Competitive sorption of organic contaminants in chalk

In the Negev desert, Israel, a chemical industrial complex is located over fractured Eocene chalk formations where transfer of water and solutes between fracture voids and matrix pores affects migration of contaminants in the fractures due to diffusion into the chalk matrix. This study tests sorption and sorption competition between contaminants in the chalk matrix to make it possible to evaluate the potential for contaminant attenuation during transport in fractures. Single solute sorption isotherms on chalk matrix material for five common contaminants (m-xylene, ametryn, 1,2-dichloroethane, phenanthrene, and 2,4,6-tribromophenol) were found to be nonlinear, as confirmed in plots of Kd versus initial solution concentration. Over the studied concentration ranges, m-xylene Kd varied by more than a factor of 100, ametryn Kd by a factor of 4, 1,2-dichloroethane Kd by more than a factor of 3, phenanthrene Kd by about a factor of 2, and 2,4,6-tribromophenol Kd by a factor of 10. It was earlier found that sorption is to the organic matter component of the chalk matrix and not to the mineral phases (Chemosphere 44 (2001) 1121). Nonlinear sorption isotherms indicate that there is at least some finite sorption domain. Bi-solute competition experiments with 2,4,6-tribromophenol as the competitor were designed to explore the nature of the finite sorption domain. All of the isotherms in the bi-solute experiments are more linear than in the single solute experiments, as confirmed by smaller variations in Kd as a function of initial solution concentration. For both m-xylene and ametryn, there is a small nonlinear component or domain that was apparently not susceptible to competition by 2,4,6-tribromophenol. The nonlinear sorption domain(s) is best expressed at low solution concentrations. Inert-solvent-normalized single and bi-solute sorption isotherms demonstrate that ametryn undergoes specific force interactions with the chalk sorbent. The volume percent of phenanthrene sorbed at the liquid solubility limit is calculated to be 13% v:v in both the single and bi-solute experiments. This value exceeds what may be reasonably interpreted as partitioning of phenanthrene into organic matter, despite the relative linearity of the phenanthrene sorption isotherm (compared with other compounds) in both single and bi-solute systems.     

Populations, longevity, mortality and fecundity of Chrysoperla carnea (Neuroptera, Chrysopidae) from olive-orchards with different agricultural management systems

The influence that different styles of olive-orchard management (conventional, integrated, and organic) exert on the predator Chrysoperla carnea has been studied to strengthen this insect’s role in the integrated management against pests. For this, the adult chrysopid populations were determined by McPhail traps, and laboratory examinations were made of certain biological characteristics of the first generation of adults captured in each of the olive orchards studied. The chrysopid populations increasing significantly during some months in the integrated and organic olive orchard. The most abundant species in all the zones was C. carnea, representing 95% of all captures in the conventional olive orchard. It was found that the larvae from the integrated olive orchard took longer to develop, while the pupae from the organic orchard evolved most rapidly to adulthood. The highest mortality rate was for larvae in the conventional olive orchard. The fecundity of the females from the organic orchards was significantly greater, presumably due to their greater longevity and shorter pre-oviposition period. These results can be used to improve conservation strategies and to increase C. carnea populations and their predatory activity.     

Evaluating the Risk of Potential Acid Sulfate Soils and Habitat Modification for Mosquito Control (Runneling) in Coastal Salt Marshes: Comparing Methods and Managing the Risk

Coastal environments in Australia are under development pressures. Human settlement encroaches on disease vector salt marsh mosquito breeding areas that are underlain by potential acid sulfate soils (PASS). Altering the hydrology by runneling solves the mosquito problem but may lead to acid sulfate problems. Appropriate analytical tools can assess the risk to the environment. The objective of the research was to compare three methods of assessing PASS. The study area was a low-lying intertidal subtropical salt marsh that was being considered for runneling. The results indicated that using field pH and field peroxide pH (and the relationship between these), and also the peroxide oxidation-combined acidity and sulfate (POCAS) test, appeared to overestimate the potential acidity. This was because the source of acidity in the intertidal salt marsh includes a large organic content, which is not a major environmental concern. The chromium-reducible sulfur test, which is not affected by organic content, was found to provide the most appropriate assessment, and is recommended for use in highly organic salt marshes.     

Women and natural resource management: Illustrations from India and Nepal

This article attempts to delineate women's roles in natural resource management by highlighting their roles in management of water, agriculture, livestock, forestry and fishery. The article is based on the findings of case studies in rural areas of India and Nepal done during 2003 and 2004 by the author as well as by other researchers. Taking women as primary respondents, empirical work used participatory techniques, such as in‐depth surveys, focus group discussions and participant observation. Findings suggest that women clearly outdo men in terms of their involvement in use and management of all the studied sectors, i.e., water, agriculture, livestock, forestry and fishery. Yet, they face categorical exclusion and denial of equal sharing of benefits from natural resources. In order to ensure sustainable use of these resources, the article recommends that policy makers, planners and development workers must have a better understanding of the relative and often shifting roles of men and women in natural resource management, including division of labour, access to resources, decision‐making and traditional knowledge and practices. The article concludes with sector‐specific recommendations.     

Poly(vinyl alcohol)/Compost Composites for Biofiltration of Swine Waste Volatiles

In this study, a Poly(vinyl alcohol)(PVA)/compost composite bead is prepared and is indicated suitable as a filter material for biofiltration. The optimal preparation process is with the compost size of 16–35 mesh, the ratio of water to compost of 40 g/15 g compost, and the immersion time in the phosphate solution of 60 min. The composite bead prepared by this process is a porous spherical particle with a diameter between 2.4 and 6.0 mm and a density of 0.96 g/cm³. It contains 9.43 mg P/g dry solid and 12.1 mg N/g dry solid. The equilibrium moisture content of the composite bead bed from adsorption and holding experiments is 50.5 and 54.6% on a wet basis respectively, which is about 1.74 times higher than that of swine manure compost bed. It corresponds to the optimal filter material required and is sufficient to sustain biological activity as the composite bead adsorbs equilibrium moisture. The bulk compressive strength of the composite bead bed is about 1.15 times larger than that of swine manure compost bed to ensure even distribution of air flow and reduce the head loss as the air flow stream passed through. The pH value of the filter bed could maintain in the 6.9–7.2 range during the operation period due to the composite bead has the phosphate buffer capacity. The percentage of ethyl acetate removal could remain at over 99% for 40 days operation while the composite beads adsorbed inorganic nitrate nutrients. The pressure drop of two kind composite beads and pig manure compost filter beds are 0 and 2 mm H₂O, respectively, after operating for 40 days.     

High-Efficiency Production of Bioplastics from Biodegradable Organic Solids

Microbial polyhydroxyalkanoates (PHAs) have been extensively studied as environmentally friendly biodegradable thermoplastics. The major obstacle to wide acceptance of PHAs is their high price, mainly attributed to the costs of raw materials and polymer recovery. A large amount of organic solids are discarded from food production and consumption and may be used as carbonaceous raw materials for production of PHAs. A novel technology was investigated at bench-top scale to produce PHAs from food scraps. The harvested cell mass had a high PHA content (72.6% of dry cell mass), the same as obtained from pure glucose and organic acids. The organic solid was first digested in an acidogenic reactor in which about 60% solid was converted to fermentative products, including short-chain fatty acids. The four major acids were acetic, propionic, butyric, and lactic acids at concentrations of 6, 2, 27, and 33 g/L, respectively. The acids were transported through a membrane barrier via molecular diffusion to an airlift bioreactor, where the acids were utilized by an enriched culture of Ralstonia eutropha for PHA synthesis. Purification of fermentative acids was not performed in this molecular diffusion–based integration of acidogenesis and polymerization. By using a dialysis membrane as the barrier, the dry cell mass concentration and PHA content reached 22.7 g/L and 72.6%, respectively. The PHA was a copolymer of poly (3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) with 2.8 mole % of hydroxyvalerate.     

Characterization of waste materials originating from Quebec supermarkets and an assessment of recycling potential

This study evaluated, both qualitatively and quantitatively, waste materials from several major Quebec grocery stores. Averaged over nine sampling dates, cardboard, paper and wood products represented 43 and 74% of waste material, based on weight and volume, respectively while organic matter including fruits, vegetables, baked goods and meat products represented 40 and 10% of waste material based on weight and volume. Plastics, wrapping and bagging materials, represented over 7 and 13% of waste material based on weight and volume, respectively, and other recyclable waste materials such as glass, metal and various miscellaneous objects, represented 4 and 2% of waste material based on weight and volume. On average, 60.6 kg waste/employee per week was generated by the three stores. Store size was not a determining factor in the composition of grocery store waste material. These results suggest that costs associated with supermarket waste disposal may be substantially reduced by source-separation of recyclable and compostable materials while reducing pressure for incineration or landfill. Therefore, the adoption of recycling and source-separation programs, and studies to determine problems and costs associated with the implementation of such programs are recommended.     

SURFACE WATER QUALITY IMPACTS OF TILLAGE PRACTICES UNDER LIQUID SWINE MANIJRE APPLICATION1

ABSTRACT: Field studies were conducted to investigate the effects of tillage practices on the saturated hydraulic conductivity, and quantity and quality of surface runoff water resulting from the application of the liquid swine manure as a fertilizer. As part of the study, infiltration experiments were conducted on silt-loam soil with no-tillage (NT) and disk tillage (DT) practices. Liquid swine manure was applied on test plots, and the rainfall was applied by the portable rainfall simulator. The infiltration data was analyzed for the saturated hydraulic conductivity (K8) and runoff volume determinations. The surface runoff water was analyzed for total N, total P, ammonia, and nitrate concentration determinations. The study indicated that the tillage had significant effects on K_s, and quantity and quality of runoff water. The K_s values of the NT plots were found to vary from 0.693 to 1.734 mm/min, with a mean of 1.494 mm/min, while they varied from 1.056 to 2.543 mm/min, with a mean of 2231 mm/mm in the DT plots. The total N, total P, ammonium nitrogen and nitrate nitrogen concentrations were lower in runoff generated from DT plots, compared to that from the NT plots. The chemical concentration levels were significantly different in runoff waters collected one-day after manure application than in those collected 40-days after the manure application. Study suggested that the DT practice must be preferred over the NT practice if liquid swine manure is used as the fertilizer. The study is further continued to assess the long-term impacts of swine manure application and tillage on the quantity and quality of surface runoff water.     

无公害蔬菜基地规划建设中的几个环境问题探讨

无公害蔬菜生产是农业产业结构调整的重要内容,也是农民增收的重要途径。在无公害蔬菜基地的规划建设中要充分考虑土壤、大气、水源等方面的环境因素,以确保产品的安全性。基地的规划建设要尽可能远离城市和污染较重的工厂区域,要与公路保持一定的距离,基地附近要有清洁的水源,不得使用城市污水直接灌溉,城市污泥作为有机肥施用要首先进行无害化处理。     

几种常见废有机溶剂的回收利用

蒸馏在有机化工生产中具有较为广泛的应用。经过简单蒸馏对一些废有机溶剂进行回收利用，一般是通过间歇蒸馏和萃取蒸馏来处理，只要根据不同的有机物沸点适当地调节蒸馏温度即可，简单蒸馏不但生产工艺简单，而且回收成本低，回收率高，既减少了废水有机溶剂对环境的危害性，又可以使废物得到充分的回收利用，实现了环境治理中“减量化，资源化，无害化”的方针，在目前环保治理中具有较为广泛的应用价值。