Assessing Economic Changes Due to an Expanding Dairy Industry in the Texas High Plains

The dairy industry in the Texas High Plains has experienced rapid expansion in the past two decades. This study assesses the impact of the increased presence of dairies on overall water use, crop composition, and the local economy. The increase in water use related to the dairy industry from 2000 to 2015 was primarily due to an increase in demand for drinking by the cows (direct water) as well as an increased demand for silage (indirect water). However, a comparative analysis (dairy presence vs. no dairy presence) from a single year indicates minimal impacts on total water use due to dairies. During the same time period, the number, size, and employment of related local business establishments have increased economic activity in rural areas. Editor's note : This paper is part of the featured series on Optimizing Ogallala Aquifer Water Use to Sustain Food Systems. See the February 2019 issue for the introduction and background to the series.     

Reassessment of the Ocean-To-Atmosphere Flux of Carbon Monoxide

Abstract

Carbon monoxide (CO) in the surface sea waters is produced predominantly by photochemical processes, oxidized by micro-organisms and outgassed to the atmosphere. to assess carbon monoxide flux from the oceans to the atmosphere, the photochemical production and microbial oxidation of carbon monoxide in the oceanic mixed-layer was investigated during several oeanographic cruises and in the laboratory. the photoproduction rate of carbon monoxide was found to be well correlated to the concentration of dissolved organic carbon (DOC) in coastal and open ocean surface waters. Taking a global average carbon monoxide production rate of 10 ± 2 nmole litre^?1 (mg DOC hr)^?1 in the surface open ocean water, and 25 ± 7 nmole litre^?1 (mg DOC hr)^?1 in coastal sea water, at cloud-free summer solar noon, the photochemical production of carbon monoxide in the global oceans is estimated to be at a rate of 1200 ± 200 Tg CO y^?1. the microbial carbon monoxide turnover time in the mixed-layer was observed to range from hours in a coastal estuary to 16 days in the Pacific along 1057deg; W in dark incubations. Natural sunlight can largely inhibit the microbial consumption of carbon monoxide in surface water. On a global scale, microbial consumption is responsible for the loss of less than 10% of photochemical produced carbon monoxide in the surface ocean. Field measurements have shown that the net transport of carbon monoxide from the euphotic zone to the underlying deeper ocean water is limited and that the overall life time in surface sea waters is less than 3-4 hours. When combined, these field measurements with the photoproduction and microbial consumption rates obtained, we estimate the oceanic flux to the atmosphere is about 1000 ± 200 Tg CO y^?1, which represents the largest single source of atmospheric carbon monoxide.     

Genotoxicity of syrian hamster lung cells treated in vivo with diesel exhaust particulates

Polycyclic aromatic hydrocarbons extracted and concentrated from diesel exhaust particulates have been shown to be mutagenic and carcinogenic, but attempts to induce pulmonary tumors through chronic inhalation of diesel exhaust by experimental animals have failed. We have attempted to resolve this incongruity by measuring chromosomal damage in lung tissue of chronically exposed hamsters, using the highly sensitive test for genotoxic chemical agents, sister chromatid exchange (SCE) analysis. To determine the degree of responsiveness of the test system to both diesel exhaust particulates and benzo(a)pyrene (BaP), these agents were instilled intratracheally into anesthetized hamsters as suspensions in 0.25 ml volumes of Hank's balanced salt solution (HBSS). Lung tissues from these animals were subsequently cultured in vitro and chromosomes from the resulting cell divisions were scored for exchanges of chromatin between sister chromatids. Control animals, treated weekly with 0.25 ml of BSS for 10 weeks, showed an average value of 12 SCE's per cell, while animals treated weekly with 200 ng BaP over a 10-week period showed an average of 17 SCE's per cell. HBSS, given as a single treatment, also produced an average of 12 SCE's per cell in control animals, but animals treated with a single instillation of 12.5 μg BaP showed an average SCE value of 19. These data confirmed that the procarcinogen BaP can be metabolically activated by lung cells in vivo and also demonstrated the efficacy of using this technical approach to study the effect of chemical mutagens that enter the lungs. Diesel exhaust particulates, administered in a range from 0 to 20 mg per hamster over a 24 h exposure period, produced a linear SCE dose-response ranging from 12 to 26 SCE's per metaphase. This curve suggested that a concentration of 3 mg of diesel particulates per hamster would not produce a statistically significant increase in SCE's above control values. One group of 8 hamsters, chronically exposed to diesel exhaust particulates for 3 months showed an average of 12 SCE's per cell. This was equivalent to a set of 5 control animals which also showed an average of 12 SCE's per cell. Although the scope of this study was limited, the data demonstrated that diesel exhaust particulates can induce genotoxic damage but a 3-month exposure to 6 mg/m³ of diesel exhaust particulates was insufficient to produce measurable mutagenic changes in lung cells. This negative response is consistent with the results from other studies in which similar exposures failed to produce pulmonary tumors.     

Precopulatory sexual interaction in an arctiid moth (Utetheisa ornatrix): Role of a pheromone derived from dietary alkaloids

Summary Males of Utetheisa ornatrix have a pair of brushlike glandular structures, the coremata, which they evert from the abdomen during close-range precopulatory interaction with the female. Males experimentally deprived of coremata are less acceptable to females. The principal chemical associated with the coremata, identified as a pyrrolizine (hydroxydanaidal), has a proven pheromonal role: males raised under conditions where they fail to produce hydroxydanaidal are also less likely to succeed in courtship, and the compound itself, as its (-)-isomer, is capable of inducing the principal receptive response (wing raising) of the female. Evidence is presented indicating that Utetheisa derive hydroxydanidal from defensive pyrrolizidine alkaloids that they sequester from their larval foodplants (Crotalaria spp.). It is proposed that in addition to signalling male presence to the female, hydroxydanaidal may provide the means whereby the female assesses the alkaloid content of the male and therefore his degree of chemical protectedness. The argument is made that such pheromonal assessment of defensive capacity may occur also in other insects, including danaid butterflies, many of which share with Utetheisa a dependence on pyrrolizidine alkaloids for sex-pheromone production.     

An evaluation of the LPG vehicles program in the metropolitan area of Mexico City

The environmental agency in the metropolitan area of Mexico City has launched a program to introduce more energy-efficient modes of transport, one of which is the use of alternative and less polluting fuels. With the perspective in mind, a liquefied petroleum gas (LPG) fleet of vehicles is exempt of the mandatory "one day without a car" program if the emission of pollutants is below the standard authorized for that specific purpose. Today, about 28,000 light-duty vehicles and heavy-duty trucks circulate in the area, most of them as aftermarket converted vehicles. In this work, we evaluated regulated exhaust emission and other parameters on 134 representative vehicles of that fleet. From the data obtained, an estimate of emission factors and their contribution to the global emission in the metropolitan area is provided. It is concluded that more than 95% of the in-use vehicles using LPG presented regulated emissions which exceeded in one or more the environmental regulations values required for certification. The poor maintenance of the vehicles and the type of conversion kit installed could be the culprits of the results obtained.     

Differential activity of non-fluorinated and fluorinated analogues of the European corn borer pheromone

Summary.  The differing antagonist activity of (Z)-13-hexadecen-2-one (Z11 – 14 :MK, 1) and its 1,1,1-trifluoro derivative (Z11 –14 :TFMK, 2), two closely related analogues of the European corn borer pheromone Ostrinia nubilalis (Z strain), and their rationale is reported. Both chemicals exhibited some electrophysiological activity, and topical application of 10 pg of pheromone analogue on male antennae was sufficient to induce significantly lower depolarization responses to the pheromone versus untreated insects. In a wind tunnel, the number of European corn borer males attracted to sources containing mixtures of 1 + pheromone in ratios ≥ 1 :1 was significantly lower than the number attracted to a source containing pheromone alone. Source contact behaviour was dramatically impaired when the 1 + pheromone blend reached a ratio of 10 :1, in which only 2% of males displayed source contact in the presence of antagonist. When compound 1 was present at the source, males usually flew upwind with occasional downwind reversals; when compound 2 was present at the lure, males performed wider crosswind reversals, with little progress toward the source. In the field, traps baited with mixtures of both compounds with the pheromone in ratios of 5 :1 and 10 :1 elicited a significantly decreased number of male catches. In esterase inhibition assays, compound 2 was a potent inhibitor (IC₅₀ = 70 nM), whereas the non-fluorinated compound 1 was not. The different activity of both compounds is presumed to be due to different mechanisms of action; considerations for using methyl ketone analogues as new behavioural antagonists of the pheromone are outlined.