Estimating life cycle greenhouse gas emissions from corn–ethanol: a critical review of current U.S. practices

This study reviews corn–ethanol life cycle assessment studies and modeling tools to identify key discrepancies between studies, and shortcomings in analysis of greenhouse gas emissions. The primary conclusions are that direct land use change modeling, soil N₂O emissions modeling, and co-product crediting were either poorly treated or treated inconsistently across most or all studies. Despite the existence of improved methods and tools proposed by institutional bodies and the broader research community, the state of the practice tends towards over-simplified and highly generalized methods that increase potential uncertainty in greenhouse gas estimates and prevents differentiation among producers of corn ethanol.     

Tolerance to iron accumulation and its effects on mineral composition and growth of two grass species

This study aimed to assess the influence of excess iron on the capacity of accumulation of this heavy metal, mineral composition, and growth of Setaria parviflora and Paspalum urvillei. Seedlings were submitted to 0.009; 1; 2; 4; and 7 mM of Fe-EDTA. In both species there was an increase in the concentration of Fe, Zn, P, and Ca and a decrease in Mn, K, and Mg in the iron plaque. Both species accumulated more iron in roots. In the shoots, S. parviflora showed higher iron content, except at 7 mM. Iron altered the contents of Fe, Cu, K, and Mg in roots, and of Fe, Mn, Zn, N, P, K, Ca, and Mg in shoots. The two species tolerated high iron concentrations and accumulated high content of this element in both shoots and roots. The iron did not reduce their growth. Both species are indicated for studies aiming restoration of iron-contaminated areas.     

Relation of Environmental Characteristics to Fish Assemblages in the Upper French Broad River Basin, North Carolina

Fish assemblages at 16 sites in the upper French Broad River basin, North Carolina were related to environmental characteristics using detrended correspondence analysis, principal components analysis, and linear regression. The primary gradient affecting sites in this basin was related to agricultural influence, characterized by high levels of agricultural land cover, nitrate plus nitrite, sulfate, specific conductance, and sediment. Agricultural influence on the fish assemblage was represented as a trophic shift from specialized insectivores to generalized insectivores and an herbivore. A secondary influence on variation among sites was related to urban land cover, population density, increased concentrations of metals, and soil erodibility. This primarily urban gradient was characterized by an increase in the number of native and introduced fish species, particularly sunfish and omnivores species, and a decline in the percent of piscivores. These results support the identification of indicators for different environmental influences, which can improve the ability of resource managers to diagnose impairment in this basin and in similar basins.     

The Public Policy Aspects of Biological Monitoring: Budget and Land-Use Planning Implications at the County Level

Montgomery County, Maryland faces a growing problem that confronts local governments across the country: the cumulative impacts that population growth and the resulting land-use changes are having on local streams and their accompanying ecosystems. County officials found they needed an affordable tool to serve as a report card for stream health, and began a biomonitoring program in 1994. By 1997 county officials had monitored all 23 watersheds within the county's boundaries, and in 1998 the county published its first Countywide Stream Protection Strategy (CSPS). The County uses the CSPS to prioritize its watershed restoration efforts to those areas most in need of immediate remediation. Six primary programs now support or require the use of information from Montgomery County's biomonitoring program. And, the lessons learned from Montgomery County can help other county and local governments develop similar programs of their own.     

Residences with anomalous soil concentrations of dioxin-like compounds in two communities in Michigan, USA: a case study

Most contamination of residential property soil with dioxin-like compounds occurs as a result of proximity to industrial activity that produces such compounds and, outside the industrially impacted zone, the soil concentrations are at background levels. However, as part of the University of Michigan Dioxin Exposure Study, residential properties in the lower peninsula of Michigan, USA, were identified that were located far enough from known sources of these compounds that the soil concentrations should have been at background levels and yet the toxic equivalent (TEQ) of some properties' soil was greater than 2.5 standard deviations above the mean background level. In the three cases presented here from Midland/Saginaw Counties, the anomalously high-TEQ values were primarily due to the presence of polychlorinated dibenzofurans. Based on interviews with the residents and a comparison of soil congener profiles, it was deduced that these values resulted from anthropogenic soil movement from historically contaminated areas. In the cases from Jackson/Calhoun Counties, the unusually high-TEQ values were primarily due to polychlorinated biphenyls. In the case profiled here, it appears that the soil became contaminated through sandblasting to remove paint from the swimming pool. This study identified two mechanisms for soil contamination outside zones of industrial impact; thus, an assumption of background levels of soil contamination outside industrial zones may not be valid.     

Ammonia emissions from field-simulated cattle defecation and urination

Atmospheric ammonia (NH(3)) is a concern because of its environmental impact. The greatest contribution to atmospheric NH(3) comes from agricultural sources. This study quantified NH(3) volatilization from cattle defecation and urination on pasture under field conditions in Auburn, Alabama. Treatments consisted of beef feces, dairy feces, dairy urine, and a control. The experiment was conducted during four seasons from June 2003 to April 2004. Fresh feces or urine was applied onto grass swards, and NH(3) volatilization was measured up to 14 d after application using an inverted chamber method. Dairy urine was the only significant source of NH(3). Ammonia nitrogen (N) loss differed among seasons, ranging from 1.8% in winter to 20.9% during the warmer summer months. Cumulative volatilization was best described in this experiment by the equation % NH(3)-N loss = N(max) (1 - e(-ct))(i). The highest rate of NH(3) volatilization generally occurred within 24 h. This study suggests that NH(3) volatilization from cattle urine on pasture is significant and varies with season, whereas NH(3) volatilization from cattle feces is negligible.     

A fully reproductive fighting morph in a soldier clade of gall-inducing thrips (Oncothrips morrisi)

We present the first life history data for Oncothrips morrisi, a species in a clade of haplodiploid, Australian gall-inducing thrips that has a micropteran fighting morph in the first generation of the gall. Micropterans in other species in the clade have lower fecundity than their mother, and these species are considered eusocial. There is no such reproductive skew in O. morrisi, and the species is not eusocial by any definition. The volume of O. morrisi galls is between 4 and 20 times greater in than eusocial species in the clade and the dispersing-brood size varies between 5 and 15 times larger than that of other species. The lack of skew in O. morrisi could be associated with large gall volume, reducing competition between females for space and feeding sites for their offspring. As O. morrisi is in a lineage basal to eusocial Oncothrips, we also discuss selective factors for the evolution of a non-dispersing fighting morph in this clade. The costs involved in dispersal and latency to reproduction may have lowered the selective threshold for the evolution of a non-dispersing morph. Once non-dispersal evolved, selection to defend one's offspring may have promoted the evolution of soldier-like morphology and behaviour.     

Hemiparasites generate environmental heterogeneity and enhance species coexistence in salt marshes.

Tidal inundation and salinity are considered to be controlling factors in salt marsh species distributions. Parasitic plants may also influence community organization as parasite-host interactions may play a functional role in stress amelioration due to physiological mechanisms for salinity tolerance and resource acquisition. Endangered root hemiparasites (Cordylanthus maritimus ssp. palustris and Cordylanthus mollis ssp. mollis) occupy unique habitat within fragmented northern California tidal wetlands. My objective was to examine the effects of these root hemiparasites on soil salinity, aeration, and community composition. I compared experimentally established bare patches, shaded and unshaded, and parasite removal patches to controls with hemiparasites across intertidal elevation gradients. Plant community composition, soil salinity, and redox potential were measured as response variables. In this field removal experiment, I demonstrated that parasite-host associations can enhance the amelioration of physical stress conditions in the salt marsh exceeding the passive role of shading by vegetation. Consumer-driven reduction of physical stress resulted in increased plant species richness, and the effect was most pronounced with elevated salinity and hypoxia stress. Although previous studies have demonstrated that removal of dominant plant biomass by herbivores can increase physical stress in salt marshes, this is one of the first examples of a positive indirect effect of a consumer on community diversity through physical stress relief. Greater understanding of biological interactions coupled with abiotic factors may improve rare plant conservation and salt marsh restoration success.