Since weed killers were developed in the early part of the decade beginning in 1940, herbicides have been increasing in use until they are now widely used to control weeds . The application of herbicides has thus become a regular agricultural and ecological practice. Some of the herbicides are applied directly to soils and accompanied by a light irrigation to wash them into the soil in order to increase their efficiency . Some of these chemicals accumulate in the soil and should be removed in order to avoid toxic effect on succeeding plants (Klingman, 1961) . The toxic effect of herbicidal residues in soil and water to human subjects , livestock , and wildlife has been repor•ted (Paynter et al., 1960; Carpenter et al., 1961). When these materials are leached out of the soil , they may pollute the water supply. The movement of water and herbicides in soils is thus closely connected to both their herbicidal and toxic effect and is becoming a serious economic problem. It is the purpose of this investigation to study the simultaneous movement of water and herbicides in unsaturated soils by using the thermodynamic theory of irreversible processes. The adsorption of herbicides, the energy of adsorption, and the break-through curve will also be studied.

With  the development of Chinese  economy  and market,  the Chinese brand  is going out  of China, more  and more  overseas Chinese  enterprises  have  attracted  attention outside of China. Among all these overseas Chinese, a group of people called Wenzhounese, famous for Wenzhou Model they created in China, bought back the dynamic industry cluster in regions in Italy. Blooming Chinese  brands  are  increasing  in  the corner  of  streets  and  their  industrial  clusters  range  from  leather  shoes  and  bags  to electric parts, apparel and so on. The purpose of this study is to explore whether the Chinese Wenzhounese immigrant companies in Italy perceive that they have particular common problems and/or benefits in branding themselves in Italy. Through analysis of the role of the brand management in these companies under the context of European/developed market, we aim to find which internal and external factors influence these obstacles and opportunities.

Cadmium (Cd) from the soil can accumulate in our bodies via the consumption of our crops and cause serious health problems. While it has been documented that long-term cultivation affects physical and chemical properties of soil, little is known about its effect on the phytoavailability, solid-phase speciation, and profile distribution of soil Cd. The objectives for this study were to determine the effect of long-term cultivation on: (1) a cadmium availability index (CAI) that reflects phytoavailable Cd for durum wheat, and related soil properties, (2) the solid-phase species of soil Cd and relationships between the CAI and the solid-phase species of soil Cd and related solid-phase soil component properties, and (3) the profile distribution of total soil Cd in the past, and the profile distribution of total soil Cd over the next 100 years. One Orthic Chemozemic soil profile was investigated from a virgin and an adjacent long-term cultivated field at eight sites in the Brown, Dark Brown, and Black soil zonesof Saskatchewan, Canada. Long-term cultivation significantly decreased the CAI. A decrease in total Cd, total Zn, and CEC, and an increase in aromaticity of the soil organic matter and soil pH all contributed to the decrease in the CAI. Both the virgin and cultivated soils had the same solid-phase Cd species with the same order of relative abundance: metal-organic complex-bound > easily reducible metal oxide-bound > H2O2 extractable organic-bound > crystalline metal oxide-bound > exchangeable. However, metal-organic complex-bound Cd and H2O2 extractable organic-bound Cd decreased significantly with long-term cultivation. In the virgin soils two solid-phase Cd species correlated significantly with the CAI: exchangeable Cd (r = 0.93) and easily reducible metal oxide-bound Cd (r = -0.88). In the cultivated soils three solid-phase Cd species correlated significantly with the CAI: exchangeable Cd (r = 0.95), metal-organic complex-bound Cd (r = 0.71), and crystalline metal oxide-bound Cd (r = 0.86). For both the virgin and cultivated soils, the concentration of A horizon Cd > C horizon Cd > B horizon Cd. In the past, A horizon Cd concentration decreased significantly with long-term cultivation. However, it is estimated that in 100 years, with the use of phosphate fertilizer made from Idaho ore, the total A horizon Cd content in these soils could be 3.5 times higher and reach a concentration of 1.18 mg Cd kg-1 soil which is in the critical region where the phytoavailability of soil Cd could increase dramatically. The present study has advanced the frontiers of knowledge on the effect of long-term cultivation on the Cd content and distribution in the soil profile, its phytoavailability index, solid-phase species, and the soil properties related to its phytoavailability. Extending research such as this to other major agricultural soil types and farming practices will assist in the development of innovative management strategies to curtail Cd contamination of the terrestrial food chain.

The impacts of El Nino Southern Oscillation (ENSO) on precipitation, reference evapotranspiration, and vegetation in a three-state region of central Mexico were investigated using daily weather data from 20 weather stations for the years 1970 through 1990, which included 5 El Nino years, 5 La Nina years, and 11 Neutral years. In addition, two years, 1997 (El Nino), and 1998 (La Nina) of 10-day NDVI composites were analyzed during the growing season (May-Oct) along with precipitation and reference evapotranspiration (ETo) over central Mexico. Regional precipitation trends were analyzed using the normalized rainfall departures. The interannual variation of vegetation cover was analyzed using the NDVI on 10-day and monthly bases. The Food and Agricultural Organization (FAO) Penman-Monteith method was used to calculate ETo. The dynamics of the soil water balance in central Mexico was evaluated according to the method proposed by Thornthwaite and Mather. Analyses indicate that driest conditions occurred within the northern part of the region and during neutral ENSO years. Rainfall amounts during El Nino and Neutral years were not statistically different however, La Nina years were about 30% wetter than N and EN years (0.05 level). The correlation coefficient between NDVI and precipitation was 0.79 in 1997, and 0.52 in 1998, in June and July, respectively. Negative correlation was found between NDVI and reference evapotranspiration during the rainy months of July and August. The spatio-temporal variability of NDVI showed that there was significant statistical difference in NDVI between regions, but not between years. Regional soil water balance determinations indicated that conditions were most favorable in the Southern part of the region for crop growth during La Nina years. In general, soil water deficits were reduced by about 50% during the growing season compared to the annual soil water deficits.

The objective of this study was to evaluate the effects of mesquite overstory removal and modifications of soil properties due to mulching treatments on herbaceous production. The three overstory treatments were complete removal of mesquite overstory with no removal of regrowth, complete removal of mesquite overstory with removal of regrowth and an untreated control. The mulching treatments included applications of chip mulch, commercial compost, lopped-and-scattered mesquite branchwood and a control. Both overstory treatments resulted in an increase of over 20% in total annual herbaceous production. The overstory treatment of complete removal of mesquite overstory with no removal of regrowth had the greatest impact on fall production of native herbaceous species during years of relatively high precipitation, at times increasing production by almost 2-fold. Mulching treatments had no effect on herbaceous production; however, soil pH and plant available phosphorus was affected by some of the mulching treatments.

In the arid Southwest where groundwater levels are rapidly declining, reuse of wastewater for groundwater recharge is currently being practiced. Since this practice is known to improve the chemical and biological quality of wastewater, it has been referred to as Soil Aquifer Treatment (SAT). This study investigated the fate of enteric viruses during SAT in Los Angeles, California, and Tucson, Arizona. The sites differed by both the quality and quantity of wastewater applied to spreading basins. At the Tucson site, secondary treated wastewater was applied. In Los Angeles, some sites received stormwater run-off combined with tertiary treated wastewater and others received only tertiary treated wastewater. A major concern with recharge of groundwater is the possible introduction of disease-causing organisms from inadequately treated wastewater. Although harmful bacteria, viruses, and protozoa may be present in wastewater, viruses cause the greatest concern regarding groundwater contamination due to their small size and long-term survival capabilities in the environment--making them less likely to be removed by the process of soil filtration. Integrating the DNA amplification method Polymerase Chain Reaction (PCR) with cell culture, a new technique called Integrated Cell Culture-Polymerase Chain Reaction (ICC-PCR) was adopted to study the occurrence of viruses after SAT. ICC-PCR was used in this study for the detection of non-cytopathogenic effect (CPE) producing enteroviruses in cell culture lysates. Primers had a sensitivity of 1 PFU/mul in cell culture lysate fluid. ICC-PCR products were confirmed with semi-nested PCR and sequencing of the viral nucleic acid. Two hundred eighty-two CPE negative cell culture lysates were analyzed via ICC-PCR. Twenty-seven of these cell culture lysates were found to be positive by ICC-PCR. These twenty-seven cell culture lysates encompassed four tertiary treated wastewater samples, three reclaimed groundwater monitoring well samples, three deep potable groundwater well samples from the Los Angeles area, two secondary wastewater effluent samples, and one reclaimed groundwater monitoring well sample from Tucson, AZ. Coliphages were detected in the groundwater at the Tucson SAT site more often than indicator bacteria. There was no evident relationship between the occurrence of indicators and isolation of non-CPE producing enteroviruses at the Tucson site.

Carbon sequestration in small-scale farming systems in semi-arid regions offers the possibility to increase local soil fertility, improve crop yields, enhance rural people's wellbeing, and strengthen the resilience of agricultural systems while reducing CO2 accumulation in the atmosphere and, thus, contributing to climate change mitigation. A variety of management practices and land use options have been proposed to increase carbon uptake and reduce system losses. So far, less attention has been paid to local smallholders, the ultimate agents of anticipated community carbon projects, and the complexity, diversity, and dynamics of their livelihoods in a highly variable and risk-prone environment. A hybrid research approach, combining biophysical, economic, cultural, and institutional analysis, was used to assess the potential for soil carbon sequestration in the Old Peanut Basin of Senegal. In situ soil and biomass measurements provided current carbon accounts. Historic carbon changes and future sequestration rates under various management practices were simulated with CENTURY, a biogeochemical model. The simulation results well represented general historic trends and carbon storage potential. However, they did not accurately reflect variable and flexible site-specific management strategies as farmers adapt to stress, shock, and crises over time. To account for these, distinct pathways of agricultural and environmental change were examined in Wolof and Serer villages and viable options for carbon sequestration were evaluated. Systems analysis was used to explore the various components that influence farmers' perceptions, choices, and decisions with respect to land management. Results showed that resource endowment and institutional and policy incentives determine which carbon sequestration activities might be most appropriate for different groups of farmers. Finally, a cost-benefit analysis and a cash-flow analysis (using STELLA) were performed to assess the financial profitability and economic feasibility of proposed management strategies. The study reveals large differences in these measures between farmers with low and high resource endowments. In most cases, local smallholders are not likely to have the investment capital necessary to implement the alternative management practices. A farmer-centered approach to carbon sequestration, as proposed by the study, can be used to more effectively address the needs and capacities of smallholders in dryland carbon offset programs.

The general objective of this research is to develop a methodology that will allow mapping and quantifying shrub encroachment with remote sensing. The multitemporal properties of the Moderate Resolution Imaging Spectroradiometer (MODIS) -250m, 16-day vegetation index products were combined with the hyperspectral and high spatial resolution (3.6m) computation of the Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) to detect the dynamics of mesquite and grass/soil matrix at two sites of high (19.5%) and low (5.7%) mesquite cover in the Santa Rita Experimental Range (SRER). MODIS results showed separability between grassland and mesquite based on phenology. Mesquite landscapes had longer green peak starting in April through February, while the grassland only peaked during the monsoon season (July through October). AVIRIS revealed spectral separability, but high variation in the data implicated high heterogeneity in the landscape. Nonetheless, the methodology for larger data was developed in this study and combines ground, air and satellite data.

Air-water interface plays an important role in the transport of many contaminants in the vadose zone. It is also a limiting factor for many processes involve mass or energy transfer between air and water phases in vadose zone. In this research, the gas-phase partitioning tracer method was used to measure air-water interfacial area for eight porous media. The experimental results were used to investigate the influencing factors of the magnitude of air-water interfacial area and the relationship between the air-water interfacial area and water saturation, and capillary pressure. The porous media comprised a series of sands with narrow particle-size ranges, a sand with a wider particle-size distribution, a sandy soil, and a loamy sandy soil. The measurement range was extended to very low water contents in an attempt to determine upper limits for air-water interfacial areas. The measured values were compared to the normalized surface areas of the porous media. The results of the experiments showed that the magnitude of the air-water interfacial areas increased with decreasing water saturation, and approached that of the normalized surface areas. Generally, air-water interfacial areas were larger for media with larger specific surface areas. The change in air-water interfacial area with changing water saturation was less near saturated water contents and greater at smaller values. In addition, the change was greater for the poorly-sorted media than the well-sorted media. An empirical model was developed to describe the observed relationship between air-water interfacial area and water saturation. The coefficients of the model were found to correlate to the porous-medium uniformity coefficient. With this model and associated correlations, only bulk density, specific surface area, and uniformity coefficient are needed to estimate air-water interfacial area for a given water saturation. The model was shown to provide a reasonable description of a literature data set. Potential relationships between air-water interfacial area and capillary pressure under higher water-content conditions are investigated for unsaturated sandy porous media. A conceptual relationship between air-water interfacial area and capillary pressure is hypothesized, and is tested using air-water interfacial area data obtained from gas-phase tracer tests and saturation-pressure data obtained from water-drainage experiments. The results show that the magnitude of the air-water interfacial area increases with increasing capillary pressure, which corresponds to decreasing water content. (Abstract shortened by UMI.)

Concern for environmental management of our natural resources is most often focused on the human impacts upon these resources. Minor stresses on surface materials in sensitive desert landscapes can greatly increase the rate and character of erosion. The National Training Center, Ft. Irwin, located in the middle of the Mojave Desert, California, provides a study area of intense off-road vehicle (ORV) activity spanning a 50-year period. This study documents a case of concentrated ORV activity on sensitive desert environments, and the resulting environmental impacts. Geomorphic surfaces from two study sites within the Ft. Irwin area were mapped from 1:28,400 scale black and white aerial photographs taken in 1947. Surface disruption attributed to military activity was then mapped for the same areas from 1993, 1:12,000, black and white aerial photographs. Several field checks were conducted to verify this mapping. Images created from SPOT panchromatic and Landsat Thematic Mapper (TM) multispectral data acquired during the spring of 1987 and 1993 were analyzed to assess both the extent of disrupted surfaces and the surface geomorphology discernable from satellite data. Classified and merged images were then created from these data and demonstrate the capabilities of satellite data to aid in the delineation of disrupted geomorphic surfaces. Correlations were also established between highly disrupted surfaces and soil surface conditions on selected geomorphic surfaces. Disruption maps produced from the air photos indicate that the amount of disrupted surfaces within the study sites grew from a combined total of 1.3 km² in 1947 to 33.4 km² by 1993. A combination of 6 bands of Landsat TM data with a seventh band of SPOT panchromatic data yielded a product that delineated broad geomorphic surfaces that closely correlate with those mapped from the aerial photography. An error matrix between these two products resulted in an overall accuracy of 83.36% and a Kappa Index of Agreement of 77.28%. A 15-class unsupervised classification of the SPOT panchromatic data produced the representation of the extent and levels of disruption present in the study areas that closely matched field observations. Field sampling of soil strength and clay/silt percentages on disturbed and undisturbed surfaces reveals that these arid land surfaces react to intense ORV activity by becoming more compact and exhibiting higher percentages of clays and silts.