ECONOMIC ANALYSIS OF IRRIGATION PRODUCTION FUNCTIONS: AN APPLICATION OF LINEAR PROGRAMMING1

ABSTRACT: Economic analysis of irrigation production functions is discussed using linear programming. The method provides advantages over the partial one-crop type of analyses because it captures intercrop tradeoffs in water and land use in response to economic policies or changes in water supply. A numerical example is used.     

Chromium toxicity in plants

Due to its wide industrial use, chromium is considered a serious environmental pollutant. Contamination of soil and water by chromium (Cr) is of recent concern. Toxicity of Cr to plants depends on its valence state: Cr(VI) is highly toxic and mobile whereas Cr(III) is less toxic. Since plants lack a specific transport system for Cr, it is taken up by carriers of essential ions such as sulfate or iron. Toxic effects of Cr on plant growth and development include alterations in the germination process as well as in the growth of roots, stems and leaves, which may affect total dry matter production and yield. Cr also causes deleterious effects on plant physiological processes such as photosynthesis, water relations and mineral nutrition. Metabolic alterations by Cr exposure have also been described in plants either by a direct effect on enzymes or other metabolites or by its ability to generate reactive oxygen species which may cause oxidative stress. The potential of plants with the capacity to accumulate or to stabilize Cr compounds for bioremediation of Cr contamination has gained interest in recent years.     

Anaerobic degradation of hexachlorocyclohexane isomers in liquid and soil slurry systems

Gamma-hexachlorocyclohexane (gamma-HCH or lindane), one of the most commonly used insecticides, has been mainly used in agriculture. Organochloride compounds are known to be highly toxic and persistent, causing serious water and soil pollution. The objective of the present study is the evaluation of the anaerobic degradation of alpha-, beta-, gamma-, delta-HCH in liquid and slurry cultures. The slurry system with anaerobic sludge appears as an effective alternative in the detoxification of polluted soils with HCH, as total degradation of the four isomers was attained. While alpha- and gamma-HCH disappeared after 20-40d, the most recalcitrant isomers: beta- and delta-HCH were only degraded after 102d. Intermediate metabolites of HCH degradation as pentachlorocyclohexane (PCCH), tetrachlorocyclohexene (TCCH), tri-, di- and mono-chlorobenzenes were observed during degradation time.     

Some Lessons Learned from Public Health on the Process of Adaptation

Lessons learned from more than 150 years of public health research and intervention can provide insights to guide public health professionals and institutions as they design and implement specific strategies, policies, and measures to increase resilience to climate variability and change. This paper identifies both some modifications to public health systems that may enhance adaptive capacity, and lessons drawn from the history of managing environmental and other threats in the public health sector that may have relevance for other sectors as they design approaches to increase their adaptive capacity to more effectively cope with climate variability and change. The views expressed are the author’s own and do not represent official US EPA policy.     

Evaluation of heavy metal acute toxicity and bioaccumulation in soil ciliated protozoa

Laboratory toxicity tests, using ciliated protozoa, are scarce and they have been carried out usually with freshwater species. In this study, we have analysed the acute cytotoxicity of Cd, Zn and Cu in five different strains of very common soil ciliate species (Colpoda steinii, Colpoda inflata and Cyrtolophosis elongata), which were isolated from very different soil samples (polluted or not with heavy metals). Soil ciliates are quite resistant to heavy metals pollution with regard to ciliates from other habitats. The toxicity sequence was Cd>Cu>Zn. Results from Cd+Zn mixtures indicated that Cd cytotoxicity decreases in the presence of low or moderate Zn concentrations. A broad heavy metal resistance level diversity exists among isolates of colpodid ciliates and it is seen to be a genetic feature rather than a habitat dependence. Bioaccumulation is seen to be the main mechanism involved in the metal resistance, except for Cu. For the first time in ciliates, a fluorescent method has been applied to detect Zn intracellular deposits. This methodology might be an useful tool for monitoring heavy metal pollution in soils.     

Is ionizing radiation effective in removing pharmaceuticals from wastewater?

Environmental Science and Pollution Research - Wastewater and effluent discharges are the main causes of receiving water body pollution and important challenges in water quality management. Among...     

Elevation of biochar application as regulator on denitrification/NH3 volatilization in saline soils

Environmental Science and Pollution Research - Denitrification and NH3 volatilization are the main removal processes of nitrogen in coastal saline soils. In this incubation study, the effects of...     

Advanced oxidation/reduction technologies: a perspective from Iberoamerican countries

Environmental Science and Pollution Research -     

Urban wild meat consumption and trade in central Amazonia

The switch from hunting wild meat for home consumption to supplying more lucrative city markets in Amazonia can adversely affect some game species. Despite this, information on the amounts of wild meat eaten in Amazonian cities is still limited. We estimated wild meat consumption rates in 5 cities in the State of Amazonas in Brazil through 1046 door-to-door household interviews conducted from 2004 to 2012. With these data, we modeled the relationship between wild meat use and a selection of socioeconomic indices. We then scaled up our model to determine the amounts of wild meat likely to be consumed annually in the 62 urban centers in central Amazonia. A total of 80.3% of all interviewees reported consuming wild meat during an average of 29.3 (CI 11.6) days per year. Most wild meat was reported as bought in local markets (80.1%) or hunted by a family member (14.9%). Twenty-one taxa were cited as consumed, mostly mammals (71.6%), followed by reptiles (23.2%) and then birds (5.2%). The declared frequency of wild meat consumption was positively correlated with the proportion of rural population as well as with the per capita gross domestic product of the municipality (administrative divisions) where the cities were seated. We estimated that as much as 10,691 t of wild meat might be consumed annually in the 62 urban centers within central Amazonia, the equivalent of 6.49 kg per person per year. In monetary terms, this amounts to US$21.72 per person per year or US$35.1 million overall, the latter figure is comparable to fish and timber production in the region. Given this magnitude of wild meat trade in central Amazonia, it is fundamental to integrate this activity into the formal economy and actively develop policies that allow the trade of more resilient taxa and restrict trade in species sensitive to hunting.