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91.
Due to the enormous annual increase in the volume of municipal solid waste, society's attention is focused on how to manage the solid waste problem. Plastic materials not only contribute a great deal to the litter problem but also create serious danger to the ecology. Every year, countless birds, sea turtles, and other marine mammals die from eating or getting entangled in plastic litter. Synthesizing degradable polymers can have a great impact on solving the problem of plastic litter. We have modified the structure of poly(ethylene terephthalate) to make it degradable in typical environmental conditions in presence of water. The change of physical properties of modified poly(ethylene terephthalate), resulting from hydrolysis, has been monitored and compared with those of pure poly(ethylene terephthalate). 相似文献
92.
Pocillopora damicornis (Linnaeus) and Montipora verrucosa (Lamarck) were collected from Hawaiian reefs. In two experiments (September 1979-January 1980: ca. 4 mo; August-October 1980; ca. 2 mo), these reef corals were grown under sunlight passed through filters producing light fields of similar quantum flux but different spectral composition. In vitro cultures of symbiotic zooxanthellae (Symbiodinium microadriaticum Freudenthal) from M. verrucosa were cultured under similar conditions for 15 d. Blue or white light promoted more coral skeletal growth than green or red light. In both coral species, blue light increased the total amount of chlorophyll a of the coral-zooxanthellae association. In the perforate species, M. verrucosa, the pigment concentration was elevated by an increase in the density of zooxanthellae, but the pigment concentrations per algal cell remained unchanged; in the non-perforate species, P. damicornis, it appears that pigment concentration was elevated by an increase in pigment per algal cell, and not by an increase in density of zooxanthellae. The sunloving reef-flat coral P. damicornis did not grow as rapidly as the shade-species M. verrucosa at the low quantum flux (about 10% sunlight) provided by the experimental treatments. The in vitro cultures of zooxanthellae from M. verrucosa exhibited growth rates in light of altered spectral quality that correlated with the responses of the host coral species: blue and white light supported significantly greater growth than green light, and red light resulted in the lowest growth rate.Contribution No. 678 of the Hawaii Institute of Marine Biology 相似文献
93.
Most agricultural information is reported by government sources on a state or county basis. The purpose of this study was
to demonstrate use of geospatial data, the 2002 Agricultural Cropland Data Layer (CDL) for the mid-Atlantic region, to characterize
agricultural, environmental, and other scientific parameters for the Chincoteague Bay subbasin using geographic information
systems. This study demonstrated that agriculture can be characterized accurately on subbasin and subwatershed bases, thus
complimenting various assessment technologies. Approximately 28% of the dry land of the subbasin was cropland. Field corn
was the largest crop. Soybeans, either singly or double-cropped with wheat, were the second most predominant crop. Although
the subbasin is relatively small, cropping practices in the northern part were different from those in the southern portion.
Other crops, such as fresh vegetables and vegetables grown for processing, were less than 10% of the total cropland. A conservative
approximation of the total pesticide usage in the subbasin in 2002 was over 277,000 lbs of active ingredients. Herbicides
represented the most frequently used pesticides in the subbasin, both in number (17) and in total active ingredients (over
261,000 lbs). Ten insecticides predominated in the watershed, while only small quantities of three fungicides were used. Total
pesticide usage and intensity were estimated using the CDL. Nutrient inputs to cropland from animal manure, chemical fertilizer,
and atmospheric deposition were modeled at over 30 million pounds of nitrogen and over 7 million pounds of phosphorous. Crops
under conservation tillage had the largest input of both nutrients. 相似文献
94.
Thao Nguyen Duma Hlangothi Raul A. Martinez III Durelle Jacob Kevin Anthony Herb Nance 《Journal of environmental science and health. Part. B》2013,48(12):1097-1102
Polyaromatic hydrocarbons (PAH) content from seven commercial waterpipe charcoals were determined during the smoking process to estimate how much PAHs would not be trapped by the water trap and could reach the lungs of the smokers. Naphthalene, 2-methylnaphthalene, acenaphthylene, acenaphthene, phenanthrene and fluoranthene were the most abundant PAH compounds produced during smoking. Naphthalene was the highest in all of the smoke contents and levels of 5 to 405 μg/15 minutes could be inhaled by the smoker. The amounts of PAHs produced during the smoking events in absence of tobacco varied greatly among different brands of charcoal. The amount and composition of the emitted PAH were not related to the amount and composition of the original chemicals in the charcoal prior to burning. Our findings suggest that public health agencies should regulate smoked charcoal products alongside tobacco. 相似文献
95.
Schauffler M Nelson SJ Kahl JS Jacobson GL Haines TA Patterson WA Johnson KB 《Environmental monitoring and assessment》2007,126(1-3):39-53
Paleoecological reconstructions of forest stand histories for two upland watersheds at Acadia National Park in Maine were
completed to support related watershed chemistry studies. The project hypothesis was that forest type and fire history influence
long-term cycling and storage of atmospheric mercury and nitrogen within watersheds. The reconstructions document differences
in major vegetation composition and disturbance between the burned and unburned watersheds during the past several centuries.
Pollen and charcoal stratigraphies from organic sediment accumulations in forested wet depressions indicate that the present
experimental design of contrasting disturbance and forest histories has persisted during recent centuries. The unburned watershed
has been dominated by spruce (Picea rubens) and fir (Abies balsamea) for 500 years or more and has not recently burned or been substantially cleared. The burned watershed is dominated by a
heterogeneous forest of patchy hardwood, mixed wood, and softwood stands. A large portion of this watershed burned severely
in 1947 and probably more than once in the 1800s, and has supported heterogeneous successional forests for 200 years or longer.
Overall, these results support the underlying premise that the experimental design of this watershed research can be used
to infer landscape controls on biogeochemical processes. 相似文献
96.
Alexander Braczkowski Matthew H. Holden Christopher O'Bryan Chi‐Yeung Choi Xiaojing Gan Nicholas Beesley Yufang Gao James Allan Peter Tyrrell Daniel Stiles Peadar Brehony Revocatus Meney Henry Brink Nao Takashina Ming‐Ching Lin Hsien‐Yung Lin Niki Rust Severino G. Salmo III James E.M. Watson Paula Kahumbu Martine Maron Hugh P. Possingham Duan Biggs 《Conservation biology》2018,32(4):765-773
Recent increases in ivory poaching have depressed African elephant populations. Successful enforcement has led to ivory stockpiling. Stockpile destruction is becoming increasingly popular, and most destruction has occurred in the last 5 years. Ivory destruction is intended to send a strong message against ivory consumption, both in promoting a taboo on ivory use and catalyzing policy change. However, there has been no effort to establish the distribution and extent of media reporting on ivory destruction events globally. We analyzed media coverage of the largest ivory destruction event in history (Kenya, 30 April 2016) across 11 nation states connected to ivory trade. We used an online‐media crawling tool to search online media outlets and subjected 5 of the largest print newspapers (by circulation) in 5 nations of interest to content analysis. Most online news on the ivory burn came from the United States (81% of 1944 articles), whereas most of the print news articles came from Kenya (61% of 157 articles). Eighty‐six to 97% of all online articles reported the burn as a positive conservation action, whereas 4–50% discussed ivory burning as having a negative impact on elephant conservation. Most articles discussed law enforcement and trade bans as effective for elephant conservation. There was more relative search interest globally in the 2016 Kenyan ivory burn than any other burn in 5 years. Ours is the first attempt to track the reach of media coverage relative to an ivory burn and provides a case study in tracking the effects of a conservation‐marketing event. 相似文献
97.
Richard T. Kazmaier Eric C. Hellgren ‡ Donald C. Ruthven III † David R. Synatzske† 《Conservation biology》2001,15(4):1091-1101
Abstract: Considerable effort has been exerted in attempts to understand the complex ecological effects of grazing. North American tortoises, by virtue of their distribution, provide a good model taxon through which to study how grazing effects vary with grazing regime, habitat, and climate. We studied the Texas tortoise ( Gopherus berlandieri ) , which is restricted primarily to privately owned rangelands of southern Texas and northeastern Mexico. Management of this species is hampered by a lack of information on the effects of common land-use practices. We evaluated the effects of moderate grazing by cattle (short-duration, winter-spring rotational grazing regime; 6–28 animal-unit days/ha/year) on this tortoise by comparing two grazed and two ungrazed sites in the Western Rio Grande Plains, Texas ( U.S.A.), from April 1994 to October 1997. We made 132 captures of 106 individuals in the ungrazed pastures and 324 captures of 237 individuals in the grazed pastures. We also radiotracked 22 tortoises in the ungrazed pastures and 25 tortoises in the grazed pastures. Comparisons of relative abundance, body-size distribution, age distribution, body mass, sex ratio, adult survival, proportion of juveniles, and growth rates revealed no differences ( p > 0.05 for all parameters) between tortoises on grazed and ungrazed areas. Based on these results, we suggest that moderate grazing by cattle is not incompatible with maintenance of Texas tortoise populations. Our data were consistent with a general model of tortoise biogeography and tolerance of disturbance which suggests that Texas tortoises are tolerant to intermediate levels of disturbance. Generalities about the effect of cattle grazing on the four North American tortoises should be avoided unless they can be placed in the context of grazing regime, precipitation, habitat quality, and tortoise requirements. 相似文献
98.
99.
The number and size of infill oversized houses, or McMansions, has increased in the U.S. and the world. To maintain desirable neighborhood appearances, communities should know what constitutes “too big.” This paper reports six studies that used color simulations of blocks of houses to examine compatibility and visual appeal in relation to attributes of the infill house and its context. Following psychophysical findings, the relative size of the infill house should have larger effects on response than its actual size. The studies confirmed that the infill ratio had more weight than size for perceived compatibility. Compatibility did not always translate into visual appeal. For visual appeal, infill style had larger effects than did size or size ratio, height had larger effects than width, and, for larger sizes and ratios, infill ratio had larger effects than actual size. To maintain visual quality in relation to infill houses, communities should first seek an architecturally compatible style, and then try to control its relative size (the infill façade area). Tests of responses to real infill houses can show how well these findings generalize. 相似文献
100.
Trevor Platt George N. White III Li Zhai Shubha Sathyendranath Shovonlal Roy 《Ecological modelling》2009
Remote sensing offers many advantages in the development of ecosystem indicators for the pelagic zone of the ocean. Particularly suitable in this context are the indicators arising from time series that can be constructed from remotely sensed data. For example, using ocean-colour radiometry, the phenology of phytoplankton blooms can be assessed. Metrics defined in this way show promise as informative indicators for the entire pelagic ecosystem. A simple phytoplankton–substrate model, with forcing dependent on latitude and day number is used to explore the qualitative features of bloom phenology for comparison with the results observed in a suite of 10-year time series of chlorophyll concentration, as assessed by remote sensing, from the Northwest Atlantic Ocean. The model reveals features of the dynamics that might otherwise have been overlooked in evaluation of the observational data. 相似文献