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991.
We demonstrated that environmentally relevant levels of UVA and UVB can reduce sperm motility (UVA: by 38–58%; UVB: by 42–85%; P < 0.05) and subsequently fertilisation success (UVA: by 38–72%; UVB: by 91–98%; P < 0.05) of urchins (Anthocidaris crassispina) in a dose-dependent manner, implicating that recruitment of urchin populations might be reduced by UVR (ultraviolet radiation) prevailing in their natural habitats. Concomitantly, reactive oxygen species (ROS) production was enhanced by UVA and UVB in a dose-dependent manner (UVA: by 1.3-fold; UVB: by 6.6–7.3-fold; P < 0.05), and the increase in ROS resulted in an increase in lipid peroxidation (LPO) in urchin sperm (UVA: by 4.2–7.2-fold; UVB: by 2.3–2.7-fold; P < 0.05). This study demonstrated that ROS production and oxidative damages enhanced by UVR may account for the observed declines in sperm motility and fertilisation, and suggests that levels of UVR prevailing in the environment may pose a significant threat to the reproductive success of natural populations of urchins spawning in shallow waters. 相似文献
992.
A new method for the assessment of the effects of several contaminants on marine microalgae,Tetraselmis suecica (Kyling) Butcher,Skeletonema costatum (Grev.) Cleve, andProrocentrum lima (Ehrenberg) Dodge was developed in 1990. The method is based on the measurement of cell esterase activity using a fluorimetric stain, fluorescein diacetate (FDA), selected from amongst three stains (FDA, Neutral Red, thiazolyl tetrazolium bromure) for its higher sensitivity. Biochemical (K
m,V
max) and physiological (growth, specific activity) aspects of the enzymatic activity as revealed by the FDA method are discussed. Different categories of compounds (weed-killers, insecticides, metals) and some water samples from Seine Bay were tested for their toxic effects on microalgae. Experiments were performed on microplates using a fluorimetric microplate reader. The various steps of the experiments and data-processing were controlled by software. Applications of the system to rapid ecotoxicological tests (determination of the IC50, i.e., the concentration at which 50% inhibition of growth occurs) and to the assessment of environment quality by studying the toxic effect of water samples on microalgae are proposed. 相似文献
993.
Thermochemical studies of the toxic actions of heavy metal ions on Rhizopus nigricans 总被引:3,自引:0,他引:3
By using a LKB2277 BioActivity Monitor (heat conduction microcalorimeter), stopped-flow method, the thermogenetic curves of Rhizopus nigricans growth at 25 degrees C inhibited by four kinds of heavy metal ions are determined, parameters such as growth rate constants k, inhibitory ratio I, half inhibitory concentration IC50 et al. are obtained. The experimental results show that heavy metal ions can inhibit Rhizopus nigricans growth obviously, low concentration of Cu2+ has promoting action. The inhibitory sequence is Cd2+ > Hg2+ > Pb2+ > Cu2+, half inhibitory concentration of them are Cd+ 0.8 micro g x ml(-1), Hg2+ 1.7 micro g x ml(-1), Pb2+ 48.0 micro g x ml(-1), Cu2+ 110 micro g x ml(-1). This microclorimetric bioassay for acute cellular toxicity is based on metabolic heat evolution from cultured cells. The assay is quantitative, inexpensive, and versatile; moreover, toxicological information can be obtained with cell from other species of interest. 相似文献
994.
Selecting the proper primary variables is a critical step in efficiently modeling the highly nonlinear problem of multiphase subsurface flow in a heterogeneous porous-fractured media. Current simulation and ground modeling techniques consist of (1) spatial discretization of mass and/or heat conservation equations using finite difference or finite element methods; (2) fully implicit time discretization; (3) solving the nonlinear, discrete algebraic equations using a Newton iterative scheme. Previous modeling efforts indicate that the choice of primary variables for a Newton iteration not only impacts computational performance of a numerical code, but may also determine the feasibility of a numerical modeling study in many field applications. This paper presents an analysis and general recommendations for selecting primary variables in simulating multiphase, subsurface flow for one-active phase (Richards' equation), two-phase (gas and liquid) and three-phase (gas, water and nonaqueous phase liquid or NAPL) conditions. In many cases, a dynamic variable switching or variable substitution scheme may have to be used in order to achieve optimal numerical performance and robustness. The selection of primary variables depends in general on the sensitivity of the system of equations to the variables selected at given phase and flow conditions. We will present a series of numerical tests and large-scale field simulation examples, including modeling one (active)-phase, two-phase and three-phase flow problems in multi-dimensional, porous-fractured subsurface systems. 相似文献
995.
Groundwater contaminated by dense, non-aqueous phase liquids (DNAPLs) such as chlorinated solvents has become a serious problem in some regions of Taiwan. The sources of these contaminants are due to industrial discharges. These chlorinated volatile organic compounds (VOCs) have been proven to be carcinogenic to humans. The groundwater is used for domestic drinking water supply in some cities of Taiwan and the severely contaminated groundwater has to be treated in order to meet the requirement of drinking water standards. This study covers two areas of work. In the first part, polluted groundwater samples were collected from the contaminated site and analytical results indicated measurable concentrations of 12 representative chlorinated VOCs in water samples. The primary VOCs detected included trichloroethene (TCE), tetrachloroethene (PCE), 1,1,2-trichloroethane (1,1,2-TCA), and 1,1-dichloroethene (1,1-DCE). Second, to remove VOCs groundwater was treated using adsorption on activated carbon fiber (ACF). This involved pumping groundwater through vessels containing ACF. Most VOCs, including TCE, PCE, 1,1,2-TCA, and DCE, were readily adsorbed onto ACF and are removed from the water stream. Our study showed that the technology was able to significantly reduce chlorinated VOCs concentrations in groundwater. 相似文献
996.
Groundwater, used in this study, contaminated predominantly with aromatic compounds, was biologically treated in a fluidized-bed reactor (FBR) with immobilized cells. The aromatics were completely decomposed, while cis-1,2-dichloroethylene (cis-DCE) and trichloroethylene (TCE) were decomposed only approximately 20% and 5%, respectively. In these studies a significant improvement of the decomposition efficiency for chlorinated ethylenes was achieved by utilizing cometabolism. Methanol (MeOH) and toluene were used as the substrate in the case of one-stage reactor (Single Reactor). MeOH (187 mg l(-1)) increased the decomposition efficiency up to 40% and 60% for cis-DCE and TCE, respectively, while toluene (20 mg l(-1)) increased the decomposition efficiency of cis-DCE to 92% and the decomposition efficiency of TCE to 76%. In the case of two-stage reactor system (Reactor 1 and Reactor 2), MeOH and methane (CH4) were used as the substrate. In this system, cells grown on MeOH or CH4 in the Reactor 1 were continuously fed into Reactor 2 and groundwater was fed into Reactor 2 only. When MeOH (384 mg l(-1) d(-1)) was used as substrate the decomposition efficiency of cis-DCE and TCE were 60% and 70%, respectively. Similar decomposition efficiency was observed for a small amount of CH4 (19.3 mg l(-1) d(-1)). 相似文献
997.
This paper examines potential uses of naturally growing aquatic plants for wastewater purification. These plants enhance the removal of pollutants by consuming part of them in the form of plant nutrients. This applies to urban and agricultural wastewater, in particular, where treatment units of different sizes can be applied at the pollution source. The effectiveness of wastewater purification by different plants was tested on laboratory and pilot scales. The growth rate of the plants was related to the wastewater content in the water. Batch and semicontinuous experiments verified that the plants are capable of decreasing all tested indicators for water quality to levels that permit the use of the purified water for irrigation. This applies to biochemical oxygen demand (BOD), chemical oxygen demand, total suspended solids. pH, and turbidity. In specific cases, the turbidity reached the level of drinking water. Comparison of BOD concentrations with typical levels in water treatment facilities across the country indicates the effectiveness of water purification with plants. A major effect of treatment with plants was elimination of the disturbing smell from the wastewater. It is shown that mixtures of wastewater and polluted water from the Kishon River are amenable in varying degrees to treatment by the plants. The higher the wastewater content in the mixture, the more effective the treatment by the plants. In this context, a scheme for rehabilitation and restoration of the Kishon River is presented and technical and economical aspects of the purification technology are considered. 相似文献
998.
The effect of the photosensitizer riboflavin (0, 10, 50, 100 microM) on the fate of atrazine (10 mg/l) in a freshwater environment was studied. It was found that at 100 microM riboflavin significantly enhanced the degradation of atrazine and more than 80% of atrazine in a natural water environment was depleted in 72 h. The relative contribution of microbial assemblages and the freshwater matrix to the degradation of atrazine and the degradation kinetics of atrazine were compared under different experimental conditions. The products and pathways of atrazine transformation were studied with GC-MS and HPLC with a photodiode array detector. The results show that dealkylation and alkyl chain oxidation are involved in the degradation of atrazine. 相似文献
999.
Xu Y Zhang J Li W Schramm KW Kettrup A 《Environmental pollution (Barking, Essex : 1987)》2002,120(3):683-690
Silver carp (Hypophthalmichthys molitrix) samples were collected from five selected sites that represent diverse levels of downgraded persistent organic pollutants (POPs) contamination in Ya-Er Lake in October 1999. Hepatic ethoxyresorufin-O-deethylase (EROD) and UDP glucuronosyltransferase (UDPGT) activities, hepatosomatic index (HSI), hepatic retinoids, serum thyroid hormones were measured. It was found that hepatic retinol and serum free 3,5,3'- tetraiodothyronine (FT3) significantly increased (P < 0.01) when both hepatic EROD and UDPGT activities significantly declined (P < 0.01) from pond 1 to 5 with decrease in the degree of pollution. This significant negative correlation (P < 0.01) suggests that the persistent organochlorinated contaminants could induce hepatic EROD and UDPGT activities, alter retinoid and thyroid hormone homeostasis, and finally lead to the reduction of retinol and FT3, the two biologically active forms of retinoids and thyroid hormone in silver carp of Ya-Er Lake. 相似文献
1000.
Richardson BJ Zheng GJ Tse ES De Luca-Abbott SB Siu SY Lam PK 《Environmental pollution (Barking, Essex : 1987)》2003,122(2):223-227
The ability of mussels (Perna viridis) and semi-permeable membrane devices (SPMDs) to accumulate polycyclic aromatic hydrocarbons (PAHs) and petroleum hydrocarbons (PHCs) from five sites in Hong Kong's coastal waters was compared. Mussels consistently had higher levels of contaminants, but their utility was limited at one highly polluted site due to mortality. Mussels and SPMDs ranked sites differently in terms of individual contaminant levels. Although SPMDs overcome many of the disadvantages of using living organisms to measure contaminants in marine waters, they cannot be used as "mimics" due to different PAH and PHC accumulation patterns. 相似文献