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Henning S. Jensen Tina Bendixen Frede Ø. Andersen 《Water, Air, & Soil Pollution: Focus》2006,6(5-6):547-555
Danish rivers carry >50% of the phosphorus (P) transport as particulate P (PP). In five of six rivers sampled in November
1998 iron-bound P made up > 59% of PP and loosely adsorbed P ranged between 2% and 13%. This fraction could potentially be
released in 14‰ seawater. The behaviour of dissolved and particulate P fractions was studied during seven month in a 2 km
long estuary with low freshwater retention time and low tidal range. The river carried ∼10% of PP as loosely adsorbed P but
increased concentrations of dissolved inorganic P (DIP) relative to the estuarine mixing line was only observed in the summer
month with low freshwater flow and was more likely due to DIP release from the bottom sediment. Instead estuarine particles
were always enriched with oxidized iron (ox.Fe) and iron-bound P as well as loosely adsorbed P and during May–September this
coincided with increasing concentration of PP in estuary. We suggest that flocculation of ox.Fe and adsorption of DIP onto
the particles with subsequent transport seawards is a major loss process for P during the summer month. During winter month
where 85% of the run-off occurs the dominant process in the estuary is sedimentation of larger particles, however, a comparison
of river particles with surface sediment clearly reveals that most PP is mobilized again from the bottom sediments. 相似文献
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The general perceptions of prescribed burning were elicited from forest users for an area that has been subject to this form
of land management for at least 20 years. The largest group consisted of local residents living in and around the Wombat State
Forest with two smaller groups of students from a nearby university campus and local professional land managers. A questionnaire
was given to each participant in order to explore how the forest was used, to determine the level of knowledge of burning
in the targeted forest and Victoria and the perception of the appearance, effectiveness of protection, and accessibility to
the forest after prescribed burning. Generally all groups had similar responses with community members having stronger views
on the effectiveness and practicalities of prescribed burning, whereas students were more neutral in their opinions. All participants
claimed knowledge of prescribed burning activities within Victoria, but fewer had experience of planned fires in the Wombat
State Forest. All groups agreed that areas that had not been recently burned had a better appearance than those that had,
but this result may have included a range of value judgments. Land managers had a greater understanding of the ecological
importance of season and timing of burning; however, some students and community members were equally knowledgeable. Prescribed
burning did not impede access to the forest, nor did smoke from prescribed burns pose any great problem. The majority of the
participants felt that the amount of prescribed burning done in the forest was adequate for engendering a feeling of protection
to life and property, yet many were still suspicious of this management practice. These initial findings indicate several
areas in which further research would be useful including the efficacy of education programs for community members and improved
communication of burn plans by land managers. 相似文献
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Heather Reese Mats Nilsson Tina Granqvist Pahln Olle Hagner Steve Joyce Ulf Tingelf Mikael Egberth Hkan Olsson 《Ambio-人类环境杂志》2003,32(8):539-545
瑞典约有55%的土地面积被森林所覆盖.目前,瑞典的森林覆盖没有统一的和地理学上明晰的描述.现存的独立性数据源是Landsat TM和SPOT HRV卫星数据、地图蒙片(map mask)和森林清查样地.它们在一起,使森林变量(如材枳和林分年龄)的计算机估计成为可能.这些估计的精确度在像素水平上是低的,但在林分水平上较高.在规划木材资源应如何加以利用或出于监测目的时,这类基于栅格的森林数据对政府来说是有帮助的.本文描述了以有效成本建立森林变量估计全国数据库的生成流程.我们在林分水平上评价了瑞典西南部某地森林变量估计的精确度.结果表明,总材积估计的整体均方根误差为33%,年龄估计的整体均方根误差为23%. 相似文献
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Tina Elersek Sara Milavec Maša Korošec Polona Brezovsek Noelia Negreira Bozo Zonja Miren López de Alda Damià Barceló Ester Heath Janez Ščančar Metka Filipič 《Environmental science and pollution research international》2016,23(15):14780-14790
The residues of antineoplastic drugs are considered as new and emerging pollutants in aquatic environments. Recent experiments showed relatively high toxicity of 5-fluorouracil (5-FU), imatinib mesylate (IM), etoposide (ET) and cisplatin (CP) that are currently among most widely used antineoplastic drugs, against phytoplankton species. In this study, we investigated the toxic potential of the mixture of 5-FU?+?IM?+?ET against green alga Pseudokirchneriella subcapitata and cyanobacterium Synechococcus leopoliensis, and the stability and sorption of these drugs to algal cells. Toxic potential of the mixture was predicted by the concepts of ‘concentration addition’ and ‘independent action’ and compared to the experimentally determined toxicity. In both test species, the measured toxicity of the mixture was at effects concentrations EC10–EC50 higher than the predicted, whereas at higher effect concentration (EC90), it was lower. In general, P. subcapitata was more sensitive than S. leopoliensis. The stability studies of the tested drugs during the experiment showed that 5-FU, IM and CP are relatively stable, whereas in the cultures exposed to ET, two transformation products with the same mass as ET but different retention time were detected. The measurements of the cell-linked concentrations of the tested compounds after 72 h exposure indicated that except for CP (1.9 % of the initial concentration), these drugs are not adsorbed or absorbed by algal cells. The results of this study showed that in alga and cyanobacteria exposure to the mixture of 5-FU?+?ET?+?IM, in particular at low effect concentration range, caused additive or synergistic effect on growth inhibition, and they suggest that single compound toxicity data are not sufficient for the proper toxicity prediction for aquatic primary producers. 相似文献
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Daren Harmel Kevin Wagner Emily Martin Doug Smith Pauline Wanjugi Terry Gentry Lucas Gregory Tina Hendon 《Environmental monitoring and assessment》2016,188(3):170
Storm water runoff is increasingly assessed for fecal indicator organisms (e.g., Escherichia coli, E. coli) and its impact on contact recreation. Concurrently, use of autosamplers along with logistic, economic, technical, and personnel barriers is challenging conventional protocols for sample holding times and storage conditions in the field. A common holding time limit for E. coli is 8 h with a 10 °C storage temperature, but several research studies support longer hold time thresholds. The use of autosamplers to collect E. coli water samples has received little field research attention; thus, this study was implemented to compare refrigerated and unrefrigerated autosamplers and evaluate potential E. coli concentration differences due to field storage temperature (storms with holding times ≤24 h) and due to field storage time and temperature (storms >24 h). Data from 85 runoff events on four diverse watersheds showed that field storage times and temperatures had minor effects on mean and median E. coli concentrations. Graphs and error values did, however, indicate a weak tendency for higher concentrations in the refrigerated samplers, but it is unknown to what extent differing die-off and/or regrowth rates, heterogeneity in concentrations within samples, and laboratory analysis uncertainty contributed to the results. The minimal differences in measured E. coli concentrations cast doubt on the need for utilizing the rigid conventional protocols for field holding time and storage temperature. This is not to say that proper quality assurance and quality control is not important but to emphasize the need to consider the balance between data quality and practical constraints related to logistics, funding, travel time, and autosampler use in storm water studies. 相似文献
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Michael Van Loy Tina Bahadori Ron Wyzga Ben Hartsell Eric Edgerton 《Journal of the Air & Waste Management Association (1995)》2013,63(8):1446-1458
ABSTRACT The Aerosol Research and Inhalation Epidemiology Study (ARIES) was designed to provide high-quality measurements of PM25, its components, and co-varying pollutants for an air pollution epidemiology study in Atlanta, GA. Air pollution epidemiology studies have typically relied on available data on particle mass often collected using filter-based methods. Filter-based PM2.5 sampling is susceptible to both positive and negative errors in the measurement of aerosol mass and particle-phase component concentrations in the undisturbed atmosphere. These biases are introduced by collection of gas-phase aerosol components on the filter media or by volatilization of particle phase components from collected particles. As part of the ARIES, we collected daily 24-hr PM2.5 mass and speciation samples and continuous PM2.5 data at a mixed residential-light industrial site in Atlanta. These data facilitate analysis of the effects of a wide variety of factors on sampler performance. We assess the relative importance of PM2.5 components and consider associations and potential mechanistic linkages of PM2.5 mass concentrations with several PM2.5 components. For the 12 months of validated data collected to date (August 1, 1998-July 31, 1999), the monthly average Federal Reference Method (FRM) PM2 5 mass always exceeded the proposed annual average standard (12-month average = 20.3 ± 9.5 ug/m3). The particulate SO4 2- fraction (as (NH4)2SO4) was largest in the summer and exceeded 50% of the FRM mass. The contribution of (NH4)2SO4 to FRM PM2.5 mass dropped to less than 30% in winter. Particu-late NO3 - collected on a denuded nylon filter averaged 1.1 ± 0.9 ug/m3. Particle-phase organic compounds (as organic carbon × 1.4) measured on a denuded quartz filter sampler averaged 6.4 ± 3.1 ug/m3 (32% of FRM PM2 5 mass) with less seasonal variability than SO4 2-. 相似文献