Ronald E. Lacey

Change in ecosystem service values in the San Antonio area, Texas☆

San Antonio is one of the fastest growing metropolitan areas in the USA. Urban sprawl may significantly impact ecosystem services and functions but such effects are difficult to quantify and watershed-level estimates are seldom attempted. The objective of the study reported here was to determine whether LANDSAT MSS could be used to quantify changes in land-use and ecosystem services due to urban sprawl in Bexar County, TX, in which San Antonio is centered. The size of six land cover categories in the summer of 1976, 1985, and 1991 were estimated in the 141 671 ha of three watersheds in Bexar County. Coefficients published by Costanza and co-workers in 1997 [Nature 387 (1997) 253] were used to value changes in ecosystem services delivered by each land cover category, and a sensitivity analysis was conducted to determine the effect of manipulating these coefficients on the estimated values. Although we estimated that there was a 65% decrease in the area of rangeland and a 29% increase in the area of urbanized land use between 1976 and 1991, there appeared to be only a 4% net decline in the estimated annual value of ecosystem services in the study area (i.e.

Effect of hypobaric conditions on ethylene evolution and growth of lettuce and wheat.

5.58 ha − 1 per year, with a 15-year cumulative total value of

Separating the effects of hypobaria and hypoxia on lettuce: growth and gas exchange

6.24 million for the whole study area). This relatively small decline could be attributed to the neutralizing effect of the estimated 403% increase in the area of the woodlands, which were assigned the highest ecosystem value coefficient. When we assumed that the shift of rangelands to woodlands produced no net change in the value of ecosystem services per hectare, the estimated annual ecosystem service value declined by 15.4% (

Ethylene reduces gas exchange and growth of lettuce plants under hypobaric and normal atmospheric conditions

23.22 ha − 1 per year) between 1976 and 1991. When conducting time-series studies of ecosystem services, it is important to identify parallel changes in land cover types in order to quantify the potentially neutralizing influence of positive land cover changes on the negative effects of urban sprawl on ecosystem services.

Inherent biases of PM10 and PM2.5 samplers based on the interaction of particle size and sampler performance characteristics

Elevated levels of ethylene occur in enclosed crop production systems and in spaceflight environments, leading to adverse plant growth and sterility. There are engineering advantages in growing plants at hypobaric (reduced atmospheric pressure) conditions in biomass production for extraterrestrial base or spaceflight environments. Objectives of this research were to characterize the influence of hypobaria on growth and ethylene evolution of lettuce (Lactuca sativa) and wheat (Triticum aestivum). Plants were grown under variable total gas pressures [from 30 to 101 kPa (ambient)]. In one study, lettuce and wheat were direct seeded, germinated and grown in the same chambers for 28 d at 50 or 101 kPa. Hypobaria increased plant growth and did not alter germination rate. During a 10-day study, 28-day-old lettuce and 40-day-old wheat seedlings were transplanted together in the same low and ambient pressure chambers; ethylene accumulated in the chambers, but the rate of production by both lettuce and wheat was reduced more than 65% under 30 kPa compared with ambient pressure (101 kPa). Low O2 concentrations [partial pressure of O2 (pO2) = 6.2 kPa] inhibited ethylene production by lettuce under both low (30 kPa) and ambient pressure, whereas ethylene production by wheat was inhibited at low pressure but not low O2 concentration. There was a negative linear correlation between increasing ethylene concentration and decreasing chlorophyll content of lettuce and wheat. Lettuce had higher production of ethylene and showed greater sensitivity to ethylene than wheat. The hypobaric effect on reduced ethylene production was greater than that of just hypoxia (low oxygen).

Effect of hydrocarbon tail-groups of transition metal alkoxide based amphiphilic catalysts on transesterification

The objectives of this research were to determine the influence of hypobaria (reduced atmospheric pressure) and reduced partial pressure of oxygen (pO2) [hypoxia] on carbon dioxide (CO2) assimilation (C(A)), dark-period respiration (DPR) and growth of lettuce (Lactuca sativa L. cv. Buttercrunch). Lettuce plants were grown under variable total gas pressures [25 and 101 kPa (ambient)] at 6, 12 or 21 kPa pO2)(approximately the partial pressure in air at normal pressure). Growth of lettuce was comparable between ambient and low total pressure but lower at 6 kPa pO2 (hypoxic) than at 12 or 21 kPa pO2. The specific leaf area of 6 kPa pO2 plants was lower, indicating thicker leaves associated with hypoxia. Roots were most sensitive to hypoxia, with a 50-70% growth reduction. Leaf chlorophyll levels were greater at low than at ambient pressure. Hypobaria and hypoxia did not affect plant water relations. While hypobaria did not adversely affect plant growth or C(A), hypoxia did. There was comparable C(A) and a lower DPR in low than in ambient total pressure plants under non-limiting CO2 levels (100 Pa pCO2, nearly three-fold that in normal air). The C(A)/DPR ratio was higher at low than at ambient total pressure, particularly at 6 kPa pO2- indicating a greater efficiency of C(A)/DPR in low-pressure plants. There was generally no significant interaction between hypoxia and hypobaria. We conclude that lettuce can be grown under subambient pressure ( congruent with25% of normal earth ambient total pressure) without adverse effects on plant growth or gas exchange. Furthermore, hypobaric plants were more resistant to hypoxic conditions that reduced gas exchange and plant growth.

Automation for Food Engineering : Food Quality Quantization and Process Control

Elevated levels of ethylene occur in controlled environment agriculture and in spaceflight environments, leading to adverse plant growth and sterility. The objectives of this research were to characterize the influence of ethylene on carbon dioxide (CO(2)) assimilation (C(A)), dark period respiration (DPR) and growth of lettuce (Lactuca sativa L. cv. Buttercrunch) under ambient and low total pressure conditions. Lettuce plants were grown under variable total gas pressures of 25 kPa (hypobaric) and 101 kPa (ambient) pressure. Endogenously produced ethylene accumulated and reduced C(A), DPR and plant growth of ambient and hypobaric plants. There was a negative linear correlation between increasing ethylene concentrations [from 0 to around 1000 nmol mol(-1) (ppb)] on C(A), DPR and growth of ambient and hypobaric plants. Declines in C(A) and DPR occurred with both exogenous and endogenous ethylene treatments. C(A) was more sensitive to increasing ethylene concentration than DPR. There was a direct, negative effect of increasing ethylene concentration reducing gas exchange as well as an indirect ethylene effect on leaf epinasty, which reduced light capture and C(A). While the C(A) was comparable, there was a lower DPR in hypobaric than ambient pressure plants - independent of ethylene and under non-limiting CO(2) levels (100 Pa pCO(2), nearly three-fold that in normal air). This research shows that lettuce can be grown under hypobaria ( congruent with25% of normal earth ambient total pressure); however, hypobaria caused no significant reduction of endogenous ethylene production.

A process-based approach for ammonia emission measurements at a free-stall dairy

Agricultural operations across the United States are encountering difficulties in complying with the current air pollution regulations for particulate matter. EPA has interpreted that the property line concentration limit must be less than the National Ambient Air Quality Standards (NAAQS). For PM10 and PM2.5, the 24-hour NAAQS are 150 and 65 mg/m 3 , respectively. Compliance with the PM NAAQS is determined by property line sampling, using EPA approved samplers, or dispersion modeling. Ultimately, these samplers would produce an accurate measure of the pollutant indicator for instance, a PM10 sampler would produce an accurate measure of PM less than or equal to 10 mm. However, samplers are not perfect and biases are introduced due to the interaction of the particle size and sampler performance characteristics. The focus of this manuscript is to theoretically simulate these biases and demonstrate how these biases result in unequal regulation between industries.

A distributed control system for low-pressure plant growth chambers

In liquid/liquid/solid (L/L/S) systems pertinent to two immiscible reactant liquids mixed with a solid catalyst, the reaction efficacy depends on the mass transfer limitations at the L/L/S phase boundary. Formation of an emulsion in such a system will likely reduce the mass transfer barrier significantly. The stability of such an emulsion system depends on the hydrophilicity of the head group of the catalytic emulsifier toward the more polar liquid reactant and the hydrophobicity of the tail group toward the more nonpolar liquid reactant. This study looks at the effect of the alkyl groups with varying carbon numbers in titanium alkoxide as a catalyst that also has emulsification (amphiphilic) properties to transesterify triglycerides in alcohols. All forms of oligomeric titanium alkoxides tested were highly basic. Those with smaller alkoxide groups (lower carbon numbers) tended to be more basic than those with higher carbon numbers. The chirality did not affect the degree of basicity of the alkoxides. The maximum ester yield noticed was 64.25% (with 63.85% selectivity towards transesterification) with titanium methoxide after 3 hours of reaction. It was observed that higher the number of carbon atoms in the tail group the lower the catalytic ability of the amphiphile towards transesterification. It is expected that longer the carbon-chain in the tail group stronger the emulsification ability of the amphiphile in oil-in-alcohol systems. However, when looking at the efficacy of the amphiphile for the combined emulsification and catalytic ability, it is apparent that the length of the alkoxide group needs to be compromised.

The recovery of ammonia and hydrogen sulfide from ground-level area sources using dynamic isolation flux chambers: bench-scale studies.

Introduction Food Quality: A Primary Concern of Food Industry Automated Evaluation of Food Quality Food Quality Quantization and Process Control Typical Problems in Food Quality Evaluation and Process Control How to Learn the Technologies Data Acquisition Sampling Concepts and Systems for Data Acquisition Image Acquisition Data Analysis Data Pre-Processing Data Analysis Image Processing Modeling Modeling Strategy Linear Statistical Modeling ANN Modeling Prediction Prediction and Classification One-Step-Ahead Prediction Multiple-Step-Ahead Prediction Control Process Control Internal Model Control Predictive Control Systems Integration Food Quality Quantization Systems Integration Food Quality Process Control Systems Integration Food Quality Quantization and Process Control Systems Development Concluding Remarks