Soil column experiments used as a means to assess transport,sorption, and biodegradation of pesticides in groundwater

Soil column experiments are used to investigate the fate of three pesticides of high, intermediate, and low solubility in groundwater: N- phosphonomethyl glycine (glyphosate); O,O-diethyl-S-[(ethylthio)methyl]phosphorodithioate (phorate); (2,4-dichlorophenoxy)acetic acid (2,4-D). Feed solutions are prepared by adding each pesticide (100 mg/L glyphosate, 50 μ g/L phorate, 50 mg/L 2,4-D) along with conservative tracer, KBr, in synthetic groundwater. The concentration of the pesticides in effluents is detected by ion chromatography (glyphosate, 2,4-D) and GC-FID (phorate). The Br^? breakthrough curves are employed to estimate the dispersion coefficient and mean pore velocity in each column. Solute transport and reactive models accounting for equilibrium/non-equilibrium sorption and biodegradation are coupled with inverse modeling numerical codes to estimate the kinetic parameters for all pesticides.     

基于SPOT VGT/NDVI的陕西省关中地区冬小麦遥感估产

冬小麦是关中地区的主要粮食作物之一。对冬小麦产量估算的研究可使国家有关部门及时掌握粮食生产状况,对国家制定粮食政策和经济计划,及时进行宏观调控有着重要的意义。以陕西省关中地区为研究区域,利用1999—2007年的SPOT VGT/NDVI遥感数据对冬小麦产量进行预测。首先,选取冬小麦关键生长期内0.2—0.8范围内的旬NDVI数据,利用最大值合成法合成后的月NDVI数据建立与冬小麦产量之间的关系;其次,使用相关分析方法筛选出冬小麦关键期内与产量相关性较好的月份和旬,分别建立这些月份、旬与冬小麦产量之间的回归关系模型,最后对模型进行精度验证。结果显示,NDVI与产量之间有很好的相关性,其中4月上旬的相关性最好,其相关系数R2为0.605,即利用4月份上旬的数据预测冬小麦产量最好。在预测产量与实际产量对比的基础上,得出估产的相对误差为-5.2%—-7.9%,表明估产精度良好,可运用于冬小麦的实际估产。     

机械搅拌萃取塔中氯仿萃取DMF的传质系数

萃取-精馏法处理N,N-二甲基甲酰胺(DMF)废水是一种节能工艺,相关的工艺研究多有报道.为了对萃取传质过程进行研究,在机械搅拌萃取塔中采用氯仿萃取废水中DMF,在考虑萃取传质系数沿塔高变化的基础上建立了传质数学模型.根据实验数据,结合辛普森积分法和最优化方法一单纯形法对传质模型进行参数估计,获得传质系数与萃取轻重两相...     

Design-based estimators and power analyses of trend tests for the proportion of fish that exhibit gross pathological disorders

Methods for estimating the proportion of fish that exhibit gross pathological disorders and for estimating the variance of these estimates are defined. The methods are for the situation in which a probability-based sampling design is used to collect fish for examination, but geographic locations (rather than individual fish) are assigned probabilities of being selected for sampling. To illustrate the use of the methods, they are applied to data collected during the 1992 EMAP- Estuaries sampling program in the Louisianian Province (i.e., the Gulf of Mexico). Separate estimates of the proportion of fish with gross pathological disorders are computed for demersal species, commercial species, pelagic species, and all species as one group. In addition, a test for trend in the proportion of fish that exhibit gross pathological disorders is defined, and analyses of the power of the test are presented. The power analyses are based on a general underlying model of the random distribution patterns of fish and the random process of catching fish. The power analyses also take into account the features of the sampling designs used for collecting fish. Component parameter estimates were computed using data from the 1992 EMAP-Estuaries sampling program in the Louisianian Province. Results from these analyses suggest that the EMAP-Estuaries sampling designs are capable of detecting a 0.15% change per year in the proportion of fish (all species groups combined) with gross pathological disorders in estuaries of the Louisianian Province over a 12-year period with a power of at least 80%. © Rapid Science 1998     

Line transect sampling of Karner blue butterflies ( Lycaeides melissa samuelis)

Line transect sampling is an effective survey method for estimating butterfly densities because it provides unbiased estimates of site-density (provided key assumptions are met), and estimates are comparable among sites. For monitoring Karner blue butterflies in Wisconsin, USA, comparable estimates are required because each year a different selection of sites will be monitored. Annual state-wide indices of species abundance can be derived from the site-surveys and compared to previous year's indices to monitor trends. We advocate that line transect sampling is preferable to Pollard-Yates transects as a survey technique for monitoring Karner blue butter- flies. The Pollard-Yates surveys do not adjust for diferences in site detectability. As a consequence, estimates of among-site from Pollard-Yates surveys can be biased. © Rapid Science 1998     

运用遗传算法进行污水厂费用函数拟合

污水厂费用函数的建立是城市污水厂建设规划中的重要环节之一。为了探索建立该函数的有效方法,本研究采用遗传算法,用收集到的若干污水厂的设计建设费用,进行污水厂费用函数的参数估计,并用牛顿法及其改进方法与其进行比较,结果显示遗传算法的拟合效果优于比较方法,说明运用遗传算法进行污水厂费用函数拟合是可行的。     

ANALYSIS OF PUMPING TESTS: SIGNIFICANCE OF WELL DIAMETER,PARTIAL PENETRATION,AND NOISE1

ABSTRACT: The nonlinear least squares (NLS) method was applied to pumping and recovery aquifer test data in confined and unconfined aquifers with finite diameter and partially penetrating pumping wells, and with partially penetrating piezometers or observation wells. It was demonstrated that noiseless and moderately noisy drawdown data from observation points located less than two saturated thicknesses of the aquifer from the pumping well produced an exact or acceptable set of parameters when the diameter of the pumping well was included in the analysis. The accuracy of the estimated parameters, particularly that of specific storage, decreased with increases in the noise level in the observed drawdown data. With consideration of the well radii, the noiseless drawdown data from the pumping well in an unconfined aquifer produced good estimates of horizontal and vertical hydraulic conductivities and specific yield, but the estimated specific storage was unacceptable. When noisy data from the pumping well were used, an acceptable set of parameters was not obtained. Further experiments with noisy drawdown data in an unconfined aquifer revealed that when the well diameter was included in the analysis, hydraulic conductivity, specific yield and vertical hydraulic conductivity may be estimated rather effectively from piezometers located over a range of distances from the pumping well. Estimation of specific storage became less reliable for piezometers located at distances greater than the initial saturated thickness of the aquifer. Application of the NLS to field pumping and recovery data from a confined aquifer showed that the estimated parameters from the two tests were in good agreement only when the well diameter was included in the analysis. Without consideration of well radii, the estimated values of hydraulic conductivity from the pumping and recovery tests were off by a factor of four.     

事故损失预估方法的探讨

应用模糊数学的方法来评估企业的安全状况 ,在此基础上预估企业事故发生的概率及其可能产生的损失 ,为可靠地评价安全投资项目效益创造条件     

可燃制冷剂泄漏及爆炸危害评价的研究

建立了计算可燃工质泄漏后在房间内可燃工质浓度变化的模型。计算结果表明,小型空调器可燃工质泄漏引发的爆炸隐患仅局限于空调系统附近的局部区域内。用压力－冲量准则,对可燃工质泄漏产生的最大爆炸当量、危害范围与危害等级进行分析研究。结果表明,使用充装量很小的可燃制冷剂,泄漏产生爆炸的危险性很小,火灾隐患是主要的。     

TRANSIENT STORAGE ASSESSMENTS OF DYE‐TRACER INJECTIONS IN RIVERS OF THE WILLAMETTE BASIN,OREGON1

ABSTRACT: Rhodamine WT dye‐tracer injections in rivers of the Willamette Basin yield concentration‐time curves with characteristically long recession times suggestive of active transient storage processes. The scale of drainage areas contributing to the stream reaches studied in the Willamette Basin ranges from 10 to 12,000 km². A transient storage assessment of the tracer studies has been completed using the U.S. Geological Survey's One‐dimensional Transport with Inflow and Storage (OTIS) model, which incorporates storage exchange and decay functions along with the traditional dispersion and advection transport equation. The analysis estimates solute transport of the dye. It identifies first‐order decay coefficients to be on the order of 10^?5/sec for the nonconservative Rhodamine W.T. On an individual subreach basis, the first‐order decay is slower (typically by an order of magnitude) than the transient storage process, indicating that nonconservative tracers may be used to evaluate transient storage in rivers. In the transient storage analysis, a dimensionless parameter (A_s/A) expresses the spatial extent of storage zone area relative to stream cross section. In certain reaches of Willamette Basin pool‐and‐riffle, gravel‐bed rivers, this parameter was as large as 0.5. A measure of the storage exchange flux was calculated for each stream subreach in the simulation analysis. This storage exchange is shown subjectively to be higher at higher stream discharges. Hyporheic linkage between streams and subsurface flows is the probable physical mechanism contributing to a significant part of this inferred active transient storage. Hyporheic linkages are further suggested by detailed measurements of river discharge with an Acoustic Doppler Current Profiler system delineating zones in two large rivers where water alternately enters and leaves the surface channels through gravel‐and‐cobble riverbeds. Measurements show patterns of hyporheic exchange that are highly variable in time and space.