Comparison of different disinfection processes in the effective removal of antibiotic-resistant bacteria and genes

This study compared three different disinfection processes(chlorination, E-beam, and ozone) and the efficacy of three oxidants(H2O2, S2O-8, and peroxymonosulfate(MPS)) in removing antibiotic resistant bacteria(ARB) and antibiotic resistance genes(ARGs) in a synthetic wastewater. More than30 mg/L of chlorine was needed to remove over 90% of ARB and ARG. For the E-beam method, only1 dose(kGy) was needed to remove ARB and ARG, and ozone could reduce ARB and ARG by more than 90% even at 3 mg/L ozone concentration. In the ozone process, CT values(concentration × time)were compared for ozone alone and combined with different catalysts based on the 2-log removal of ARB and ARG. Ozone treatment yielded a value of 31 and 33(mg·min)/L for ARB and ARGs respectively. On the other hand, ozone with persulfate yielded 15.9 and 18.5(mg·min)/L while ozone with monopersulfate yielded a value of 12 and 14.5(mg·min)/L. This implies that the addition of these catalysts significantly reduces the contact time to achieve a 2-log removal, thus enhancing the process in terms of its kinetics.     

The economics of adoption and management of alley cropping in Haiti

The Haitian people are facing serious problems of environmental degradation that threaten the economic livelihoods of many resource-poor farmers. Structures to retard the process of soil loss have been adopted reluctantly and, even when adopted, the management and maintenance have been less than desirable. We evaluate the factors that influence the adoption and management of alley cropping in Haiti. Results of the adoption model show that institutional factors, such as membership in a local peasant organization and training in soil conservation practices, favorably influence adoption. Socio-economic factors such as gender, per capita income, and interaction between education and per capita income also significantly influence adoption of alley cropping in Gaita and Bannate. The management of alley cropping is influenced by demographic, socio-economic, institutional, and physical factors. The relative importance of each factor on the probability of adoption and management of alley cropping varies from one variable to another. The study generates important information for resource allocation in the establishment of alley cropping as a soil conservation structure.     

Plant facilitation of a belowground predator

Interest in facilitative predator plant interactions has focused upon above-ground systems. Underground physical conditions are distinctive, however, and we provide evidence that bush lupine, Lupinus arboreus, facilitates the survival of the predatory nematode Heterorhabditis marelatus. Because H. marelatus is prone to desiccation and lupines maintain a zone of moist soil around their taproots even during dry periods, we hypothesized that dry-season nematode survival under lupines might be higher than in the surrounding grasslands. We performed field surveys and measured nematode survival in lupine and grassland rhizospheres under wet- and dry-season conditions. Nematodes survived the crucial summer period better under lupines than in grasslands; however, this advantage disappeared in wet, winter soils. Modeling the probability of nematode population extinction showed that, while even large nematode cohorts were likely to go extinct in grasslands, even small cohorts in lupine rhizospheres were likely to survive until the arrival of the next prey generation. Because this nematode predator has a strong top-down effect on lupine survival via its effect on root-boring larvae of the ghost moth Hepialus californicus, this facilitative interaction may enable a belowground trophic cascade. Similar cases of predator facilitation in seasonally stressful environments are probably common in nature.     

Influence of sulfide (S2-) on preservation and speciation of inorganic arsenic in drinking water

Generally, H2SO4, HNO3, HCl or the combination of ethylenediaminetetraacetate with acetic acid (EDTA-HAc) have been used to preserve arsenite and arsenate species prior to analysis. When these acidic preservatives are added in sulfidic water, instantaneous precipitation of poorly crystalline orpiment, As2S3(am), occurs, thereby lowering the total arsenic, As(Tot), analysis. A new method for the determination of As(Tot) was developed in which acid-preserved sulfidic water samples were oxidized with NaOCl, converting As2S3(am) and thioarsenic species to arsenate. A new method was also developed for the separation of uncharged arsenite and charged thioarsenic species in fresh, unpreserved sulfidic water by adsorbing the charged thioarsenic species while allowing uncharged arsenite to pass through a strong-base resin unhindered. The adsorbed thioarsenic species could be eluted efficiently with 0.16 M NaOCl solution.     

Cell-free fetal DNA coming in all sizes and shapes

Cell-free fetal DNA analysis has an established role in prenatal assessments. It serves as a source of fetal genetic material that is accessible non-invasively from maternal blood. Through the years, evidence has accumulated to show that cell-free fetal DNA molecules are derived from placental tissues, are mainly of short DNA fragments and have rapid post-delivery clearance profiles. But questions regarding how they come to being short molecules from placental cells and in which physical forms do they exist remained largely unanswered until recently. We now know that the distributions of ending sites of cell-free DNA molecules are non-random across the genome and bear correlations with the chromatin structures of cells from which they have originated. Such an insight offers ways to deduce the tissue-of-origin of these molecules. Besides, the physical nature and sequence characteristics of the ends of each cell-free DNA molecule provide tell-tale signs of how the DNA fragmentation processes are orchestrated by nuclease enzymes. These realizations offered opportunities to develop methods for enriching cell-free fetal DNA to facilitate non-invasive prenatal diagnostics. Here we aimed to collate what is known about the biological and physical characteristics of cell-free fetal DNA into one article and explain the implications of these observations.     

ONTARIO'S WATER TAKING PERMIT PROGRAM1

ABSTRACT. Most water takings in Ontario in excess of 10,000 gallons per day for purposes other than domestic, farm, or fire fighting require authorization by permit by the Ontario Ministry of the Environment. The legislation imposes control beyond that under common law, but does not remove common-law obligations. Permits may not be assigned without the Ministry's consent and do not create property rights in water. Permits to take ground-water require permittees to ensure that sufficient water is made available for the needs of prior users who suffer serious water-supply interference due to the taking, or to reduce the rate and amount of taking. Permits to take surface water require permittees to maintain sufficient downstream flow to protect downstream uses of water and natural functions of streams. Specific permit requirements for city wells in the rural Hunsburger Creek basin protect existing well supplies and require maintenance of streamflow for pond levels and fish. Tobacco irrigation in the Big Creek basin reduced streamflow significantly and requires development of more detailed water-management plans for years of extreme demand. Ontario's permit program serves to resolve water-use conflicts, furnishes information on use and provides one means for implementing management plans.     

Below-cost timber sales and the political marketplace

Political pressures exist to increase the economic efficiency of timber management and production on the national forests managed by the USDA Forest Service. There is growing belief both outside and within the Forest Service that current levels of timber production, and most particularly uneconomic timber production, should be reduced. Many argue that eliminating uneconomic timber management programs will both save money and reduce environmental degradation. This article traces the political evolution of the focus on economic efficiency in timber production and explores the political-institutional factors that are shaping the current policy debate. The below-cost issue is less about economic efficiency than it is about political advantage and alternative political visions of the societal role of the nation's national forests now and in the future.     

CHANGE IN LAKE TROPHIC STATE AND INTERNAL PHOSPHORUS RELEASE AFTER ALUMINUM SULFATE APPLICATION1

ABSTRACT: Recovery of eutrophic lakes after nutrient diversion may be delayed if the lake experiences significant internal phosphorus (p) loading to the water column. A maximum dose of aluminum sulfate, defined herein, was applied to the anaerobic sediments of the hypolimnia of two dimictic Ohio lakes following septic tank diversion, with the objective of attaining long term control of the release of phosphorus to the water column from these sediments. The results were compared to a similar, downstream, untreated lake. Total phosphorus concentration declined sharply after treatment and has remained so through 1980 for both lakes, a period of 5 and 6 years of control, respectively. Internal P loading from anaerobic, hypolimnetic sediments was partially controlled by the treatment but there are other important sources, perhaps in the littoral zone, in these lakes. Algal biomass is Smaller and water transparency has increased. Both lakes became mesotrophic after treatment, as described by the Carlson (1977) trophic state index, and remain in that improved condition to date. No deleterious side effects were observed, although one lake experienced a significant decrease in diversity of planktonic microcrustacea and a lakeward extension of the macrophyte community. This method appears to be an effective and lasting means of accelerating the recovery of a eutrophic lake following nutrient diversion.