Tooth hardness increases with zinc-content in mandibles of young adult leaf-cutter ants

A wide variety of arthropods and members of other phyla have elevated concentrations of Zn, Mn, other heavy metals and halogens in their jaws, leg claws, and other "tools" for interacting with the environment. While measured Zn concentrations reach 25% of dry mass in scorpion stings, concentrations are often lower than this and the enriched structures are not heavily biomineralized like vertebrate teeth and the radula of mollusks. For this reason, the degree to which the inorganic components of these structures modify their mechanical properties is in question. Here we address this problem by measuring hardness during the development of Zn accumulations in ant mandibles. We found that Zn is incorporated into the mandibular teeth of leaf-cutter ants during early adult life, reaching concentrations of about 16% of dry mass. We show that the hardness of the mandibular teeth increases nearly three-fold as the adults age and that hardness correlates with Zn content (r=0.91). We suggest that young adults rarely cut leaves partly because their mandibles are not yet rich in Zn. Zinc enrichment (along with enrichment by other heavy metals and halogens) may play an unrecognized role in the behavioral ecology and evolution of a wide variety of invertebrates.     

Microporous aluminophosphate AlPO4-22: a framework topology with two new building units,and encapsulated phosphate

We thank S. T. Wilson for supplying the sample and for helpful discussion, and W. J. Dytrych for assistance in data collection and model building. We thank NSF for grants CHE 8618041 and NSF-DMR-8519460 (Materials Research Laboratory). JWR is supported by the U.S. Department of Energy under contract W-31-109-ENG-38.     

Subsurface sediment contamination during borehole drilling with an air-actuated down-hole hammer

Drilling methods can severely alter physical, chemical, and biological properties of aquifers, thereby influencing the reliability of water samples collected from groundwater monitoring wells. Because of their fast drilling rate, air-actuated hammers are increasingly used for the installation of groundwater monitoring wells in unconsolidated sediments. However, oil entrained in the air stream to lubricate the hammer-actuating device can contaminate subsurface sediments. Concentrations of total hydrocarbons, heavy metals (Cu, Ni, Cr, Zn, Pb, and Cd), and nutrients (particulate organic carbon, nitrogen, and phosphorus) were measured in continuous sediment cores recovered during the completion of a 26-m deep borehole drilled with a down-hole hammer in glaciofluvial deposits. Total hydrocarbons, Cu, Ni, Cr and particulate organic carbon (POC) were all measured at concentrations far exceeding background levels in most sediment cores. Hydrocarbon concentration averaged 124 +/- 118 mg kg(-1) dry sediment (n = 78 samples) with peaks at depths of 8, 14, and 20 m below the soil surface (maximum concentration: 606 mg kg(-1)). The concentrations of hydrocarbons, Cu, Ni, Cr, and POC were positively correlated and exhibited a highly irregular vertical pattern, that probably reflected variations in air loss within glaciofluvial deposits during drilling. Because the penetration of contaminated air into the formation is unpreventable, the representativeness of groundwater samples collected may be questioned. It is concluded that air percussion drilling has strong limitations for well installation in groundwater quality monitoring surveys.     

Age,growth and population structure of <Emphasis Type="Italic">Modiolus barbatus</Emphasis> from the Adriatic

Age, growth and population structure of Modiolus barbatus from Mali Ston Bay, Croatia were determined using modal size (age) classes in length frequency distributions, annual pallial line scars on the inner shell surface, internal annual growth lines in shell sections of the middle nacreous layer and Calcein marked and transplanted mussels. The length frequency distributions indicated that M. barbatus attain a length of ∼40 mm in 5–6 years indicating that a large proportion of the population in Mali Ston Bay is <5 years old. Some mussels of ∼60 mm were predicted to be 14 years old using the Von Bertalanffy growth (VBG) equation. Up to the first 6 pallial line scars were visible in young (<6 years) mussels but in older shells the first scars became obscured by nacre deposition as the mussel increased in length and age. The age of the older shells (>6 years) was determined from the middle nacreous lines in shell section, which formed annually in winter between February and March; the wider dark increments forming during summer (June to September). The oldest mussel, determined from the middle nacreous lines, was >12 years, with the majority of mussels aged between 3 and 6 years of age. The ages of mussels ascertained using the growth lines were not dissimilar to the ages predicted from the length frequency distributions. Age at length curves produced using modal size class data were not different from the data obtained using the pallial scar rings and internal growth lines. Taken together these data suggest that M. barbatus attains a length of 40 and 50 mm within 5 and 8 years, respectively. Eighty one percent of individual M. barbatus injected with a Calcein seawater solution (300 mg Calcein l⁻¹), into their mantle cavity successfully deposited a fluorescent line, which was visible in suitably prepared shell sections under ultra violet light. Incorporation of Calcein into the mussel shells was seasonally variable with the lowest frequency of incorporation in mussels marked in February and recovered in May. Seasonal shell growth was observed with significantly higher growth rates in mussels marked in May and removed in August (ANCOVA, F _3,149 = 23.11, P < 0.001). Mussels (∼18 to 22 mm) marked in May and recovered in August displayed maximal growth rates of >2.5 mm month⁻¹ compared with a mean mussel growth rate of 1.2 ± 0.6 mm month⁻¹. At other times of the year mussel shell growth ranged from immeasurable to 1.48 mm month⁻¹.     

Defended versus undefended home range size of carnivores,ungulates and primates

Summary We tested the hypothesis that undefended home ranges are larger than defended home ranges using data collected from the literature for three groups of mammals. A matched-pairs analysis of populations within species or species within genera showed that undefended home ranges were larger than defended home ranges for carnivores and male ungulates, but not for primates. Primates may have been an exception because they violated a key assumption of the hypothesis, that defence costs increase with the size of the defended area. Undefended home ranges were 5.4 and 15.2 times larger than defended home ranges for carnivores and male ungulates, respectively. Whether or not a home range is defended is an important source of variation that should be included in future studies of home range size. Correspondence to: J.W.A. Grant     

Effect of NOx control processes on mercury speciation in utility flue gas

The speciation of Hg in coal-fired flue gas can be important in determining the ultimate Hg emissions as well as potential control options for the utility. The effects of NOx control processes, such as selective catalytic reduction (SCR) and selective non-catalytic reduction (SNCR), on Hg speciation are not well understood but may impact emissions of Hg. EPRI has investigated the reactions of Hg in flue gas at conditions expected for some NOx control processes. This paper describes the methodology used to investigate these reactions in actual flue gas at several power plants. Results have indicated that some commercial SCR catalysts are capable of oxidizing elemental Hg in flue gas obtained from the inlets of SCR or air heater units. Results are affected by various flue gas and operating parameters. The effect of flue gas composition, including the presence of NH3, has been evaluated. The influence of NH3 on fly ash Hg reactions also is being investigated.     

Patterns of organochlorine pesticide contamination in neotropical migrant passerines in relation to diet and winter habitat

Eleven species of Neotropical migrant passerines collected in Illinois (USA) during May 1996, were analyzed for the presence of organochlorine (OC) pesticides. At least one of five OC pesticide residues was detected in 66 of 72 birds, representing all species examined. The contaminants most frequently detected were p,p'-DDE, dieldrin and heptachlor epoxide, all of which were present in the 10-30 ng/g range. Insectivores had significantly higher levels of these compounds than did non-insectivores, while there was no significant main effect of winter habitat (forest and scrub). Future research on OC pesticide contamination in resident New World passerines may allow more accurate predictions regarding the sources of contamination in Neotropical migrants.     

The gastropod statolith: a tool for determining the age of<Emphasis Type="Italic"> Nassarius reticulatus</Emphasis>

The microstructure, shape and appearance of the growth rings in statoliths of Nassarius reticulatus (L.) were investigated. This species possesses two statocysts, each containing a single spherical statolith of calcium carbonate of up to 0.22 mm in diameter in the largest animals. The relationship between statolith diameter (SD) and total shell height (TSH) is exponential [ln(TSH)=26.3SD–0.842], although the function is site specific. Statoliths of the largest whelks (>29 mm) contained three or four clearly defined rings, corresponding to TSH values of ~1.1, 4.6–5.3, 12.0–13.5 and 18.5 mm, respectively. The first ring likely represents the metamorphic ring that was deposited at the time of larval metamorphosis when the post-larval whelk adopted a benthic lifestyle. The estimated size of the whelks at formation of the second, third and fourth statolith rings closely matched the TSH inferred from the shell rings. It is concluded that the patterns of growth rings present in statoliths can provide information about the age and growth of N. reticulatus.Communicated by O. Kinne, Oldendorf/Luhe     

A new technique helps to uncover unknown peptides and disinfection by-products in water

正Environmental water samples can be extremely complex,with potentially thousands of molecules that can derive from natural organic matter(NOM)and thousands that derive from anthropogenic contaminants.As complex as these samples are,drinking water can be even more complex.Due to disinfectants that are used to treat drinking water(e.g.,chlorine,chloramines,     

A ComprehensiveNoise Management Strategy for an Urbanized River Catchment

The Brisbane River serves multiple functions in both its upper catchment and its lower reaches. The lower reaches are highly urbanized where the river flows through Australia's third largest city, and here the river sustains transport activities, waste water disposal, a port, and both motorized recreation and active and passive non-motorized recreation. In the city the river also serves as a locality for community events, as a cultural icon and as a residential neighbour. Many of these functions are spatially and temporally congruent and, amongst other issues, this congruency has the potential to generate significant levels of noise conflict. This paper describes the approach adopted to assess the nature and extent of noise conflicts and to develop a comprehensive strategy of noise management-allas part of a larger scheme for an integrated approach to manage the Brisbane River and its catchment. Noise management strategies recommended for implementation include noise zoning of the river, planning and approval processes for land-based waterway facilities, noise planning and approval processes for residential and other noise-sensitive uses, codes of practice for rowing and similar activities, as well as the more conventional approach of regulatory limits on river-based noise sources. The paper demonstrates that a wide range of strategies are necessary to handle complex pollution problems of this sort, and provides a model of comprehensive action for management of noise from river-related activities that may find application elsewhere.