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121.
四川不同海拔稻田生态条件与杂交水稻生长发育及其应用研究 总被引:5,自引:0,他引:5
对φ(N)32°14′~32°56′,λ(E)104°36′~104°51′范围内400~1400m稻田小气候进行了观测,发现海拔(halt)不同,稻田生态环境相差很大:halt每升高100m,平均气温(θar)递减0.72℃,年降雨量递增63.0mm(400~600m)~106.8mm(800~1400m),相对湿度递增1%,日照时数呈抛物线上升变化.halt400m日均温稳定通过12.0℃的初期为3月中旬,halt每升高100m,该时间延迟5~7d.不同halt>12℃的有效积温分别为3621.2℃(400m)、3245.0℃(600m)、3149.9℃(800m)、2804.8℃(1000m)、2082.1℃(1200m)、1950.1℃(1400m).在相对较高的halt,存在明显的逆温和南北坡效应,相应存在杂交水稻局部高产区.本研究结果为四川不同海拔区杂交水稻品种合理布局和应用高产优质栽培技术提供了基础理论依据 相似文献
122.
123.
纳米Ag粒子原位杂化PVDF超滤膜的抗污染性能 总被引:2,自引:2,他引:0
以AgNO3为前驱体,聚偏氟乙烯(PVDF)为聚合物基体,聚乙烯吡咯烷酮(PVP)为分散剂和成孔剂,N,N-二甲基甲酰胺(DMF)为还原剂和溶剂,利用相转化法制备了纳米Ag粒子原位杂化PVDF超滤膜.采用扫描电镜、透射电镜、原子力显微镜及接触角测定仪对杂化膜的结构和性能进行了表征.结果表明:原位形成的纳米Ag粒子均匀地分散在聚合物基体中,纳米Ag粒子的添加改善了PVDF膜的亲水性能.以腐殖酸和牛血清蛋白作为污染物的代表,考察了Ag/PVDF膜的抗有机污染性能.以大肠杆菌、耐甲氧西林金黄色葡萄球菌及活性污泥作为微生物的代表,考察了杂化膜的抗生物污染性能.结果证实了与纯PVDF膜相比,Ag/PVDF膜通量衰减较慢,可有效抑制微生物的生长,表面受活性污泥污染程度小,具有显著的抗有机污染和抗生物污染性能. 相似文献
124.
Two hybrid processes including ozonation-ceramic membrane-biological activated carbon (BAC) (Process A) and ceramic membrane-BAC (Process B) were compared to treat polluted raw water. The performance of hybrid processes was evaluated with the removal efficiencies of turbidity, ammonia and organic matter. The results indicated that more than 99% of particle count was removed by both hybrid processes and ozonation had no significant effect on its removal. BAC filtration greatly improved the removal of ammonia. Increasing the dissolved oxygen to 30.0 mg/L could lead to a removal of ammonia with concentrations as high as 7.80 mg/L and 8.69 mg/L for Processes A and B, respectively. The average removal efficiencies of total organic carbon and ultraviolet absorbance at 254 nm (UV254, a parameter indicating organic matter with aromatic structure) were 49% and 52% for Process A, 51% and 48% for Process B, respectively. Some organic matter was oxidized by ozone and this resulted in reduced membrane fouling and increased membrane flux by 25%-30%. However, pre-ozonation altered the components of the raw water and affected the microorganisms in the BAC, which may impact the removals of organic matter and nitrite negatively. 相似文献
125.
The combination of subsoil and the incorporation of corn stover affect physicochemical properties of soil and corn yield in semi-arid China 总被引:2,自引:0,他引:2
ABSTRACTThe main objective of this study was to investigate the effects of combining subsoil and incorporation of corn stover on soil profile, soil physicochemical properties, and corn yield. A five-year field trial was conducted that consisted of two treatments arranged in a completely random design and replicated three times. Two soil management operations were tested: subsoil + corn stover incorporation (plow construction [PC] treatment) and conventional rotary tillage (control check [CK] treatment). Compared with rotary tillage, it was found that combining subsoil and corn stover incorporation significantly affected corn grain yield in all seasons. Further, combining subsoil and corn stover incorporation significantly increased the thickness of the plow layer, quantity of plow layer soil, thickness of the plow pan and soil bulk density, as well as soil organic matter, available nitrogen, available phosphorus, and available potassium. Evidence indicates that reconstructing the soil plow layer through combination of subsoil and corn stover incorporation improved soil structure, nutrient content, and corn yield. It is of interest that farmers are now applying subsoil and returning crop straw instead of solely relying on rotary tillage. 相似文献
126.
R. W. Hill A. Leon Huber E. K. Israelsen J. P. Riley 《Journal of the American Water Resources Association》1972,8(5):909-921
ABSTRACT. As demands upon available water supplies increase, there is an accompanying increase in the need to assess the downstream consequences resulting from changes at specific locations within a hydrologic system. The problem is approached in this study by hybrid computer simulation of the hydrologic system. Modeling concepts are based upon the development of basic relationships which describe the various hydrologic processes. Within a system these relationships are linked by the continuity-of-mass principle. Spatial resolution is achieved by considering the modeled areas as a series of subbasins. The time increment adopted for the model is one month, so that time varying quantities are expressed in terms of mean monthly values. The model is general in nature and is applied to a particular hydrologic system through a programmed verification procedure whereby model coefficients are evaluated for the particular system. In this study the model is applied to the Bear River basin of western Wyoming, southern Idaho, and northern Utah. Comparisons between observed and computed outflow hydrographs show good agreement. The utility of the model is demonstrated by predicting the effects of various possible water resource management alternatives. The verified hybrid computer program can be digitized for application to the digital computer. 相似文献
127.
Jimmie L. Thomas J. Paul Riley Eugene K. Israelsen 《Journal of the American Water Resources Association》1972,8(5):922-934
ABSTRACT. A hybrid computer program was developed to predict the water and salt outflow from a river basin in which irrigation is the major user of water. The model combines a chemical model which predicts the quality of water percolated through a soil profile with a general hydrologic model. The chemical model considers the reactions that occur in the soil, including the exchange of calcium, magnesium, and sodium cations on the soil complex, and the dissolution and precipitation of gypsum and lime. The chemical composition of the outflow is a function of these chemical processes within the soil, plus the blending of undiverted inflows, evaporation, transpiration, and the mixing of sub surface return flows with groundwater. The six common ions of western waters, namely calcium (Ca++), magnesium (Mg++), sodium (Na+), sulfate (SO4=), chloride (Cl?), and bicarbonate (HCO3?) were considered in the study. Total dissolved solids (TDS) outflow was obtained by adding the individual ions. The overall model operates on a monthly time unit. The model was tested on a portion of the Little Bear River basin in northern Utah. The model successfully simulated measured outflows of water and each of the six ions for a 24-month period. The usefulness of the model was demonstrated by a management study of the prototype system. For example, preliminary results indicated that the available water supply could be used to irrigate additional land without unduly increasing the salt outflow from the basin. With minor adjustments the model can be applied to other hydrologic areas. 相似文献
128.
为解决石油污染土壤中以石油为唯一碳源的土著微生物生长缓慢的问题,研究了分别添加玉米淀粉、玉米粉、可溶性淀粉和葡萄糖4种碳源对土样细菌总量和石油烃降解率的影响。研究结果表明:玉米淀粉作为碳源时土样TN和TP的下降幅度均最大;添加玉米淀粉和玉米粉比添加可溶性淀粉和葡萄糖更有利于细菌的生长繁殖;细菌对直链烷烃化合物均具有较好的降解效果,但对较为复杂的芳香烃化合物降解效果较差。降解反应第40天时,分别添加玉米淀粉、玉米粉、可溶性淀粉和葡萄糖的石油烃降解率分别为67.25%、48.60%、46.30%和28.57%。 相似文献
129.
130.
Kris E. Spence Jay-lin Jane Anthony L. Pometto Jr 《Journal of Polymers and the Environment》1995,3(2):69-74
Dialdehyde starch (DAS) and zein, a hydrophobic corn protein, were investigated to produce biodegradable plastics with improved water resistance and mechanical properties. In the study, dialdehyde starch and zein ratio, plasticizers, and degree of starch oxidation were examined. Increased molding temperature and level of starch oxidation decreased water absorption of the plastic. Tensile strength and Young's modulus increased with starch oxidation. The biodegradation of starting materials and ground plastic specimens was studied in aerobic soil reactors maintained at 25°C for 180 days. Biodegradation of corn starch, zein, and dialdehyde starch for 180 days produced CO2 equivalent to 64, 63, and 10% of theoretical carbon, respectively. Specimens of molded DAS and zein (3 : 1) plastic showed accelerated CO2 evolution compared to DAS and other raw materials alone. By 180 days, specimens made with starch of low oxidation (1 and 5% oxidized) demonstrated a 60% biodegradation, and specimens with highly oxidized starch (90% oxidized) achieved 37% biodegradation.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts.Journal Paper J-15927 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Project No. 3258. 相似文献