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351.
Phytoavailability of biosolids phosphorus 总被引:1,自引:0,他引:1
O'Connor GA Sarkar D Brinton SR Elliott HA Martin FG 《Journal of environmental quality》2004,33(2):703-712
Efficient utilization of biosolids P for agronomic purposes requires accounting for differences in the phytoavailability of P in various biosolids. Greenhouse studies were conducted with a common pasture grass grown in two P-deficient soils amended with 12 biosolids and a commercial fertilizer (triple superphosphate, TSP) to quantify P uptake and to assess the relative phytoavailabilities of the P sources. Biosolids were grouped into three general categories of phytoavailability relative to TSP: high (> 75% of TSP), moderate (25-75% of TSP), and low (< 25% of TSP). Two biosolids, produced via biological phosphorus removal (BPR) processes, were in the high category, and mimicked fertilizer P with regard to P phytoavailability. Most biosolids produced by conventional wastewater and solids digestion and additional treatments like composting were in the moderate category. Also included in this category was a BPR that had been pelletized and another BPR supplemented with Al. The low category included biosolids containing greater than normal (> 50 g kg(-1)) total Fe and Al concentrations and processed to high (> 60%) solids content. 相似文献
352.
The non-geniculate crustose coralline alga (CCA) Mastophora pacifica can induce the metamorphosis of competent Haliotis asinina (Vetigastropoda) larvae. The ability to respond to this natural cue varies considerably with larval age, with a higher proportion of older larvae (e.g. 90 h) able to metamorphose in response to M. pacifica than younger larvae (e.g. 66 h). Here we document the variation in time to acquisition of competence within a larval age class. For example, after 18 h of exposure to M. pacifica, approximately 15 and 36% of 84 and 90-h-old H. asinina larvae had initiated metamorphosis, respectively. This age-dependent response to M. pacifica is also observed when different aged larvae are exposed to CCA for varying periods. A higher proportion of older larvae require shorter periods of exposure to CCA than younger larvae in order to initiate metamorphosis. In this experiment, as in the previous, a small proportion of young larvae were able to respond to brief periods of CCA exposure, suggesting that they had developed the same state of competency as the majority of their older counterparts. Comparisons of the proportions of larvae undergoing metamorphosis between families reveals that parentage also has a significant (P<0.05) affect on whether an individual will initiate metamorphosis at a given age. These familial differences are more pronounced when younger, largely pre-competent larvae (i.e. 66 h old) are exposed to M. pacifica, with proportions of larvae undergoing metamorphosis differing by as much as 10 fold between families. As these data suggest that variation in the rate of development of the competent state has a genetic basis, and as a first step towards identifying the molecular basis to this variation, we have identified numerous genes that are differentially expressed later in larval development using a differential display approach. Spatial expression analysis of these genes suggests that they may be directly involved in the acquisition of competence, or may play a functional role in the postlarva following metamorphosis.Communicated by M.S. Johnson, Crawley 相似文献
353.
The people of the Democratic Republic of Congo for decades have been living in a situation of chronic crisis. Violence, population displacement and the destruction of infrastructure and health services have devastated the health of the population. In 2001, Médicins Sans Frontières conducted a survey in five areas of western and central DRC to assess mortality, access to health-care, vaccination coverage and exposure to violence. High mortality rates were found in front-line zones, mainly due to malnutrition and infectious diseases. In Basankusu approximately 10 per cent of the total population and 25 per cent of the under-five population had perished in the year before the survey. Humanitarian needs remain acute across the country, particularly near the front line. Infectious-disease control and treatment are a priority, as is increasing access to health-care. Humanitarian assistance must be increased considerably, especially in rural areas and zones that have been affected directly by conflict. 相似文献
354.
Durbin DR Kallan M Elliott M Cornejo RA Arbogast KB Winston FK 《Traffic injury prevention》2003,4(1):58-63
The objectives of this study were to estimate the prevalence of children's exposure to passenger air bag (PAB) deployments and to determine the relative risk of both minor and more serious nonfatal injuries to restrained children exposed to PABs in frontal impact collisions. Data were collected from 1 December 1998 to 30 November 2001 from a large-scale, child-specific crash surveillance system based on insurance claims, a telephone survey, and on-site crash investigations. Vehicles qualifying for inclusion were State Farm-insured, model year 1990 or newer, and involved in a crash with at least one child occupant < or =15 years of age. Qualifying crashes were limited to those that occurred in 15 states and the District of Columbia. A stratified cluster sample was designed in order to select vehicles (the unit of sampling) for the conduction of a telephone survey with the driver. For cases in which child occupants were seriously injured or killed, in-depth crash investigations were performed. The prevalence of exposure to PABs was calculated as the number of children occupying the right front seat in a PAB deployment crash among all children occupying the right front seat in vehicles equipped with PABs. Complete interview data were obtained on 9,779 vehicles involving 15,341 children. Among PAB-exposed children, 175 (14%) suffered serious injuries versus 41 (7.5%) of those in the comparison group (OR 2.0; 95% CI, 1.1-3.7). The overall risk of any injury (both minor and serious) was 86% among children exposed to PABs, compared to 55% among the comparison group (OR 5.3; 95% CI, 2.1-13.4). Exposure to PABs increased the risk of both minor injuries, including facial and chest abrasions, and more serious injuries, particularly upper extremity fractures. 相似文献
355.
356.
357.
Sharks are apex predators, and their evolutionary success is in part due to an impressive array of sensory systems, including
vision. The eyes of sharks are well developed and function over a wide range of light levels. However, whilst close relatives
of the sharks—the rays and chimaeras—are known to have the potential for colour vision, an evolutionary trait thought to provide
distinct survival advantages, evidence for colour vision in sharks remains equivocal. Using single-receptor microspectrophotometry,
we measured the absorbance spectra of visual pigments located in the retinal photoreceptors of 17 species of shark. We show
that, while the spectral tuning of the rod (wavelength of maximum absorbance, λmax 484–518 nm) and cone (λmax 532–561 nm) visual pigments varies between species, each shark has only a single long-wavelength-sensitive cone type. This
suggests that sharks may be cone monochromats and, therefore, potentially colour blind. Whilst cone monochromacy on land is
rare, it may be a common strategy in the marine environment: many aquatic mammals (whales, dolphins and seals) also possess
only a single, green-sensitive cone type. It appears that both sharks and marine mammals may have arrived at the same visual
design by convergent evolution. The spectral tuning of the rod and cone pigments of sharks is also discussed in relation to
their visual ecology. 相似文献
358.
359.
The electrosensory capabilities of wobbegong sharks are of particular interest, partly because very little is known about
their behavioural ecology and specifically because of their unusual ambush predatory strategy and benthic lifestyle. While
several biological functions of electroreception have been proposed, less consideration has been given to the functional significance
of interspecific differences in the morphology and topographic distribution of the ampullary organs. The morphology of the
ampullary organs was examined in four species of wobbegong shark, and the distribution of electroreceptive pores was mapped
in two species. The ampullary systems of wobbegongs are similar in morphology to other marine elasmobranchs. The number of
alveoli per ampullae is not significantly different between the four species; however, differences are seen between ampullary
cell size in some species. Ampullary pore distribution patterns are relatively unique, with the majority of pores occurring
on the dorsal region of the head. Wobbegongs feed primarily on demersal teleost fishes, and as the benthic and well-camouflaged
wobbegong remains motionless, these fish could be easily detected by the dorsal pores when swimming within range. 相似文献
360.
Brandt RC Elliott HA Adviento-Borbe MA Wheeler EF Kleinman PJ Beegle DB 《Journal of environmental quality》2011,40(2):431-437
Surface application of manure in reduced tillage systems generates nuisance odors, but their management is hindered by a lack of standardized field quantification methods. An investigation was undertaken to evaluate odor emissions associated with various technologies that incorporate manure with minimal soil disturbance. Dairy manure slurry was applied by five methods in a 3.5-m swath to grassland in 61-m-inside-diameter rings. Nasal Ranger Field Olfactometer (NRO) instruments were used to collect dilutions-to-threshold (D/T) observations from the center of each ring using a panel of four odor assessors taking four readings each over a 10-min period. The Best Estimate Threshold D/T (BET10) was calculated for each application method and an untreated control based on preapplication and <1 h, 2 to 4 h, and approximately 24 h after spreading. Whole-air samples were simultaneously collected for laboratory dynamic olfactometer evaluation using the triangular forced-choice (TFC) method. The BET10 of NRO data composited for all measurement times showed D/T decreased in the following order (a = 0.05): surface broadcast > aeration infiltration > surface + chisel incorporation > direct ground injection Sshallow disk injection > control, which closely followed laboratory TFC odor panel results (r = 0.83). At 24 h, odor reduction benefits relative to broadcasting persisted for all methods except aeration infiltration, and odors associated with direct ground injection were not different from the untreated control. Shallow disk injection provided substantial odor reduction with familiar toolbar equipment that is well adapted to regional soil conditions and conservation tillage operations. 相似文献