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631.
Woo-Jung Choi Gwang-Hyun Han Sang-Mo Lee Goon-Taek Lee Kwang-Sik Yoon Soo-Myung Choi Hee-Myong Ro 《Agriculture, ecosystems & environment》2007,120(2-4):259-268
An understanding of the long-term changes in the nitrate contamination pattern of unconfined groundwater is critical to conservation of drinking water in rural areas supporting mixed land-use activities such as cropping, livestock farming, and residence. To examine the effect of different land-use activities on nitrate contamination, groundwater samples were collected monthly for 3 years (1997–1999) from 12 wells in rural areas with different land-use activities and analyzed for the concentrations and N isotopic ratios (δ15N) of nitrate. The characteristics of nitrate contamination clearly differed with land-use activities. The percentages of samples that had a nitrate concentration exceeding the national standard for drinking water (10 mg N L−1) were 0, 23, 43, and 67% for the uncontaminated natural area, cropping area, cropping-livestock farming complex area, and residential area, respectively. The range of δ15N values was between +1.4 and +4.5‰ for groundwater nitrate from the uncontaminated natural area. In the cropping area, the δ15N values were slightly different with the type of fertilizer applied to fields in the vicinity of the well, and the values ranged between +8.7 and +14.4‰ for the compost-applied area and between +4.5 and +8.5‰ for the area where urea was applied with compost. The δ15N values of the cropping-livestock farming complex area ranged from +1.0 to +17.7‰, probably resulting from mixed contamination sources (inorganic fertilizer and livestock manure). The well located closest to the livestock feedlot had relatively higher δ15N values, with a range between +8.7 and +17.6‰. In the residential area, a higher δ15N (most frequently above +10‰) of nitrate suggested that the major source of contamination was effluent from leaky septic tanks. Our data showed that unconfined groundwater is susceptible to land-use activities above the aquifers, and the impacts of the activities could be more precisely inferred from long-term data on the concentration and δ15N of nitrate. By determining the impacts, more effective (specific to contamination sources) measures for preventing groundwater quality could be implemented. 相似文献
632.
Considerable concern has arisen over the possibility that the discharge of taconite tailings into Lake Superior could affect algal primary productivity. In 1972, primary productivity studies utilizing the carbon-14 technique were run in the Silver Bay area. Samples were collected and analyzed on a weekly basis for a three month period that included a five week plant shutdown period. Resultant productivity data indicate that there is no apparent relationship between primary productivity and the discharge of taconite tailings. Productivity trends in the Silver Bay area tend to conform to the known seasonal behavior of phytoplankton in western Lake Superior. 相似文献
633.
Lee Alan Dugatkin 《Behavioral ecology and sociobiology》1991,29(2):127-132
Summary One well-known solution to the iterated Prisoner's Dilemma is the TIT FOR TAT strategy. This strategy has three characteristics associated with it. TIT FOR TAT is nice (cooperates on the first move of a game), retaliatory (plays defect against an individual that defected on the prior move), and forgiving (cooperates with an individual which has defected in the past but cooperates in the present). Predator inspection behavior in guppies (Poecilia reticulata) was examined in order to determine whether guppies displayed these three characteristics. Results indicate that while it can be quite difficult to translate the abstract concepts of niceness, retaliation, and forgiveness into measurable behaviors, the data support the hypothesis that guppies display the three characteristics associated with the TIT FOR TAT strategy.The selfish herd and dilution effect are discussed as possible alternative explanations for the observed behavior. These hypotheses alone were insufficient to explain the results. 相似文献
634.
Airborne particulate matter (PM) concentrations were measured in Iksan, a suburban area in South Korea during April, 2003.
PM2.5 (particles with an aerodynamic diameter less than 2.5 μm) and PM10 (particles with an aerodynamic diameter less than 10 μm) samples were collected, and the chemical characteristics of particles
were examined for diurnal patterns, yellow dust/rainfall influences, and scavenging effects. Average concentrations of PM2.5 and PM10 mass measured were 37.3 ± 16.2 μg m−3 and 60.8 ± 29.5 μg m−3, respectively. The sum of ionic chemical species concentrations for PM2.5 and PM10 was 16.9 ± 7.3 and 23.1 ± 10.1 μg/m3, respectively. A significant reduction in PM mass concentrations during rainfall days was observed for coarse mode (PM2.5 − 10) particles, but less reduction was found for fine (PM2.5) mass concentration. SO4
2−, NH4
+, and K+ predominated in fine particulate mode, NO3
− and Cl− predominated in fine particle mode and coarse particle mode, but Na+, Mg2+, and Ca2+ mostly existed in coarse mode. The high concentration of ammonium due to local emissions and long-range transport neutralized
sulfate and nitrate to ammonium sulfate and ammonium nitrate, which were major forms of airborne PM in Iksan. Average mass
concentrations of PM10 in daytime and at night were 57.6 and 70.0 μg m−3, and those of PM2.5 were 35.4 and 42.5 μg m−3, respectively. NO3
− and Cl− in both PM2.5 and PM10 were about double at night than in the daytime, while the rest of the chemical species were equal or a little higher at night
than in the daytime. The results suggest the formation of ammonium nitrate and chloride when high ammonia concentration and
low air temperature are allowed. Backward air trajectory analyses showed that air masses arriving at the site during yellow
dust period were transported from arid Chinese regions, which resulted in high concentrations of airborne PM mass concentrations.
In the meantime, air mass trajectories during a rainfall period were mostly from the Pacific Ocean or the East China Sea,
along with a relatively low PM concentration. 相似文献
635.
Investigation into local peoples’ perceptions can produce useful information that could be incorporated into the decision-making
process to help resolve environmental problems. Within the arena of land degradation, a number of studies have also been conducted
to explore local peoples’ views of the problem. However, the perceptions of land-degrading practices of the general public
have so far not been actively solicited. This study aimed to contribute to this area of research by adopting the psychometric
scaling technique to empirically explore the lay public’s ecological risk perceptions of land-degrading activities in Minqin
County in Gansu Province, northern China. The primary data were collected via a questionnaire survey (n = 1,138) administered between 14 and 31 December 2002. The major findings of the survey were: (1) Respondents perceived the
ecological risks posed by different land-degrading activities to be different. (2) There was a considerable incongruence in
the way in which mining of groundwater was conceived by experts and laymen, respectively. (3) Respondents were pretty unsure
of expert knowledge. (4) Respondents’ ecological risk perceptions were significantly affected by their personal attributes.
As far as the policy implications of these findings are concerned, this study accentuates that we must be aware of, and involved
in, the environmental perceptions of the lay public in order to succeed in guiding any human-environment tensions along more
sustainable trajectories and navigating the transition to sustainability. 相似文献
636.
G. Darrel Jenerette Jay Lee David W. Waller Robert E. Carlson 《Environmental management》2002,29(1):67-75
The ecoregion concept is a popular method of understanding the spatial distribution of the environment', however, it has yet
to be adequately demonstrated that the environment is distributed in accordance with these bounded units. In this paper, we
generated a testable hypothesis based on the current usage of ecoregions: the ecoregion classification will allow for discrimination
between lakes of different water quality. The ecoregion classification should also be more effective better than a comparably
scaled classification based on political boundaries, land-use class, or random grouping. To test this hypothesis we used the
Environmental Monitoring and Assessment Program (EMAP) lake water chemistry data from the northeast United States. The water
chemistry data were reduced to four components using principal component analysis. For comparison to an optimal grouping of
these data we used K-means cluster analysis to define the extent at which these lakes could be segregated into distinct classes.
Jackknifed discriminant analysis was used to determine the classification rate of ecoregions, the three alternative spatial
classification methods, and the clustering algorithm. The classification based on ecoregions was successful for 35% of the
lakes included in this study, in comparison to the clustered groups accuracy of 98%. These results suggest that the large
scale spatial distribution of ecosystem types is more complicated than that suggested by the present ecoregion boundaries.
Further tests of ecoregion delineations are needed and alternative large-scale management strategies should be investigated. 相似文献
637.
We simulated the long range transport of dust emitted from dust storms that occurred in China by using a global three-dimensional chemical transport model. A modified dust emission flux scheme and a nonlocal diffusion scheme for determining the atmospheric eddy diffusivity in the atmospheric boundary layer were implemented to improve the chemical transport model. We examined the dust transport by comparing the model results with TOMS satellite images. The model calculated monthly total deposition of dust masses were used for comparison with the measurements collected at sampling stations in Japan, and good agreement was found. The model generally reproduced the temporal and spatial variations of dust reasonably well. 相似文献
638.
Chantal C Guénette Gary A Sergy Edward H Owens Roger C Prince Kenneth Lee 《Spill Science & Technology Bulletin》2003,8(3):245-256
Experimental oil spills on three mixed-sediment beaches in Svalbard, Norway, were designed to evaluate the effectiveness of in situ shoreline cleaning treatments to accelerate natural recovery. These were: sediment relocation (surf washing), mixing (tilling), bioremediation (fertilizer application), and bioremediation combined with mixing. Additionally, natural attenuation was studied as a treatment option. An intermediate fuel oil was applied to the sediment surface in the upper intertidal zone at three experimental sites, each of which had different sediment characteristics and wave-energy exposure. Over a 400-day period, the experiments quantified oil removal, documented changes in the physical character of the beach as well as oil fate and behaviour, assessed toxicity effects associated with treatment, and validated oil-mineral aggregate formation as a result of the selected treatment techniques. The three sites were chosen based on significant differences, and each treatment was quantitatively compared only with other treatments at that site.This paper describes the physical location and the experimental design of the field trials. Some of the key issues that were addressed in the design included: the methodology for application of oil, the application of treatment techniques, the realistic simulation of real-world conditions, and the sampling protocols to overcome sediment and oiling heterogeneity typical of mixed-sediment beaches in order to allow quantitative comparisons of the treatments. 相似文献
639.
Gary A Sergy Chantal C Guénette Edward H Owens Roger C Prince Kenneth Lee 《Spill Science & Technology Bulletin》2003,8(3):237-244
Experimental oil spill studies were conducted to quantify the effectiveness of selected in-situ shoreline treatment options to accelerate natural oil removal processes on mixed-sediment (sand and pebble) shorelines. At each of three distinct shoreline sites, treatment test plots and control plots were established within a 40-, 80- and 143-m continuous stretch of oiled shoreline. A total of 5500 l of oil was deposited along a 3-m wide swath in the upper intertidal zone at each site. Approximately one week after oiling, a different treatment technique was applied to each plot. The treatment techniques were: sediment relocation (surf washing), mixing (tilling), bioremediation (fertilizer application), and bioremediation combined with mixing. One plot at each site was monitored for natural attenuation. The quantity of oil removed from the plots was measured six times up to 60 days post-treatment and then again one year later. Changes in the physical character of the beach, oil penetration, movement of oil to the subtidal environment, toxicity, and biodegradation were monitored over the 400-day period.The results verified quantitatively that relocation of oiled sediments significantly accelerated the rate of oil removal from the shoreline by more than one year. Microscopic observations and image analyses confirmed that the oil-mineral aggregate formation process was active and was increased by sediment relocation. Oil biodegradation occurred in this arctic environment, both in the oiled sediments and on the fine mineral particles removed from the sediment by natural physical processes. The biodegradation of oil in sediment was significantly stimulated by simple bioremediation protocols. Mixing (by tilling) did not clearly stimulate oil loss and natural recovery in the context of this experimental design. None of the treatment techniques elevated toxicity in the nearshore environment to unacceptable levels, nor did they result in consequential alongshore or nearshore oiling. 相似文献
640.