Stress ethylene: A bioassay for rhizosphere-applied phytotoxicants

A bioassay for rhizosphere-applied phytotoxicants was developed and evaluated with a broad range of chemicals. Test substances were applied to the rhizosphere of whole, intact bush bean plants (Phaseolus vulgaris L. cv. Bush Blue Lake 290) grown in a solid support medium and the resultant ethylene production was measured to detect the presence of phytotoxic materials. The beans were encapsulated in plastic bags for 2 hr following treatment and then incubated for 24 hr in the dark. Ethylene and ethane accumulating within the bags were quantified via gas-solid chromatography. The application of various concentrations of inorganic and organic chemicals induced various responses. No single equation adequately described the dose-response curves; therefore, a critical value (a statistically significant increase in stress ethylene) was computed for each test substance. A phytotoxic-response threshold for each test substance was defined as the test-substance concentration that caused ethylene production to exceed its respective critical-value concentration. Based on threshold concentrations determined by analysis of stress ethylene production, the relative phytotoxicity rankings of the inorganic test substances were: CdCl₂>CuCl₂>Pb(C₂H₃O₂)₂>LiCl, while those of the organic test substances were 2,4-D esters>paraquat dichloride>1-butanol>2-propanone>2-propanol. Both stress ethylene and ethane production were nonresponsive to hydrogen-ion concentration (measured before application) over a broad pH range. However, significant ethane production was detected at pH 2 and stress ethylene was produced at pH 1. The measurement of stress-induced ethylene provides a rapid and simple means to determine the relative phytoxicity of rhizosphere-applied substances.     

Enhanced anaerobic bioremediation in a DNAPL residual source zone: Test Area North case study

An Interstate Technology and Regulatory Council (ITRC) forum was recently held that focused on case studies in which bioremediation of dense nonaqueous‐phase liquids (DNAPLs) was performed. This first case study, the Test Area North (TAN) site of the Idaho National Engineering and Environmental Laboratory, involves a trichloroethene (TCE) residual source area in a deep, fractured basalt aquifer that has been undergoing enhanced bioremediation since January 1999. Complete dechlorination from TCE to ethene was documented within nine months of operation, and sodium lactate injections were shown to enhance TCE mass transfer from the residual source. Since that time, optimization of injection strategies has maintained efficient dechlorination while demonstrating accelerated cleanup at a lower cost by changing to a whey powder amendment that solubilizes DNAPL. © 2006 Wiley Periodicals, Inc.     

Conservation of Biodiversity in a World of Use

Abstract: Biodiversity conservation has become the stated objective of national governments, state agencies, local communities, and scientific organizations. Yet despite this attention the term biodiversity remains poorly defined. One of the unfortunate consequences of this lack of definition is a proliferation of claims that biodiversity can be both used and conserved. This claim is difficult to assess without a more precise way of defining biodiversity. We offer a heuristic framework for measuring the consequences of human use for biodiversity. Our definition of biodiversity includes three components: genetic, population/species, and community/ecosystem. Each component has its own three attributes: composition, structure, and function. Using this definition, we assessed the effects of different types of human use on the different components and attributes of biodiversity. We show that (1) different degrees of human use or alteration result in differential conservation of biodiversity components; (2) some components and attributes of biodiversity are more sensitive to human use than others; and (3) only extremely limited use or virtually no alteration will protect all components.     

NUTRIENTS DISCHARGED TO THE MISSISSIPPI RIVER FROM EASTERN IOWA WATERSHEDS, 1996.19971

ABSTRACT: The introduction of nutrients from chemical fertilizer, animal manure, wastewater, and atmospheric deposition to the eastern Iowa environment creates a large potential for nutrient transport in watersheds. Agriculture constitutes 93 percent of all land use in eastern Iowa. As part of the U.S. Geological Survey National Water Quality Assessment Program, water samples were collected (typically monthly) from six small and six large watersheds in eastern Iowa between March 1996 and September 1997. A Geographic Information System (GIS) was used to determine land use and quantify inputs of nitrogen and phosphorus within the study area. Streamliow from the watersheds is to the Mississippi River. Chemical fertilizer and animal manure account for 92 percent of the estimated total nitrogen and 99.9 percent of the estimated total phosphorus input in the study area. Total nitrogen and total phosphorus loads for 1996 were estimated for nine of the 12 rivers and creeks using a minimum variance unbiased estimator model. A seasonal pattern of concentrations and loads was observed. The greatest concentrations and loads occur in the late spring to early summer in conjunction with row‐crop fertilizer applications and spring nmoff and again in the late fall to early winter as vegetation goes into dormancy and additional fertilizer is applied to row‐crop fields. The three largest rivers in eastern Iowa transported an estimated total of 79,000 metric tons of total nitrogen and 6,800 metric tons of total phosphorus to the Mississippi River in 1996. The estimated mass of total nitrogen and total phosphorus transported to the Mississippi River represents about 19 percent of all estimated nitrogen and 9 percent of all estimated phosphorus input to the study area.     

Multigenerational genetic analysis of tropical secondary regeneration in a canopy palm

Iriartea deltoidea (Arecaceae) is an abundant canopy palm with a wide geographic distribution in Neotropical wet forests. We analyzed the genetic profile across three generations of Iriartea within a 43-ha area encompassing two areas of second-growth and adjoining old-growth forest at La Selva Biological Field Station in northeastern Costa Rica. A total of 311 reproductively mature trees, 99 large saplings, 207 small saplings, and 601 seedlings were genotyped using 141 AFLP loci. Parentage analysis revealed high dispersal distances, both for seed (over 2.3 km) and pollen (over 3.8 km), indicating a large genetic neighborhood within La Selva Biological Station. In a 20-ha area of second growth, the founding palm population was dominated by a small number of parental trees located in the adjacent old-growth forest; two old-growth trees contributed 48% of the second-growth genes. The genetic diversity of reproductively mature trees in this second-growth forest was significantly reduced compared to adjacent old-growth forest. Within 400 m of the border with old-growth forest, we observed a similar reduction of genetic diversity in saplings, and an even greater loss of genetic diversity in the second generation of seedlings. Nearly half of these seedlings were offspring of local parents. In contrast, in the distant portion of second-growth forest (400-800 m from the old-growth border), parentage analysis showed that 40% of seedlings originated from outside the study area and only 10% were offspring of local parents. These high levels of gene flow maintained genetic diversity in saplings and seedlings similar to levels observed in old-growth forest. Our findings highlight the importance of gene flow from diverse seed and pollen sources for sustaining levels of genetic diversity of tree populations in second-growth forests.     

Groundwater Vulnerability,Brownfield Redevelopment and Land Use Planning

An understanding of groundwater vulnerability in urban watersheds is important for the prevention of both surface water and groundwater contamination and can therefore be a useful tool in brownfield redevelopment and land use planning. Although industrial activity in southeastern Michigan has historically been restricted to the urbanized sections of metropolitan Detroit, new industrial development is rapidly taking place in rural and undeveloped areas. Although environmentalists and urban planners agree that industrial site recycling in urban centres (a.k.a. brownfield redevelopment) is preferable to developing green areas, many older sites remain undeveloped due to real and perceived risks. Using a PC-based geographic information system, a conceptual model of solute transport in soil was developed to evaluate potential impacts to both groundwater and surface water quality resulting from industrial development. The model was used to create a map of groundwater vulnerability within the Rouge River watershed of southeastern Michigan. The map has been used to pin-point several rural and undeveloped areas where groundwater quality is threatened by proposed development. It has also clearly demonstrated that many older brownfield sites, within the City of Detroit, are located on materials that have a much lower vulnerability to groundwater contamination and may therefore be far less costly to redevelop than greenfield sites in undeveloped areas of the watershed.     

Taking Sustainable Cities Seriously: A comparative analysis of twenty-four US cities

After briefly reviewing some conceptual underpinnings of sustainable cities, this paper analyses and compares sustainable cities initiatives in 24 US cities. The central question addressed in the paper is why some cities seem to take sustainability more seriously than others. Numerous demographic, socioeconomic and other characteristics of the cities are correlated with an Index of Taking Sustainability Seriously, which is a composite of some 34 different variables indicating whether each city engages in specific sustainability programmes, policies or activities. Many of the standard explanations, such as the income and wealth of the community, the liberalness of the city and the growth pressures placed on the city, are found to exhibit no correlation with the seriousness of the sustainability effort. What do correlate with the Index are: reliance on manufacturing, where having more residents employed in manufacturing industries is associated with less seriousness; and, the age of the population, where cities with older populations take sustainability more seriously. This has three implications for the future development of sustainable cities. First, some of the cities that might be said to need sustainability programmes the most—cities with heavy manufacturing that are more prone to pollution production—are the least likely to take such programmes seriously. Secondly, as cities' manufacturing bases decline, they should find it increasingly feasible to engage in sustainability initiatives. And, thirdly, as the populations of cities age, policy-makers should also find it easier to support, develop and take seriously sustainability programmes.     

A novel method for reducing acid mine drainage using green liquor dregs

When exposed to the weather, sulfidic minerals release sulfuric acid, metals and metalloids. This leachate can devastate nearby ecosystems for centuries. This article reports a novel barrier system based on green liquor dregs that reduces acid generation, is inexpensive, and is practical for implementation at operational mines. Two waste rock piles were constructed. One pile was left open to the atmosphere, and the other was sealed with green liquor dregs and partially capped with a polyethylene liner. This test was designed in collaboration with personnel from Boliden Mineral AB, a Swedish mining company in order to ensure that the results would be practical to implement at an operational mine. Leachate flow and chemistry were monitored in both piles over a period of 12 months. Effluent volume was 40 % lower in the test pile, while thirteen of the twenty elements assessed showed average concentrations that were 50 % lower in the test pile than in the control pile. For the most environmentally toxic elements As, Cd, Pb and Hg, reductions were even more significant, ranging between 67 and 87 %. These positive results are hypothesized to be primarily due to the chemical and physical characteristics of the green liquor dregs. The novelty of this result is that it is the first barrier system that fulfills the multiple needs of the Swedish mining industry: It is effective in reducing acid mine drainage while remaining both economical and practical. No other barrier system meets these requirements.     

An assessment of coastal land-use and land-cover change from 1974–2008 in the vicinity of Mobile Bay,Alabama

The purpose of this research is to quantify and assess geospatial land-use and land-cover (LULC) changes in the coastal counties of Mobile and Baldwin, Alabama using nine Landsat images from 1974–2008. A study-specific classification scheme was devised comprising upland herbaceous, upland forest, non-woody and woody wetlands, open water, and urban categories. Upland forest was the most dominant terrestrial cover type. Wetlands averaged 17% and urban averaged 7%. A majority of the urban expansion occurred between 1974 and 1979 (26%). Thirty-four percent of the 2008 urban areas were upland forest in 1974. Watershed-scale analysis of Three Mile Creek and D’Olive Bay highlights the temporal and spatial differences of urbanization for watersheds found within the same region. This study is a Gulf of Mexico Alliance (GOMA) Application Pilot project that uses NASA data products to benefit coastal environmental managers and community members. Results have led to increased effectiveness of coastal conservation decision-making, increased understanding of post-hurricane LULC change, continued research on habitat change impacts, and contributed to timely conservation planning efforts. This study has benefited the development of watershed management plans by the Mobile Bay National Estuary Program, which is especially important given projected climate change.