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51.
锑的表生地球化学行为与环境危害效应 总被引:12,自引:0,他引:12
锑(Sb)是一种典型的有毒有害重金属元素。由于自然过程和人为活动的影响,锑及其化合物广泛分布于大气、土壤、水体等表生环境中,锑的环境污染日益严重。Sb不是植物必需元素,但能够被植物体及农作物吸收。Sb对人体和动物体产生慢性毒性及潜在致癌性。本文主要通过分析Sb的主要矿物、锑及其化合物在表生环境中的分布与迁移特性,来阐述人体可能的锑暴露途径及由此产生的环境危害效应。 相似文献
52.
Paula K. Hudson Mark A. Young Paul D. Kleiber Vicki H. Grassian 《Atmospheric environment (Oxford, England : 1994)》2008,42(24):5991-5999
Simultaneous size distributions and Fourier transform infrared (FTIR) extinction spectra have been measured for several representative components of mineral dust aerosol (quartz, calcite, and dolomite) in the fine particle size mode (D=0.1–1 μm). Optical constants drawn from the published literature have been used in combination with the experimentally determined size distributions to simulate the extinction spectra. In general, Mie theory does not accurately reproduce the peak position or band shape for the prominent IR resonance features in the 800–1600 cm−1 spectral range. The resonance peaks in the Mie simulation are consistently blue shifted relative to the experimental spectra by 20–50 cm−1. Spectral simulations, derived from a simple Rayleigh-based analytic theory for a “continuous distribution of ellipsoids” particle shape model, better reproduce the experimental spectra, despite the fact that the Rayleigh approximation is not strictly satisfied in these experiments. These results differ from our previous studies of particle shape effects in silicate clay mineral dust aerosols where a disk-shaped model for the particles was found to be more appropriate. 相似文献
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54.
Pace MN Mayes MA Jardine PM McKay LD Yin XL Mehlhorn TL Liu Q Gürleyük H 《Journal of contaminant hydrology》2007,91(3-4):267-287
Strontium-90 has migrated deep into the unsaturated subsurface beneath leaking storage tanks in the Waste Management Areas (WMA) at the U.S. Department of Energy's (DOE) Hanford Reservation. Faster than expected transport of contaminants in the vadose zone is typically attributed to either physical hydrologic processes such as development of preferential flow pathways, or to geochemical processes such as the formation of stable, anionic complexes with organic chelates, e.g., ethylenediaminetetraacetic acid (EDTA). The goal of this paper is to determine whether hydrological processes in the Hanford sediments can influence the geochemistry of the system and hence control transport of Sr(2+) and SrEDTA(2-). The study used batch isotherms, saturated packed column experiments, and an unsaturated transport experiment in an undisturbed core. Isotherms and repacked column experiments suggested that the SrEDTA(2-) complex was unstable in the presence of Hanford sediments, resulting in dissociation and transport of Sr(2+) as a divalent cation. A decrease in sorption with increasing solid:solution ratio for Sr(2+) and SrEDTA(2-) suggested mineral dissolution resulted in competition for sorption sites and the formation of stable aqueous complexes. This was confirmed by detection of MgEDTA(2-), MnEDTA(2-), PbEDTA(2-), and unidentified Sr and Ca complexes. Displacement of Sr(2+) through a partially-saturated undisturbed core resulted in less retardation and more irreversible sorption than was observed in the saturated repacked columns, and model results suggested a significant reservoir (49%) of immobile water was present during transport through the heterogeneous layered sediments. The undisturbed core was subsequently disassembled along distinct bedding planes and subjected to sequential extractions. Strontium was unequally distributed between carbonates (49%), ion exchange sites (37%), and the oxide (14%) fraction. An inverse relationship between mass wetness and Sr suggested that sandy sediments of low water content constituted the immobile flow regime. Our results suggested that the sequestration of Sr(2+) in partially-saturated, heterogeneous sediments was most likely due to the formation of immobile water in drier regions having low hydraulic conductivities. 相似文献
55.
Küster A Pohl K Altenburger R 《Environmental science and pollution research international》2007,14(6):377-383
Background, Goals and Scope During the last years the miniaturization of toxicity test systems for rapid and parallel measurements of large quantities
of samples has often been discussed. For unicellular algae as well as for aquatic macrophytes, fluorescence-based miniaturized
test systems have been introduced to analyze photosystem II (PSII) inhibitors. Nevertheless, high-throughput screening should
also guarantee the effect detection of a broad range of toxicants in order to ensure routinely applicable, high-throughput
measuring device experiments which can cover a broad range of toxicants and modes of action others than PSII inhibition. Thus,
the aim of this study was to establish a fast and reproducible measuring system for non-PSII inhibitors for aquatic macrophyte
species to overcome major limitations for use.
Methods A newly developed imaging pulse-amplitude-modulated chlorophyll fluorometer (I-PAM) was applied as an effect detector in short-term
bioassays with the aquatic macrophyte species Lemna minor. This multiwell-plate based measuring device enabled the incubation and measurement of up to 24 samples in parallel. The
chemicals paraquat-dichloride, alizarine and triclosan were chosen as representatives for the toxicant groups of non-PSII
herbicides, polycyclic aromatic hydrocarbons (PAHs) and pharmaceuticals and personal care products (PPCPs), which are often
detected in the aquatic environment. The I-PAM was used (i) to establish and validate the sensitivity of the test system to
the three non-PSII inhibitors, (ii) to compare the test systems with standardized and established biotests for aquatic macrophytes,
and (iii) to define necessary time scales in aquatic macrophyte testing. For validation of the fluorescence-based assay, the
standard growth test with L. minor (ISO/DIS 20079) was performed in parallel for each chemical.
Results The results revealed that fluorescence-based measurements with the I-PAM allow rapid and parallel analysis of large amounts
of aquatic macrophyte samples. The I-PAM enabled the recording of concentration-effect-curves with L. minor samples on a 24-well plate with single measurements. Fluorescence-based concentration-effect-curves could be detected for
all three chemicals after only 1 h of incubation. After 4–5 h incubation time, the maximum inhibition of fluorescence showed
an 80–100% effect for the chemicals tested. The EC50 after 24 h incubation were estimated to be 0.06 mg/L, 0.84 mg/L and 1.69
mg/L for paraquatdichloride, alizarine and triclosan, respectively.
Discussion The results obtained with the I-PAM after 24 h for the herbicide paraquat-dichloride and the polycyclic aromatic hydrocarbon
alizarine were in good accordance with median effective concentrations (EC50s) obtained by the standardized growth test for
L. minor after 7 d incubation (0.09 mg/L and 0.79 mg/L for paraquat-dichloride and alizarine, respectively). Those results were in
accordance with literature findings for the two chemicals. In contrast, fluorescence-based EC50 of the antimicrobial agent
triclosan proved to be two orders of magnitude greater when compared to the standard growth test with 7 d incubation time
(0.026 mg/L) as well as with literature findings.
Conclusion Typically, aquatic macrophyte testing is very time consuming and relies on laborious experimental set-ups. The I-PAM measuring
device enabled fast effect screening for the three chemicals tested. While established test systems for aquatic macrophytes
need incubation times of ≥ 7 d, the I-PAM can detect inhibitory effects much earlier (24 h), even if inhibition of chemicals
is not specifically associated with PSII. Thus, the fluorescence-based bioassay with the I-PAM offers a promising approach
for the miniaturization and high-throughput testing of chemicals with aquatic macrophytes. For the chemical triclosan, however,
the short-term effect prediction with the I-PAM has been shown to be less sensitive than with long-term bioassays, which might
be due to physicochemical substance properties such as lipophilicity.
Recommendations and Perspectives The results of this study show that the I-PAM represents a promising tool for decreasing the incubation times of aquatic macrophyte
toxicity testing to about 24 h as a supplement to existing test batteries. The applicability of this I-PAM bioassay on emergent
and submerged aquatic macrophyte species should be investigated in further studies. Regarding considerations that physicochemical
properties of the tested substances might play an important role in microplate bioassays, the I-PAM bioassay should either
be accompanied by evaluating physicochemical properties modeled from structural information prior to an experimental investigation,
or by intensified chemical analyses to identify and determine nominal concentrations of the toxicants tested. The chemicals
paraquat-dichloride, alizarine and triclosan were chosen as representatives for the toxicant groups of non-PSII herbicides,
PAHs and PPCPs which are often detected in the aquatic environment. Nevertheless, in order to ensure a routinely applicable
measuring device, experiments with a broader range of toxicants and samples of surface and/or waste waters are necessary.
ESS-Submission Editor: Dr. Markus Hecker (MHecker@Entrix.com) 相似文献
56.
Growth, photosynthetic and respiratory responses to sub-lethal copper concentrations in Scenedesmus incrassatulus (Chlorophyceae) 总被引:1,自引:0,他引:1
Perales-Vela HV González-Moreno S Montes-Horcasitas C Cañizares-Villanueva RO 《Chemosphere》2007,67(11):2274-2281
In the present paper we investigated the effects of sub-lethal concentrations of Cu2+ in the growth and metabolism of Scenedesmus incrassatulus. We found that the effect of Cu2+ on growth, photosynthetic pigments (chlorophylls and carotenoids) and metabolism do not follow the same pattern. Photosynthesis was more sensitive than respiration. The analysis of chlorophyll a fluorescence transient shows that the effect of sub-lethal Cu2+ concentration in vivo, causes a reduction of the active PSII reaction centers and the primary charge separation, decreasing the quantum yield of PSII, the electron transport rate and the photosynthetic O2 evolution. The order of sensitivity found was: Growth > photosynthetic pigments content = photosynthetic O2 evolution > photosynthetic electron transport > respiration. The uncoupled relationship between growth and metabolism is discussed. 相似文献
57.
Suarez-Ojeda ME Guisasola A Baeza JA Fabregat A Stüber F Fortuny A Font J Carrera J 《Chemosphere》2007,66(11):2096-2105
This study examines the feasibility of coupling a Catalytic Wet Air Oxidation (CWAO), with activated carbon (AC) as catalyst, and an aerobic biological treatment to treat a high-strength o-cresol wastewater. Two goals are pursued: (a) To determine the effect of the main AC/CWAO intermediates on the activated sludge of a municipal WasteWater Treatment Plant (WWTP) and (b) To demonstrate the feasibility of coupling the AC/CWAO effluent as a part of the influent of a municipal WWTP. In a previous study, a high-strength o-cresol wastewater was treated by AC/CWAO aiming to establish the distribution of intermediates and the biodegradability enhancement. In this work, the biodegradability, toxicity and inhibition of the most relevant intermediates detected in the AC/CWAO effluent were determined by respirometry. Also, the results of a pilot scale municipal WWTP study for an integrated AC/CWAO-aerobic biological treatment of this effluent are presented. The biodegradation parameters (i.e. maximum oxygen uptake rate and oxygen consumption) of main AC/CWAO intermediates allowed the classification of the intermediates into readily biodegradable, inert or toxic/inhibitory compounds. This detailed study, allowed to understand the biodegradability enhancement exhibited by an AC/CWAO effluent and to achieve a successful strategy for coupling the AC/CWAO step with an aerobic biological treatment for a high-strength o-cresol wastewater. Using 30%, as COD, of AC/CWAO effluent in the inlet to the pilot scale WWTP, the integrated AC/CWAO-biological treatment achieved a 98% of total COD removal and, particularly, a 91% of AC/CWAO effluent COD removal without any undesirable effect on the biomass. 相似文献
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