A new design of groundwater sampling device and its application

Compounds in the atmosphere contaminate samples of groundwater. An inexpensive and simple method for collecting groundwater samples is developed to prevent contamination when the background concentration of contaminants is high. This new design of groundwater sampling device involves a glass sampling bottle with a Teflon-lined valve at each end. A cleaned and dried sampling bottle was connected to a low flow-rate peristaltic pump with Teflon tubing and was filled with water. No headspace volume was remained in the sampling bottle. The sample bottle was then packed in a PVC bag to prevent the target component from infiltrating into the water sample through the valves. In this study, groundwater was sampled at six wells using both the conventional method and the improved method. The analysis of trichlorofluoromethane（ CFC-11 ） concentrations at these six wells indicates that all the groundwater samples obtained by the conventional sampling method were contaminated by CFC-11 from the atmosphere. The improved sampling method greatly eliminated the problems of contamination, preservation and quantitative analysis of natural water.     

COMPARATIVE STUDY OF OPTIMIZATION TECHNIQUES FOR IRRIGATION PROJECT PLANNING1

ABSTRACT: This study presents three optimization techniques for on‐farm irrigation scheduling in irrigation project planning: namely the genetic algorithm, simulated annealing and iterative improvement methods. The three techniques are applied to planning a 394.6 ha irrigation project in the town of Delta, Utah, for optimizing economic profits, simulating water demand, and estimating the crop area percentages with specific water supply and planted area constraints. The comparative optimization results for the 394.6 ha irrigated project from the genetic algorithm, simulated annealing, and iterative improvement methods are as follows: (1) the seasonal maximum net benefits are $113,826, $111,494, and $105,444 per season, respectively; and (2) the seasonal water demands are 3.03*10³ m³, 3.0*10³ m³, and 2.92*10³ m³ per season, respectively. This study also determined the most suitable four parameters of the genetic algorithm method for the Delta irrigated project to be: (1) the number of generations equals 800, (2) population size equals 50, (3) probability of crossover equals 0.6, and (4) probability of mutation equals 0.02. Meanwhile, the most suitable three parameters of simulated annealing method for the Delta irrigated project are: (1) initial temperature equals 1,000, (2) number of moves equal 90, and (3) cooling rate equals 0.95.     

Residues of endosulfan and other selected organochlorine pesticides in farm areas of the Lower Fraser Valley, British Columbia, Canada

Crop soils, ditch sediments, and water flowing from several farm areas to salmon tributary streams of the Fraser River in the Lower Fraser Valley (LFV) of British Columbia, Canada, were sampled in 2002-2003 to quantify for residues of an organochlorine cyclodiene pesticide, endosulfan (END = alpha-endosulfan + beta-endosulfan + endosulfan sulfate). Residues from historical use of other selected organochlorine pesticides, namely, cyclodienes (aldrin, alpha-chlordane, gamma-chlordane, dieldrin, endrin, endrin aldehyde, heptachlor, and heptachlor epoxide), hexachlorocyclohexanes [alpha-benzene-hexachloride (alpha-BHC), beta-BHC, delta-BHC, and gamma-BHC (lindane)], and DDT-related compounds (p,p-DDT, p,p-DDD, p,p-DDE, and methoxychlor) were also determined. Reference and background levels of these pesticides in ditches leading to fish streams were obtained from pristine watershed areas. Varying amounts of END residues were detected in soils (<0.02-5.60 mg kg(-1) dry wt.) and ditch sediments (<0.02-3.33 mg kg(-1) dry wt.) in mainly three of five farm areas sampled. Likewise, residues (excluding END) of other selected organochlorine compounds such as aldrin, BHC, chlordane, endrin, p,p-DDT, methoxychlor, and their respective major transformation products (endosulfan sulfate, dieldrin, endrin aldehyde, heptachlor, heptachlor epoxide, p,p-DDD, and p,p-DDE) were found in crop soils (<0.02-16.2 mg kg(-1) dry wt.) and sediments (<0.02-9.73 mg kg(-1) dry wt.). Most of these pesticides (END: <0.01-1.86 microg L(-1); other selected organochlorine pesticides: <0.0.1-1.50 microg L(-1)) were also found in ditch water leading to salmon streams in several farms. The END levels of crop soils from the same LFV study farms in 1994 and 2003 indicated an estimated decline of 22% to 1.35 mg kg(-1) dry wt. during that period. This reduction was probably due to the increasing use of alternate pesticides (e.g., organophosphorus compounds). Some possible biological implications of these pesticide residues on nontarget organisms in the LFV are discussed.     

Bird species migration ratio in East Asia, Australia, and surrounding islands

Bird migration and its relationship with the contemporary environment have attracted long-term discussion. We calculated the avian migration ratio (the proportion of breeding species that migrate) in the areas from 70°E to 180°E and examined its relationship with the annual ranges of ambient temperature, primary productivity (estimated by the Enhanced Vegetation Index), and precipitation, along with island isolation and elevational range. The avian migration ratio increased with increasing latitude in general but varied greatly between the two hemispheres. Additionally, it showed minimal differences between continents and islands. Our analyses revealed that the seasonality of ambient temperature, which represents the energy expenditure of birds, is the dominant factor in determining bird species migration. Seasonality in primary productivity and other environmental factors play an indirect or limited role in bird species migration. The lower avian migration ratio in the Southern Hemisphere can be attributed to its paleogeographical isolation, stable paleoclimate, and warm contemporary environment. Under current trends of global warming, our findings should lead to further studies of the impact of warming on bird migration.     

Pressurized CO2/zero valent iron system for nitrate removal

A fluidized zero valent iron (ZVI) reactor pressurized by CO(2) gas for controlling pH was employed for nitrate reduction. The proposed CO(2) pressurized system potentially has advantages of using less CO(2) gas and reaching equilibrium pH faster than CO(2)-bubbled system. However, due to weak acid nature of carbonic acid, system pH gradually increased with increasing oxidation of ZVI and reduction of nitrate. As pH increased with progress of reaction, nitrate removal rate decreased continuously. The results indicate that nitrate removal efficiency increases with increasing initial ZVI dosage but reaches plateau at ZVI doses of higher than 8.25gl(-1), and initial nitrate concentration up to 100mg l(-1) as N has minimal impact on the removal efficiency. Unlike the fluidized system with pH control by strong acid reported in our pervious study, near 100% of nitrogen recovery was observed in the current process, indicating that nitrate reduction by ZVI with different pH controlled mechanisms will have different reaction routes.     

Evaluation of marine outfall with three-dimensional hydrodynamic and water quality modeling

Numerical models are often used to evaluate the potential impact of human alternation of natural water bodies and to help the design of the alternation to mitigate its impacts. In the past decade, three-dimensional hydrodynamic and reactive transport modeling has matured from a research subject to a practical analysis technology. This paper presents a practical study in which a three-dimensional hydrodynamic and water quality model [hydrodynamic eutrophication model (HEM-3D)] was applied to determine the optimal location for treated wastewater discharged from marine outfall system in the Keelung harbor and the adjacent coastal sea. First, model validation was conducted with respect to surface elevation, current, and water quality variables measured in the Keelung harbor station and its coastal sea. The overall performance of the model was in qualitative agreement with the available field data. The model was then used to evaluate several scenarios of the locations from marine outfall system. Based on model simulation results, a location at the northeast of Ho-Ping Island was recommended for adoption because the environmental impact is smaller than any other alternative.

High Toughness and Fast Crystallization Poly(Lactic Acid)/Polyamide 11/SiO<Subscript>2</Subscript> Composites

A poly(lactic acid) (PLA)/polyamide 11 (PA11)/SiO₂ composite was mixed from PLA, PA11, and nanosilica particles through twin-screw extrusion. The PLA/PA11/SiO₂ composite was evaluated with tensile and Izod impact tests, light transmission and haze measurement, and isothermal and nonisothermal crystallization behavior determinations. The PLA/PA11/SiO₂ (97.0/3.0) composite had approximately 10.8% less ultimate tensile strength than neat PLA, but it had greater ductility and approximately ninefold greater elongation at break. A dimple morphology was observed on the fractural surface of the PLA/PA11/SiO₂ composite, indicating that the incorporation of PA11 and nanosilica particles increased the ductility of the PLA matrix. PLA with less than 3 wt% of PA11 and 0.5 phr of nanosilica particles had an Izod impact strength of 8.72 kJ/m². PA11 and nanosilica particles effectively toughened this PLA polymer; they accelerated both isothermal and nonisothermal crystallization rates and increased the crystallinities of the resulting composites under isothermal and nonisothermal crystallization processes.     

Effect of Common Chemical Treatments on the Process Kinetics and Mechanical Properties of Flax/Epoxy Composites Manufactured by Resin Infusion

Chemical treatments are widely employed to improve the fiber-matrix adhesion in composites based on eco-friendly fibers such as flax. To better understand the influence of these treatments on processing behavior, this study characterized the surface chemistry and morphology of woven flax fabrics treated by acetone, alkaline, silane and diluted epoxy. Flax/epoxy composites were then manufactured by resin infusion and the flow front and preform thickness evolution was monitored. The alkaline treatment was shown to result in a 50 % increase in equivalent permeability due to an increase in porosity which led to a decrease in flexural properties. The processing results were found to be in good agreement with predictions of a 1-dimensional model. This study suggests that infusion times are not considerably affected by the observed changes in surface energy. However, other implications of the treatments such as an increase in fibrillation can alter the infusion times significantly.

     

The crude oil market and the gold market: Evidence for cointegration,causality and price discovery

Given that the gold market and the crude oil market are the main representatives of the large commodity markets, it is of crucial practical significance to analyze their cointegration relationship and causality, and investigate their respective contribution, from the perspective of price discovery, to the common price trend so as to interpret the dynamics of the whole large commodity market and forecast the fluctuation of crude oil and gold prices.