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1.
Speciation and Seasonal Variations of Dissolved Inorganic Arsenic in Jiaozhou Bay,North China 总被引:1,自引:0,他引:1
J. L. Ren J. Zhang D. D. Li Y. Cheng S. M. Liu 《Water, Air, & Soil Pollution: Focus》2007,7(6):655-671
The distributions and biogeochemical cycles of arsenic in the aquatic environment have captured the interest of geochemists
due to arsenic’s multiple chemical forms, the toxicity of certain arsenic species and large anthropogenic input. Seasonal
variations in the dissolved inorganic arsenic concentration and speciation in Jiaozhou Bay, which is located on the west coast
of the Yellow Sea in northern China, are presented here. Three cruises were carried out in Jiaozhou Bay under varying tidal
regimes, one at neap tide and one at spring tide in August and one at spring tide in October of 2001. In addition to the transect
surveys, the main sources of dissolved inorganic arsenate and arsenite in Jiaozhou Bay, including riverine input from five
major tributary rivers, atmospheric dry and wet depositions, and groundwater and wastewater input, were collected in different
seasons to estimate arsenic transport through different sources. The mean concentrations of total dissolved inorganic arsenic
(TDIAs, As (V+III)) in Jiaozhou Bay were statistically comparable between summer and autumn, with higher concentrations at
the northwest and northeast parts of the bay, reflecting human activities. The As (III)/TDIAs ratio ranged between 0.045 and
0.68, with an average of 0.16, implying that arsenate was the dominating species in Jiaozhou Bay. A preliminary box model
was established to estimate the water-mass balance and arsenic budgets for Jiaozhou Bay, which demonstrated that river inputs
and atmospheric depositions were the main sources of arsenic into Jiaozhou Bay. The concentrations of dissolved inorganic
arsenic in Jiaozhou Bay have decreased in the last two decades. Compared with other areas in the world, the concentration
of arsenic in Jiaozhou Bay remains at the natural level and this region can be characterized as a less disturbed area. 相似文献
2.
J. Bai K. R. Li D. Y. Liu J. Zhang H. F. Zhang G. S. Liu J. L. Li Z. Y. Li D. M. Gao 《Water, Air, & Soil Pollution: Focus》2007,7(6):673-681
The distribution patterns and factors affecting uptake rates and turnover times of dissolved inorganic nutrients by heterotrophic
bacterioplankton (HB) in Jiaozhou Bay were studied based on in situ surveys and laboratory culturing. The uptake rates of
dissolved inorganic phosphorus (DIP) and dissolved inorganic nitrogen (DIN) by HB are limited by the temperature of the water
and the concentration of dissolved organic carbon. The turnover times of DIP and DIN by HB are regulated by the concentrations
of the nutrients and the numbers of HB, which show significant spatiotemporal variability in Jiaozhou Bay. HB may aggravate
the P-limitation of phytoplankton by competing for phosphorus in summer in Jiaozhou Bay. HB play an important role in the
biogeochemical cycling of nutrients and may increase the N:P ratio and the accumulation of DIN, thereby accelerating the imbalance
of the N:P ratio in Jiaozhou Bay. 相似文献
3.
Zhe Liu Hao Wei Jie Bai Jing Zhang Dongyan Liu Sumei Liu 《Water, Air, & Soil Pollution: Focus》2007,7(6):607-623
A 3-D biological model was developed and coupled to a hydrodynamic model, i.e., Princeton Ocean Model, to simulate the seasonal
variation and budget of dissolved inorganic nitrogen, phosphate, and silicate in Jiaozhou Bay. The modeled nutrients distribution
pattern is consistent with observation. Silicate, the most important limiting element for phytoplankton growth, is characterized
by consumption in spring, increase in summer and autumn, and accumulation in winter, whereas dissolved inorganic nitrogen
and phosphorous have increasing trend with low rates in spring, due to excessive river loads. Phytoplankton plays an important
role in nutrient renewal by photosynthesis and respiration processes. During an annual cycle, 7.83 × 103 t N, 0.28 × 103 t P, and 3.93 × 103 t Si are transported to the bay’s outer sea, i.e., the Yellow Sea, suggesting that Jiaozhou Bay is a significant source of
nutrients for the Yellow Sea. The spatial distribution of nutrients is characterized by vertically homogeneous profiles, with
high concentration inside the bay and low concentration toward the bay channel. These features are mainly governed by strong
turbulent mixing, fluvial influx, water exchange rate, and Yellow Sea water intrusion. Numerical experiments suggest that
the government should pay enough attention to proper layout of sewage drainage. 相似文献
4.
CH4 concentrations in both the surface and bottom waters of Jiaozhou Bay were determined during four surveys in 2003, which showed
variability with both seasons and tidal cycles. Atmospheric fluxes of CH4 in Jiaozhou Bay showed obvious seasonal and spatial variations, with the highest values occurring in summer and the lowest
in winter. The annual emission of CH4 from Jiaozhou Bay was estimated to be . CH4 in the water column of Jiaozhou Bay was found to come from several land-sources including riverine water input, sewage water
input and groundwater input. The spatial and temporal variation in distributions and atmospheric fluxes of CH4 in Jiaozhou Bay was influenced mainly by the input of polluted river waters and the sewage effluents along the eastern coast,
which highlights the effects of human impacts on CH4 emission rates. 相似文献
5.
Tony R. Walker 《补救:环境净化治理成本、技术与工艺杂志》2014,24(3):103-117
This article reviews a comprehensive marine environmental effects monitoring program (MEEMP) comprised of components capable of detecting changes in the marine environment over short or extended temporal scales during remediation of one of Canada's most polluted sites at the Sydney Tar Ponds. The monitoring components included: water and sediment quality, amphipod toxicity testing, mussel tissue, crab hepatopancreas tissue, and benthic community assessments. The MEEMP was designed to verify the impact predictions for the remediation project (i.e., no immediate damage to the marine ecosystem through remediation activities). Some components were capable of providing conclusive data (e.g., sediment and water quality), while others only yielded data that were inconclusive or difficult to attribute to remediation activities (e.g., intertidal community assessments and amphipod toxicity testing). Components that provided only inconclusive results or were difficult to attribute to remediation activities were discontinued, resulting in substantial cost savings during the project, but without compromising the overall objectives of the program, which was to monitor for potential adverse environmental effects of remediation on the marine environment in Sydney Harbor and to verify environmental effects predictions made in the Environmental Impact Statement for the project. The rationale for discontinuing certain MEEMP components and discussion of conclusive results are incorporated into “lessons learned” for environmental remediation practitioners and regulators working on similar large‐scale multiyear remediation projects. © 2014 Wiley Periodicals, Inc. 相似文献
6.
G. Q. Liu S. Y. Wang X. J. Zhu S. M. Liu J. Zhang 《Water, Air, & Soil Pollution: Focus》2007,7(6):593-605
The health of near shore marine ecosystems has long been a concern because of its importance to coastal areas. Jiaozhou Bay
(JZB) is one such marine ecosystem experiencing rapid water quality degradation in the last several decades. From the area
surrounding the bay, the nutrients discharged into the bay through surface water and groundwater has been greatly changed.
The thickness of the aquifers and the permeability is relatively high, the concentrations of nutrients in the groundwater
are generally high, and so the groundwater discharged into JZB is very significant. However, no attempt has ever been made
to evaluate the amount of nutrients discharged into the bay area via groundwater. In this study, the cross-section method
and water balance method were used to estimate the amount of groundwater and nutrients discharged into JZB via the subsurface.
Groundwater was monitored and sampled at aquifers surrounding the bay area, and some previously available data was also analyzed.
The results indicated that groundwater from the Baisha Aquifer east of JZB now is the major source of nutrients (nitrate,
dissolved SiO2) being discharged into the bay. The concentrations of nutrients in the groundwater have been increasing with intensive agricultural
land use. However, Dagu Aquifer, the largest aquifer north of JZB, only provides limited nutrients to the bay area because
of the construction of a low permeability subsurface dam. Historically, during the 1970s to the 1990s, the Baisha Aquifer
experienced seawater intrusion due to excessive groundwater withdrawal. The same was true for the Dagu Aquifer from the 1980s
to the 1990s. Because of this, no significant nutrients were discharged into the bay. 相似文献
7.
Trygve Hesthagen Bjørn Walseng Leif Roger Karlsen Roy M. Langåker 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):339-345
We studied the effects of liming on fish and crustaceans in a watershed which is in a region known to have one of the highest
diversity of aquatic biota in Norway. This watershed, Enningdal, is shared between Norway (1/3) and Sweden (2/3) and includes
61 lakes > 1.0 ha in Norway. Liming started on a large scale in the 1980s. Currently, a total of 26 of lakes (43%) are limed,
covering 93% of the total lake area. The mean value ± S.D. of pH and the concentration of inorganic labile Al in these lakes
is 6.62 ± 0.35 and 3 ± 4 μg l−1, respectively. Historical data of fish communities have been obtained from surveys, while test-fishing and sampling of crustaceans
were conducted in 24 lakes in recent years (2002–2004). The present study shows that crustaceans to a greater extent than
fish has responded to improved water quality after more than 20 years of liming. Of a total of 120 fish populations, 42 (35%)
have gone extinct. Only five of the lost fish populations (12%) have been re-established, all due to human re-introductions.
Physical barriers are considered to be the main factor preventing fish from invading limed lakes. In contrast, crustaceans
have been re-established in most limed lakes. This may be mainly due to their good spreading capacity. However, they might
also have survived in refuges within the watershed, or as resting-eggs in the sediment. 相似文献
8.
Mary Beth Adams James N. Kochenderfer Pamela J. Edwards 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):267-273
In 1989, a watershed acidification experiment was begun on the Fernow Experimental Forest in West Virginia, USA. Ammonium
sulfate fertilizer (35.5 kg N ha−1 yr−1and 40.5 kg S ha−1 yr−1) was applied to a forested watershed (WS3) that supported a 20-year-old stand of eastern deciduous hardwoods. Additions of
N and S are approximately twice the ambient deposition of nitrogen and sulfur in the adjacent mature forested watershed (WS4),
that serves as the reference watershed for this study. Acidification of stream water and soil solution was documented, although
the response was delayed, and acidification processes appeared to be driven by nitrate rather than sulfate. As a result of
the acidification treatment, nitrate solution concentrations increased below all soil layers, whereas sulfate was retained
by all soil layers after only a few years of the fertilization treatments, perhaps due to adsorption induced from decreasing
sulfate deposition. Based on soil solution monitoring, depletion of calcium and magnesium was observed, first from the upper
soil horizons and later from the lower soil horizons. Increased base cation concentrations in stream water also were documented
and linked closely with high solution levels of nitrate. Significant changes in soil chemical properties were not detected
after 12 years of treatment, however. 相似文献
9.
《Spill Science & Technology Bulletin》2000,6(2):173-185
We developed a new numerical model to investigate the dynamics of tidal flat ecosystems and their role in water quality in terms of the carbon cycle. This model was applied to Isshiki, a natural tidal flat area, which is the largest in Mikawa Bay, Japan.This model dealt with variations of biochemical or physical interaction among dissolved oxygen and C–N–P species (comprised of carbon, nitrogen, and phosphorus elements) both on a short-time scale (<24 h) as well as over a long-time scale (seasonal variation). The model indicated that the time dependence on phytoplankton, NH4–N, NOx–N, and PO4–P are more sensitive to daily environmental variation than to seasonal environmental variation. This means that the rotation speed of these materials in the tidal flat area is fast. Here, we defined the rotation speed as the ratio of total fluxes of substance to the mass of the substance. Phytoplankton with a high rotation speed in the tidal flat area means that the tidal flat has the potential to recover from rapidly increasing phytoplankton: red tide. The model also indicated that the peculiar feature of the tidal flat is the mineralization of organic material. The effect on a long term base, is that it prevents the accumulation of sediment, which results in controlling the increase of oxygen consumption in benthic system, which is the cause of oxygen depleted water. 相似文献
10.
Strongly decreasing atmospheric emissions and acidic deposition during the 1990s have initiated chemical reversal from acidification
in several drinking-water reservoirs of the Erzgebirge, SE Germany. We studied responses of phytoplankton, zooplankton and
fish stocks in five reservoirs and at enclosure scale after experimental neutralization of 1,200 m3 of lake water. About 4 months after this treatment, diatoms and cryptomonads replaced the predominating chrysophytes and
dinoflagellates. The colonization by acid-sensitive species of green algae, cryptomonads, rotifers and Cladocera (e.g. Bosmina longirostris) is explained by the occurrence of dormant stages or by survival of individuals in very low abundances. Analogous to the
enclosure experiment, three reservoirs showed significantly (p < 0.01) falling trends of chlorophyll a and phytoplankton biovolume, mainly due to the decline of dinoflagellates. Picoplankton and diatoms increased slightly in
two reservoirs. The zooplankton communities were dominated by rotifers and small Cladocera. Representatives of the genus Daphnia were lacking. Two reservoirs were re-colonized by zooplanktivorous fish populations of either perch (Perca fluviatilis) or sunbleak (Leucaspius delineatus). The latter exhibited extremely high fluctuating abundance and biomass and even suffered from a population crash. This natural
mortality was caused by a limited food supply. Hence, severe top-down control may delay the recovery of larger zooplankton
species like daphnids. Fishery management comprising the introduction of predatory fishes can help to control zooplanktivorous
fish populations and to prevent their mass mortality. 相似文献
11.
Marine debris (marine litter) is one of the most pervasive and solvable pollution problems plaguing the world’s oceans and waterways. Nets, food wrappers, cigarette filters, bottles, resin pellets,
and other debris items can have serious impacts on wildlife, habitat, and human safety. Successful management of the problem
requires a comprehensive understanding of both marine debris and human behavior. Knowledge is key for consumers to make appropriate
choices when it comes to using and disposing of waste items. Education and outreach programs, strong laws and policies, and
governmental and private enforcement are the building blocks for a successful marine pollution prevention initiative. The
plastic industry also has a role to play in educating its employees and customers, and searching for technological mitigation
strategies. 相似文献
12.
Biofouling and ensuing microbial mediated degradation of Bisphenol A polycarbonate was studied by immersing the samples in
sea water of Bay of Bengal (Chennai, India) for 3 months and also under controlled laboratory conditions with marine mixed
microbial consortia for 12 months. A 9% weight loss in the sample was observed after 1 year of incubation under in vitro laboratory
conditions. A 5% reduction in number average molecular weight and an additional oligomer with a molecular weight of 930 was
observed in the same sample. Contact angle decreased by 11% indicating an increase in the surface hydrophilicity. The specific
heat decreased by 44% and glass transition temperature decreased by 3 °C with respect to the control indicating chain scission.
Formation of new hydroxyl groups and cleavage of carbonate bonds in polycarbonate suggested biodegradation. About 9 μg mL−1 of Bisphenol A, a monomer of polycarbonate, as well as its oxidized products were detected in the supernatant. The nature
of degradation in field and in vitro was different. It was predominantly oxidation in the former and hydrolysis in the later
environment. A strain exhibiting hydrolase activity was isolated at the end of the 12 months from the in vitro mixed consortia
and was identified, based on biochemical and 16S rDNA tests, as Pseudomonas sp. BP2 (GenBank accession no. EU920674). 相似文献
13.
Agnieszka Guzman Helena Janik Alicja Kosakowska 《Journal of Polymers and the Environment》2010,18(4):679-684
Several new biodegradable polymer materials have recently come onto the global market. Mostly the results on degradation kinetic
studies are presented. This paper suggests using one of the tests to estimate the impact of polymer packaging material on
sea life. The microorganism chosen was Anabaena variabilis (identified in many waters, including those of the Baltic Sea, especially in the Gulf of Gdańsk and Puck Bay; this cyanobacterium
has a tendency to move with deep-sea waters causing algal blooms that upset the ecological balance of the marine environment
[1]). The chosen polymer materials were polycaprolactone modified with thermoplastic starch (PCL/TPS > 85%) or with calcium
carbonate (60% PCL/40% CaCO3). They were incubated in seawater in the presence of A. variabilis. The chlorophyll a content was determined as the criterion of cyanobacterial growth in the presence of the tested polymers. The polymer surface
and colour changes in the cyanobacterium culture were recorded photographically. The experimental results indicate that the
addition of polymer samples to the cyanobacterium culture affects its biological balance. During the experiment in seawater,
cyanobacteria adhered to the polymer surfaces and their growth was stimulated to different degree by the polymers. Thus, the
suggested test differentiate the behaviour of both materials studied. Cyanobacterial growth was lower in the presence of PCL
modified with calcium carbonate than in the presence PCL/TPS blend. 相似文献
14.
Contaminant mass flux and forensic assessment of polycyclic aromatic hydrocarbons: Tools to inform remediation decision making at a contaminated site in Canada 下载免费PDF全文
Tony R. Walker N. Devin MacAskill Andrew H. Thalheimer Lanying Zhao 《补救:环境净化治理成本、技术与工艺杂志》2017,27(4):9-17
Polycyclic aromatic hydrocarbons (PAHs) and metal(loid) mass flux estimates and forensic assessment using PAH diagnostic ratios were used to inform remediation decision making at the Sydney Tar Ponds (STPs) and Coke Ovens cleanup project in eastern Canada. Environmental effects monitoring of surface marine sediments in Sydney Harbor indicated significantly higher PAH concentrations during the first year of remediation monitoring compared to baseline. This was equivalent to PAH loadings of ~2,000 kg over a 15‐month period. Increases in sediment PAH concentrations raised serious concerns for regulators, who requested cessation of remediation activities early in the $400 M (CAD) project. Historically, the STPs were reported as the primary source of PAH contamination in Sydney Harbor with estimated discharges of 300 to 800 kg/year between 1989 and 2001. Mass flux estimates of PAHs and metal(loid)s and PAH diagnostic ratios were used to evaluate if increases in PAH concentrations in marine sediments were the result of the STPs remediation activities. PAH mass flux estimates approximated that 17 to 97 kg/year were discharged from the STPs during three years of remediation and were corroborated by an independent PAH flux estimate of 119 kg in year 1. PAH fluxes to the Sydney Harbor were mostly surface water derived, with groundwater contributing negligible quantities (0.002–0.005 kg/year). Fluxes of metal(loid)s to harbor sediments were stable or declining across all years and were mirrored in sediment metal(loid) concentrations, which lacked temporal variation, unlike total PAH concentrations. Flux results were also corroborated using PAH diagnostic ratios, which found a common source of PAHs. Coal combustion was likely the principal source of PAHs and not migration from the STPs during remediation. Although short‐term residual sediment PAH increases during onset of remediation raised concerns for regulators, calls for premature cessation of remediation early in the project were unwarranted based on only one year of monitoring data. Mass flux estimates and forensic assessments using PAH diagnostic ratios proved useful tools to inform remediation decision making that helped environmental protection and reduced costs associated with lost cleanup time. 相似文献
15.
Yu-Chi Weng Takeshi Fujiwara Yuzuru Matsuoka 《Journal of Material Cycles and Waste Management》2009,11(2):110-122
Industrialization and urbanization result in significant changes in lifestyle. These lifestyle changes seem to lead to unsustainable
consumption patterns and increase the generation of various kinds of environmental loads, especially the amount of municipal
solid waste (MSW). Taiwan is a small island with scarce natural resources. The economic development in Taiwan has resulted
in the generation of large amounts of MSW. As a result, the Taiwan Environmental Pollution Administration (TEPA) has produced
regulations for waste minimization and has imposed several important policy measures that have successfully reduced the MSW
discard rate in recent years and have established a public recycling network as a part of the MSW collection. Nowadays, the
objective of the MSW policies in Taiwan is to develop a “zero-waste society.” This article aims to review the MSW management
progress in Taiwan and to project future MSW discards up to 2011 based on the national plan and assumed scenarios for socioeconomic
variables. According to the analysis results, a more sustainable consumption pattern can be proposed and the corresponding
MSW management system can be planned so as to develop a low-waste-discard society. 相似文献
16.
《Waste management & research》1995,13(3):241-257
Taiwan has a high population density. Recently, rapid advances of medical activities have caused an environmental problem in managing the wastes generated by hospitals or clinics. Government regulations, public concern and an increased commitment to a clean environment have also brought more attention to the handling problems of medical waste. A project to plan and manage the first centralized incineration plant for infectious hospital waste has been carried out in Taiwan. This paper summarizes the results of the execution of this project. It addresses the experience gained in siting a regional incinerator, its technical operation to meet local environmental regulations and the management of the regional plant. Public concern against incineration was considered to be the most important criterion to address during establishment of the incinerator, as well as good operational performance. The operational problems encountered most frequently in the regional plant with possible causes and solutions to the problems are summarized in this paper. It was also found that a delivery manifest was useful to manage the delivery of infectious waste. 相似文献
17.
《Spill Science & Technology Bulletin》1996,3(3):107-122
This paper discusses the changes in spilled oil properties over time and how these changes affect differential density separation. It presents methods to improve differential density, and operational effectiveness when oil-water separation is incorporated in a recovery system. Separators function because of the difference in density between oil and seawater. As an oil weathers this difference decreases, because the oil density increases as the lighter components evaporate. The density also increases as the oil incorporates water droplets to form a water-in-oil emulsion. These changes occur simultaneously during weathering and reduce the effectiveness of separators. Today, the state-of-the-art technologies have limited capabilities for separating spilled marine oil that has weathered.For separation of emulsified water in an emulsion, the viscosity of the oil will have a significant impact on drag forces, reducing the effect of gravity or centrifugal separation. Since water content in an emulsion greatly increases the clean up volume (which can contain as much as two to five times as much water as the volume of recovered oil), it is equally important to remove water from an emulsion as to remove free water recovered owing to low skimmer effectiveness. Removal of both free water and water from an emulsion, has the potential to increase effective skimming time, recovery effectiveness and capacity, and facilitate waste handling and disposal. Therefore, effective oil and water separation in marine oil spill clean-up operations may be a more critical process than credited because it can mean that fewer resources are needed to clean up an oil spill with subsequent effects on capital investment and basic stand-by and operating costs for a spill response organization.A large increase in continuous skimming time and recovery has been demonstrated for total water (free and emulsified water) separation. Assuming a 200 m3 storage tank, 100 m3 h−1 skimmer capacity, 25% skimmer effectiveness, and 80% water content in the emulsion, the time of continuous operation (before discharge of oil residue is needed), increases from 2 to 40 h and recovery of oil residue from 10 to 200 m3.Use of emulsion breakers to enhance and accelerate the separation process may, in some cases, be a rapid and cost effective method to separate crude oil emulsions. Decrease of water content in an emulsion, by heating or use of emulsion breakers and subsequent reduction in viscosity, may improve pumpability, reduce transfer and discharge time, and can reduce oily waste handling, and disposal costs by a factor of 10. However, effective use of emulsion breakers is dependant on the effectiveness of the product, oil properties, application methods and time of application after a spill. 相似文献
18.
W. Keller N. D. Yan J. M. Gunn J. Heneberry 《Water, Air, & Soil Pollution: Focus》2007,7(1-3):317-322
Over 7,000 lakes around Sudbury, Ontario, Canada were acidified by S deposition associated with emissions from the Sudbury
metal smelters and more distant S sources. Air pollution controls have led to widespread changes in damaged Sudbury lakes,
including increased pH and decreased concentrations of SO4, metals and base cations. While chemical improvements have often been substantial, many lakes are still acidified, although
water quality recovery is continuing. Biological recovery has been observed in some lakes among various groups of organisms
including fish, zooplankton, phytoplankton and zoobenthos. Generally, however, biological recovery is still at an early stage.
Lakes around Sudbury are also showing that the recovery of acid-damaged lakes is closely linked to the effects of other major
environmental stressors such as climate change, base cation depletion and UV-B irradiance. Future studies of the recovery
of acid-damaged lakes around Sudbury, and in other regions, will need to consider the interactions of these and other stressors. 相似文献
19.
The SO4–S and NO3–N concentrations and pH in bulk precipitation, throughfall, stemflow and soil water for the 1994–2004 period were studied
in pine forests in Latvia (Rucava and Taurene Integrated Monitoring stations). The SO4–S and NO3–N concentrations decreased over the study period, simultaneously with a decrease of acidity in precipitation. The changes
were more evident in the western part of Latvia, probably due to declining long-range air pollution from West Europe. The
trend of decreasing sulphate concentrations and increasing pH in precipitation were not followed by respective changes in
soil water. In the upper soil horizon sulphate ion concentrations and acidity increased in soil water. Over the observation
period, nitrate concentrations also showed an increasing trend in soil water at Rucava and Taurene, but these changes were
not statistically significant. 相似文献
20.
Maria Rutkowska Katarzyna Krasowska Aleksandra Heimowska Grażyna Adamus Michał Sobota Marta Musioł Henryk Janeczek Wanda Sikorska Andrej Krzan Ema Žagar Marek Kowalczuk 《Journal of Polymers and the Environment》2008,16(3):183-191
Degradation of atactic poly[(R,S)-3-hydroxybutyrate] (a-PHB) binary blends with natural poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV, 12 mol% of 3HV units), has been investigated and compared with plain PHBV in the compost containing
activated sludge and under marine exposure conditions in the dynamic water of the Baltic Sea. Characteristic parameters of
compost and the Baltic Sea water were monitored during the incubation period (6 weeks) and their influence on the degree of
biodegradation is discussed. After specified degradation times of the experiments the weight loss of the samples, surface
changes, changes in molecular weight and polydispersity as well as changes of the composition and thermo-mechanical properties
of the blends have been evaluated. Macroscopic observations of the samples were accompanied by investigations using optical
microscopy, size-exclusion chromatography (SEC), nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC)
and tensile testing. The degree of degradation of blends of a-PHB with PHBV depends on the blend composition and environmental
conditions. In both environments studied the weight loss of plain PHBV was more significant than changes the molecular weight.
In both environments only enzymatic degradation of the blends, which proceeds via surface erosion mechanisms, was observed
during the incubation period. 相似文献