This study evaluated the feasibility of combining potassium chloride (KCl) leaching and electrokinetic (EK) treatment for the remediation of cadmium (Cd) and other metals from contaminated soils. KCl leaching was compared at three concentrations (0.2%, 0.5%, and 1% KCl). EK treatment was conducted separately to migrate the metals in the topsoil to the subsoil. The combined approach using KCl leaching before or after EK treatment was compared. For the single vertical EK treatment, the removal of Cd, lead (Pb), copper (Cu) and zinc (Zn) from the topsoil (0–20 cm) was 9.38%, 4.80%, 0.95%, and 10.81%, respectively. KCl leaching at 1% KCl removed 84.06% Cd, 9.95% Pb, 4.34% Cu, and 19.93% Zn from the topsoil, with higher removal efficiency than that of the 0.2% and 0.5% KCl leaching treatments. By combining the KCl leaching and EK treatment, the removal efficiency of heavy metals improved, in particular for the 1% KCl + EK treatment, where the removal rate of Cd, Pb, Cu, and Zn from the upper surface soil reached 97.79%, 17.69%, 14.37%, and 41.96%, respectively. Correspondingly, the soil Cd content decreased from 4 to 0.21 mg/kg, and was below the Chinese standard limit of 0.3 mg/kg soil. These results indicate that 1% KCl + EK treatment is a good combination technique to mitigate Cd pollution from contaminated soils used for growing rice and leafy vegetables.
The circumstances of the lack of attention to the interdependence of family functions and external employment in the research to date are considered. Major problems and barriers to progress are noted. One problem is the conceptual-theoretical barrier of viewing work as masculine and family responsibility as feminine. A second problem is a differential focus in the research to date in which either the family is studied with inadequate attention given to work, or the work setting is studied with insufficient consideration of family responsibilities. Research strategies are reviewed and discussed, including the need to identify combinations of types of occupations and family situations. Five work-family groups are identified. One of the five groups, single parent is used to illustrate policies pertaining to the interdependence of work and family roles. The relevance of research on role interdependence for both governmental policy and organizational policy is considered in a discussion of the effects of policy on effective integration of work and family roles. 相似文献
Chlorinated and brominated diphenyl ether compounds (DPEs) have been detected by gas Chromatography/ mass spectrometry (GC/MS) in eggs and carcasses of fish-eating birds from Louisiana, Michigan, Ohio, Rhode Island, Texas, Virginia, and Ontario, Canada. Three of these compounds were quantified; the highest concentration of 0.90 ppm tetrachloro DPE was found in a common tern carcass (
) from Rhode Island. This is the first time that the halogenated DPEs have been reported in avian tissues. The significance of these residues is unknown. 相似文献
Summary One color-banded black-capped chickadee flock was studied intensively at a winter feeder in Wisconsin. Flock structure was examined by measuring association among flock members in three ways: spatial proximity, temporal association, and association of individuals during flock movements. Additional information was obtained on aggressive interactions at and near the feeder. By midwinter, the strongest attachments were between males and females who subsequently mated; pair attachments strengthened as the breeding season approached. Lower ranked individuals in the dominance hierarchy showed weaker associations with other flock members in early spring than did more dominant individuals. The strong attachment to the mate may have implications for altruistic behavior within the winter flock. 相似文献
INTRODUCTION: The Airline Lifesaver (AL) is a 13.3 cm x 9.8 cm card any passenger can deliver to the attendant of a commercial airline in order to prompt the delivery of an important safety message. In particular, the AL requests the following safety--belt reminder be added to the regular announcements given at the end of the flight-"Now that you have worn a seat belt for the safest part of your trip, the flight crew would like to remind you to buckle-up during your ground transportation." METHOD: The AL card was handed to 1,258 flight attendants over a 17-year period and compliance with the request for the safety message was systematically tracked. Slightly more than one-third of the AL cards (n=460) included an incentive for making the announcement. RESULTS: Without the incentive, compliance to give the buckle-up reminder was 35.5% of 798 flights. With the incentive, compliance was significantly higher (i.e., 53.3%). IMPACT: The validity of the AL intervention is discussed with regard to its: (a) relevance to cognitive dissonance and consistency theory, and (b) broad-based applicability as a component of community-wide efforts to facilitate a safety-focused culture. The 17-year study also demonstrated a practical and cost-effective application of a behavior-based incentive program. 相似文献
Water quality concerns and revised regulations are changing how confined animal feeding operations manage manure. Devising acceptable and feasible changes in manure practices requires a full understanding of the forces shaping current manure management decisions. Previous theoretical models have shown that a wide range of factors influence the lowest cost solution for manure management. We used a mechanistic model to characterize the manure management practices on 39 swine operations (20 unagitated lagoon and 19 slurry operations) in five states (Iowa, Missouri, North Carolina, Oklahoma, and Pennsylvania). Information was collected from each operation about animal numbers, feed and water use, manure handling and storage characteristics, field locations, crop rotation, fertilizer need, and equipment inventory and usage. Collected data were used as input and to validate results from a mechanistic model that determined acres required for manure application, manure application rate, time required for manure application, value of manure, and costs of manure management. The 39 farms had a mean of 984 animal units (AU) per operation, 18.2 AU ha(-1) (7.4 AU acre(-1)), and manure application costs of dollar 10.49 AU(-1) yr(-1). Significant factors affecting manure management included operation size, manure handling system, state, and ownership structure. Larger operations had lower manure management costs (r2 = 0.32). Manure value potentially exceeded manure application costs on 58% of slurry and 15% of lagoon operations. But 38% of slurry operations needed to apply manure off the farm whereas all lagoon operations had sufficient land for N-based manure management. Manure management was a higher percentage of gross income on contract operations compared with independents (P < 0.01). This research emphasized the importance of site-specific factors affecting manure management decisions and the economics of U.S. swine operations. 相似文献
There has been much recent research on site selection for species preservation, although most of this research has focused on terrestrial plant and animal species. There is increasing evidence that lack of suitable habitat for migratory birds is contributing to their diminishing numbers. We extend the literature of site selection with a specific application to migratory birds. We develop reserve planning models, based on the novel idea of Directed Conditional Covering, to identify superior configurations of locations to be included in migratory flyways. 相似文献
We collected fish and mammals in several radioactively contaminated locations in the Chornobyl Exclusion Zone and analyzed them for 137Cs content. Frequency distributions were built for populations of channel catfish, yellow-necked mice and bank voles. We combined our data with similar data from several other studies to demonstrate the relationship between the standard deviations and means of 137Cs of fish and mammal populations. The frequency distributions of 137Cs in populations of fish and mammals are not normal, as indicated by the strong relationship between standard deviation and mean. Distributions for mammals are more skewed than those for fish. Fish and mammals probably use their environments in fundamentally different ways. The highest concentrations and thus greatest risks are therefore confined to relatively few individuals in each population. 相似文献
A precision scale landscape model designed for agricultural applications is described in this paper. The Precision Agricultural Landscape Modeling System (PALMS) is a combination of two process‐based models: a diffusive wave runoff model with ponding (described in detail) and a biosphere model with a crops module (briefly reviewed). Several innovations, including numerical formulations for the hydrologic properties of the soil surface with crusting, slope/tillage angle interactions, and change of roughness and detention storage with cumulative precipitation have been included. The model is compared to observations on one 1.8 ha field planted with maize and soybeans during four growing seasons, and one 24 ha field planted with maize during one growing season. Daily average soil moisture is simulated well (within 5 percent volumetric), except in extended runoff/ponding episodes. Physical processes not simulated in the model suggest possible explanations for model errors. Planned improvements for PALMS are also presented. 相似文献