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PubMed2005

Experimental landfill caps for semi-arid and arid climates.

The United States EPA Subtitle D municipal solid waste landfill requirements specify that the permeability of a cap to a landfill be no greater than the permeability of the underliner. In recent years the concept of the evapotranspirative (ET) cap has been developed in which the cap is designed to store all rain infiltration and re-evapotranspire it during dry weather. Concern at the long period required for landfilled municipal solid waste to decompose and stabilize in arid and semi-arid climates has led to an extension of the concept of the ET cap. With the infiltrate-stabilize-evapotranspire (ISE) cap, rain infiltration during wet weather is permitted to enter the underlying waste, thus accelerating the decomposition and stabilization process. Excess infiltration is then removed from both waste and cap by evaporation during dry weather. The paper describes the construction and operation of two sets of experimental ISE caps, one in a winter rainfall semi-arid climate, and the other in a summer rainfall semi-arid climate. Observation of the rainfall, soil evaporation and amount of water stored in the caps has allowed water balances to be constructed for caps of various thicknesses. These observations show that the ISE concept is viable. In the limit, when there is insufficient rainfall to infiltrate the waste, an ISE cap operates as an ET cap.

Aluminum Silicates↗
PubMed2005

Phylogeography of the longhorn cactus beetle Moneilema appressum LeConte (Coleoptera: Cerambycidae): was the differentiation of the Madrean sky islands driven by Pleistocene climate changes?

Although it has been suggested that Pleistocene climate changes drove population differentiation and speciation in many groups of organisms, population genetic evidence in support of this scenario has been ambiguous, and it has often been difficult to distinguish putative vicariance from simple isolation by distance. The sky island communities of the American Southwest present an ideal system in which to compare late Pleistocene range fragmentations documented by palaeoenvironmental studies with population genetic data from organisms within these communities. In order to elucidate the impact of Pleistocene climate fluctuations on these environments, biogeographic patterns in the flightless longhorn cactus beetle, Moneilema appressum were examined using mitochondrial DNA sequence data. Gene tree relationships between haplotypes were inferred using parsimony, maximum-likelihood, and Bayesian analysis. Nested clade analysis, Mantel tests, and coalescent modelling were employed to examine alternative biogeographic scenarios, and to test the hypothesis that Pleistocene climate changes drove population differentiation in this species. The program mdiv was used to estimate migration and divergence times between populations, and to measure the statistical support for isolation over ongoing migration. These analyses showed significant geographic structure in genetic relationships, and implicated topography as a key determinant of isolation. However, although the coalescent analyses suggested that a history of past habitat fragmentation underlies the observed geographic patterns, the nested clade analysis indicated that the pattern was consistent with isolation by distance. Estimated divergence times indicated that range fragmentation in M. appressum is considerably older than the end of the most recent glacial, but coincided with earlier interglacial warming events and with documented range expansions in other, desert-dwelling species of Moneilema.

Animals↗
PubMed1993

[Current problems in occupational hygiene of the construction industry in hot climate conditions].

The article covers results of long-standing hygienic investigations analyzing the occupational factors development in technologic process of nonmetalliferous building materials production, ferroconcrete large-panel constructions production and their assembling during various seasons and shift times. The study pointed out the main hazards influencing the quality of workplace in the stated enterprises. The hazards are hygienically evaluated in connection with the functional parameters of cardiovascular, central nervous and muscular systems, thermoregulation, work hardiness and strain.

Adaptation, Physiological↗
PubMed2004

Hierarchy of responses to resource pulses in arid and semi-arid ecosystems.

In arid/semi-arid ecosystems, biological resources, such as water, soil nutrients, and plant biomass, typically go through periods of high and low abundance. Short periods of high resource abundance are usually triggered by rainfall events, which, despite of the overall scarcity of rain, can saturate the resource demand of some biological processes for a time. This review develops the idea that there exists a hierarchy of soil moisture pulse events with a corresponding hierarchy of ecological responses, such that small pulses only trigger a small number of relatively minor ecological events, and larger pulses trigger a more inclusive set and some larger ecological events. This framework hinges on the observation that many biological state changes, where organisms transition from a state of lower to higher physiological activity, require a minimal triggering event size. Response thresholds are often determined by the ability of organisms to utilize soil moisture pulses of different infiltration depth or duration. For example, brief, shallow pulses can only affect surface dwelling organisms with fast response times and high tolerance for low resource levels, such as some species of the soil micro-fauna and -flora, while it takes more water and deeper infiltration to affect the physiology, growth or reproduction of higher plants. This review first discusses how precipitation, climate and site factors translate into soil moisture pulses of varying magnitude and duration. Next, the idea of the response hierarchy for ecosystem processes is developed, followed by an exploration of the possible evolutionary background for the existence of response thresholds to resource pulses. The review concludes with an outlook on global change: does the hierarchical view of precipitation effects in ecosystems provide new perspectives on the future of arid/semiarid lands?

Adaptation, Physiological↗
PubMed2003

The Sahara as a vicariant agent, and the role of Miocene climatic events, in the diversification of the mammalian order Macroscelidea (elephant shrews).

Although the Sahara is a major geographical feature of the African continent, its role in the diversification of animal species is not well understood. We present here a molecular phylogeny for members of the endemic African mammalian order Macroscelidea (elephant shrews) with molecular-clock calculations; this molecular phylogeny provides convincing evidence that the genus Elephantulus is diphyletic. Elephantulus rozeti, the only elephant shrew species that resides north of the Sahara, is the sister group of a species from a different genus (Petrodromus tetradactylus), which resides just south of the Sahara. The split between these taxa coincided with major Miocene climatic events, which triggered the cooling and aridification of midlatitude continental regions, and a shift in the Sahara from a tropical to an arid environment. Thus, the North African distribution of E. rozeti is not the result of dispersion from an eastern species of the genus, but instead the result of a vicariant event involving the formation of the Sahara. The splitting events involved with most Elephantulus species in our analysis appear to coincide with these climatic events. This coincidence suggests that the environmental consequences associated with this period played an important role in the radiation of this order of mammals. The strongly supported phylogeny provides compelling evidence for a complex history of mosaic evolution, including pronounced bradytelic morphological evolution in some lineages, accelerated morphological evolution in others, and a remarkably slow rate of evolution of the male reproductive structure.

Adaptation, Physiological↗
PubMed2005

Viability and infectiousness of eggs of Echinococcus granulosus aged under natural conditions of inferior arid climate.

We studied the viability and infectiousness of aged Echinococcus granulosus eggs by in vivo evaluation in ovines. Our results demonstrated that after 41 months of ageing of the eggs under environmental conditions of an inferior arid climate (Patagonia, Argentina), they were still able to produce infection in 4/4 ovines challenged with 1200 eggs per ovine. In the ovines experimentally infected with these aged eggs, the occurrence of hepatic and pulmonary cysts was determined by necropsy, histologic and genetic studies. The eggs were found in a semi-senescent stage, thus keeping their capacity to generate an infection in the intermediary ovine host.

Animals↗
PubMed1983

[Blood circulation in healthy persons in the arid region of Turkmenia. I. Studies in the supine and orthostatic positions].

The active orthostatic test was used to investigate 164 normal male residents of Ashkhabad during the cool season, 143 in summer and 66 during the transition period, i. e. first hot summer days. During the cool season, the pattern and markedness of orthostatic circulatory shifts in Ashkhabad residents were similar to those observed in moderate climate. In summer, orthostatic drop in systolic BP, cardiac index and circulating blood volume is more pronounced as compared to values of the cool season, while the rise in heart rate and diastolic BP is less pronounced. Orthostatic shifts are the most marked in the first hot days of summer: systolic BP, stroke and cardiac indices drop considerably, whereas diastolic BP and peripheral resistance to blood flow remain unchanged or slightly increase, with heart rate showing the most marked rise.

Adult↗
PubMed2006

Hydrochemical changes over time in the Zahedan Aquifer, Iran.

Groundwater in the Zahedan Aquifer located in the arid southeast of Iran was chemically characterized to understand both the nature of the alluvium aquifer and the effect of human activities, specifically sewage disposal on groundwater quality. Concentrations of major cations and anions in the Zahedan Aquifer are much higher than concentrations observed in groundwater of similar settings. Although the nature of the aquifer and climatic parameters have affected the chemistry of groundwater, human impacts on the groundwater quality are more significant. The electrical conductivity in some areas of the Zahedan aquifer increased up to 7,500 microS/cm in 25 years. Human influences in some areas are so prevalent, that the groundwater type changed from a Na(+)-HCO(3) (-) in 1976 to a Na(+)-Cl(-) type in 2000. The impact of human influences on the groundwater quality is also indicated through observed nitrate concentration up to 4.81 meq/L in the urban area.

Desert Climate↗
PubMedDate not supplied

[Seasonal dynamics of the indices of humoral immunity in children aged 3 months to 1 year in relation to nutrition in an arid zone].

The paper reports seasonal data on humoral immunity of 245 Turkmen and 240 European infants aged 3-12 months. Allowances were made for climatic conditions of the arid zone and essential feeding. In summer there were reduced levels of IgM, IgG in the serum and insufficient supply with thiamine and ascorbic acid. IgA serum level was the lowest in spring. IgA strongly correlated (r = 0.7-0.8) with thiamine and ascorbic acid intake in spring, IgM and IgG with retinol and thiamine in summer. The above changes in humoral immunity in summer are associated with growing incidence of intestinal diseases and lower body mass in the infants in the condition of arid zone.

Asian People↗
PubMed2003

A comparison of desiccant materials used for monitoring atmospheric tritium concentrations in a semi-arid climate.

Atmospheric tritium monitoring involves the collection of tritiated water vapor by collecting atmospheric moisture from air that is drawn through a bed of desiccant material. This study is a comparison between molecular sieve and silica gel adsorbent media used for atmospheric moisture sampling conducted in the semi-arid climate of the Idaho National Engineering and Environmental Laboratory. Water vapor was collected simultaneously using two columns containing different desiccant materials (one column containing molecular sieve and the other containing silica gel). Data collected during air sampling periods were compared with meteorological data collected, and atmospheric moisture collection efficiencies were determined. Breakthrough of atmospheric moisture past the desiccant material was suspected with both media at elevated temperatures indicating that smaller sample volumes, lower volumetric flow rates, or longer adsorbent columns should be used during summer when ambient temperatures are elevated.

Air Pollutants, Radioactive↗
PubMed1987

Early-onset hay fever in Israeli children.

In order to investigate the influence of climate and vegetation on the age of onset and clinical picture of hay fever (HF), we examined 116 children with typical HF living in a single climatic area: fifty-four were from rural farming settlements and sixty-two from towns and cities. Overall age of onset was low; 72% of rural children developed HF between the ages of 2 years and 4 years compared to only 24% of urban children (P less than 0.005). At the same time, 57% of rural children had positive skin tests to more than three pollen extracts out of nineteen allergens tested, compared to 19% of urban children (P less than 0.005). There were no significant differences between the rural and urban groups with regard to the incidence of asthma as part of their HF, nor were there differences in total IgE levels. The results of this study suggest that Israeli children develop hay fever earlier than generally reported in the literature, and that this is most marked in the rural areas. This can be explained by their specific environment, which consists of a basically dry, desert-like climate where lawns, crops and trees are extensively irrigated, leading to the dissemination into the environment of large amounts of pollen grains, which are not washed away because of the lack of rain.

Adolescent↗
PubMed2001

Catastrophic shifts in ecosystems.

All ecosystems are exposed to gradual changes in climate, nutrient loading, habitat fragmentation or biotic exploitation. Nature is usually assumed to respond to gradual change in a smooth way. However, studies on lakes, coral reefs, oceans, forests and arid lands have shown that smooth change can be interrupted by sudden drastic switches to a contrasting state. Although diverse events can trigger such shifts, recent studies show that a loss of resilience usually paves the way for a switch to an alternative state. This suggests that strategies for sustainable management of such ecosystems should focus on maintaining resilience.

Animals↗
PubMedDate not supplied

[Adaptive and maladaptive reactions of the external respiration in the climatic conditions of an arid zone].

Physical performance was assessed in 134 healthy males aged 18-28, residents of the southern Uzbekistan. They were divided into two groups according to the results of bicycle exercise. Group I subjects (32 natives and 38 non-natives) exhibited high physical efficacy, group II subjects--low efficacy (30 and 34 natives and non-natives, respectively). Meteorotropic responses of the external respiration were studied in relation to thermal discomfort, sand storms eve and invasions. Group I subjects, natives in particular, responded by efficient and adequate external respiration, in contrast to group II non-natives who developed pulmonary hyperventilation. The latter is thought a compensatory reaction aimed at maintenance of homeostasis achieved at the expense of inefficient function of the respiratory system.

Adaptation, Physiological↗
PubMed2003

Reactive glass and vegetation patterns.

The formation of vegetation patterns in the arid and the semiarid climatic zones is studied. Threshold for the biomass of the perennial flora is shown to be a relevant factor, leading to a frozen disordered pattern in the arid zone. In this "glassy" state, vegetation appears as singular plant spots separated by irregular distances, and an indirect repulsive interaction among shrubs is induced by the competition for water. At higher precipitation rates, the diminishing of hydrological losses in the presence of flora becomes important and yields spatial attraction and clustering of biomass. Turing patterns with characteristic length scale emerge from the disordered structure due to this positive-feedback instability.

Biomass↗
PubMed1987

Some effects of water quality on the performance of high yielding cows in an arid climate.

The water from wells in Saudi Arabia is often high in mineral content. The cows in this study had been receiving water containing between 4000 and 5000 ppm total dissolved solids. Four groups of 16 cows were calved down and milked under similar conditions in the hot summer months. Two of the groups were given normal well water and the other two groups received water after desalination in a reverse osmosis plant. One group on each type of water also had their water cooled. The groups of cows receiving treated water drank more water, consumed more concentrate and produced significantly more milk than the groups given normal well water. A similar effect on feed intake and milk production was seen when treated water was given to a 1000-cow unit with a similar number of control cows.

Animals↗
PubMed1998

Outbreaks of Dermatophilus congolensis infection in camels (Camelus dromedarius) from the Butana region in eastern Sudan.

Natural Dermatophilus congolensis infection of camels has been reported in Kenya in semi-arid areas. Research is being conducted to discover how widespread the condition is in neighbouring countries with similar eco-climatic conditions. Severe skin infections of camels from the Butana region of Eastern Sudan were examined. The infections were first found in two herds of adult camels, of which 50%-75% of the animals were affected. In the other thirteen herds examined, camel calves were more likely to be infected (34%) than adults (8.9%), and lesions were more severe and involved most parts of the body. The lesions began as hair matting and later developed into hard crusts. The case fatality rate ranged from 10% to 30%. D. congolensis was isolated from the scabs. Camel dermatophilosis was found to be among the most serious problems faced by camel herders in the Butana region.

Actinomycetales↗
PubMed2005

Moisture retention of municipal solid waste mixed with sewage sludge and ash in a semi-arid climate.

Mechanisms involved in moisture storage in refuse are explored using data from four sets of experiments in a semi-arid climate. Two laboratory series of experiments contained municipal solid waste (MSW) amended with sewage sludge, one with higher proportions of ash in the MSW than the other. Outdoor experiments contained waste streams with different proportions of ash. Field cells compared moisture retention of refuse and MSW co-disposed with sewage sludge. Sewage sludge at high loads was found to increase the moisture storage relative to unamended MSW. Belt-pressed sludge retained water as bound water that was released by decay and changing pH. Sun-dried sludge also retained more moisture than MSW alone. In gravimetric terms, ash reduced the storage potential of MSW, in laboratory and outdoor experiments. However, outdoor experiments released less leachate from ash-rich refuse than middle-income waste with no ash fraction.

Coal↗
PubMed1997

Thermophysiological responses under the influences of two types of clothing at an ambient temperature of 32 degrees C with sun radiation.

This study aimed to examine the different thermophysiological responses between two types of clothing (HALF, shirts with half sleeves and knee-length trousers; and LONG, shirts with long sleeves and long trousers) in a warm environment with artificial sun radiation. Seven females volunteered as subjects. The subject sat on a balance for 1 h in a climatic chamber with artificial sun. The artificial sun radiation was 600 kcal.m-2.h-1 in front of the subject. The ambient temperature was increased gradually from 27 to 31 degrees C over the experimental period. The globe temperature also increased from 27 to 43 degrees C in 15 min and was kept at 44 degrees C on additional 45 min. The main results were summarized as follows: 1) Extent of rise in rectal and mean skin temperatures during 1 h exposure was significantly higher in HALF than in LONG. 2) Local sweat rate was greater in HALF. 3) The subjects felt wetter and less comfortable in LONG. These results suggest that LONG could weaken heat stress when the subjects were exposed to sun radiation even under moderate warm ambient temperature.

Adult↗