咸菜腌制过程中亚硝酸盐日变化量观察

为了解决咸菜腌制过程中亚硝酸盐的日变化量,避免在亚硝酸盐高峰期食用。我们在4～5月份对我市某村8个农户家中对此进行了跟踪观察。 1 材料与方法 1.1 观察对象:我市某村8个农户家中缸内腌制过程中的咸菜。 1.2 采样方法:考虑到直接检测咸菜,由于苓叶重量差别,取样比例不一,会导致较大误差,缩小纵向可比性,而咸菜和咸水相互渗透,始终于平衡状态。

郑州市5～8月逐日最高气温预报

利用郑州市 1 996～ 1 998年 5～ 8月的历史气象资料 ,选取低云日际变化量、降水日际变化和风向日际变化为预报因子 ,建立了 5～ 8月最高气温日变化量多元回归预报方程。根据预报日前 1天实况和预报日的预报量 。

基于地下连续墙变形规律的数值分析研究

基于基坑监测数据,分析地下连续墙的变形规律,地下连续墙日变化量报警点出现在开挖面附近。基于HS本构模型利用分析软件Plaxis分析监测数据与数值模拟吻合度,分析日变形量的主要影响因素并对影响因素分析,分析建议南京地区的基坑开挖深度为H时,其最保险的地下连续墙厚度约为5%H左右,这与研究对象的地下连续墙设计厚度一致。

Interannual variations in energy conversion and interaction between the mesoscale eddy field and mean flow in the Kuroshio south of Japan

Using 19-year satellite altimetric data, variations in the eddy kinetic energy, energy exchanges and interaction between the eddy fi eld and mean fl ow are discussed for the Kuroshio south of Japan. In the seasonal cycle, the eddy kinetic energy level is a minimum in December/January and a maximum in April/May. In addition to seasonal variations, the eddy kinetic energy undergoes interannual changes. The energy transfers mainly from the mean fl ow to the eddy fi eld in the Kuroshio south of Japan, and dominant energy exchanges mainly occur along the Kuroshio path south of Japan in each year from 1993 to 2011. In addition, there is often barotropic instability south of Honshu. Regarding interactions between the eddy fi eld and mean fl ow, cyclonic and anticyclonic accelerations are also found along the Kuroshio path and they fl ank each other. There is cyclonic acceleration always imposed on southeast of Kyushu, and anticyclonic acceleration dominates south of Honshu from 2001 to mid-2005. Reynolds stress is used to explain the dynamic process of energy exchange. Furthermore, lag-correlation and linear regression analysis show that variability of the energy conversion rate and Reynolds stress involve responses to eddy acceleration at two time scales. The enhanced eddy acceleration induces large Reynolds stress, and enhanced Reynolds stress or barotropic instability further enforces energy transfer from the mean fl ow to the eddy fi eld.

Diurnal Variation of Soil CO2 Efflux and Its Optimal Measuring Time-window of Temperate Meadow Steppes in Western Songnen Plain, China

In order to study the diurnal variation of soil CO2 effiux from temperate meadow steppes in Northeast China, and determine the best time for observation, a field experiment was conducted with a LI-6400 soil CO2 flux system under five typical plant communi- ties （Suaeda glauca （Sg）, Chloris virgata （Cv）, Puecinellia distans （Pd）, Leymus chinensis （Lc） and Phragmites australis （Pa）） and an alkali-spot land （As） at the meadow steppe of western Songnen Plain. The results showed that the diurnal variation of soil CO2 effiux exhibited a single peak curve in the growing season. Diurnal maximum soil respiration （Rs） often appeared between 1 1：00 and 13：00, while the minimum occurred at 21：00-23：00 or before dawn. Air temperature near the soil surface （Ta） and soil temperature at 10 cm depth （Tlo） exerted dominant control on the diurnal variations of soil respiration. The time-windows 7：00-9：00 could be used as the optimal measuring time to represent the daily mean soil CO2 effiux at the Cv, Pd, Lc and Pa sites. The daily mean soil CO2 effiux was close to the soil COz effiux from 15：00 to 17：00 and the mean of 2 individual soil CO2 effiux from 15：00 to 19：00 at the As and Sg sites, respectively. During nocturnal hours, negative soil CO2 fluxes （CO2 downwards into the soil） were frequently observed at the As and Sg sites, the magnitude of the negative CO2 fluxes were 0.10-1.55 gmol/（m2.s） and 0.10-0.69 gmol/（m2.s）at the two sites. The results im- plied that alkaline soils could absorb CO2 under natural condition, which might have significant implications to the global carbon budget accounting.

Geomagnetic Field Measurement over Akure Using Ground Based Magnetometer Observatory

The geomagnetic field over Akure, southern Nigeria （7°15＇ N; 5°12＇ E） was investigated from direct observation for a period of two years （2005-2006）. Geomagnetic field over Akure was monitored and measured using a locally produced magnetometer. The geomagnetic data generated were evaluated at every local time hour. Diurnal, monthly and Seasonal effects were investigated. The results of the analyses from the magnetic data generated provide a comprehensive understanding of the geomagnetic variation over the region. This research validates the instrument and presents a direct measurement opportunity to capture the influence of local sources.

Survey on Gamasyab River Water Quality in Nahavand Township, Iran

Gamasyab River, which is the biggest river of Hamadan Province, is sourced from Karstic Springs in Nahavand Township Southern Mountainous Region and supplies a major part of water needs of the region. In this research seasonal variation of water quality and also the degree of pollution related to Gamasyab River water have been assessed. First the general status of the river was studied and four sampling stations were determined. In this research, the quality of river water including Dissolved Oxygen （DO）, five days Biochemical Oxygen Demand （BOD）5, Chemical Oxygen Demand （COD）, Nitrate, phosphate, temperature, Total Hardness（TH）, Total Suspended Solid （TSS）, Total Dissolved Solid （TDS） and PH have been determined and assessed on a monthly basis within a five years period. The results were reported as seasonally and presented using statistical tables and graphs. These results showed that Nitrate concentration in Gamasyab River is strongly depending on distance from Gamasyab spring. By increasing the distance from Gamasyab spring, nitrate concentration increased. The amount of DO in the river water is stable in each station within the year. Air temperature changes have had no effect in the amount of DO. Therefore, it is recommended that the river pollution control plans be implemented more serious than before, non point source pollution related to agricultural activities be managed and prevent from pouring untreated rural wastewaters to the mentioned river.

Diurnal Variations of Greenhouse Gas Fluxes from Mixed Broad-leaved and Coniferous Forest Soil in Dinghushan

The subtropical mixed broad-leaved and coniferous forest, a typical successional monsoon forest, is one of the major forests in the subtropics of China. Therefore, it is very important to estimate the fluxes of the greenhouse gases from the forest soil in order to evaluate the impact of subtropical forests on the greenhouse gas emissions or absorptions. This study investigated the diurnal variations of fluxes of three greenhouse gases （CO 2 , CH 4 , and N 2 O） from a mixed broad-leaved and coniferous forest soil. A static chamber-gas chromatograph technique was used to measure the fluxes of three greenhouse gases. By using the improved gas chromatography sampling system, the fluxes were analyzed with a single injection. In order to find out the effects of litter and seedling on the emissions or absorptions of these greenhouse gases, three treatments were set in the field:（1）bare soil surface （litter was removed previously）; （3） litter + soil; （3） seedling + litter + soil. The experimental results demonstrated that the forest soil was a source of CO 2 , N 2 O and a weak sink of CH 4 .The daily fluxes of CO 2 , CH 4 , and N 2 O from the soil surface were in the range of 488.99700.57, 0.0490.108 and –0.025 –0.053 mg/（m 2 ·h ）, respectively. CO 2 from the litter decomposition accounted for about 1/3 of the total CO 2 emission from the soil surface, while the litter and seedling had no significant effect on the fluxes of CH 4 and N 2 O. The fluxes of CO 2 and N 2 O measured at 9:00 11:00 a.m. were significantly different from their daily averages. Therefore, caution must be taken if the CO 2 and N 2 O fluxes measured within 9:0011:00 a.m. are used for extrapolation.