Adsorption, desorption, soil mobility and aqueous persistence of fensulfothion and its sulfide and sulfone metabolites

Soil/water interactions with the insecticide fensulfothion and its sulfide and sulfone metabolites and described. Adsorption to, and desorption from four soils were studied. There was a general inverse relationship between water solubilities of the three chemicals and their adsorption K values. Order of adsorption was f. sulfide greater than f. sulfone greater than fensulfothion. Adsorption K values correlated significantly with soil organic content. Desorption of fensulfothion and the sulfone were similar whereas the less soluble sulfide desorbed to a lesser extent. To facilitate comparison of desorption tendencies of the three compounds of desorption index was developed. Mobilities through the soils were directly related to the water solubilities of the three chemicals. Mobilities in decreasing order were - fensulfothion greater than f. sulfone greater than f. sulfide. Persistence of fensulfothion was similar in both sterile and non-sterile natural water - about 50% remaining at the end of the 16 wk experiment. Under reducing conditions fensulfothion disappeared from water in 8-12 wk with almost complete conversion to the sulfide.     

A method for estimating dietary intake of environmental trace contaminants: Cadmium — a case study

Variations in either food content or dietary habit affect dietary intake of trace contaminants. Trace contaminants enter the human food chain through many environmental pathways, including contamination of water used for drinking or irrigation, sludge used on cropland, fertilizers and other agricultural chemicals, chemicals leached from disposal sites to water, or airborne deposition on soil, water, or crops. A flow chart (Fig. 1) summarizes these pathways.Dietary exposure to environmental trace contaminants places some segments of the U.S. population at substantially higher risk than others. A methodology to calculate population distribution curves for dietary intake of trace contaminants is presented in this report, using cadmium (Cd) as the specific example. This methodology can be applied both to calculate the distribution of daily individual intake of trace contaminants, as well as to estimate the size of the potentially at-risk population. The methodology is developed with both a stochastic approach and a matrix approach. The matrix approach is coded as program SCOPE, and the stochastic as program MONTE.The dietary habits of the U.S. population were determined by using computer codes to analyse and synthesize an array of dietary data. The 15- to 20-yr-old male population was selected for analysis because this group has the largest gram-caloric intake of any age-sex classification. Data from the U.S. Department of Agriculture and the Food and Drug Administration were analyzed to define Cd concentration distribution for 34 food categories, into which 1880 food items were classified. Food consumption frequency histograms were generated with this information, using data synthesis routines and SCOPE.A 1974 FDA survey of metal concentrations in selected foods at 71 U.S. sampling sites yielded tabular, truncated frequency histograms for Cd concentrations in 32 of the food categories studied. Histograms were then constructed by integrating consumption and Cd concentration for each food category for the total diet.The World Health Organization (WHO) recommended in 1972 a tolerable limit of Cd intake of approximately 70 μg per day. A comparison of SCOPE and MONTE total diet Cd intake frequency histograms indicates the likelihood of high Cd intake, at-rick populations. SCOPE results predict that approximately 13% of the 15- to 20-yr-old males studied ingest Cd at a rate greater than 70 μg per day. MONTE predicts that 14%, with a 12–17% range, ingest amounts greater than the WHO-recommended limit on a daily basis. This percentage represents a potential at-risk population. The actual at-risk population would be those persons who consistently ingest more than 70 μg/day.The percentage of the population projected to ingest more than 70 μg of Cd per day needs to be defined by geography, ethnicity, race, and dietary preference in order to fully evaluate Cd intake risks and to set parameters for epidemiological surveys needed for confirmation. Assuming validity for this methodology, there is justification for preventing significant increases in Cd dietary intake by way of man's activities.     

Microbes do not follow the elevational diversity patterns of plants and animals

The elevational gradient in plant and animal diversity is one of the most widely documented patterns in ecology and, although no consensus explanation exists, many hypotheses have been proposed over the past century to explain these patterns. Historically, research on elevational diversity gradients has focused almost exclusively on plant and animal taxa. As a result, we do not know whether microbes exhibit elevational gradients in diversity that parallel those observed for macroscopic taxa. This represents a key knowledge gap in ecology, especially given the ubiquity, abundance, and functional importance of microbes. Here we show that, across a montane elevational gradient in eastern Peru, bacteria living in three distinct habitats (organic soil, mineral soil, and leaf surfaces) exhibit no significant elevational gradient in diversity (r2<0.17, P>0.1 in all cases), in direct contrast to the significant diversity changes observed for plant and animal taxa across the same montane gradient (r2>0.75, P<0.001 in all cases). This finding suggests that the biogeographical patterns exhibited by bacteria are fundamentally different from those of plants and animals, highlighting the need for the development of more inclusive concepts and theories in biogeography to explain these disparities.     

Decreasing phosphorus runoff losses from land-applied poultry litter with dietary modifications and alum addition

Phosphorus (P) losses from pastures fertilized with poultry litter contribute to the degradation of surface water quality in the United States. Dietary modification and manure amendments may reduce potential P runoff losses from pastures. In the current study, broilers were fed a normal diet, phytase diet, high available phosphorus (HAP) corn diet, or HAP corn + phytase diet. Litter treatments were untreated control and alum added at 10% by weight between flocks. Phytase and HAP corn diets reduced litter dissolved P content in poultry litter by 10 and 35%, respectively, compared with the normal diet (789 mg P kg(-1)). Alum treatment of poultry litter reduced the amount of dissolved P by 47%, while a 74% reduction was noted after alum treatment of litter from the HAP corn + phytase diet. The P concentrations in runoff water were highest from plots receiving poultry litter from the normal diet, whereas plots receiving poultry litter from phytase and HAP corn diets had reduced P concentrations. The addition of alum to the various poultry litters reduced P runoff by 52 to 69%; the greatest reduction occurred when alum was used in conjunction with HAP corn and phytase. This study demonstrates the potential added benefits of using dietary modification in conjunction with manure amendments in poultry operations. Integrators and producers should consider the use of phytase, HAP corn, and alum to reduce potential P losses associated with poultry litter application to pastures.     

CHARACTERIZATION OF GROUND WATER FLOW FROM SPRING DISCHARGE IN A CRYSTALLINE ROCK ENVIRONMENT1

ABSTRACT: Recent investigations describing the hydrogeology of the Blue Ridge Province of Virginia suggest the occurrence of multiple aquifers and flow paths that may be responsible for the variable flow behavior of springs and seeps appearing throughout the region. Deep, confined aquifers associated with ubiquitous faults and shallow, variably confined saprolite aquifers may contribute water to spring outlets resulting in significantly different quantities of discharge and water quality. Multiple analyses are required to adequately identify the flow paths to springs. In this investigation, hydrograph analyses, surface electrical resistivity surveys, aquifer tests, and nitrate concentrations are used in conjunction with previously reported analyses from borehole logs and age dating of ground water to identify two distinct flow paths. Results indicate that base flow occurs from a deep fault zone aquifer and such discharge can be maintained even during prolonged periods of drought, while increased discharge identified on hydrograph peaks suggests the occurrence of rapid flow through the saprolite aquifer within a radius of about 25 meters of the spring orifice. Springflow hydrograph analysis is suitable for rapid characterization of flow paths leading to spring outlets. Rapid characterization is important for evaluation of potential water quality problems arising from contamination of shallow and deep aquifers and for evaluation of water resource susceptibility to drought. The techniques evaluated here are suitable for use in other locations in fractured crystalline rock environments.     

Geological and geochemical factors affecting the radon concentration in homes in Cornwall and Devon,UK

Recently collected data for radon levels in houses in Devon and Cornwall are compared with geological and geochemical information. The region is underlain by granites intruded into folded sedimentary rocks. The highest incidence of affected houses is on granites. The granites are characterised by moderate uranium concentrations, a deep weathering profile and uranium in mineral phase which is easily weathered. However, while the uranium may be removed, radium, the immediate precursor of radon, can remain in situ. Radon is emanated easily from the host rock, and high values of radon in ground and surface waters and soil gases have been detected. The granite areas are also characterised by high values of uranium in stream sediments and waters. In contrast, other zones of high uranium in stream sediment samples do not necessarily exhibit high house radon concentrations, especially when underlain by relatively impermeable rocks. Permeable ground can give rise to high incidences, of affected houses despite having uranium levels close to the crustal abundance. It is concluded that the most efficient method of identifying zones of high radon potential is the soil gas radon survey.     

The cost of mating with a non-virgin male in a monandrous butterfly: experimental evidence from the speckled wood, Pararge aegeria

Contrary to vertebrates, sperm production in insects may bear considerable costs for males. This is especially true in species that donate spermatophores containing sperm and nutrient-rich accessory gland products like in butterflies. Hence, spermatophores at first and subsequent copulations can differ in a quantitative and qualitative way. Such effects have particularly been shown in polyandrous species providing large spermatophores. Here we experimentally tested the effect of male mating status (virgin male vs recently mated male) on copulation duration, spermatophore size and females’ fitness components in a monandrous butterfly Pararge aegeria that typically donates small spermatophores. Copulations with non-virgin males lasted on average five times longer than that with virgin males and resulted in a spermatophore which was on average three times smaller. Number of eggs laid and female life span were not affected by the mating status treatment, but there was a significant effect on the number of living caterpillars a female produced, as copulations with virgin males resulted in higher numbers of larval offspring. Interestingly, the difference in spermatophore mass at the first and the second copulation increased with male body size. This suggests differential spermatophore allocation decisions among males of different size. Consequences for females and potential mechanisms influencing female fitness components are discussed. Given the small absolute size of spermatophores in P. aegeria, components other than consumable nutrients (perhaps hormones) should cause the observed effects.     

Why are larger convict cichlid (Cichlasoma nigrofasciatum) fry sometimes adopted into broods of smaller fry?

Females of Elasmucha grisea defend their eggs and small nymphs against invertebrate predators. Females sometimes guard their clutches side by side on the same birch leaf. We studied benefits of this joint guarding both in the field and in the laboratory. We found that adjacent females had significantly larger clutches than solitary females. In the laboratory, we studied the effectiveness of joint versus single defence against ant (Formica uralensis) predators. We established female pairs from initially singly guarding females by cutting off pieces of leaves with egg clutches and pasting them beside another female guarding her clutch. In the control group the females with their clutches were similarly cut off but these clutches were placed on another leaf without any female. The birch twigs where females guarded their clutches were placed in cages in close proximity to laboratory ant nests. In the experimental treatment, two females guarded their clutches together and at the same nest there was another birch twig without a female. In the control treatment two twigs with one female on each were placed close to another ant nest. Two females defended their clutches significantly more successfully, losing fewer eggs than did the single females. This primitive form of female sociality in parent bugs resembles colonial nesting in birds, where communal defence is also important. However, to our knowledge this is the first experiment where the benefit of joint guarding has been tested directly by manipulating the size of the breeding group rather than by measuring the risk of predation in groups of different size.