Carbonyl atmospheric reaction products of aromatic hydrocarbons in ambient air

To convert gaseous carbonyls to oximes during sampling, an XAD-4 resin denuder system pre-coated with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine and followed by analysis with methane positive chemical ionization gas chromatography/mass spectrometry was used to measure carbonyls in ambient air samples in Riverside, CA. In conjunction with similar analyses of environmental chamber OH radical-initiated reactions of o- and p-xylene, 1,2,4-trimethylbenzene, ethylbenzene, 4-hydroxy-2-butanone and 1,4-butanediol, we identified benzaldehyde, o-, m- and p-tolualdehyde and acetophenone and the dicarbonyls glyoxal, methylglyoxal, biacetyl, ethylglyoxal, 1,4-butenedial, 3-hexene-2,5-dione, 3-oxo-butanal, 1,4-butanedial and malonaldehyde in the ambient air samples. As discussed, these carbonyls and dicarbonyls can be formed from the OH radical-initiated reactions of aromatic hydrocarbons and other volatile organic compounds emitted into the atmosphere, and we conclude that in situ atmospheric formation is a major source of these carbonyls in our Riverside, CA, ambient air samples.     

AGGREGATE MARGINAL RETURNS FROM WESTERN IRRIGATED AGRICULTURE1

ABSTRACT: Pressure is increasing in the western United States to reallocate water from irrigated agriculture to other competitive uses. Since water is normally allocated through water rights and not necessarily by the price system, the question of economic efficiency is a continual concern. Study results show that returns per acre-foot of water used in western irrigation are quite high and are closely tied to the livestock industry. Returns per acre-foot of water used for crops ranged from $60 to $1,500. When water was used to support livestock, returns per acre-foot ranged from $100 to $600. Clearly, losses of water supply that reduced irrigation production could also lower farm income significantly. Estimated returns also show what alternative uses would have to pay for water under competitive market conditions. Production elasticities are also shown for various states.     

Population control of exotic rainbow trout in streams of a natural area park

Expansion of the distribution of exotic rainbow trout is thought to be a leading cause for the decline of native brook trout since the 1930s in Great Smoky Mountains National Park, USA. An experimental rehabilitation project was conducted from 1976 to 1981 using backpack electrofish shockers on four remnant brook trout populations sympatric with rainbow trout. The objectives were to evaluate the effectiveness of the technique to remove the exotic rainbow trout, to determine the population responses by native brook trout, and to evaluate the usefulness of the technique for trout management in the park.Rainbow trout populations were greatly reduced in density after up to six years of electrofishing, but were not eradicated. Rainbow trout recruitment, however, was essentially eliminated. Brook trout populations responded by increasing in density (including young-of-the-year), but rates of recovery differed among streams. The maximum observed densities ir each stream occurred at the end of the project.The findings suggest that electrofishing had a major negative impact on the exotic species, which was followed by positive responses from the native species in the second and third order study streams. The technique would probably be less effective in larger (fourth-order) park streams, but as an eradication tool the technique may have its highest potential in small first order streams. Nonetheless, the technique appears useful for population control without causing undue impacts on native aquatic species, although it is labor intensive, and capture efficiency is greatly influenced by fish size and stream morphology. To completely remove the exotic fish from selected streams, different technologies will have to be explored and developed.     

FLOOD FREQUENCY ANALYSIS FOR SMALL WATERSHEDS IN SOUTHERN ILLINOIS1

ABSTRACT: Twenty-two gaging stations were selected for developing a regional flood frequency curve for small (area less than 2 square miles) watersheds in southern Illinois. Five probability functions were compared, and the extreme value type I function was selected to develop the regional flood curve. The curve was generated with the index flood method and also another empirical method that related the function parameters to the watershed area. Estimated peak discharges with various return periods were compared with the results obtained from multiple regression analysis.     

Energy and carbon balances of wood cascade chains

In this study we analyze the energy and carbon balances of various cascade chains for recovered wood lumber. Post-recovery options include reuse as lumber, reprocessing as particleboard, pulping to form paper products, and burning for energy recovery. We compare energy and carbon balances of chains of cascaded products to the balances of products obtained from virgin wood fiber or from non-wood material. We describe and quantify several mechanisms through which cascading can affect the energy and carbon balances: direct cascade effects due to different properties and logistics of virgin and recovered materials, substitution effects due to the reduced demand for non-wood materials when wood is cascaded, and land use effects due to alternative possible land uses when less timber harvest is needed because of wood cascading. In some analyses we assume the forest is a limiting resource, and in others we include a fixed amount of forest land from which biomass can be harvested for use as material or biofuel. Energy and carbon balances take into account manufacturing processes, recovery and transportation energy, material recovery losses, and forest processes. We find that land use effects have the greatest impact on energy and carbon balances, followed by substitution effects, while direct cascade effects are relatively minor.     

Ecological Modernisation in Los Angeles and Toronto

This article presents the results of a comparative study of environmental policy making in Toronto and Los Angeles. The study was intended to explain how social formations at the urban scale play an increasingly important role in constructing environmental policy and practice as articulated in docu ments, rhetoric and political actions. It is suggested that environmental policy is embedded in broader and more long-term political goals, and that ecological discourse is not only about the environment but also brings together various social projects under the environmental protection flag. The four case studies-- in Toronto, contaminated soil and the Don River were examined, and in Los Angeles air pollution and the Los Angeles River--revealed considerable vari ation but all reflected an agenda of ecological modernisation. In particular it was found that demands for maintaining or improving environmental integrity and coherence have lost legitimacy to concerns for efficiency, competitiveness, marketability, flexibility and development. Similarly, market driven regulation and an openness to civil society have played a major role in transforming policy making apparatuses. In contrast, the cases revealed that relationships between nature and society go beyond those expected in ecological modernisation theory and include both social ecology and urban ecology.     

A MATHEMATICAL MODEL FOR OPTIMUM DESIGN AND CONTROL OF METROPOLITAN WASTEWATER MANAGEMENT SYSTEMS1

ABSTRACT: A comprehensive mathematical model (Urban Wastewater Management Model) has been developed to continuously simulate time-varying wastewater flows and qualities in complex metropolitan combined sewerage systems. The model serves three functions: (1) assessment of existing or planned system performance in relation to other wastewater discharges in either a metropolitan or river basin area; (2) determination of the optium operation or automatic control of existing or planned systems during rainstorms; and (3) determination of the most economically feasible combination of design alternatives for improving or expanding existing systems to meet specified performance criteria. The model provides an efficient engineering tool for evaluating and controlling pollutant discharges from combined sewerage systems (including treatment plants) to receiving waters, while considering the time and spacial variations of rainfall and dry-weather flows and qualities as well as economic constraints.     

Stable carbon isotope ratio and composition of microbial fatty acids in tropical soils

The soil microbial community plays a critical part in tropical ecosystem functioning through its role in the soil organic matter (SOM) cycle. This study evaluates the relative effects of soil type and land use on (i) soil microbial community structure and (ii) the contribution of SOM derived from the original forest vegetation to the functioning of pasture and sugarcane (Saccharum spp.) ecosystems. We used principal components analysis (PCA) of soil phospholipid fatty acid (PLFA) profiles to evaluate microbial community structure and PLFA stable carbon isotope ratios (delta13C) as indicators of the delta13C of microbial substrates. Soil type mainly determined the relative proportions of gram positive versus gram negative bacteria whereas land use primarily determined the relative proportion of fungi, protozoa, and actinomycetes versus other types of microorganisms. Comparison of a simple model to our PLFA delta13C data from land use chronosequences indicates that forest-derived SOM is actively cycled for appreciably longer times in sugarcane ecosystems developed on Andisols (mean turnover time = 50 yr) than in sugarcane ecosystems developed on an Oxisol (mean turnover time = 13 yr). Our analyses indicate that soil chronosequence PLFA delta13C measurements can be useful indicators of the contribution that SOM derived from the original vegetation makes to continued ecosystem function under the new land use.     

Effects of alum and aluminum chloride on phosphorus runoff from swine manure

Phosphorus (P) runoff from fields fertilized with swine (Sus scrofa domesticus) manure may contribute to eutrophication. The objective of this study was to evaluate the effect of aluminum sulfate (alum) and aluminum chloride applications to swine manure on P runoff from small plots cropped to tall fescue (Festuca arundinacea Shreb.). There were six treatments in this study: (i) unfertilized control plots, (ii) untreated manure, (iii) manure with alum at 215 mg Al L(-1), (iv) manure with aluminum chloride at 215 mg Al L(-1), (v) manure with alum at 430 mg Al L(-1), and (vi) manure with aluminum chloride at 430 mg Al L(-1). Manure application rates were equivalent to approximately 125 kg N ha(-1). Alum and aluminum chloride additions lowered soluble reactive phosphorus (SRP) levels from about 130 mg P L(-1) to approximately 30 mg P L(-1) at low rates. At high rates, SRP levels in swine manure were around 1 mg P L(-1). Soluble reactive P concentrations in runoff were 5.50, 3.66, 3.00, 0.87, 0.87, and 0.55 mg P L(-1), for normal manure, low alum, low aluminum chloride, high alum, high aluminum chloride, and unfertilized control plots, respectively. Hence, high alum and aluminum chloride reduced SRP concentrations in runoff by 84% and were not statistically different from SRP concentrations in runoff from unfertilized control plots. These data indicate that treating swine manure with alum or aluminum chloride could result in significant reductions in nonpoint-source P runoff.