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21.
Summary Tandem leaders of Pachycondyla tesserinoda mark their way during nest moving. While scouting and foraging for food in an unknown area, chemical orientation is used as well. The origin of the trail substance could not be identified. Secretions of gastral exocrine glands did not induce trail following behavior. Nor do these secretions elicit tandem-following reactions; rather the latter is released by the general body surface odor. The trail substance and the substance used for marking the nest entrance are colony-specific. Moreover, individual tandem leaders recognize and show a preference for their own trails. This extraordinary effect is independent of the age of the trail. P. tesserinoda workers search individually for food and new nest sites. Targets which are important for the colony are directly shown to nestmates by tandem running. Due to this type of foraging and scouting individual-specific trails may be advantageous for this ant. 相似文献
22.
Oswald van Cleemput Annick Vermoesen Cornelis-Jan de Groot Karla van Ryckeghem 《Environmental monitoring and assessment》1994,31(1-2):145-152
Grazed grassland which received 295 kg ha–1 N-fertilizer (NH4NO3), split-applied, was used to measure nitrous oxide emission. The closed box method was used. At the same time, also soil cores were taken for incubation in the presence of acetylene. During 280 days in 1992, a total emission of 8.4 kg N2O-N ha–1 was found. This was close to 50 % of the total denitrification, which was 18.7 kg (N2O+N2)-N ha–1 over 280 days. A variability study on N2O emission was carried out on a surface of 1, 100 and 10,000 m2, respectively. This study confirmed the lognormal distribution of data with variation coefficients of 20 to 25%. It was also found that the effect of application of 200 kg KNO3-N on N2O emission was limited to 2 weeks upon fertilization. It more than doubled the emission rate during this period. 相似文献
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24.
Reginatto Cleomar Cecchin Iziquiel Salvagni Heineck Karla Thomé Antonio Reddy Krishna R. 《Environmental science and pollution research international》2020,27(9):9288-9296
Environmental Science and Pollution Research - Contaminated clay soils pose problems to public health and the environment in several parts of the world. Very little is known about the transport of... 相似文献
25.
Pablo Higueras Roberto Oyarzun Joze Kotnik José María Esbrí Alba Martínez-Coronado Milena Horvat Miguel Angel López-Berdonces Willians Llanos Orlando Vaselli Barbara Nisi Nikolay Mashyanov Vladimir Ryzov Zdravko Spiric Nikolay Panichev Rob McCrindle Xinbin Feng Xuewu Fu Javier Lillo Jorge Loredo María Eugenia García Pura Alfonso Karla Villegas Silvia Palacios Jorge Oyarzún Hugo Maturana Felicia Contreras Melitón Adams Sergio Ribeiro-Guevara Luise Felipe Niecenski Salvatore Giammanco Jasna Huremović 《Environmental geochemistry and health》2014,36(4):713-734
Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, \( {\text{Hg}}_{\text{gas}}^{0} \) ), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration of atmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m?3, that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m?3) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m?3. We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au–Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical–chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans. 相似文献
26.
Sedeño-Díaz Jacinto Elías López-López Eugenia Rodríguez-Romero A. Joseph Leos Karla Fierro Martínez Melissa Tiburcio Sánchez Oscar Emiliano Escobar 《Environmental science and pollution research international》2022,29(41):61630-61642
Environmental Science and Pollution Research - Qanats in the aquifer of the Tehuacán Valley (Mexico) represent an ancient way of using groundwater that is still practiced today. They are used... 相似文献
27.
Klinčić Darija Dvoršćak Marija Jagić Karla Mendaš Gordana Herceg Romanić Snježana 《Environmental science and pollution research international》2020,27(6):5744-5758
Environmental Science and Pollution Research - Polybrominated diphenyl ethers (PBDEs) are a class of brominated flame retardants (BFRs), present in the environment, animals, and humans. Their... 相似文献
28.
Mendoza G Gutierrez L Pozo-Gallardo K Fuentes-Rios D Montory M Urrutia R Barra R 《Environmental science and pollution research international》2006,13(1):67-74
- DOI: http://dx.doi.org/10.1065/espr2006.01.011
Goal, Scope and Background Chile signed the Stockholm Convention, which establishes measures to reduce or eliminate Persistent Organic Pollutants (POPs)
release into the environment, including the prohibition of their use and reduction of secondary products release, as well
as management related with waste treatment. Among POPs, PCBs are a family of 209 compounds that differ in chlorine level and
position. These substances present a wide variability in their physicochemical properties such as vapor pressure, water solubility
and partition coefficients that determine their behavior and mobility within the different environmental compartments. In
Chile, as in other countries, the use of these compounds were and continue to occur in diverse industrial applications such
as dielectric fluid in transformers and condensers, with a use in Chile of approximately 550,000 L. A sampling of bivalves
was performed during the years 2000-2002 in order to obtain information on the spatial distribution of the PCB levels for
the length of the long Chilean coast (180–540 South latitude, 4,200 km), contributing in this way to a better understanding
of the PCB trend and eventual fractionation along latitudinal gradients in Chile, using as the bivalve Perumytilus purpuratus
('Chorito Maico') bioindicator.
Methods The marine bivalves Perumytilus purpuratus were collected in 16 localities in northern and southern Chile. All samples were
lyophilized, and PCBs (51 congeners) were extracted in a Soxhlet system (24 h) with n-hexane. Samples were cleaned in florisil
and analyzed by GC-ECD. Blanks, certified reference materials and standards were processed along with the samples.
Results and Discussion The results obtained for P. purpuratus indicate a congeneric distribution profile associated to a latitudinal gradient, and
the statistical analysis of the congeneric composition of the PCBs indicated five groups in relation to the molecular weight
(number of chlorines), where the lighter congeners were observed in areas corresponding to high latitudes with total PCB values
of 298 ng/g dry weight.
Conclusion P. purpuratus turns out to be a good bioindicator of PCB levels in the coastal areas of Chile due to its wide distribution.
The highest concentrations and the more volatile congeners were found in southern Chile, which could be the result of processes
of long-range transport or illegal discharge occurring in such remote areas. These results confirm previous data from the
International Mussel Watch project ten years ago.
Recommendation and Outlook Future studies are needed to confirm our findings utilizing another environmental matrix such as soil/sediments and air samples. 相似文献
29.
Robert L. Beschta William L. Jackson Karla D. Knoop 《Journal of the American Water Resources Association》1981,17(4):635-641
The transport of bedload and suspended sediments and particulate organic matter was evaluated in Huntington Creek, Utah, during a controlled release of water from Electric Lake Reservoir from August 7–10, 1979. Effects of the release on channel geometry and riffle composition also were assessed. Bedload transport rates increased from zero to 1,650 and 1,500 kg/hr at two cross sections as discharge was increased from 0.4 to 4.9 m3/s; transport rates then decreased erratically as discharge was held constant. Cross section measurements and sediment size analysis indicate that flows were insufficient to transport riffle sediments. Rapid increases in the transport rates of suspended sediments and particulate organic matter also occurred during rising discharge and again decayed when discharge became constant. Suspended sediment concentrations for samples obtained with an automatic pumping sampler were generally less than those found for samples obtained with a DH-48 sampler. Biological measurements still are needed to determine if such a release can improve fisheries habitat by removing fine sediments. 相似文献
30.
Roger Popper Karla Andino Mario Bustamante Beatriz Hernandez Luis Rodas 《Environmental management》1996,20(2):241-248
Throughout Central America, the United States Agency for International Development (USAID), and the Zamorano Pan-American Agricultural School support a Safe Pesticide Use program. In 1993, a study of results was carried out among farmers and housewives in eastern Guatemala. Aspects of the methodology included: (1) participation of extension workers in all aspects of the study; (2) small, region-focused samples (eight cells, 30 interviews per cell); (3) comparison to control groups of untrained farmers and housewives; (4) a traditional questionnaire for studying acquisition of specific knowledge; and (5) a flexible instrument for building a cognitive map of knowledge and beliefs regarding pesticides. The cognitive map is a step toward applying modern psychocultural scaling, an approach already well developed for medicine and public health, to environmental problems. Positive results detected include progress at learning the meaning of colors on containers that denote toxicity and where to store pesticides. Pesticide application problems detected were mention by farmers of highly toxic, restricted pesticides as appropriate for most pest problems and of insecticides as the correct solution to fungus problems, and the widespread belief that correct pesticide dosage depends on number of pests seen rather than on land or foliage surface. Health-related problems detected were admission by a vast majority of housewives that they apply highly toxic pesticides to combat children's head-lice; low awareness that pesticides cause health problems more serious than nausea, dizziness, and headaches; and a common belief that lemonade and coffee are effective medicines for pesticide poisoning. 相似文献