Sustainable soil management practices and quality of potato grown on erodible lands

Land productivity can decline when top soil is lost. In Kentucky, limited resource farmers often produce vegetable crops on erodible lands. The objectives of this study were 1) to quantify the impact of three soil management practices (SMPs) on quantity of potato produced on erodible land, 2) to evaluate the impact of pyrethrin and azadirachtin insecticides on potato tuber quality, and 3) to assess the impact of yard waste compost on the chemical composition (ascorbic acid, free sugars, phenol contents) of potato tubers. Potatoes (Solanum tuberosum L. cv. Kennebec) were grown in a silty loam soil of 10% slope. Plots (n= 18) were 3.7 m wide and 22 m long (10% slope), with metal borders of 20 cm above ground level. Two botanical insecticides, Multi-Purpose Insecticide (containing pyrethrin 0.2%) and Neemix 4EC (containing 0.25% azadirachtin) were sprayed twice on potato foliage during each of two growing seasons (1997 and 1999) at the recommended rates of 6 lbs and 2 gallons.acre(-1), respectively. The SMPs were tall fescue strips (FS) intercropped between each two potato rows, soil mixed with yard waste compost (COM) and no-mulch (NM) treatment (roto-tilled bare soil). The experimental designwas a 2 x 3 x 3 factorial with main factors of two insecticides and three SMPs replicated three times. Average potato yield was lowest in NM and FS and highest in COM treatments. Yield obtained from the bottom of the plots was greater than that obtained from the top of plots. Tuber defects (rot, scab, sun green, hollow heart, necrosis, and vascular discoloration) were significantly different between the two growing seasons. The two insecticidal treatments did not have much influence on potato yield or tuber defects. Tubers obtained from tall fescue treatments had low levels of ascorbic acid and reducing sugars compared to compost treatments.     

Discrimination of factors influencing biota of a stream receiving multiple-source perturbations

Blaine Creek is a fifth-order stream located in eastern Kentucky that has been subject to contamination by oil brines, surface mining, and a coal fly ash settling pond discharge. Toxicity tests, effluent and receiving water chemical monitoring, and Blaine Creek benthic sampling were used to evaluate the effect of the ash pond effluent on the creek. Reproductive impairment of Ceriodaphnia was demonstrated at effluent concentrations ranging from 30 to 100%, but no instream impact on benthic invertebrates could be found at effluent flows that provided up to 65% of the creek's discharge. Correlation and regression analysis of physicochemical versus benthic monitoring data indicated that upstream oil brine contamination and scouring of the creek's predominately shifting sand substrate during rainfall events were the primary factors affecting the benthic fauna, and appeared to override potential effects from other sources. These results demonstrated the value of integrated field/laboratory investigations for effluent impact assessments.     

Increasing UV-B radiation at the earth's surface and potential effects on aqueous mercury cycling and toxicity

In the past two decades, a great deal of attention has been paid to the environmental fate of mercury (Hg), and this is exemplified by the growing number of international conferences devoted uniquely to Hg cycling and its impacts on ecosystem functions and life. This interest in the biogeochemistry of Hg has resulted in a significant improvement of our understanding of its impact on the environment and human health. However, both past and current research, have been primarily oriented toward the study of direct impact of anthropogenic activities on Hg cycling. Besides a few indirect effects such as the increase in Hg methylation observed in acid-rain impacted aquatic systems or the reported enhanced Hg bioaccumulation in newly flooded water reservoirs; changes in Hg transformations/fluxes that may be related to global change have received little attention. A case in point is the depletion of stratospheric ozone and the resulting increase in solar UV-radiation reaching the Earth. This review and critical discussion suggest that increasing UV-B radiation at earth's surface could have a significant and complex impact on Hg cycling including effects on Hg volatilization (photo-reduction), solubilization (photo-oxidation), methyl-Hg demethylation, and Hg methylation. Therefore, this paper is written to provoke discussions, and more importantly, to stimulate research on potential impacts of incoming solar UV-radiation on global Hg fluxes and any toxicity aspects of Hg that may become exacerbated by UV-radiation.     

Effects of plant densities and management of purple nutsedge on sugarcane yield and effect of growth stages and main way of herbicides contact and absorption on the control of tubers

Field experiments carried out with Cyperus rotundus L. at low (58-246), medium (318-773), and high (675-1198 shoots/m2) densities showed sugarcane yield reductions of 13.5, 29.3, and 45.2%, respectively in relation to the control. In the second field experiment, the integration of a mechanic method with two sequences of plowing and disking operations in the dry season, and complementary applications of trifloxysulfuron-sodium + ametrine and sulfentrazone (rainy season) was studied. Average of the chain connected to original shoot showed 92, 95, and 65% of reduction with trifloxysulfuron-sodium + ametrine and surfactant, at the application stages "early," preflowering, and full flowering, respectively.     

Sequential extraction of heavy metals during composting of sewage sludge

The major limitation of soil application of sewage sludge compost is the total heavy metal contents and their bioavailability to the soil-plant system. This study was conducted to determine the heavy metal speciation and the influence of changing the physico-chemical properties of the medium in the course of composting on the concentrations, bioavailability or chemical forms of Cu, Zn, Pb and Ni in sewage sludge. Principal physical and chemical properties and FTIR spectroscopical characterization of sludge compost during treatment show the stability and maturity of end product. The total metal contents in the final compost were much lower than the limit values of composts to be used as good soil fertilizer. Furthermore, it was observed by using a sequential extraction procedure in sludge compost at different steps of treatment, that a large proportion of the heavy metals were associated to the residual fraction (70-80%) and more resistant fractions to extraction X-NaOH, X-EDTA, X-HNO3 (12-29%). Less than 2% of metals bound to bioavailable fractions X-(KNO3+H2O). Heavy metal distribution and bioavailability show some changes during composting depending on the metal itself and the physico-chemical properties of the medium. Bioavailable fractions of all elements tend to decrease except Ni-H2O. Zn and mainly Cu present more affinity to organic and carbonate fractions. In contrast, Pb is usually preferentially bound to sulfide forms X-HNO3. Nickel shows a significant decrease of organic form. Significant degrees of correlation were found between heavy metal fractions and changes of some selected variables (e.g. pH, ash, organic matter, humic substance) during the course of composting. Mobile fractions of metals are poorly predictable from the total content. The R2 value was significantly increased by the inclusion of other variables such as the amount of organic matter (OM) and pH.     

Variations in heavy metal contamination of stream water and groundwater affected by an abandoned lead–zinc mine in Korea

This study evaluated variations in heavy metal contamination of stream waters and groundwaters affected by an abandoned lead–zinc mine, where a rockfill dam for water storage will be built 11 km downstream. For these purposes, a total of 10 rounds of stream and groundwater samplings and subsequent chemical analyses were performed during 2002–2003. Results of an exploratory investigation of stream waters in 2000 indicated substantial contamination with heavy metals including zinc (Zn), iron (Fe) and arsenic (As) for at least 6 km downstream from the mine. Stream waters near the mine showed metal contamination as high as arsenic (As) 8,923 μg L⁻¹, copper (Cu) 616 μg L⁻¹, cadmium (Cd) 223 μg L⁻¹ and lead (Pb) 10,590 μg L⁻¹, which greatly exceeded the Korean stream water guidelines. Remediation focused on the mine tailing piles largely improved the stream water qualities. However, there have still been quality problems for the waters containing relatively high concentrations of As (6–174 μg L⁻¹), Cd (1–46 μg L⁻¹) and Pb (2–26 μg L⁻¹). Rainfall infiltration into the mine tailing piles resulted in an increase of heavy metals in the stream waters due to direct discharge of waste effluent, while dilution of the contaminated stream waters improved the water quality due to mixing with metal free rain waters. Levels of As, Cu and chromium (Cr) largely decreased after heavy rain but that of Pb was rather elevated. The stream waters were characterized by high concentrations of calcium (Ca) and sulfate (SO₄), which were derived from dissolution and leaching of carbonate and sulfide minerals. It was observed that the proportions of Ca and SO₄ increased while those of bicarbonate (HCO₃) and sodium and potassium (Na+K) decreased after a light rainfall event. Most interestingly, the reverse was generally detected for the groundwaters. The zinc, being the metal mined, was the most dominant heavy metal in the groundwaters (1758–10,550 μg L⁻¹) near the mine, which far exceeded the Korean standard of 1000 μg L⁻¹ for drinking water. The decreases in the heavy metals contents in the groundwaters associated with reduced rainfall were quite different from the increases observed for the stream waters, which is not clearly understood at this time and warrants further investigation.     

The willingness to pay to remove billboards and improve scenic amenities

We use the contingent valuation method to measure the amount citizens are willing to pay to improve scenic mountain-view amenities through the removal of billboards. Our approach addresses both the perceived property rights as well as the perceptions of the status quo in the southern Appalachian Mountains. We find that individuals who retire to the mountains have different preferences for land use and mountain views than individuals who have ancestors who lived in Watauga County. In the aggregate, we find that citizens are willing to pay almost one-half million dollars to remove billboards from Watauga County roadsides. This study provides insights to the debate surrounding land use along public roads.     

Integrated Measures of Anthropogenic Stress in the U.S. Great Lakes Basin

Integrated, quantitative expressions of anthropogenic stress over large geographic regions can be valuable tools in environmental research and management. Despite the fundamental appeal of a regional approach, development of regional stress measures remains one of the most important current challenges in environmental science. Using publicly available, pre-existing spatial datasets, we developed a geographic information system database of 86 variables related to five classes of anthropogenic stress in the U.S. Great Lakes basin: agriculture, atmospheric deposition, human population, land cover, and point source pollution. The original variables were quantified by a variety of data types over a broad range of spatial and classification resolutions. We summarized the original data for 762 watershed-based units that comprise the U.S. portion of the basin and then used principal components analysis to develop overall stress measures within each stress category. We developed a cumulative stress index by combining the first principal component from each of the five stress categories. Maps of the stress measures illustrate strong spatial patterns across the basin, with the greatest amount of stress occurring on the western shore of Lake Michigan, southwest Lake Erie, and southeastern Lake Ontario. We found strong relationships between the stress measures and characteristics of bird communities, fish communities, and water chemistry measurements from the coastal region. The stress measures are taken to represent the major threats to coastal ecosystems in the U.S. Great Lakes. Such regional-scale efforts are critical for understanding relationships between human disturbance and ecosystem response, and can be used to guide environmental decision-making at both regional and local scales.     

Mothers Against Drunk Driving (MADD): the first 25 years

Mothers Against Drunk Driving (MADD) has arguably been one of the most successful public-health grassroots citizen advocacy organizations in the United States in the past century. In 2005, MADD celebrated the 25th anniversary of its founding. Based on a national poll by the Gallup Organization in 2005, MADD is recognized by 94% of citizens. It is generally given credit for changing American attitudes toward drinking and driving. Since MADD's founding in 1980, alcohol-related traffic deaths in the United States have decreased from an estimated 30,000 to 16,694 in 2004, according to the National Highway Traffic Safety Administration. This article examines the growth of MADD since its founding and attempts to gauge its contribution to the public's understanding of the impaired-driving problem and to the reductions in alcohol-related highway deaths and injuries that have occurred in the first 25 years of its existence.     

Accumulation of weathered polycyclic aromatic hydrocarbons (PAHs) by plant and earthworm species

Experiments were conducted to assess the bioavailability of polyclycic aromatic hydrocarbons (PAHs) in soil from a Manufactured Gas Plant site. Three plant species were cultivated for four consecutive growing cycles (28 days each) in soil contaminated with 36.3 microg/g total PAH. During the first growth period, Cucurbita pepo ssp. pepo (zucchini) tissues contained significantly greater quantities of PAHs than did Cucumis sativus (cucumber) and Cucurbita pepo ssp. ovifera (squash). During the first growth cycle, zucchini plants accumulated up to 5.47 times more total PAH than did the other plants, including up to three orders of magnitude greater levels of the six ring PAHs. Over growth cycles 2-4, PAH accumulation by zucchini decreased by 85%, whereas the uptake of the contaminants by cucumber and squash remained relatively constant. Over all four growth cycles, the removal of PAHs by zucchini was still twice that of the other species. Two earthworm species accumulated significantly different amounts of PAH from the soil; Eisenia foetida and Lumbricus terrestris contained 0.204 and 0.084 microg/g total PAH, respectively, but neither species accumulated measurable quantities 5 or 6 ring PAHs. Lastly, in abiotic desorption experiments with an aqueous phase of synthetically prepared organic acid solutions, the release of 3 and 4 ring PAHs from soil was unaffected by the treatments but the desorption of 5-6 ring constituents was increased by up to two orders of magnitude. The data show that not only is the accumulation of weathered PAHs species-specific but also that the bioavailability of individual PAH constituents is highly variable.