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961.
Chowdhury Z Edwards RD Johnson M Naumoff Shields K Allen T Canuz E Smith KR 《Journal of environmental monitoring : JEM》2007,9(10):1099-1106
We have developed a small, light, passive, inexpensive, datalogging particle monitor called the "UCB" (University of California Berkeley particle monitor). Following previously published laboratory assessments, we present here results of tests of its performance in field settings at high particle concentrations. We demonstrate the mass sensitivity of the UCB in relation to gravimetric filter-based PM(2.5) mass estimates as well as commercial light-scattering instruments co-located in field chamber tests and in kitchens of wood-burning households. The coefficient of variation of the unadjusted UCB mass response in relation to gravimetric estimates was 15%. Although requiring adjustment for differences in sensitivity, inter-monitor performance was consistently high (r(2) > 0.99). Moreover, the UCB can consistently estimate PM(2.5) mass concentrations in wood-burning kitchens (Pearson r(2) = 0.89; N = 99), with good agreement between duplicate measures (Pearson r(2) = 0.94; N = 88). In addition, with appropriate cleaning of the sensing chamber, UCB mass sensitivity does not decrease with time when used intensively in open woodfire kitchens, demonstrating the significant potential of this monitor. 相似文献
962.
Little EE Calfee RD Theodorakos P Brown ZA Johnson CA 《Environmental science and pollution research international》2007,14(5):333-337
Background Cobalt cyanide complexes often result when ore is treated with cyanide solutions to extract gold and other metals. These have
recently been discovered in low but significant concentrations in effluents from gold leach operations. This study was conducted
to determine the potential toxicity of cobalt-cyanide complexes to freshwater organisms and the extent to which ultraviolet
radiation (UV) potentiates this toxicity. Tests were also conducted to determine if humic acids or if adaptation to UV influenced
sensitivity to the cyanide complexes.
Methods Rainbow trout (Oncorhynchus mykiss), Daphnia magna, and Ceriodaphnia dubia were exposed to potassium hexacyanocobaltate in the presence and absence of UV radiation, in the presence and absence of
humic acids. Cyano-cobalt exposures were also conducted with C. dubia from cultures adapted to elevated UV.
Results With an LC50 concentration of 0.38 mg/L, cyanocobalt was over a 1000 times more toxic to rainbow trout in the presence of
UV at a low, environmentally relevant irradiance level (4 μW/cm2 as UVB) than exposure to this compound in the absence of UV with an LC50 of 112.9 mg/L. Toxicity was immediately apparent,
with mortality occurring within an hour of the onset of exposure at the highest concentration. Fish were unaffected by exposure
to UV alone. Weak-acid dissociable cyanide concentrations were observed in irradiated aqueous solutions of cyanocobaltate
within hours of UV exposure and persisted in the presence of UV for at least 96 hours, whereas negligible concentrations were
observed in the absence of UV. The presence of humic acids significantly diminished cyanocobalt toxicity to D. magna and reduced mortality from UV exposure. Humic acids did not significantly influence survival among C. dubia. C. dubia from UV-adapted populations were less sensitive to metallocyanide compounds than organisms from unadapted populations.
Conclusions The results indicate that metallocyanide complexes may pose a hazard to aquatic life through photochemically induced processes.
Factors that decrease UV exposure such as dissolved organic carbon or increased pigmentation would diminish toxicity. 相似文献
963.
Johnson KB Haines TA Kahl JS Norton SA Amirbahman A Sheehan KD 《Environmental monitoring and assessment》2007,126(1-3):55-67
Throughfall and bulk precipitation samples were collected for two watersheds at Acadia National Park, Maine, from 3 May to
16 November 2000, to determine which landscape factors affected mercury (Hg) deposition. One of these watersheds, Cadillac
Brook, burned in 1947, providing a natural experimental design to study the effects of forest type on deposition to forested
watersheds. Sites that face southwest received the highest Hg deposition, which may be due to the interception of cross-continental
movement of contaminated air masses. Sites covered with softwood vegetation also received higher Hg deposition than other
vegetation types because of the higher scavenging efficiency of the canopy structure. Methyl mercury (MeHg) deposition was
not affected by these factors. Hg deposition, as bulk precipitation and throughfall was lower in Cadillac Brook watershed
(burned) than in Hadlock Brook watershed (unburned) because of vegetation type and watershed aspect. Hg and MeHg inputs were
weighted by season and vegetation type because these two factors had the most influence on deposition. Hg volatilization was
not determined. The total Hg deposition via throughfall and bulk precipitation was 9.4 μg/m2/year in Cadillac Brook watershed and 10.2 μg/m2/year in Hadlock Brook watershed. The total MeHg deposition via throughfall and bulk precipitation was 0.05 μg/m2/year in Cadillac Brook watershed and 0.10 μg/m2/year in Hadlock Brook watershed. 相似文献
964.
Littoraria cingulata (Philippi, 1846) is a Western Australian, mangrove littorine snail, represented by two morphologically distinct subspecies,
whose distributions are separated by >300 km. The southern subspecies, L. cingulata pristissini, is distinguished from the northern subspecies, L. cingulata cingulata, by having a thinner, keelless shell with more primary grooves, and lower and much more numerous ribs. In contrast with these
striking differences, L. cingulata cingulata is morphologically very similar to another species, L. sulculosa, with which it also shares a nearly coincident geographic range. Allozyme comparisons at 22 presumptive loci confirmed a
large genetic distance between L. cingulata and L. sulculosa, and the apparent conspecificity of the morphologically divergent subspecies of L. cingulata. Based on geological evidence, the geographical separation of the morphologically divergent forms of L. cingulata has developed within the past 5000 to 10 000 yr. The extensive continuous distribution of the northern subspecies, L. cingulatacingulata, and the large geographic disjunction between the northern and Shark Bay subspecies, L. cingulata pristissini, allowed a test of the genetic importance of this relatively recent disjunction. Within the continuous distribution of the
two subspecies, a pattern of isolation by distance was visible up to distances of 300 km. Beyond 300 km, genetic subdivision,
measured by pairwise G
ST
(the proportion of genetic diversity due to differences between populations), averaged 0.028, whereas subdivision between
Shark Bay and northern populations averaged 0.055 over the same range of distances. Although the relative paucity of barriers
to gene flow tends to limit genetic subdivision in marine species with planktotrophic larvae, the results for L. cingulata suggest that subdivision can occur within a continuous distribution, but that special events leading to major disjunctions
can substantially increase divergence, even over a relatively short period of time.
Received: 16 February 1998 / Accepted: 23 April 1998 相似文献
965.
Managing complex problems in socio-ecological systems (SES) requires innovative approaches, which account for multiple scales, large datasets, and diverse lived experiences. By combining two commonly utilized mixed-methods, public participation GIS (PPGIS) and Q-method (Q), Q + PPGIS has the potential to reveal competing agendas and reduce conflict, but its benefits and weaknesses are comparatively understudied. Using a systematic review, we evaluated how different studies have employed and implemented the Q + PPGIS method. We found 16 studies, comprising 30 publications, with considerable variation in their geographic foci, research disciplines, and addressed SES challenges. These studies exhibit a lack of cohesion between methodological design and implementation and the absence of a consistent application of the method. Nonetheless, Q + PPGIS offers a tool that can guide policy, better inform stakeholders, and reduce conflict based on misconceptions. Resolving the shortcomings identified here will broaden Q + PPGIS utility in geographically situating and representing multiple realities within complex socio-ecological systems challenges.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-022-01709-z. 相似文献
966.
Christian Hermans Ann C. Vandaele Michel Carleer Sophie Fally Réginald Colin Alain Jenouvrier Bernard Coquart Marie-France Mérienne 《Environmental science and pollution research international》1999,6(3):151-158
Absorption spectroscopy, which is widely used for concentration measurements of tropospheric and stratospheric compounds,
requires precise values of the absorption cross-sections of the measured species. NO2, O2 and its collision-induced absorption spectrum, and H2O absorption cross-sections have been measured at temperature and pressure conditions prevailing in the Earth’s atmosphere.
Corrections to the generally accepted analysis procedures used to resolve the convolution problem are also proposed. 相似文献
967.
M Deshusses C T Johnson G Leson 《Journal of the Air & Waste Management Association (1995)》1999,49(8):973-979
To date, biofilters have been used primarily to control dilute, usually odorous, off-gases with relatively low volatile organic compound (VOC) concentrations (< 1 g m-3) and VOC loads (< 50 g m-3 hr-1). Recently, however, U.S. industry has shown an interest in applying biofilters to higher concentrations of VOCs and hazardous air pollutants (HAPs). In this study, the behavior of biofilters under high loads of binary VOC mixtures was studied. Two bench-scale biofilters were operated using a commercially available medium and a mixture of wood chips and compost. Both were exposed to varying mixtures of ethyl acetate and toluene. Concentration profiles and the corresponding removal efficiencies as a function of VOC loading were determined through frequent grab-sampling and GC analysis. Biofilter response to two frequently encountered operating problems--media dry-out and operating temperatures exceeding 40 degrees C--was also evaluated under controlled conditions. Microbial populations were also monitored to confirm the presence of organisms capable of degrading both major off-gas constituents. The results demonstrated several characteristics of biofilters operating under high VOC load conditions. Maximum elimination capacities for ethyl acetate were typically in the range of 200 g m-3 hr-1. Despite the presence of toluene degraders, the removal of toluene was inhibited by high loads of ethyl acetate. Several byproducts, particularly ethanol, were formed. Short-term dry-out and temperature excursions resulted in reduced performance. 相似文献
968.
The fire-prone shrublands of southwestern Australia are renowned for their high plant species diversity and prominence of canopy seed storage (serotiny). We compared species richness, abundance, and life history attributes for soil and canopy seed banks in relation to extant vegetation among four sites with different substrate conditions and high species turnover (50-80%) to identify whether this unusual community-level organization of seed storage might contribute to maintenance of high species richness. Soil seed bank (SSB) densities were low to moderate (233-1435 seeds/m2) compared with densities for other Mediterranean-type vegetation and were lowest for sites with highest canopy seed bank (CSB) species richness and lowest nutrient availability, but not richness or abundance of resprouters. Annuals were infrequent in the lowest nutrient sites, but there was no evidence that small SSB size was due to low seed inputs or a trade-off between seed production/storage and seed size in response to low nutrient availability. Sorensen's similarity between SSB and extant vegetation was 26-43% but increased to 54-57% when the CSB was included, representing levels higher than reported for most other ecosystems. Resprouting species were well represented in both the SSB and CSB, and there was no evidence for lower seed production in resprouters than in non-sprouters overall. The SSB and CSB held no species in common and were characterized by markedly different seed dispersal attributes, with winged or small seeds in the CSB and seeds dispersed by ants, birds, and wind (though none with wings) in the SSB. There was no evidence of spatial differentiation in the distribution of seeds of SSB species between vegetated and open microsites that might facilitate species coexistence, but most woody non-sprouters showed aggregation at scales of 1-2 m, implying limited seed dispersal. High similarity between overall seed bank (SSB + CSB) and extant species composition, high number of resprouting species, and seed dispersal processes before (SSB) and after fire (CSB) leading to differential spatial aggregation of post-fire recruits from the two seed bank types may buffer species composition against rapid change and provide a mechanism for maintaining species coexistence at the local scale. 相似文献
969.
Luke Christopher Evans Matthew P. Greenwell Victoria L. Boult Thomas Frederick Johnson 《Conservation biology》2023,37(4):e14070
Social media is an arena of debate for contentious political and social topics. One conservation topic debated online is the acceptability of trophy hunting, a debate that has implications for national and international policy. We used a mixed-methods approach (grounded theory and quantitative clustering) to identify themes in the trophy hunting debate on Twitter. We examined commonly co-occurring categories that describe people's stances on trophy hunting. We identified 12 categories and 4 preliminary archetypes opposing trophy hunting—activism, scientific, condemning, and objecting—whose opposition derived from different moral reasoning. Few tweets (22) in our sample of 500 supported trophy hunting, whereas 350 opposed it. The debate was hostile; 7% of tweets in our sample were categorized as abusive. Online debates can be unproductive, and our findings may be important for stakeholders wishing to effectively engage in the trophy hunting debate on Twitter. More generally, we contend that because social media is increasingly influential, it is important to formally contextualize public responses to contentious conservation topics in order to aid communication of conservation evidence and to integrate diverse public perspectives in conservation practice. 相似文献
970.
Nicholas S. Johnson Azizah Muhammad Henry Thompson Jongeun Choi Weiming Li 《Behavioral ecology and sociobiology》2012,66(12):1557-1567
Characterization of vertebrate chemo-orientation strategies over long distances is difficult because it is often not feasible to conduct highly controlled hypothesis-based experiments in natural environments. To overcome the challenge, we couple in-stream behavioral observations of female sea lampreys (Petromyzon marinus) orienting to plumes of a synthesized mating pheromone, 7α,12α,24-trihydroxy-5α-cholan-3-one-24-sulfate (3kPZS), and engineering algorithms to systematically test chemo-orientation hypotheses. In-stream field observations and simulated movements of female sea lampreys according to control algorithms support that odor-conditioned rheotaxis is a component of the mechanism used to track plumes of 3kPZS over hundreds of meters in flowing water. Simulated movements of female sea lampreys do not support that rheotaxis or klinotaxis alone is sufficient to enable the movement patterns displayed by females in locating 3kPZS sources in the experimental stream. Odor-conditioned rheotaxis may not only be effective at small spatial scales as previous described in crustaceans, but may also be effectively used by fishes over hundreds of meters. These results may prove useful for developing management strategies for the control of invasive species that exploit the odor-conditioned tracking behavior and for developing biologically inspired navigation strategies for robotic fish. 相似文献