Land-Use and Land-Cover Dynamics in the Central Rift Valley of Ethiopia

Understanding the complexity of land-use and land-cover (LULC) changes and their driving forces and impacts on human and environmental security is important for the planning of natural resource management and associated decision making. This study combines and compares participatory field point sampling (pfps) and remote sensing to explore local LULC dynamics. The study was conducted in two peasant associations located in the central Ethiopian Rift Valley, which is a dry-land mixed farming area exposed to rapid deforestation. From 1973–2006, the area of cropland doubled at the expense of woodland and wooded-grassland in both of the study sites. Major deforestation and forest degradation took place from 1973–1986; woodland cover declined from 40% to 9% in one of the study sites, while the other lost all of its original 54% woodland cover. Our study concludes that assessing LULC dynamics using a combination of remote sensing and pfps is a valuable approach. The two methods revealed similar LULC trends, while the pfps provided additional details on how farmers view the changes. This study documents dramatic trends in LULC over time, associated with rapid population growth, recurrent drought, rainfall variability and declining crop productivity. The alarming nature of these trends is reflected in a decrease in the livelihood security of local communities and in environmental degradation. Given these dry-land conditions, there are few opportunities to improve livelihoods and environmental security without external support. If negative changes are to be halted, action must be taken, including building asset bases, instituting family planning services, and creating opportunities outside these marginal environments.     

Pediatrician attitudes, knowledge, and practice behavior regarding teen driving safety

Problem

Each year about 4,000 teens ages 16-19 die on U.S. roads. Injury prevention counseling is recommended as a valuable and cost-effective part of routine health supervision. This study describes pediatrician knowledge and practice regarding teen driving safety.

Methods

A 31-item self-administered survey was mailed to pediatricians.

Results

160 of 392 pediatricians (41%) completed the survey. During a health supervision visit 93% of pediatricians reported discussing seat belt use, 89% impaired driving, 54% teen licensing laws, and 16% parent teen contract. Half reported having a teen in their practice killed in a crash.

Conclusions

A majority surveyed report discussing and counseling teens on first wave teen driver safety issues (seat belts, alcohol use), but most do not discuss graduated driver licensing laws or related issues. Impact on Industry: Broadly adopted, this inexpensive counseling approach, could lead to reductions in teen motorvehicle crash injuries.     

Effect of Water and Carbon Dioxide in Chemiluminescent Measurement of Oxides of Nitrogen

ABSTRACT

This paper reports results of studies using a biotrickling filter with blast-furnace slag packings (sizes = 2–4 cm and specific surface area = 120 m²/m³) for treatment of ethylether in air stream. Effects of volumetric loading, superficial gas velocity, empty bed gas retention time, recirculation liquid flow rate, and biofilm renewal on the ethylether removal efficiency and elimination capacity were tested. Results indicate that ethylether removal efficiencies of more than 95% were obtained with an empty bed retention time (EBRT) of 113 sec and loadings of lower than 70 g/m³/hr. At an EBRT of 57 sec, removal efficiencies of more than 90% could only be obtained with loadings of lower than 35 g/m³/hr. The maximum elimination capacities were 71 and 45 g/m³/hr for EBRT = 113 and 57 sec, respectively. The maximum ethylether elimination capacities were 71 and 96 g/m³/hr, respectively, before and after the renewal at EBRT = 113 sec. With an EBRT of 113 sec and a loading of lower than 38 g/m³/hr, the removal efficiency was nearly independent of the superficial liquid recirculation velocity in the range of 3.6 to 9.6 m³/m²/hr. From data regression, simplified mass-transfer limited, and reaction- and mass-transfer limited models correlating the contaminant concentration and the packing height were proposed and verified. The former model is applicable for cases of low influent contaminant concentrations or loadings, and the latter is applicable for cases of higher ones. Finally, CO₂ conversion efficiencies of approximately 90% for the influent ethylether were obtained. The value is comparable to data reported from other related studies.     

Evolution of the Magnitude and Spatial Extent of the Weekend Ozone Effect in California’s South Coast Air Basin, 1981–2000

Abstract

Since the mid-1970s, ozone (O₃) levels in portions of California’s South Coast Air Basin (SoCAB) on weekends have been as high as or higher than levels on weekdays, even though emissions of O₃ precursors are lower on weekends. Analysis of the ambient data indicates that the intensity and spatial extent of the weekend O₃ effect are correlated with day-of-week variations in the extent of O₃ inhibition caused by titration with nitric oxide (NO), reaction of hydroxyl radical (OH) with nitrogen dioxide (NO₂), and rates of O₃ accumulation. Lower NO mixing ratios and higher NO₂/oxides of nitrogen (NO_x) ratios on weekend mornings allow O₃ to begin accumulating approximately an hour earlier on weekends. The weekday/weekend differences in the duration of O₃ accumulation remained relatively constant from 1981 to 2000. In contrast, the rate of O₃ accumulation decreased by one-third to one-half over the same period; the largest reductions occurred in the central basin on weekdays. Trends in mixing ratios of O₃ precursors show a transition to lower volatile organic compound (VOC)/NO_x ratios caused by greater reductions in VOC emissions. Reductions in VOC/NO_x ratios were greater on weekdays, resulting in higher VOC/NO_x ratios on weekends relative to weekdays. Trends in VOC/NO_x ratios parallel the downward trend in peak O₃ levels, a shift in the location of peak O₃ from the central to the eastern portion of the basin, and an increase in the magnitude and spatial extent of the weekend O₃ effect.     

Trophodynamics and distribution of silver in a Patagonia mountain lake

Silver (Ag) ions are among the most toxic metallic ions to aquatic biota. In southern Argentina, fish from Patagonian lakes have liver Ag concentrations [Ag] among the highest ever reported globally. Silver concentration in phytoplankton from Lake Moreno (1.82 ± 3.00 μg g⁻¹ dry weight, DW) was found to be significantly higher than [Ag] in zooplankton (0.25 ± 0.13 μg g⁻¹). Values in snails and decapods (0.60 ± 0.28 μg g⁻¹ and 0.47 ± 0.03 μg g⁻¹ respectively), were higher than in insect larvae (0.28 ± 0.39 μg g⁻¹ for Trichoptera). We examined trophic transfer of Ag in the biota using stable nitrogen and carbon isotopes ratios (δ¹⁵N and δ¹³C respectively). Silver concentrations in the biota of Lake Moreno were not associated with any particular C source, as assessed by δ¹³C. Hepatic [Ag] significantly increased with trophic position, as measured by δ¹⁵N, within the brook trout sample set. Biodilution of Ag was observed between primary producers and small forage fish when whole body [Ag] was analyzed. Nevertheless, when considering whole food web biomagnification and hepatic [Ag] of top predator fish, a significant positive regression was found between [Ag] and trophic position, as measured by δ¹⁵N. The importance of species-specific and tissue-specific considerations to obtain more information on Ag trophodynamics than that usually presented in the literature is shown. To the best of our knowledge, this is the first study in assessing Ag trophodynamics and tissue-specific biomagnification in a whole freshwater food web.     

Biologically directed environmental monitoring, fate, and transport of estrogenic endocrine disrupting compounds in water: A review

Endocrine disrupting compounds (EDCs) are contaminants that may be hormonally active at low concentrations and are emerging as a major concern for water quality. Estrogenic EDCs (e-EDCs) are a subclass of EDCs that, when organisms are exposed to them, function as estrogens. Given that there are numerous e-EDCs that can negatively affect humans and wildlife, general screening techniques like biologically based assays (BBAs) may provide major advantages by estimating the total estrogenic effects of many e-EDCs in the environment. These techniques may potentially be adapted for field portable biologically directed sampling and analyses. This article summarizes available BBAs used to measure estrogenic e-EDCs in the environmental samples and also presents results relating to fate and transport of e-EDCs. Estrogenic EDCs appear to be almost ubiquitous in the environment, despite low solubility and high affinity of organic matter. Potential transport mechanisms may include: (1) transport of more soluble precursors, (2) colloid facilitated transport, (3) enhanced solubility through elevated pH, and (4) the formation of micelles by longer-chain ethoxylates. Due to their persistent and ubiquitous nature, source control strategies for e-EDCs may reduce influent concentration to wastewater treatment plants so that the post treatment effluent will decrease concentrations to estrogenically inactive levels. Alternatively if source reduction is not possible, then more testing is needed on tertiary treatment technologies and treatment efficiencies for e-EDCs. There is still a need for research on remediation and restoration approaches for habitats disturbed by elevated e-EDC concentrations.     

Comparison of regression coefficient and GIS-based methodologies for regional estimates of forest soil carbon stocks

Estimates of forest soil organic carbon (SOC) have applications in carbon science, soil quality studies, carbon sequestration technologies, and carbon trading. Forest SOC has been modeled using a regression coefficient methodology that applies mean SOC densities (mass/area) to broad forest regions. A higher resolution model is based on an approach that employs a geographic information system (GIS) with soil databases and satellite-derived landcover images. Despite this advancement, the regression approach remains the basis of current state and federal level greenhouse gas inventories. Both approaches are analyzed in detail for Wisconsin forest soils from 1983 to 2001, applying rigorous error-fixing algorithms to soil databases. Resulting SOC stock estimates are 20% larger when determined using the GIS method rather than the regression approach. Average annual rates of increase in SOC stocks are 3.6 and 1.0 million metric tons of carbon per year for the GIS and regression approaches respectively.     

Empirical Validation of Turbine Engine Exhaust Measurements

The reliability and validity of gas turbine engine exhaust measurements are of concern to all who measure these effluents. In the past, one measure of reliability has been a carbon balance between the fuel used and the C, CO, hydrocarbons, and CO₂ emitted which requires that a F/A ratio be known accurately and that the analyzed sample be representative. In addition to this carbon balance, we have considered the relationships between the concentrations of the several component species. For example, the plot of volume percent of CO₂ versus the volume percent of O₂, both properly corrected to complete combustion, is a straight line. The intercept on the Y-axis (zero oxygen) is a function of the H to C mole ratio in the fuel. This relation has been theoretically established and also established by empirical calculations. For all valid measurements, all points corresponding to CO₂ and O₂ analyses fall on the straight line. In addition, smooth functional relationships exist between other exhaust gas constituents as well, although the form is not a simply derivable linear relationship like that for O₂-CO₂. We have found it useful to employ the following correlations: CO₂ vs. log NO_x, log CO vs. log THC, log CO vs. CO₂, and log THC vs. CO₂- These relationships serve to indicate the probability of reliable data and point out sampling problems and instrument problems such as drift. Subtle changes in engine operation such as opening of the accessory bleed ports in the compressor discharge of the engine can be detected.

The use of a combination of these curves can serve to indicate which measurement is in error. If the O₂-CO₂ relation is linear and the CO-CO₂ relation is smooth, then problems with the total hydrocarbon analyses are indicated when the CO-THC relation is erratic. This would be confirmed by a similar CO₂-THC plot. No useful smooth relationship between smoke density measurements and the other constituents has been found to date. This may indicate poor data, lack of sufficient data, or possibly no correlation.     

Integrating larval connectivity into the marine conservation decision-making process across spatial scales

Larval dispersal connectivity is typically integrated into spatial conservation decisions at regional or national scales, but implementing agencies struggle with translating these methods to local scales. We used larval dispersal connectivity at regional (hundreds of kilometers) and local (tens of kilometers) scales to aid in design of networks of no-take reserves in Southeast Sulawesi, Indonesia. We used Marxan with Connectivity informed by biophysical larval dispersal models and remotely sensed coral reef habitat data to design marine reserve networks for 4 commercially important reef species across the region. We complemented regional spatial prioritization with decision trees that combined network-based connectivity metrics and habitat quality to design reserve boundaries locally. Decision trees were used in consensus-based workshops with stakeholders to qualitatively assess site desirability, and Marxan was used to identify areas for subsequent network expansion. Priority areas for protection and expected benefits differed among species, with little overlap in reserve network solutions. Because reef quality varied considerably across reefs, we suggest reef degradation must inform the interpretation of larval dispersal patterns and the conservation benefits achievable from protecting reefs. Our methods can be readily applied by conservation practitioners, in this region and elsewhere, to integrate connectivity data across multiple spatial scales.     

Baseline concentrations of trace elements in residential soils from Southeastern Missouri

Anthropogenic sources of pollution can significantly contribute to elevated concentrations of toxic elements in soils. A preliminary survey of trace elements content and their availability in residential soils from New Madrid County, Missouri was undertaken. Mean elemental concentrations (mg kg⁻¹, dry wt) of sixty two soil samples were: As 6.6, Be 0.8, Cd 1.6, Co 9.7, Cr 24.5, Cu 18.1, Fe 9951, Mn 298, Ni 15.6, Pb 48.8, V 42.1, Zn 95.5 and Hg 0.05. The US EPA preliminary remediation goals (PRGs) was only exceeded by As (7 % of samples) and V (8% of samples). The Missouri average background values were exceeded by Pb (69%), Zn (31%), Cu (27%), As (23%), Be (19%), Co (18%), Ni (16%), V (8%) and Mn (2%). Crustal enrichments (EF_c) for As (97), Cr (6), Cu (10), Pb (121), V (7), and Hg (17) were highest for North Lilbourn soils. Fractionation experiment revealed that Fe (54–79%) was in the residual phase while Zn (70–90%), Mn (88–92%), As (59–81%) and Pb (63–79%) were potentially available in soils. Factor loadings of the element concentrations on principal components 1, 2 and 3 accounted for over 81% variance of the data set. The factor loadings suggested that apart from natural contributions of trace elements to the soils, human activities possibly accounted for other inputs in soils.