Carotenoid-derived ornaments reflect parental quality in male and female yellow-eyed penguins (<Emphasis Type="Italic">Megadyptes antipodes</Emphasis>)

The handicap principle suggests that ornamental traits that function as honest signals in mate selection must be costly to be effective. We evaluated in the sexually monochromatic yellow-eyed penguin (Megadyptes antipodes) whether the carotenoid-derived plumage and eye coloration predicts parental quality and whether males and females within pairs mate assortatively in relation to these carotenoid-derived ornaments. In addition, we investigated whether age or body condition was related to the coloration of the ornamental traits. In yellow-eyed penguins, parental quality of males and females was predicted by eye and head plumage coloration. Even when we controlled for gender- and age-specific differences, eye and head plumage coloration reflected honestly parental quality. Males and females mated assortatively in relation to these ornamental traits. While age influenced coloration of both the eye and head plumage, body condition was related only to the saturation of plumage coloration. These results provide evidence that the carotenoid-derived ornaments in yellow-eyed penguins reflect the parental abilities of birds and, therefore, may be costly signals. Potentially, female and male yellow-eyed penguins could use eye and plumage coloration as an indirect cue in assessing age and quality of individual birds during mate choice. This is only the second study to examine plumage coloration in relation to sexual selection in penguins, while conspicuous ornamental traits in other species of penguin beg the question whether they also play a role in sexual selection.Electronic Supplementary Material Supplementary material is available in the online version of this article at Communicated by C.R. Brown     

Nitric oxide formation in an iron oxide pellet rotary kiln furnace

A one-dimensional numerical model was developed to simulate the effects of heat and mass transfer on the formation of oxides of nitrogen (NOx) in a rotary kiln furnace for iron oxide pellet induration. The modeled kiln has a length-to-diameter ratio of approximately seven. The principal mechanism of heat transfer is radiation from the flame, which was described by the net radiation method. The well known Zeldovich mechanism was used to predict thermal NOx generation. Temperature fluctuations in the vicinity of the flame were estimated with a clipped Gaussian probability density function. The thermal energy and mass balance model equations were solved numerically. The model is capable of predicting temperature profiles and NOx production rates in agreement with observed plant performance. The model was used to explore the effects of process changes on the total NOx formation in the kiln. It was concluded that the gas temperature as well as the partial pressure of oxygen in the process gases controls the rate of NOx formation. Lowering the temperature of the kiln gases by increasing the secondary air flow rates requires simultaneously decreasing the pellet production rate in order to maintain the pellet temperatures needed for blast furnace conditions.     

Sustainable oil and grease removal from synthetic stormwater runoff using bench-scale bioretention studies.

One of the principal components of the contaminant load in urban stormwater runoff is oil and grease (O&G) pollution, resulting from vehicle emissions. A mulch layer was used as a contaminant trap to remove O&G (dissolved and particulate-associated naphthalene, dissolved toluene, and dissolved motor oil hydrocarbons) from a synthetic runoff during a bench-scale infiltration study. Approximately 80 to 95% removal of all contaminants from synthetic runoff was found via sorption and filtration. Subsequently, approximately 90% of the sorbed naphthalene, toluene, oil, and particulate-associated naphthalene was biodegraded within approximately 3, 4, 8, and 2 days after the event, respectively, based on decreases in contaminant concentrations coupled with increases of microbial populations. These results indicate the effectiveness and sustainability of placing a thin layer of mulch on the surface of a bioretention facility for reducing O&G pollution from urban stormwater runoff.     

Numerical simulations of radon as an in situ partitioning tracer for quantifying NAPL contamination using push-pull tests

Presented here is a reanalysis of results previously presented by [Davis, B.M., Istok, J.D., Semprini, L., 2002. Push-pull partitioning tracer tests using radon-222 to quantify non-aqueous phase liquid contamination. J. Contam. Hydrol. 58, 129-146] of push-pull tests using radon as a naturally occurring partitioning tracer for evaluating NAPL contamination. In a push-pull test where radon-free water and bromide are injected, the presence of NAPL is manifested in greater dispersion of the radon breakthrough curve (BTC) relative to the bromide BTC during the extraction phase as a result of radon partitioning into the NAPL. Laboratory push-pull tests in a dense or DNAPL-contaminated physical aquifer model (PAM) indicated that the previously used modeling approach resulted in an overestimation of the DNAPL (trichloroethene) saturation (S(n)). The numerical simulations presented here investigated the influence of (1) initial radon concentrations, which vary as a function of S(n), and (2) heterogeneity in S(n) distribution within the radius of influence of the push-pull test. The simulations showed that these factors influence radon BTCs and resulting estimates of S(n). A revised method of interpreting radon BTCs is presented here, which takes into account initial radon concentrations and uses non-normalized radon BTCs. This revised method produces greater radon BTC sensitivity at small values of S(n) and was used to re-analyze the results from the PAM push-pull tests reported by Davis et al. The re-analysis resulted in a more accurate estimate of S(n) (1.8%) compared with the previously estimated value (7.4%). The revised method was then applied to results from a push-pull test conducted in a light or LNAPL-contaminated aquifer at a field site, resulting in a more accurate estimate of S(n) (4.1%) compared with a previously estimated value (13.6%). The revised method improves upon the efficacy of the radon push-pull test to estimate NAPL saturations. A limitation of the revised method is that 'background' radon concentrations from a non-contaminated well in the NAPL-contaminated aquifer are needed to accurately estimate NAPL saturation. The method has potential as a means of monitoring the progress of NAPL remediation.     

An environmental decision-making tool for evaluating ground-level ozone-related health effects

A computer model called the Ozone Risk Assessment Model (ORAM) was developed to evaluate the health effects caused by ground-level ozone (O3) exposure. ORAM was coupled with the U.S. Environmental Protection Agency's (EPA) Third-Generation Community Multiscale Air Quality model (Models-3/CMAQ), the state-of-the-art air quality model that predicts O3 concentration and allows the examination of various scenarios in which emission rates of O3 precursors (basically, oxides of nitrogen [NOx] and volatile organic compounds) are varied. The principal analyses in ORAM are exposure model performance evaluation, health-effects calculations (expected number of respiratory hospital admissions), economic valuation, and sensitivity and uncertainty analysis through a Monte Carlo simulation. As a demonstration of the system, ORAM was applied to the eastern Tennessee region, and the entire O3 season was simulated for a base case (typical emissions) and three different emission scenarios. The results indicated that a synergism occurs when reductions in NOx emissions from mobile and point sources were applied simultaneously. A 12.9% reduction in asthma hospital admissions is expected when both mobile and point source NOx emissions are reduced (50 and 70%, respectively) versus a 5.8% reduction caused by mobile source and a 3.5% reduction caused by point sources when these emission sources are reduced individually.     

Shallow groundwater quality on dairy farms with irrigated forage crops

California's dairies are the largest confined animal industry in the state. A major portion of these dairies, which have an average herd size of nearly 1000 animal units, are located in low-relief valleys and basins. Large amounts of liquid manure are generated and stored in these dairies. In the semi-arid climate, liquid manure is frequently applied via flood or furrow irrigation to forage crops that are grown almost year-round. Little is known about the impact of manure management practices on water quality of the extensive alluvial aquifers underlying these basins. The objective of this work is to assess nitrate and salt leaching to shallow groundwater in a relatively vulnerable hydrogeologic region and to quantify the impact from individual sources on dairies. The complex array of potential point and nonpoint sources was divided into three major source areas representing farm management units: (1) manure water lagoons (ponds); (2) feedlot or exercise yard, dry manure, and feed storage areas (corrals); and (3) manure irrigated forage fields (fields). An extensive shallow groundwater-monitoring network (44 wells) was installed in five representative dairy operations in the northeastern San Joaquin Valley, CA. Water quality (electrical conductivity, nitrate-nitrogen, total Kjehldahl nitrogen) was observed over a 4-year period. Nitrate-N, reduced nitrogen and electrical conductivity (EC, salinity) were subject to large spatial and temporal variability. The range of observed nitrate-N and salinity levels was similar on all five dairies. Average shallow groundwater nitrate-N concentrations within the dairies were 64 mg/l compared to 24 mg/l in shallow wells immediately upgradient of these dairies. Average EC levels were 1.9 mS/cm within the dairies and 0.8 mS/cm immediately upgradient. Within the dairies, nitrate-N levels did not significantly vary across dairy management units. However, EC levels were significantly higher in corral and pond areas (2.3 mS/cm) than in field areas (1.6 mS/cm) indicating leaching from those management units. Pond leaching was further inferred from the presence of reduced nitrogen in three of four wells located immediately downgradient of pond berms. The estimated minimum average annual groundwater nitrate-N and salt loading from manure-treated forage fields were 280 and 4300 kg/ha, respectively. Leaching rates for ponds are estimated to be on the order of 0.8 m/year, at least locally. Since manure-treated fields represent by far the largest land area of the dairy, proper nutrient management will be a key to protecting groundwater quality in dairy regions overlying alluvial aquifers.     

Dissolved saxitoxin causes transient inhibition of sensorimotor function in larval Pacific herring (<Emphasis Type="Italic">Clupea harengus pallasi</Emphasis>)

Herring (Clupea harengus pallasi) spawning sites in Puget Sound, Washington overlap spatially and temporally with blooms of Alexandrium catenella, a toxic dinoflagellate species responsible for paralytic shellfish poisoning. Consequently, newly hatched herring larvae may be regularly exposed to the suite of dissolved paralytic shellfish toxins that are released into the water column from toxic cells during blooms. To date, virtually nothing is known about the impacts of these neurotoxins on early developmental stages of marine fish. In the present study, herring larvae at three ages, 0 days post hatch (dph), 4 dph, and 11 dph, were exposed to dissolved saxitoxin (STX) in 24-h and multi-day exposures. All larvae were examined for sensorimotor function (i.e. spontaneous swimming behavior and touch response). Significant reductions in spontaneous and touch-activated swimming behavior occurred within 1 h of exposure. EC₅₀s at 1 h of exposure were 1,500, 840, and 700 μg STX equiv. l⁻¹ for larvae introduced to STX at 0, 4, and 11 dph, respectively. This progressive age-specific increase in STX-induced paralysis suggests that older larvae were more sensitive to the toxin than younger larvae. Interestingly, herring larvae at all ages exhibited a significant degree of neurobehavioral recovery within 4–24 h of continuous exposure relative to the 1-h time point. This recovery of normal motor behaviors was not observed in previous studies with freshwater zebrafish (Danio rerio) larvae under the same continuous exposure conditions, suggesting that an adaptive detoxification or toxin sequestration mechanism may have evolved in some species of marine fish larvae. Our data reveal that (1) dissolved STX is bioavailable to marine finfish larvae, (2) the toxin is a paralytic agent with potencies that differ between developmental stages, and (3) STX-induced sensorimotor inhibition occurs rapidly but is transient in marine larvae. Collectively, these results suggest that dissolved algal toxins may have important sublethal effects on marine fish populations.     

Changes in blood lead and water lead in Edinburgh. An eight year follow-up to the Edinburgh lead study

This study aimed to measure changes in household water lead and blood lead in young people living in Edinburgh over a period of 8 years. Two hundred and twenty-three families were eligible and 207 (93%) agreed to participate. A half-hour stagnation sample of kitchen cold water was taken from each household, and 171 young people (aged 14–17 years) provided a blood sample for lead analysis. Information on plumbing changes, exposure to other sources of lead and factors which might influence blood lead was collected by questionnaire. Edinburgh is supplied with water treated in one of two treatment plants. There was a different programme of water treatment in each plant. In one (A) lime and orthophosphate was introduced in the interval between the original and follow-up studies. In the other (F) lime treatment began before the original study and orthophosphate was introduced subsequently. In water from treatment plant A, mean water lead levels fell from 34 to 4.3 gL-1 (87%). In water supplied from treatment plant F the corresponding values were 9.3 to 3.6 gL-1 (61%). These reductions were due to both water treatment and removal of lead plumbing. Houses with no lead plumbing have water lead levels 89% lower than houses with lead tanks, and 47% lower than houses with lead pipes. About one-third of households with lead tanks are predicted to have water lead levels above the current EC limit of 50 gL- 1, though only 3% or less of the remaining households would exceed this limit. If the proposed 10 gL-1 limit were introduced, 34% of households supplied from plant A and 25% from plant F would breach the limit. Blood lead levels fell from an average of 11.0 gdL-1 to 4.0 gdL-1. Males had higher values than females and the main factors influencing levels were water lead and age of house. Our results show substantial reductions in household water lead and blood lead in our sample over a period of 8 years and represent an important achievement in public health. However, more progress will be required if the proposed new limit of 10 gL-1 for water lead is to be met. There is a need for the continuing surveillance of household water lead and blood lead levels in representative samples of the population.     

Ultrastructure of the gonad and gametogenesis in the eastern oyster,Crassostrea virginica. II. Testis and spermatogenesis

The pelagic harpacticoid copepod, Macrosetella gracilis (A. Scott), is found in association with colonies of the nitrogen-fixing (diazotrophic), bloomforming cyanobacterium Trichodesmium spp. in tropical and subtropical waters. M. gracilis is one of the few direct grazers of these often toxic cyanobacteria. Experiments investigating NH ₊ ⁴ regeneration by M. gracilis were conducted in the Caribbean in September 1992 and the Coral Sea, Australia in November 1994. Rates of M. gracilis ingestion of Trichodesmium thiebautii labelled with ¹⁵N₂ measured in the eastern Caribbean indicated that M. gracilis could consume 33 to 45% of total T. thiebautii colony N d^-1 and >100% of new N fixed d^-1. We also measured the release of NH ₊ ⁴ by M. gracilis feeding on T. thiebautii, as well as by non-feeding copepods, using ¹⁵N isotope dilution methods. In non-feeding copepods, rates of NH ₊ ⁴ release increased as numbers of copepods were increased as both copepod numbers and food availability increased. In the presence of T. thiebautii colonies, M. gracilis had an average rate of NH ₊ ⁴ regeneration of 7.7±1.5 nmol N copepod^-1 h^-1 (±SE), which was significantly higher than when food was absent (1.9±0.7 nmol N copepod^-1 h^-1). Rates of M. gracilis excretion were relatively high based on excretion: ingestion ratios, which could be due to having a high-N food source readily available, to sloppy-feeding effects, or as a response to toxins in the cyanobacterium. Incubations of M. gracilis with and without T. erythraeum resulted in significant increases in [NH ₊ ⁴ ] as a function of copepod density only. Ammonium leakage from the cyanobacterium and/or microheterotroph associates was relatively low. M. gracilis, through excretion and possible mechanical breakage of cells while grazing, appears to provide a direct link between atmospherically derived new nitrogen and regenerated NH ₊ ⁴ in the oligotrophic systems where Trichodesmium spp. are abundant.