SOIL MOISTURE VARIATION PATTERNS OBSERVED IN HAND COUNTY,SOUTH DAKOTA1

ABSTRACT: Sail moisture data were taken during nine sampling events (1976-1978) at a test site in South Dakota as part of the ground truth used in NASA's aircraft experiments studying the microwave sensing of soil moisture. This portion of the study dealt only with the spatial variability observed with regard to the ground data. Samples were taken over three surface depths at each point, and the data reported as the mean field moisture content within each of three surface horizons. The results shed additional light on the relationship between ground sampling and remote sensing of soil moisture. First, it was found that it is best to partition data of well drained sites from poorly drained areas when attempting to characterize the surface moisture content throughout an area of varying soil and cover conditions. It was also found that the moisture coefficient of variation within a field decreased as the mean field soil moisture increased, and that the standard deviation was at a maximum in the mid-range of observed moisture conditions (15-25 percent). Within field sample variation also decreases as the sample is integrated over a greater surface depth. It was determined that a sampling intensity of 10 samples per kilometer was adequate to characterize the mean field soil moisture at all three depths along a transect in the areas of moderate to good drainage-.     

Monitoring the fate of chlorine from MSW sampling through combustion Part I: Analysis of the waste stream for chlorine

The total chlorine and water soluble chlorine contents of the components of municipal solid waste (MSW) have been determined from sampling studies carried out at two sites, Baltimore County, MD, and Brooklyn, NY, for a five-day period. The total chlorine contents of the MSW samples from Baltimore County, MD, and Brooklyn, NY, are 0.45 and 0.89 mass %, respectively.     

Anthropogenic Disturbance and Patch Dynamics in Circumpolar Arctic Ecosystems

Abstract: It has been 30 years since environmental concern was first expressed over the prospect of large-scale resource development in the Arctic. Human effects are more extensive within the tundra biome now than at any time in the past. With or without predicted climatic changes, interaction among different natural and contemporary anthropogenic disturbance regimes are bound to have a significant effect on local and regional vegetation patterns and plant migration. We summarize the results of recent studies of patchy anthropogenic disturbance. We pay particular attention to the natural regeneration of plant communities, emphasize patch dynamics over the medium term (20–75 years), and discuss the data in the context of popular models of vegetation change following disturbance. Disturbance is important because it produces patches of partially or totally denuded ground that permit propagule establishment but may also open affected areas to erosion. Even relatively low-intensity, small-scale disturbances have immediate and persistent effects on arctic vegetation and soils. On all but the wettest sites, the patches support new, relatively stable vegetation states. Where slope is minimal, such disturbances are capable of expanding over large areas in as short a time as 4 years. The effects result in an artificial mosaic of patches of highly variable quality and quantity that comprise feeding and nesting habitats for terrestrial herbivores.     

A method for scaling biological response of soil microcosms

An extensive series of laboratory experiments was conducted in soil microcosms to study the respiratory response of microorganisms to toxicant amendments within different types of soils. Our analysis of test results demonstrates that coupled biological and environmental factors within soil can be scaled (i.e., commensurably and analogously grouped) by means of two rate constants, one characterizing the diffusion of CO₂ in the soil matrix and another the biological production of CO₂. The two rate constants were used to classify the impact of metal compounds on diverse soil types and to predict the loss or gain of total respiratory CO₂ of amended soils relative to intact soils. This method exemplifies a more general approach, potentially useful for scaling complex physical and biological interactions in environmental assessments.     

An in-depth look at parent-imposed driving rules: their strengths and weaknesses

Introduction: With a growing interest in increasing parental involvement in teen driving, it is important to find out what parents are already doing. Method This study assessed the content, delivery, rigidity, and consequences of 143 driving rules reported by 24 parent-teen dyads. Results: Strengths included that driving rules covered the full range of concerns, especially night driving limits and passenger limits, and most parents and teens reported that violations would be followed by consequences, especially talk/warn or no driving. Weaknesses included that many rules were not very strict and only half showed parent-teen agreement on content. Conclusions: These findings suggest that teen driving rules are not clearly defined.     

Characterization of cation-pi interactions in aqueous solution using deuterium nuclear magnetic resonance spectroscopy

Chemical interactions of aromatic organic contaminants control their fate, transport, and toxicity in the environment. Recent molecular modeling studies have suggested that strong interactions can occur between the pi electrons of aromatic molecules and metal cations in aqueous solutions and/or on mineral surfaces, and that such interactions may be important in some environmental systems. However, spectroscopic evidence for these so-called cation-pi interactions has been extremely limited to date. In this paper, cation-pi interactions in aqueous salt solutions were characterized via 2H nuclear magnetic resonance (NMR) spin-lattice relaxation times (T1) and calculations of molecular correlation times (tau(c)) for a series of perdeuterated (d6-benzene) benzene-cation complexes. The T1 values for d6-benzene decreased with increasing concentrations of LiCl, NaCl, KCl, RbCl, CsCl, and AgNO3, with the largest effects observed in the AgNO3 and CsCl solutions. Upon normalizing tau(c) values by solution viscosity effects, an overall affinity trend of Ag+ > Cs+ > K+ > Rb+ > Na+ > Li+ was derived for the d6-benzene-cation complexes. The ability of Ag+ to complex d6-benzene was significantly reduced upon addition of NH3, which strongly coordinates Ag+ at high pH. Results with d6-benzene, d8-naphthalene, d2-dichloromethane, and d12-cyclohexane in 0.1 M methanolic salt solutions confirmed that spin-lattice relaxation rates are characterizing cation-pi interactions. The relatively strong cation-pi bonding observed between Ag+ and aromatic hydrocarbons probably results from covalent interactions between the aromatic pi electrons and the d orbitals of Ag+, in addition to the normal electrostatic interaction.     

Cation-pi bonding: a new perspective on the sorption of polycyclic aromatic hydrocarbons to mineral surfaces

Recent molecular modeling and spectroscopic studies have suggested that relatively strong interactions can occur between aromatic pi donors and metal cations in aqueous solutions. The objective of this study was to characterize potential cation-pi interactions between pi donors and exchangeable cations accumulated at mineral surfaces via both spectroscopic and batch sorption methods. Quadrupolar splitting in deuterium nuclear magnetic resonance ((2)H NMR) spectroscopy for d(2)-dichloromethane, d(6)-benzene, and d(8)-toluene (C(6)D(5)- moiety) in aqueous suspensions of a Na-saturated reference montmorillonite unambiguously indicated the ordering of solute molecules with respect to the clay surface. The half line broadening (Delta nu(1/2)) of (2)H NMR of d(6)-benzene in montmorillonite suspensions showed that soft exchangeable cations generally resulted in more benzene sorption compared with harder cations (e.g., Ag(+) > Cs(+) > Na(+) > Mg(2+), Ba(2+)). In batch sorption experiments, saturating minerals (e.g., porous silica gels, kaolinite, vermiculite, montmorillonite) with a soft transition metal or softer base cations generally increased the polycyclic aromatic hydrocarbon (PAH) sorption relative to harder cations (e.g., Ag(+) > Cs(+) > K(+) > Na(+); Ba(2+) > Mg(2+)). Sorption of phenanthrene to Ag(+)-saturated montmorillonite was much stronger compared with 1,2,4,5-tetrachlorobenzene, a coplanar non-pi donor having slightly higher hydrophobicity. In addition, a strong positive correlation was found between the cation-dependent sorption and surface charge density of the minerals (e.g., vermiculite, montmorillonite > silica gels, kaolinite). These results, coupled with the observations in (2)H NMR experiments with montmorillonite, strongly suggest that cation-pi bonding forms between PAHs and exchangeable cations at mineral surfaces and affects PAH sorption to hydrated mineral surfaces.     

Bringing feedback and resilience of high-latitude ecosystems into the corporate boardroom

This paper discusses the role of companies in high-latitude regions, which are conceptualized as socially and economically mediated ecosystems, and identifies a number of important social actors within the business environment. We present three examples of corporate activity at high latitudes and discuss a variety of common threads. Notably, we argue that business theory and practice needs to move beyond a narrow social or economic concept of organizational resilience and embrace the ecological resilience of high-latitude regions as a business management goal. We also suggest that regional ecosystem resilience needs to become a meaningful measure of sustainable corporate governance, one that corporate boards of directors can review and commit to. The paper concludes with a call for a detailed research agenda on the role of transnational and national companies within high-latitude regions.