Water, Endangered Fishes, and Development Perspectives in Arid Lands of Mexico

Nearly half of Mexico is arid or semiarid, with scarce waters. At least 92 springs and 2500 km of river have dried in this area. Surface waters have diminished, and phreatic waters are sinking deeper, provoking intrusion of saline waters and salinization of agricultural wells in Sonora, reversing phreatic circulation in the Comarca Laguenera, allowing arrival of arsenic to agricultural waters, and threatening metropolitan Torreón. There are nearly 200 species of freshwater fishes in this region, 120 under some threat, 15 extinct through human impact. As of 1985, an average of 68% of species was eradicated in local fish faunas. Finally, salinization of the lower Rio Bravo del Norte has replaced 32 native fish of fresh or slightly brackish water with 54 mainly marine or highly salt-tolerant species; the salinization threatens all uses of water. Some marine fishes invade up to 400 km upstream. Pollution is strong, and fish kills have been reported. These low-quality and scarce waters comprise future resources for cities such as Monterrey, which, along with its border twin cities, is expected to double its human population by 2010. Redesign of regional development is urgently needed, in keeping with the real availability of water. All water use should be equal to or less than lower recharge averages; norms of integral basin management should rely on criteria of high-use efficiency, recuperation, recycling, and reutilization. Also necessary are reduced pollution and increased treatment of residual waters. Innovative environmental vision is especially essential in light of expectations for development through the North American Free Trade Agreement, the Border Integral Environmental Plan, industrial expansion, and the modernization and internationalization of the northern Mexican border belt. These all conflict with the high priority recently decreed for species conservation by the Mexican Act, creating the National Committee on Knowledge and Use of Biodiversity.     

Determination of oxidative stress markers and serum cholinesterase among pesticide sprayers in southern Brazil

Small farmers generally spray pesticides manually and often do not use complete protective equipment. The standard test to detect pesticide exposure, which may be associated with toxicity, is the determination of serum cholinesterase, but in chronic exposure to low doses, this test is less sensitive. In this study, in a group sampled among pesticide sprayers without signs of intoxication, cholinesterase, thiobarbituric acid reactive substances (TBARS), catalase (Cat), and superoxide dismutase (Sod) activities were analyzed. Cholinesterase activity was only slightly lower in the farmer group in relation to the control group. However, TBARS and Cat activities were 3-fold increased in the farmers in comparison to the controls. Sod activity was similar in both groups. The group of pesticide sprayers that did not use the complete protective equipment presented a significantly higher level of TBARS than the group that used the complete protective equipment. Therefore, the determination of TBARS and catalase can be useful to identify individuals that are chronically exposed to low doses of pesticides.     

Prenatal exclusion of duchenne muscular dystrophy by fetal muscle biopsy

A fetal thigh muscle biopsy was performed at 18 weeks and 6 days' gestation using an automatic 18-gauge biopsy needle. A positive immunoreaction with antisera to the amino- and carboxy-terminals of dystrophin excluded Duchenne muscular dystrophy from this at-risk male.     

Testosterone stress does not increase asymmetry of a hormonally mediated sexual ornament in a lizard

The theory that fluctuating asymmetry is sensitive to both environmental and genetic stress is gaining acceptance among evolutionary biologists. Most empirical work has focused on ornamental traits on the assumption that they are more susceptible to stress. In tegumentary coloration is a common ornament in nature, and frequently has a hormonal basis. Earlier studies in the lizard Psammodromus algirus indicate that testosterone induces the development of head nuptial coloration in large males and, at the same time, produces an increase of the ectoparasite load and higher mortality. Hence, the manipulation of testosterone levels may be a way to increase ornament expression and simultaneously create conditions that may make symmetrical development difficult. This positive covariation between character size and symmetry is opposite to that expected in theory for sexually selected traits, so the predicted elevation of asymmetry due to the treatment cannot be confounded by any intrinsic association between symmetry and character size. We firstly consider the effect that testosterone supplementation has on two variables that reflect the symmetry of bilateral throat nuptial coloration in large P. algirus males. Also, we examine whether ornament symmetry is positively associated with reproductive success, a prediction of theory of sexually selected symmetry. Testosterone treatment did not increase the fluctuating asymmetry of throat coloration. Size asymmetry increased with character size in individuals with a fragmented colour pattern, but changed suddenly to a highly symmetric pattern in individuals with non-fragmented coloration. Mirror asymmetry decreased steadily with character size. These results suggest that the development of coloration on both sides of the throat midline follows a random pattern. Asymmetry did not correlate with variables that estimated reproductive success, suggesting that asymmetry is not affected by physiological stress and that this trait is not a sexually selected signal in P. algirus. Received: 1 July 1996 / Accepted after revision: 4 May 1997     

Sorption of weak organic acids in soils: clofencet, 2,4-D and salicylic acid.

The sorption behaviour of a new wheat hybridising agent (clofencet, 2-4-(chlorophenyl)-3-ethyl-2,5-dihydro-5-oxopyridazine-4-carboxylic acid) was investigated in batch equilibrium experiments and compared to that of two other organic acids (2,4-D and salicylic acid). Sorption coefficients Kd for the three compounds were determined in 18 Cambisols and Ferralsols. Kd values for clofencet were 0.3-9.4 l/kg for Cambisols and 2.1-68 l/kg for Ferralsols. Sorption of clofencet was strongly related statistically to that of salicylic acid. Sorption of clofencet and salicylic acid decreased exponentially with increasing solution pH in Cambisols whereas a bell-shaped curve was obtained for the sorption of salicylic acid in Ferralsols. Sorption of 2,4-D (2,4-dichlorophenoxyacetic acid) was not statistically related to the pH of the different soils. Positively charged oxide surfaces were shown to play a significant role in the sorption of clofencet and salicylic acid. The use of simple correlation and multiple linear regressions suggested that the main sorption mechanisms of clofencet in soils were likely to be ligand exchange on oxide surfaces and, to a lesser extent, cation bridging. Differences in the sorption behaviour of clofencet/salicylic acid and 2,4-D might be attributed to the possibility of the two former compounds forming bidentate complexes with metals.     

CC.OO. (“Comisiones Obreras”) – ISTAS (Union Institute of Work,Environment and Health) participatory action plan for a healthier work organization: A case study

Spanish workers have been among the most exposed to psychosocial risks across the European Union.CC.OO. and ISTAS decided to establish an action plan to empower workers’ health and safety representatives to have an influence on the psychosocial risk assessment processes leading to negotiations with employers over a more democratic, fair and healthier work organization.Most important outcomes included 3600 companies which have followed a participatory process culminating with the implementation of agreed upon at source preventive measures in 40% of cases.There exists some evidence that preventive actions have increased in Spain since CC.OO.’s workers’ health and safety representatives started systematically pushing for improvements in the psychosocial work environment, however the quality of such actions is less clear.Future priorities include: first, to overcome barriers related to the interaction with external agents, especially with professional and administrative bodies. Second, to increase collaboration with scientific institutions to ensure and improve quality of both risk assessment tools and preventive actions. Third, to evaluate at the source interventions at company level with special interest in looking at the involvement of worker representatives, managers and OH professionals and the impact of their involvement on the undertaking of effective preventive actions. Fourth, increasing interaction between ISTAS and CC.OO. in order to place demands for the improvement of psychosocial working conditions more centrally in collective bargaining. Fifth, trying to increase unity of action of all Spanish workers’ unions on the subject.     

Photochemical model evaluation of the surface ozone impact of a power plant in a heavily industrialized area of southwestern Spain

The characterization and evaluation of the impact that an industry is likely to have on the surrounding ozone levels is one of many problems confronting air quality managers and should be taken into consideration when authorizing its installation. The correct management of an environment, in terms of monitoring existing industries and planning new activities, requires adequate knowledge of the processes sustained by the industrial emissions therein.This paper explores the improvements in air quality management arising from taking into account the uncertainties involved in the photochemical modeling of the impact of an industry on surface ozone levels.For this, we evaluate the impact on ozone levels of a power plant located in an industrial area of southwestern Spain (Huelva). The evaluation takes into account the effects of both emissions' uncertainty and the non-linear chemistry between ozone and its precursors, thus providing a probable range of increase over the normative values (hourly and 8-hourly maximums) defined in the European Directive. The proposed methodology is easily applicable by air quality managers.Advanced modeling techniques were used for the power plant assessment, MM5 atmospheric modeling system, and air quality model CAMx. The results from meteorology and ozone forecasts have shown acceptable agreement with the observations.The spatial distribution of the impact is found to be strongly determined by mesoscale meteorological processes, which are reinforced by the local orography; there is also a marked temporal evolution. The industrial plume is observed to induce a decrease (or maintenance) of the ozone levels near the emission source (0–10 km), and an increase in the ozone concentrations farther away (with maximums between 10 and 50 km). In fact, in the meteorological episodes with a predominance of local breeze circulations, impacts have been detected at distances of more than 100 km from the emission source.Sensitivity of the power plant impact to variations in ozone precursor emissions is described, and the scenarios and the points in the domain presenting higher sensitivity and registering larger impacts are also identified. The results show that the largest impacts take place in emission scenarios where the NO_x has been reduced with respect to the base case scenario. In contrast, in scenarios where the VOC emissions are reduced with respect to the base case scenario, the impact is smaller or remains unchanged. This is important in areas like the study case, where there is a high percentage of biogenic VOC emissions and the industrial areas are close to natural protected areas and agricultural fields.     

Eco-efficiency in the SMEs of Venezuela. Current status and future perspectives

This paper presents a comparison analysis of eco-efficiency in the small and medium sized enterprises (SMEs) of Venezuela. The research can be divided into three parts: the first part reviews similar studies in the literature on the level of eco-efficiency exhibited by the companies of Venezuela and other countries. In the second place, the findings of a survey conducted on Venezuelan SMEs allowed the definition of 54 eco-efficiency profiles. Thirdly, six national experts in cleaner production and eco-efficiency were interviewed. The interview was based on a questionnaire similar to that used in the survey of the Venezuelan SMEs. At a second meeting, the experts were asked to discuss on the similarities and differences between their answers and those of the company's managers.The findings of the survey allow us to conclude that Venezuelan SMEs understand the legal environmental regulations that affect them but they do not perceive the influence of external driving forces like customers demand for green products or institutional incentives. The adoption of eco-efficiency practices is not perceived as an incentive to improve competitiveness so that the environmental strategies adopted generally aim at reducing costs or avoiding non-compliance sanctions and negative effects on the company image. Materials recycling and reuse, especially packaging materials, are common practices; however, other environmental tools or practices have not been implemented yet, e.g. environmental management systems (EMS), process, product and services design tools based on the product life cycle, renewable energy resources or green marketing. There are also differences among the eight industrial sectors analyzed, food and chemical industries having the higher index of eco-efficiency practices, and plastic and wood industries the lower.