 80 days. Nitrous oxide flux was influenced by soil water content, high water content leading to high N₂O flux. The ratio of NO-N/N₂O-N in the flux was in the range of 1.1 to 13.7, and negatively correlated to the soil water content. In the winter experiment, the total emission rate of NO was 0.48% and 0.45% of total nitrogen in the applied cattle and swine excreta, respectively. The total emission rate of N₂O was 0.085% and 0.098% in the applied cattle and swine excreta, respectively. This revised version was published online in August 2006 with corrections to the Cover Date.     

Effects of summer catch crop,residue management,soil temperature and water on the succeeding cucumber rhizosphere nitrogen mineralization in intensive production systems

Nitrogen nutrient management is crucially important in shallow-rooted vegetable production systems characterized by high input and high environmental risk. To investigate the effects of summer catch crop (sweet corn, common bean, garland chrysanthemum and edible amaranth), residue management, and soil temperature and water on the succeeding cucumber rhizosphere nitrogen mineralization in intensive production systems, we determined the rates of net nitrogen mineralization and nitrification in a 4-year field experiment on greenhouse cucumber double-cropping systems. Summer catch crop and its residue significantly increased the succeeding cucumber rhizosphere mineral nitrogen contents, when compared to conventional practices. In general, summer catch crop and its residue significantly increased the rates of both net nitrogen mineralization and net nitrogen nitrification at 4 or 40°C, and increased the rates of net nitrogen immobilization (negative mineralization) and net nitrogen nitrification at 15 or 28°C, in succeeding cucumber rhizosphere after four-year treatment. Soil temperature and water had more influence than catch crops and residue management on N mineralization. The effect of carbon on nitrogen mineralization was more pronounced than that of nitrogen, and the effect of microbial carbon on the different forms of inorganic N was more pronounced than that of organic carbon. When the effects of soil temperature and water content were eliminated, cumulative net nitrogen mineralization and nitrification in catch crop and residue management plots were 296–784 and 57–84% higher, respectively, than conventional practices plots. Catch crops and residue management influenced change of ammonium-N more significantly than that of nitrate-N. Additionally, there were complex relationships between fruit yield and soil N mineralization in catch crop- and residue management-induced systems.