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111.
Etienne Paul Delmira Beatriz Wolff Juan Carlos Ochoa Rejane Helena Ribeiro da Costa 《Water environment research》2007,79(7):765-774
The reduction of organic and nitrogen pollution of wastewater was investigated in two hybrid reactors and compared with the reduction obtained by using a conventional activated sludge reactor (ASR) run as a control. Both HR-1 and HR-2 were activated sludge systems where a low-density carrier, P1 (polyethylene) for HR-1 and P2 (recycled plastics) for HR-2, was added. Firstly, the three reactors were operated at 10 days Suspended Solid Retention Time (SRT(SS)), leading to a complete nitrification. Secondly, the SRT(SS) for each reactor was lowered to 3 days. Nitrification was lost for the ASR but remained complete for HR's. Respirometric techniques were used to measure fixed or suspended biomass activities for heterotrophic and autotrophic biomass. More than 90% of the autotrophic activity was found on the supports whatever the SRT(SS) used. The results may underline the role of the carrier geometry or surface characteristics on the autotrophic/heterotrophic microorganism distribution. 相似文献
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Soil organic matter (SOM) content was determined in two populations of soil samples that were taken from 0–2 soil depth. One population represented soil samples that were takenfrom a square of 25 cm2 in size (small-S population) and the other population represented soil samples that were taken from a square of 2500 cm2 in size (large-L population). Thesamples were collected on hillslopes in different climatic regions: Mediterranean (GIV), semi-arid (MAL), mildly-arid (MIS) and arid (KAL). The results of both S and L populationsshowed decreasing SOM mean and variance from the Mediterranean site to the arid site. Statistical and spatial characteristics of each population were compared between the climatic regions. In addition, comparison between the two populations was made foreach site. The difference in sample size did not significantly affect the mean values of SOM of the two populations in sitesGIV, MAL and KAL, but did affect the mean at site MIS. At all study sites, except for site MAL, the variance increased with decreasing sample size. At sites GIV and KAL the coefficient ofvariation of S population was higher (more than 1.5 times) thanthat of L population, whereas at sites MAL and MIS, the differences were negligible. The relationships between the valuesof S and L samples at the individual sampling points defined thebackground of the study sites, which reflects the effect of vegetation (type), grazing, biological crust and soil properties.It was found that at the extreme sites GIV and KAL the backgroundwas characterized by relatively low SOM content with small areas of high organic matter content. At site MIS the background wascharacterized by relatively high SOM with small areas of low organic matter content. At site MAL the background was not dominated by high values of SOM nor by low ones. The spatial pattern of L population became more simple with increasing aridity. At the relatively wet sites the spatial pattern did notdepend on the sample size while in the more arid sites it was sample size dependent. It was indicated that the spatial structure of SOM at the semi-arid and mildly arid sites is anisotropic whereas at the Mediterranean and arid sites it is isotropic. 相似文献
114.
Air concentrations and urinary metabolites of polycyclic aromatic hydrocarbons among paving and remixing workers 总被引:1,自引:0,他引:1
Väänänen V Hämeilä M Kontsas H Peltonen K Heikkilä P 《Journal of environmental monitoring : JEM》2003,5(5):739-746
The exposure of paving workers to polycyclic aromatic hydrocarbons (PAH) during stone mastic asphalt (SMA) paving and remixing was evaluated. The effects on the workers' PAH exposure were also evaluated during the use of an industrial by-product, coal fly ash (CFA), instead of limestone as the filler in the SMA. The PAH exposure was measured by personal air sampling and by analysing the levels of urinary naphthols, phenanthrols and 1-hydroxypyrene (1-OHP) in the workers' pre- and post-shift urine samples. The respiratory PAH exposure of the paving workers (geometric mean (GM) 5.7 microg m(-3)) was about ten-fold that of the traffic controllers (GM 0.43 microg m(-3)). The levels of PAH metabolites were significantly higher (p < 0.05) in the post-shift urine samples than in the pre-shift urine samples, and the levels of metabolites in the post-shift urine of paving workers were significantly higher than in that of the controls (p < 0.01). Urinary 1-naphthol correlated well with the airborne concentrations of the two- to three-ring PAHs (r = 0.544, p = 0.003) and naphthalene (r = 0.655, p < 0.001), when non-smoking paving workers were tested. A good correlation was observed between urinary 1-OHP and the airborne concentrations of the four- to six-ring PAHs (r = 0.524, p = 0.003) as well as total PAHs (r = 0.575, p = 0.001). The concentrations of 1-OHP and phenanthrols in the urine of the pavers were significantly higher (p < 0.01) during remixing than during SMA paving. The CFA in the asphalt had no effect on the airborne PAH exposure or on the concentrations of the PAH metabolites in the paving workers' urine. 相似文献
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116.
Lisa Dahlén Helena Åberg Anders Lagerkvist Per E.O. Berg 《Waste management (New York, N.Y.)》2009,29(6):1798-1806
The aim of this study was to provide policy-makers and waste management planners with information about how recycling programs affect the quantities of specific materials recycled and disposed of. Two questions were addressed: which factors influence household waste generation and pathways? and how reliable are official waste data? Household waste flows were studied in 35 Swedish municipalities, and a wide variation in the amount of waste per capita was observed. When evaluating the effect of different waste collection policies, it was found to be important to identify site-specific factors influencing waste generation. Eleven municipal variables were investigated in an attempt to explain the variation. The amount of household waste per resident was higher in populous municipalities and when net commuting was positive. Property-close collection of dry recyclables led to increased delivery of sorted metal, plastic and paper packaging. No difference was seen in the amount of separated recyclables per capita when weight-based billing for the collection of residual waste was applied, but the amount of residual waste was lower. Sixteen sources of error in official waste statistics were identified and the results of the study emphasize the importance of reliable waste generation and composition data to underpin waste management policies. 相似文献
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118.
Spontaneous vegetation succession at different central European mining sites: a comparison across seres 总被引:2,自引:0,他引:2
Karel Prach Kamila Lencová Klára Řehounková Helena Dvořáková Alena Jírová Petra Konvalinková Ondřej Mudrák Jan Novák Romana Trnková 《Environmental science and pollution research international》2013,20(11):7680-7685
We performed detrended correspondence analysis (DCA) ordination to compare seven successional seres running in stone quarries, coal mining spoil heaps, sand and gravel pits, and extracted peatlands in the Czech Republic in central Europe. In total, we obtained 1,187 vegetation samples containing 705 species. These represent various successional stages aged from 1 to 100 years. The successional seres studied were more similar in their species composition in the initial stages, in which synathropic species prevailed, than in later successional stages. This vegetation differentiation was determined especially by local moisture conditions. In most cases, succession led to a woodland, which usually established after approximately 20 years. In very dry or wet places, by contrast, where woody species were limited, often highly valuable, open vegetation developed. Except in the peatlands, the total number of species and the number of target species increased during succession. Participation of invasive aliens was mostly unimportant. Spontaneous vegetation succession generally appears to be an ecologically suitable and cheap way of ecosystem restoration of heavily disturbed sites. It should, therefore, be preferred over technical reclamation. 相似文献
119.
Helena Siipi 《Journal of Agricultural and Environmental Ethics》2013,26(4):797-812
Is food’s naturalness conceptually connected to its healthiness? Answering the question requires spelling out the following: (1) What is meant by the healthiness of food? (2) What different conceptual meanings the term natural has in the context of food? (3) Are some of those meanings connected to the healthiness of food? In this paper the healthiness of food is understood narrowly as food’s accordance with nutritional needs of its eater. The connection of healthiness to the following five food-related senses of the term “natural’’ is analyzed: naturalness as nutritive suitability, naturalness as moderate need satisfaction, naturalness as lack of human influence, naturalness as authenticity, and naturalness as familiarity. It is concluded that some very common current uses of the term “natural,” such as naturalness as lack of human influence, are not conceptually connected to the healthiness of food. Nevertheless, the first two senses of naturalness are strongly conceptually connected to healthiness in the food context and the last one may be indirectly related to it. Thus, desire for natural food is not necessarily mistaken and misguided. 相似文献
120.
Owusu-Sekyere Enoch Abdulai Awudu Jordaan Henry Hansson Helena 《Environmental Economics and Policy Studies》2020,22(1):39-64
Environmental Economics and Policy Studies - There is an urgent need for the development of environmentally sustainable products market in developing economies, particularly in South Africa due to... 相似文献