Effects of observability and complexity on farmers’ adoption of environmental practices

The ability of both regulators and farmers themselves to monitor the impact of environmental practices may be an issue with nonpoint source pollution. Effects that can be perceived via direct sensory evidence provide information at low cost. Results from a survey of livestock farmers suggest that a practice that has more obvious effects on water quality, manure application setbacks, is more likely to be adopted than a more complicated one with less visible effects, manure testing. Farmers’ perceptions of the profitability of the two practices were similar. The importance of observability and complexity has implications for educational programs.     

Treatment of urban stormwater for dissolved pollutants: A comparative study of natural organic filter media

Sorption capacities were evaluated for the dissolved stormwater (SW) pollutants onto two tree mulches and jute fiber. SW spiked with predetermined concentrations of copper (Cu), cadmium (Cd), hexavalent chromium (Cr ⁺⁶), lead (Pb), zinc (Zn), and benzo[a]pyrene (B[a]P), naphthalene (NP), fluoranthene (FA), 1,3‐dichlorobenzene (DCB), and butylbenzylphthalate (BBP) were used in this study. Each medium removed close to 100 percent of all the pollutants at the concentrations studied. Sorption capacities (μg/g) of the three organic media were in the order of jute > hardwood mulch > softwood mulch, and on a mole basis, both the heavy metals and the toxic organics were sorbed by the three media in an identical sequence: Cr ⁺⁶ > Cu, Zn > Cd > Pb; and NP > DCB > FA > B[a]P > BBP. Sorption capacities of the hardwood wood mulch and jute fiber for the pollutants were correlated with distinctive physical properties of the pollutants. © 2005 Wiley Periodicals, Inc.     

Directional selection by fisheries and the timing of sockeye salmon (Oncorhynchus nerka) migrations.

The timing of migration from feeding to breeding areas is a critical link between the growth and survival of adult animals, their reproduction, and the fitness of their progeny. Commercial fisheries often catch a large fraction of the migrants (e.g., salmon), and exploitation rates can vary systematically over the fishing season. We examined daily records of sockeye salmon (Oncorhynchus nerka) in the Egegik and Ugashik management districts in Bristol Bay, Alaska (USA), for evidence of such temporally selective fishing. In recent years, the early migrants have experienced lower fishing rates than later migrants, especially in the Egegik district, and the median migration date of the fish escaping the fisheries has been getting progressively earlier in both districts. Moreover, the overall runs (catch and escapement) in the Egegik district and, to a lesser extent the Ugashik district, have been getting earlier, as predicted in response to the selection on timing. The trends in timing were not correlated with sea surface temperature in the region of the North Pacific Ocean where the salmon tend to concentrate, but the trends in the two districts were correlated with each other, indicating that there may be some common environmental influence in addition to the effect of selection. Despite the selection, both groups of salmon have remained productive. We hypothesize that this resilience may result from representation of all component populations among the early and late migrants, so that the fisheries have not eliminated entire populations, and from density-dependent processes that may have helped maintain the productivity of these salmon populations.     

Role of Crosslinker on the Biodegradation Behavior of Starch/Polyvinylalcohol Blend Films

The effect of crosslinkers on the biodegradation behavior of starch/polyvinyl alcohol (PVA) blend films was investigated by weight loss study, Scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Starch/PVA films were prepared by solution casting method and 5 weight% of four different crosslinking agents like epichlorohydrin, formaldehyde, zinc oxide and borax were used in four different sets to crosslink the films. These crosslinked starch/PVA films were biodegraded in compost. Weight loss study showed that crosslinking retarded the biodegradation of the films in the first 15?days, but after that, there was a significant increase in weight loss. The DSC analysis revealed that the consumption of starch and consequent rearrangement of the PVA molecules were distinctly different in the crosslinked films due to the effect of different crosslinking agents.     

Trichinella spiralis infection in voles alters female odor preference but not partner preference

Females may choose mates based on secondary sex traits that reflect disease resistance. Accordingly, females should be able to distinguish between unparasitized and parasitized males, and should prefer to mate with unparasitized individuals. Mate and odor preferences for uninfected males or males infected with the nematode, Trichinella spiralis, were examined among prairie voles (Microtus ochrogaster) and meadow voles (M. pennsylvanicus). In a 15-min odor preference test, only female meadow voles distinguished between bedding from parasitized and unparasitized conspecific males, and preferred to spend time with bedding from unparasitized males. Although T. spiralis infection influenced odor preference in female meadow voles, there was no effect of infection status on mate preference among either species. Testosterone and corticosterone concentrations were not different between parasitized and unparasitized males. However, among prairie voles, males that spent an increased amount of time with females during the mate preference test had elevated testosterone concentrations. Taken together, these data suggest that (1) female meadow voles can discriminate between unparasitized and parasitized males, (2) the effects of infection on steroid hormone concentrations may be masked by the effects of social interactions, and (3) parasites may represent a selective constraint on partner preference in voles; however, the life cycle of parasites may influence female preference and should be considered in studies of female preference. Received: 23 April 1998 / Accepted after revision: 25 October 1998     

Recording the Response of Plants to Various Air Pollutants

A discussion of the methods used to determine the most economic design of chimney for a new thermal power station or large industrial plant is presented, with the objective that ground level concentration of pollutants will be kept at a minimum. Attention is paid to the geography and climatology of the site, with special reference to the frequency and height of inversions and the prevailing wind direction and speed.

A method is illustrated in using a large thermal power station as an example. The maximum sulfur dioxide concentrations at ground level are computed for several chimney heights and gas exit velocities. The values of these sulfur dioxide concentrations, the capital cost of the chimney, the pumping costs, and the gas pressures within the chimney are considered in selecting a suitable chimney height and a gas exit velocity which will meet most economically the stated objective.

The paper deals primarily with chimneys for industrial or power boiler plant of maximum continuous rating greater than 450 million Btu/hr (about 450,000 lbs of steam/hr), or to chimneys serving furnaces burning fuel at a maximum rate greater than 50,000 lbs/hr of coal, or 80,000 lbs/hr of oil. For chimneys serving plant with smaller heat inputs, chimney selection by reference to Clean Air Act 1956, Memorandum on Chimney Heights is suggested.