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961.
Shikha Raghuwanshi M. G. H. Zaidi Saurabh Kumar Reeta Goel 《Journal of Polymers and the Environment》2018,26(7):2661-2675
The global demand of bioplastics has lead to an exponential increase in their production commercially. Hence, biodegradable nature needs to be evaluated in various ecosystems viz. air, water, soil and other environmental conditions to avoid the polymeric waste accumulation in the nature. In this paper, we investigated the progressive response of two indigenously developed bacterial consortia, i.e., consortium-I (C-I: Pseudomonas sp. strain Rb10, Pseudomonas sp. strain Rb11 and Bacillus sp. strain Rb18), and consortium-II (C-II: Lysinibacillus sp. strain Rb1, Pseudomonas sp. strain Rb13 and Pseudomonas sp. strain Rb19), against biodegradation behavior of polyhydroxybutyrate (PHB) film composites, under natural soil ecosystem (in net house). The biodegraded films recovered after 6 and 9 months of incubation were analyzed through Fourier transform infrared spectroscopy and scanning electron microscopy to determine the variations in chemical and morphological parameters (before and after incubation). Noticeable changes in the bond intensity, surface morphology and conductivity were found when PHB composites were treated with C-II. These changes were drastic in case of blends in comparison to copolymer. The potential isolates not only survived, but, also, there was a significant increase in bacterial diversity during whole period of incubation. To the best of our knowledge, it is the first report which described the biodegradation potential of Lysinibacillus sp. as a part of C-II with Pseudomonas sp. against PHB film composites. 相似文献
962.
Silvina Vargas Gil Analia Becker Claudio Oddino Mónica Zuza Adriana Marinelli Guillermo March 《Environmental management》2009,44(2):378-386
Soil microbial populations can fluctuate in response to environmental changes and, therefore, are often used as biological
indicators of soil quality. Soil chemical and physical parameters can also be used as indicators because they can vary in
response to different management strategies. A long-term field trial was conducted to study the effects of different tillage
systems (NT: no tillage, DH: disc harrow, and MP: moldboard plough), P fertilization (diammonium phosphate), and cattle grazing
(in terms of crop residue consumption) in maize (Zea mays L.), sunflower (Heliantus annuus L.), and soybean (Glycine max L.) on soil biological, chemical, and physical parameters. The field trial was conducted for four crop years (2000/2001,
2001/2002, 2002/2003, and 2003/2004). Soil populations of Actinomycetes, Trichoderma spp., and Gliocladium spp. were 49% higher under conservation tillage systems, in soil amended with diammonium phosphate (DAP) and not previously
grazed. Management practices also influenced soil chemical parameters, especially organic matter content and total N, which
were 10% and 55% higher under NT than under MP. Aggregate stability was 61% higher in NT than in MP, 15% higher in P-fertilized
soil, and also 9% higher in not grazed strips, bulk density being 12% lower in NT systems compared with MP. DAP application
and the absence of grazing also reduced bulk density (3%). Using conservation tillage systems, fertilizing crops with DAP,
and avoiding grazing contribute to soil health preservation and enhanced crop production. 相似文献
963.
Policy and research issues in the framing and qualities of uncertainties in risks are analyzed, based on the assessments of
dioxin-like compounds (DLCs) and other ingredients in Baltic Sea fish, a high-profile case of governance. Risks are framed
broadly, to then focus on dioxins and beneficial fatty acids, fish consumption, human health, and science-management links.
Hierarchies of uncertainty (data, model, decision rule, and epistemic) and ambiguity (of values) are used to identify issues
of scientific and policy contestation and opportunities for resolving them. The associated complexity of risks is illustrated
by risk–benefit analyses of fish consumption and by evaluations of guideline values, highlighting value contents and policy
factors in presumably scientific decision criteria, and arguments used in multi-dimensional risk and benefit comparisons.
These comparisons pose challenges to narrow assessments centered, for e.g., on toxicants or on food benefits, and to more
many-sided and balanced risk communication and management. It is shown that structured and contextualized treatment of uncertainties
and ambiguities in a reflexive approach can inform balances between wide and narrow focus, detail and generality, and evidence
and precaution. 相似文献
964.
Globally, urban growth will add 1.5 billion people to cities by 2030, making the difficult task of urban water provisions
even more challenging. In this article, we develop a conceptual framework of urban water provision as composed of three axes:
water availability, water quality, and water delivery. For each axis, we calculate quantitative proxy measures for all cities
with more than 50,000 residents, and then briefly discuss the strategies cities are using in response if they are deficient
on one of the axes. We show that 523 million people are in cities where water availability may be an issue, 890 million people
are in cities where water quality may be an issue, and 1.3 billion people are in cities where water delivery may be an issue.
Tapping into groundwater is a widespread response, regardless of the management challenge, with many cities unsustainably
using this resource. The strategies used by cities deficient on the water delivery axis are different than for cities deficient
on the water quantity or water quality axis, as lack of financial resources pushes cities toward a different and potentially
less effective set of strategies. 相似文献
965.
Characteristics of aerosol types during large-scale transport of air pollution over the Yellow Sea region and at Cheongwon,Korea, in 2008 总被引:1,自引:0,他引:1
Episodes of large-scale transport of airborne dust and anthropogenic pollutant particles from different sources in the East
Asian continent in 2008 were identified by National Oceanic and Atmospheric Administration satellite RGB (red, green, and
blue)-composite images and the mass concentrations of ground level particulate matter. These particles were divided into dust,
sea salt, smoke plume, and sulfate by an aerosol classification algorithm. To analyze the aerosol size distribution during
large-scale transport of atmospheric aerosols, aerosol optical depth (AOD) and fine aerosol weighting (FW) of moderate imaging
spectroradiometer aerosol products were used over the East Asian region. Six episodes of massive airborne dust particles,
originating from sandstorms in northern China, Mongolia, and the Loess Plateau of China, were observed at Cheongwon. Classified
dust aerosol types were distributed on a large-scale over the Yellow Sea region. The average PM10 and PM2.5 ratio to the total
mass concentration TSP were 70% and 15%, respectively. However, the mass concentration of PM2.5 among TSP increased to as
high as 23% in an episode where dust traveled in by way of an industrial area in eastern China. In the other five episodes
of anthropogenic pollutant particles that flowed into the Korean Peninsula from eastern China, the anthropogenic pollutant
particles were largely detected in the form of smoke over the Yellow Sea region. The average PM10 and PM2.5 ratios to TSP
were 82% and 65%, respectively. The ratio of PM2.5 mass concentrations among TSP varied significantly depending on the origin
and pathway of the airborne dust particles. The average AOD for the large-scale transport of anthropogenic pollutant particles
in the East Asian region was measured to be 0.42 ± 0.17, which is higher in terms of the rate against atmospheric aerosols
as compared with the AOD (0.36 ± 0.13) for airborne dust particles with sandstorms. In particular, the region ranging from
eastern China, the Yellow Sea, and the Korean Peninsula to the Korea East Sea was characterized by high AOD distributions.
In the episode of anthropogenic polluted aerosols, FW averaged 0.63 ± 0.16, a value higher than that in the episode of airborne
dust particles (0.52 ± 0.13) with sandstorms, showing that fine anthropogenic pollutant particles contribute greatly to atmospheric
aerosols in East Asia. 相似文献
966.
Radon ((222)Rn) is a carcinogenic gas produced by the radioactive decay of radium ((226)Ra). It has been reported that soil and soil-gas are primary factors that could cause indoor radon problems. Six sites were selected for this study--Sanbook, Gangcheon, Jikyeong, Choojung, Geumsung and Homyoung--each was classified according to bedrock type. In order to investigate soil-gas radon activities and radon emanating power, innovated active and passive detecting methods were developed and applied under both field and laboratory conditions. Statistical analysis of results confirmed that the radon activity values measured using either active or passive methods under field or laboratory conditions could be interchangeable with each other. 相似文献
967.
968.
Nikolay A. Vinnichenko Yulia Yu. Plaksina Ksenia M. Baranova Alexey V. Pushtaev Alexander V. Uvarov 《Environmental Fluid Mechanics》2018,18(5):1045-1056
Dynamics of the surface layer in different liquids is examined by means of infrared thermography of the surface and simultaneous velocity fields measurements using surface and infrared Particle Image Velocimetry. This technique allows measurements and comparison of two velocity fields—at the surface and at small depth about 50–200 μm. In distilled water the velocity fields at the surface and at small depth exhibit significant dissimilarity. The flow field below the surface is essentially 3D, whereas the surface flow is characterized by vanishing 2D divergence of velocity, indicating predominantly planar motion. In contrast, in ethanol–butanol mixture two velocity fields are well correlated, both corresponding to 3D flow with continuous surface renewal. Thermal patterns, observed at the surface, and the flow field structure in different liquids are associated with different boundary conditions for velocity at the surface. Water surface is seldom renewed, which inhibits heat and mass exchange between the liquid and atmosphere. However, absence of vertical advection also enables organisms to live within the surface layer, to stand and walk on the free surface. This is illustrated by the difficulties a water strider faces on the surface of ultrapure water, which exhibits Marangoni convection. 相似文献
969.
Stone ML Whiles MR Webber JA Williard KW Reeve JD 《Journal of environmental quality》2005,34(3):907-917
Relationships between riparian land cover, in-stream habitat, water chemistry, and macroinvertebrates were examined in headwater streams draining an agricultural region of Illinois. Macroinvertebrates and organic matter were collected monthly for one year from three intensively monitored streams with a gradient of riparian forest cover (6, 22, and 31% of riparian area). Bioassessments and physical habitat analyses were also performed in these three streams and 12 other nearby headwater streams. The intensively monitored site with the least riparian forest cover had significantly greater percent silt substrates than the sites with medium and high forest cover, and significantly higher very fine organics in substrates than the medium and high forested sites. Macroinvertebrates were abundant in all streams, but communities reflected degraded conditions; noninsect groups, mostly oligochaetes and copepods, dominated density and oligochaetes and mollusks, mostly Sphaerium and Physella, dominated biomass. Of insects, dipterans, mostly Chironomidae, dominated density and dipterans and coleopterans were important contributors to biomass. Collector-gatherers dominated functional structure in all three intensively monitored sites, indicating that functional structure metrics may not be appropriate for assessing these systems. The intensively monitored site with lowest riparian forest cover had significantly greater macroinvertebrate density and biomass, but lowest insect density and biomass. Density and biomass of active collector-filterers (mostly Sphaerium) decreased with increasing riparian forest. Hilsenhoff scores from all 15 sites were significantly correlated with in-stream habitat scores, percent riparian forest, and orthophosphate concentrations, and multiple regression indicated that in-stream habitat was the primary factor influencing biotic integrity. Our results show that these "drainage ditches" harbor abundant macroinvertebrates that are typical of degraded conditions, but that they can reflect gradients of conditions in and around these streams. 相似文献
970.
Pambrun V Marquot A Racault Y 《Environmental science and pollution research international》2008,15(7):592-599
Background, aims, and scope Sometimes, urban wastewaters convey a more or less significant part of toxic products from industries or the craft industry.
Nitrifying activity can be affected by these substances, implying higher ammonia concentrations in the outlet effluent and
contributing to toxicity for the aquatic environment. Moreover, the more stringently treated wastewater standards now require
a reliable treatment for nitrogen. One of the key issues is the identification of the inhibition behavior of nitrifying bacteria
facing a toxic substance. This new understanding could then finally be integrated into models in order to represent and to
optimize wastewater treatment plants (WWTP) operation in cases involving ‘toxic scenarios’.
Materials and methods The toxic substances studied in this work, cadmium and 3.5-dichlorophenol (3.5-DCP), are representative of chemical substances
commonly found in municipal sewage and industrial effluents and symbolize two different contaminant groups. The effects of
Cd and 3.5-DCP on nitrification kinetics have been investigated using respirometry techniques.
Results IC50 values determination gives concentrations of 3.1 mg/L for 3.5-DCP and 45.8 mg/L for Cd at 21 ± 1°C. The variation to
low temperature seems to have no real effect on IC50 for DCP, but induces a decrease of cadmium IC50 to 27.5 mg/L at 14°C.
Finally, specific respirometric tests have been carried out in order to determine the potential effect of these toxic substances
on the nitrifying decay rate b
a
. No significant effect has been noticed for Cd, whereas the presence of 3.5-DCP (at IC50 concentration) induced a dramatic
increase of b
a
at 20°C. The same behavior has been confirmed by experiments performed in winter periods with a sludge temperature around
12°C.
Discussion The target substances have different modes of action on activity and mortality, notably due to the abilities of the contaminant
to be precipitated, accumulated, or even to be progressively degraded. Studies realized at low temperature confirmed this
assumption, and put in evidence the effect of temperature on toxic substances capable of being biosorbed. However, the change
in the sludge sample characteristics can be pointed out as a problem in the investigation of the temperature effect on nitrification
inhibition, as biosorption, bioaccumulation, and predation are directly linked to the sludge characteristics (VSS concentration,
temperature) and the plant operating conditions (loading rates, sludge age, etc.).
Conclusions This work brings new understandings concerning the action mode of these specific contaminants on nitrifying bacteria and,
in particular, on the role of temperature. The experiments lead to the determination of the IC50 values for both toxic substances
on biological nitrification. The inhibition mechanisms of Cd and 3.5-DCP on nitrifying activity have been simply represented
by a non-competitive inhibition model.
Recommendations and perspectives Other experiments carried out in a continuous lab-scale pilot plant should be done with a proper control of the operating
conditions and of the sludge characteristics in order to better understand the mechanisms of nitrification inhibition for
each contaminant. Finally, these first results show that toxic substances can have an effect on the growth rate but also on
the decay rate, depending on the characteristics of the toxic substance and the sludge. This eventual double effect would
imply different strategies of WWTP operation according to the behavior of the contaminant on the bacteria. 相似文献