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141.
G T Brooks 《Journal of environmental science and health. Part. B》1980,15(6):755-793
The wide-spread use of pesticides in modern agriculture has created a need to investigate the chemical transformation of pesticides in plants and animals. This paper reviews the chemical and biochemical fate of various pesticides and other xenobiotics. Photochemical mechanisms appear to be the most common pathways for the abiotic transformation of these chemicals. Biotic transformation includes a large group of biochemical reactions which may result in either deactivation (detoxication) or activation (toxication) of bioactive compounds. The need for quality control in the production of pesticides is also discussed. 相似文献
142.
Matthew L. Brooks 《Environmental management》1995,19(1):65-74
Human disturbance in the western Mojave Desert takes many forms. The most pervasive are livestock grazing and off-highway
vehicle use. Over the past few decades several areas within this region have been fenced to preclude human disturbance. These
areas provide opportunities to study the impact of human activities in a desert ecosystem. This paper documents the response
of plant and small mammal populations to fencing constructed between 1978 and 1979 at the Desert Tortoise Research Natural
Area, Kern County, California.
Aboveground live annual plant biomass was generally greater inside than outside the fenced plots during April 1990, 1991,
and 1992. The alien grassSchismus barbatus was a notable exception, producing more biomass in the unprotected area. Forb biomass was greater than that of alien annual
grasses inside the fence during all three years of the study. Outside the fence, forb biomass was significantly higher than
that of alien grasses only during spring 1992. Percent cover of perennial shrubs was higher inside the fence than outside,
while no significant trend was detected in density. There was als more seed biomass inside the fence; this may have contributed
to the greater diversity and density of Merriam's kangaroo rats (Dipodomys merriami), long-tailed pocket mice (Chaetodipus formosus), and southern grasshopper mice (Onychomys torridus) in the protected area.
These results show that protection from human disturbance has many benefits, including greater overall community biomass and
diversity. The significance and generality of these results can be further tested by studying other exclosures of varying
age and configurations in different desert regions of the southwestern United States. 相似文献
143.
The fossil record of late Campanian tyrannosauroids of western North America has a geographic gap between the Northern Rocky
Mountain Region (Montana, Alberta) and the Southwest (New Mexico, Utah). Until recently, diagnostic tyrannosauroids from the
Southwest were unknown until the discovery of Bistahieversor sealeyi from the late Campanian of New Mexico. Here we describe an incomplete skull and postcranial skeleton of an unusual tyrannosaurid
from the Kaiparowits Formation (Late Cretaceous) of Utah that represents a new genus and species, Teratophoneus curriei. Teratophoneus differs from other tyrannosauroids in having a short skull, as indicated by a short and steep maxilla, abrupt angle in the
postorbital process of the jugal, laterally oriented paroccipital processes, short basicranium, and reduced number of teeth.
Teratophoneus is the sister taxon of the Daspletosaurus + Tyrannosaurus clade and it is the most basal North American tyrannosaurine. The presence of Teratophoneus suggests that dinosaur faunas were regionally endemic in the west during the upper Campanian. The divergence in skull form
seen in tyrannosaurines indicates that the skull in this clade had a wide range of adaptive morphotypes. 相似文献
144.
Cerumen, or propolis, is a mixture of plant resins enriched with bee secretions. In Australia, stingless bees are important
pollinators that use cerumen for nest construction and possibly for colony’s health. While extensive research attests to the
therapeutic properties of honeybee (Apis mellifera) propolis, the biological and medicinal properties of Australian stingless bee cerumen are largely unknown. In this study,
the chemical and biological properties of polar extracts of cerumen from Tetragonula carbonaria in South East Queensland, Australia were investigated using gas chromatography-mass spectrometry (GC-MS) analyses and in
vitro 5-lipoxygenase (5-LOX) cell-free assays. Extracts were tested against comparative (commercial tincture of A. mellifera propolis) and positive controls (Trolox and gallic acid). Distinct GC-MS fingerprints of a mixed diterpenic profile typical
of native bee cerumen were obtained with pimaric acid (6.31 ± 0.97%, w/w), isopimaric acid (12.23 ± 3.03%, w/w), and gallic
acid (5.79 ± 0.81%, w/w) tentatively identified as useful chemical markers. Characteristic flavonoids and prenylated phenolics
found in honeybee propolis were absent. Cerumen extracts from T. carbonaria inhibited activity of 5-LOX, an enzyme known to catalyse production of proinflammatory mediators (IC50 19.97 ± 2.67 μg/ml, mean ± SEM, n = 4). Extracts had similar potency to Trolox (IC50 12.78 ± 1.82 μg/ml), but were less potent than honeybee propolis (IC50 5.90 ± 0.62 μg/ml) or gallic acid (IC50 5.62 ± 0.35 μg/ml, P < 0.001). These findings warrant further investigation of the ecological and medicinal properties of this stingless bee cerumen,
which may herald a commercial potential for the Australian beekeeping industry. 相似文献
145.
Agricultural BMP Effectiveness and Dominant Hydrological Flow Paths: Concepts and a Review 下载免费PDF全文
Rebecca A. Rittenburg Audrey L. Squires Jan Boll Erin S. Brooks Zachary M. Easton Tammo S. Steenhuis 《Journal of the American Water Resources Association》2015,51(2):305-329
We present a conceptual framework that relates agricultural best management practice (BMP) effectiveness with dominant hydrological flow paths to improve nonpoint source (NPS) pollution management. We use the framework to analyze plot, field and watershed scale published studies on BMP effectiveness to develop transferable recommendations for BMP selection and placement at the watershed scale. The framework is based on the location of the restrictive layer in the soil profile and distinguishes three hydrologic land types. Hydrologic land type A has the restrictive layer at the surface and BMPs that increase infiltration are effective. In land type B1, the surface soil has an infiltration rate greater than the prevailing precipitation intensity, but there is a shallow restrictive layer causing lateral flow and saturation excess overland flow. Few structural practices are effective for these land types, but pollutant source management plans can significantly reduce pollutant loading. Hydrologic land type B2 has deep, well‐draining soils without restrictive layers that transport pollutants to groundwater via percolation. Practices that increased pollutant residence time in the mixing layer or increased plant water uptake were found as the most effective BMPs in B2 land types. Matching BMPs to the appropriate land type allows for better targeting of hydrologically sensitive areas within a watershed, and potentially more significant reductions of NPS pollutant loading. 相似文献
146.
E.S. Brooks S.M. Saia J. Boll L. Wetzel Z.M. Easton T.S. Steenhuis 《Journal of the American Water Resources Association》2015,51(2):343-358
There is an increasing need for improved process‐based planning tools to assist watershed managers in the selection and placement of effective best management practices (BMPs). In this article, we present an approach, based on the Water Erosion Prediction Project model and a pesticide transport model, to identify dominant hydrologic flow paths and critical source areas for a variety of pollutant types. We use this approach to compare the relative impacts of BMPs on hydrology, erosion, sediment, and pollutant delivery within different landscapes. Specifically, we focus on using this approach to understand what factors promoted and/or hindered BMP effectiveness at three Conservation Effects Assessment Project watersheds: Paradise Creek Watershed in Idaho, Walnut Creek Watershed in Iowa, and Goodwater Creek Experimental Watershed in Missouri. These watersheds were first broken down into unique land types based on soil and topographic characteristics. We used the model to assess BMP effectiveness in each of these land types. This simple process‐based modeling approach provided valuable insights that are not generally available to planners when selecting and locating BMPs and helped explain fundamental reasons why long‐term improvement in water quality of these three watersheds has yet to be completely realized. 相似文献
147.
Featured Collection Introduction: Synthesis and Analysis of Conservation Effects Assessment Projects for Improved Water Quality 下载免费PDF全文
148.
Kohyar Kiazad Simon Lloyd D. Restubog Peter W. Hom Alessandra Capezio Brooks Holtom Thomas Lee 《组织行为杂志》2024,45(3):335-343
The question of why so many people leave science, technology, engineering and mathematics (STEM) jobs continues to echo through social science research and Government policy. This is not surprising given the considerable investments into uptake and quality of STEM education and that STEM workers have a pivotal role to play in addressing current and future grand challenges. Yet, too many individuals with tertiary degrees in STEM—disproportionately women, racial minorities, and the underprivileged—leave or pursue careers in non-STEM fields. While demand for employment in STEM continues to grow, such persistent STEM defections present a significant challenge. We offer an integrative special issue of eight empirical articles capturing current thinking and evidence on employee retention and turnover, both within and beyond the realm of STEM. Our thematic analysis of the articles reveals overarching themes around the fundamental question of why people choose to stay in their jobs and why they leave. From this, we provide a future research agenda recognizing the myriad work and nonwork factors influencing the desire and ability to stay in one's chosen profession, particularly in critical sectors where gender and minority attrition rates prevail. 相似文献
149.
In the indoor environment, settled surface dust often functions as a reservoir of hazardous particulate contaminants. In many
circumstances, a major contributing source to the dust pool is exterior soil. Young children are particularly susceptible
to exposure to both outdoor derived soil and indoor derived dust present in the indoor dust pool. This is because early in
life the exploratory activities of the infant are dominated by touching and mouthing behavior. Inadvertent exposure to dust
through mouth contact and hand-to-mouth activity is an inevitable consequence of infant development. Clean-up of indoor dust
is, in many circumstances, critically important in efforts to minimize pediatric exposure. In this study, we examine the efficiency
of vacuum cleaner removal of footwear-deposited soil on vinyl floor tiles. The study utilized a 5 × 10 foot (c. 152.5 × 305 cm)
test surface composed of 1-foot-square (c. 30.5 × 30.5 cm) vinyl floor tiles. A composite test soil with moderately elevated
levels of certain elements (e.g., Pb) was repeatedly introduced onto the floor surface by footwear track-on. The deposited
soil was subsequently periodically removed from randomly selected tiles using a domestic vacuum cleaner. The mass and loading
of soil elements on the tiles following vacuuming were determined both by wet wipe collection and by subsequent chemical analysis.
It was found that vacuum cleaner removal eliminated much of the soil mass from the floor tiles. However, a small percentage
of the mass was not removed and a portion of this residual mass could be picked up by moistened hand-lifts. Furthermore, although
the post-vacuuming tile soil mass was sizably reduced, for some elements (notably Pb) the concentration in the residual soil
was increased. We interpret this increased metal concentration to be a particle size effect with smaller particles (with a
proportionately higher metal content) remaining in situ after vacuuming. 相似文献
150.
Feeling insulted? Examining end‐of‐work anger as a mediator in the relationship between daily illegitimate tasks and next‐day CWB 下载免费PDF全文
In this daily diary study, we investigated the within‐person relationship between daily illegitimate tasks and next‐day counterproductive work behavior (CWB). We explored a moderated mediation model where the link between illegitimate tasks and CWB is mediated by daily end‐of‐work anger, with daily time pressure moderating the relationship between illegitimate tasks and end‐of‐work anger. We collected data from 114 full‐time employees across 10 consecutive working days. Results showed that within individuals, daily illegitimate tasks positively predicted next‐day CWB, and the relationship was mediated by daily end‐of‐work anger. Further, daily time pressure moderated the relationship between daily illegitimate tasks and daily end‐of‐work anger with the relationship being stronger when daily time pressure was high. 相似文献