The Economics of Conjunctive Groundwater Management with Stochastic Surface Supplies

Groundwater management with stochastic surface flows and artificial recharge is considered. Theoretical analysis characterizes the decision rules and establishes conditions for convergence of socially optimal and common property withdrawals and pumping lifts to limiting probability distributions. An empirical application to Kern County, California finds that optimal withdrawals are generally increasing in hydraulic head and decreasing in surface flows; however, nonmonotone behavior is observed in some instances. Artificial recharge is not observed in the limiting distribution due to an interaction of several factors. Optimal management implies relatively small gains over unregulated groundwater use when preferences are risk neutral.     

Exhaustible Resource Allocation in an Overlapping Generations Economy

This paper analyzes competitive allocations of an exhaustible resource in an overlapping generations economy. Conditions are given for the existence of equilibrium extraction rules such that both extraction and investment in future stocks are increasing and continuous in the current stock. The paper then considers the time paths of equilibrium allocations and shows that there are economies where equilibrium resource extractions and prices exhibit nonclassical behavior. This is illustrated through a finite horizon example in which extractions increase and prices decrease over the entire time horizon and an infinite horizon example where there are persistent cycles in extractions and prices and multiple equilibria. The paper concludes by examining welfare issues.     

Evaluation of noise environments during daily activities of university students

Noise conditions specifically in areas inside university facilities and its impact on the quality of life of university students are topics that have received little attention. This paper presents a study of the noise conditions in which university students of various institutions in Madrid, Spain, carry out their daily studies. A representative number of measurements was carried out using noise dosemeters and dataloggers in order to evaluate the levels of noise, noise dose and exposure to noise during school periods and extracurricular activities. The results were compared with the recommendations given by current environmental noise regulations. This paper was complemented with a survey to get to know how students perceive the exposure to noise in university environments.     

A cost worth paying: energetically expensive interactions with males protect females from intrasexual aggression

When approached by males, females of the Amarillo fish (Girardinichthys multiradiatus) perform a behaviour called vibration or they are aggressively challenged. We quantified vibration and assessed whether it compromises the rate of feeding attempts in dyads kept in outdoor enclosures. Male approaches resulted in female vibration and in a reduced feeding rate. Vibration was not evoked by female–female aggression, which was frequent and always ended in the subordinate fleeing from the dominant female. Using a closed respirometer we found that vibration is costly; oxygen consumption of females was greater in the presence of a male (which evoked vibration) than in the presence of a non-familiar female (when no vibration occurred). By recording interactions of females confined in aquaria in the presence and in the absence of males, we confirmed that escaping is the only available response to deal with female aggression. Females kept without males participated in frequent aggressive (even lethal) interactions that did not abate while the subordinate female was in sight of the dominant, and which caused premature births and injuries. Yet in the alternative treatment aggression ceased when a male approached, prompting vibration in both females. Thus, in the Amarillo, in as much as it evokes energetically costly female vibrations, male courtship is an expression of sexual conflict. However, in the absence of males, frequent female aggression potentially annuls the benefits of not vibrating. We propose that a complete appraisal of the consequences of sexual conflict must include an assessment of the costs imposed by intra-sexual interactions.     

Open-path tunable diode laser absorption spectroscopy for acquisition of fugitive emission flux data

Air pollutant emission from unconfined sources is an increasingly important environmental issue. The U.S. Environmental Protection Agency (EPA) has developed a ground-based optical remote-sensing method that enables direct measurement of fugitive emission flux from large area sources. Open-path Fourier transform infrared spectroscopy (OP-FTIR) has been the primary technique for acquisition of pollutant concentration data used in this emission measurement method. For a number of environmentally important compounds, such as ammonia and methane, open-path tunable diode laser absorption spectroscopy (OP-TDLAS) is shown to be a viable alternative to Fourier transform spectroscopy for pollutant concentration measurements. Near-IR diode laser spectroscopy systems offer significant operational and cost advantages over Fourier transform instruments enabling more efficient implementation of the measurement strategy. This article reviews the EPA's fugitive emission measurement method and describes its multipath tunable diode laser instrument. Validation testing of the system is discussed. OP-TDLAS versus OP-FTIR correlation testing results for ammonia (R2 = 0.980) and methane (R2 = 0.991) are reported. Two example applications of tunable diode laser-based fugitive emission measurements are presented.     

Environmental fate and ecotoxicology of paraquat: a California perspective

The herbicide paraquat belongs to the group of the bipyridylium salts. In California, it is used primarily for control of broad-leaved grasses in fruit orchards and plantations, as a cotton defoliant, and for inter-row control in many crop and non-crop areas. In plants, paraquat causes the formation of reactive radicals leading to cell membrane damage and ultimately rapid desiccation. Soil clay minerals have a greater influence on paraquat adsorption and inactivation compared with soil organic matter following an application. Degradation mechanisms include photolysis, chemical, and microbial degradation, but these processes are generally extremely slow. In California during 2000–2014, paraquat was used primarily for the cultivation of almonds, cotton, alfalfa, and grapes: median value for an application and annual mass applied statewide were 0.53 kg ion/ha and 280 Mg, respectively. Paraquat was undetected in groundwater as a non-point source pollutant. Detections in surface waters (0.42–3.6 μg/L) were <1%. In earthworms and other invertebrates there is limited paraquat accumulation as toxic effects are mitigated via soil inactivation. Paraquat is among the most embryotoxic contaminants for bird eggs, but not to adult; it causes toxic and teratogenic effects in amphibians, and toxic effects in honeybees, fish, and other aquatic species.