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1.
Background, aim, and scope The purpose of this study was to compare the suitability of different phytotoxicity testing procedures for the evaluation
of toxicity associated with both soil contamination and solid wastes, both of which can be of environmental risk to plants.
Ten different representative types of contaminated soils and solid waste samples were chosen from the Czech Republic. 相似文献
2.
Purpose Increases in dissolved organic carbon (DOC) concentrations have been reported in surface waters worldwide in the last 10 to
20 years. The causes behind these increases have been attributed to many factors, including climate change and decreasing
depositions of atmospheric sulphate (
\text SO42 - {\text{SO}}_4^{{{2} - }} ). Trends in DOC concentrations and their potential causal factors were examined in a network of 30 lakes lying in undisturbed
temperate and boreal catchments in the province of Quebec, Canada. 相似文献
3.
Metal oxide nanomaterials have exhibited toxicity to a variety of aquatic organisms, especially microbes and invertebrates. To date, few studies have evaluated the toxicity of metal oxide nanomaterials on aquatic vertebrates. Therefore, this study examined effects of ZnO, TiO 2, Fe 2O 3, and CuO nanomaterials (20-100 nm) on amphibians utilizing the Frog Embryo Teratogenesis Assay Xenopus (FETAX) protocol, a 96 h exposure with daily solution exchanges. Nanomaterials were dispersed in reconstituted moderately hard test medium. These exposures did not increase mortality in static renewal exposures containing up to 1000 mg L −1 for TiO 2, Fe 2O 3, CuO, and ZnO, but did induce developmental abnormalities. Gastrointestinal, spinal, and other abnormalities were observed in CuO and ZnO nanomaterial exposures at concentrations as low as 3.16 mg L −1 (ZnO). An EC 50 of 10.3 mg L −1 ZnO was observed for total malformations. The minimum concentration to inhibit growth of tadpoles exposed to CuO or ZnO nanomaterials was 10 mg L −1. The results indicate that select nanomaterials can negatively affect amphibians during development. Evaluation of nanomaterial exposure on vertebrate organisms are imperative to responsible production and introduction of nanomaterials in everyday products to ensure human and environmental safety. 相似文献
4.
The extensive application of cerium oxide nanoparticles (CeO2 NPs), a type of rare earth nanomaterial, led to pollution into aquatic environments. Cyanobacteria, a significant component of freshwater ecosystems, can interact with CeO2 NPs. However, little attention has been paid as to whether CeO2 NPs will have adverse effects on cyanobacteria. In the present study, Microcystis aeruginosa (FACHB-942) was exposed to different concentrations (0, 1, 10, and 50 mg/L) of CeO2 NPs. Results showed 50 mg/L CeO2 NPs inhibited algal growth (11.48%?±?5.76%), suppressed photosynthesis and induced the generation of reactive oxygen species (ROS) after 72 h exposure. The toxicity mechanism is the adsorption of CeO2 NPs on cell surface, the ROS formation and the intracellular Ce. Additionally, the intracellular microcystins (MCs) content was significantly induced (11.84%?±?1.47%) by 50 mg/L CeO2 NPs, while no significance was found in 1 and 10 mg/L CeO2 NP treatments. Results indicated high concentrations of CeO2 NPs could be toxic to algae through the adverse effects on algal growth and photosynthesis. Moreover, the promoted MCs production could also pose a threat to freshwater ecosystems due to the possible release into the environment. 相似文献
5.
Background, aim, and scope Sorption of hydrophobic organic compounds (HOCs) to natural organic matter (NOM) is an important process that affects the
transport, transformation, bioavailability, and fate of HOCs in the environment. Manufactured nanoparticles (NPs) such as
nano-oxides will inevitably enter the environment in the processes of their production, transfer, and use and could be coated
by the ubiquitous NOM. Thus, sorption of HOCs to NOM in the environment could be affected by the NP interactions with NOM.
Furthermore, the toxicity of nano-oxides could be increased due to the adsorbed HOCs. Therefore, sorption of phenanthrene
by nano-Al 2O 3 coated with humic acid (HA) was examined in this study to explore the possible effect of nanoparticles (NPs) on the environmental
behavior of HOCs and the potential environmental and health risks of NPs. 相似文献
6.
Background, aim, and scope Linear alkylbenzene sulfonate (LAS) is the most used anionic surfactant in a worldwide scale and is considered a high-priority
pollutant. LAS is regarded as a readily biodegradable product under aerobic conditions in aqueous media and is mostly removed
in wastewater treatment plants, but an important fraction (20–25%) is immobilized in sewage sludge and persists under anoxic
conditions. Due to the application of the sludge as a fertilizer, LAS reaches agricultural soil, and therefore, microbial
toxicity tests have been widely used to evaluate the influence of LAS on soil microbial ecology. However, molecular-based
community-level analyses have been seldom applied in studies regarding the effects of LAS on natural or engineered systems,
and, to our knowledge, there are no reports of their use for such appraisals in agricultural soil. In this study, a microcosm
system is used to evaluate the effects of a commercial mixture of LAS on the community structure of Alphaproteobacteria, Actinobacteria, and Acidobacteria in an agricultural soil. 相似文献
7.
Introduction The change in light intensity that takes place when an ambient air sample is drawn into the detection chamber of a chemiluminescence
monitor generates changes in the concentrations of several species, such as NO 2, NO and O 3. Although this phenomenon has been known for several decades, there is still no commonly accepted approach on when or how
to correct for it in NO 2 and O 3 readings. 相似文献
8.
Introduction The kinetics of the transformation of ammonia and acid gases into components of PM 2.5 has been examined. The interactions of existing aerosols and meteorology with the transformation mechanism have also been
investigated. The specific objective was to discern the kinetics for the gas-to-particle conversion processes where the reactions
of NH 3 with H 2SO 4, HNO 3, and HCl take place to form (NH 4) 2SO 4, NH 4NO 3, and NH 4Cl, respectively, in PM 2.5. 相似文献
9.
Introduction While the literature is replete with studies of the toxic potency of pentachlorophenol (PCP), site-specific criteria for native
aquatic species that can be used in ecological risk assessments has been lacking and application of toxicity information for
non-native species is controversial. 相似文献
11.
Tire wear particles filed from the treads of end-of-life vehicle tires have been added to sea water to examine the release of Zn and the toxicity of the resulting leachate and dilutions thereof to the marine macroalga, Ulva lactuca. Zinc release appeared to be diffusion-controlled, with a conditional rate constant of 5.4 μg[L(h) 1/2] −1, and about 1.6% of total Zn was released after 120 h incubation. Exposure to increasing concentrations of leachate resulted in a non-linear reduction in the efficiency of photochemical energy conversion of U. lactuca and, with the exception of the undiluted leachate, increasing accumulation of Zn. Phototoxicity was significantly lower on exposure to equivalent concentrations of Zn added as Zn(NO 3) 2, suggesting that organic components of leachate are largely responsible for the overall toxicity to the alga. Given the ubiquity and abundance of TWP in urban coastal sediments, the generation, biogeochemistry and toxicity of tire leachate in the marine setting merit further attention. 相似文献
12.
Background, aim, and scope Solid surfaces in contact with water have been found to be biofouled due to the attachment of various organisms. For better
understanding of the biofilm formation, the important initial stage of bacterial attachment was investigated with Pseudomonas aeruginosa PAO1 as a model microorganism. Effects of the biosurfactant rhamnolipids and the shear conditions were particularly examined. 相似文献
13.
Background, aim, and scope As emerging contaminants, transformation products of the pollutants via various environmental processes are rather unknown,
and some may predominately contribute to the environmental risks of the parent compounds. Hence, studies on transformation
products complement the assessment of the environmental safety of the parent compounds. In this study, degradation experiments
and toxicity tests using diclofop-methyl (DM), a widely used herbicide, and selected major transformation products were carried
out in algal cultures to assess the time course of DM toxicity and its relevance in the formation of new breakdown products.
Methods The alga Chlorella vulgaris was maintained in the algal growth medium HB IV. The inhibition of algal growth was determined by measuring optical density
at 680 nm (OD 680). Initially, DM and two selected breakdown products were added to the algal cultures, and following degradation experiments
analyses were carried out by high performance liquid chromatography. In addition, the possible relationship between DM degradation
and toxicity was assessed, based on physico-chemical properties of the compounds and their toxicity.
Results DM was rapidly absorbed onto the surface of the algal cells where it was hydrolyzed to diclofop (DC). Further degradation
to 4-(2, 4-dichlorophenoxy) phenol (DP) occurred in the cells. However, only a minor amount of DC was degraded to DP under
the same conditions when DC was initially added to the algal culture. When C. vulgaris was exposed to these compounds for 96 h, the determined EC 50 showed that DC was about ten times less toxic than DM (EC 50 = 0.42 mg/L) and that DP (EC 50 = 0.20 mg/L) was the most toxic.
Discussion Due to strong hydrophobicity and rare dissociation, DM has tendency toward absorption as compared to DC. The higher average
degradation rates of DC initially treated by DM revealed the damage of the cell membranes caused by the DM and, thus, enhanced
movement of DC into the cells. Following occurrence of phenolic breakdown products, DP suggested that DC should be intracellularly
degraded to DP, which had a more potent mode of action and a higher acute toxicity. Moreover, the results for EC 50 at various intervals were in accordance with degradation processes of the initial compounds, in which rapid formation of
DP was attributed to an increasing toxicity of DM.
Conclusions The toxicity of DM in algal suspensions increased with time due to its degradation to DP, which contributed significantly
to the determined toxicity. These results indicate that the toxicity of the pesticide probably depends significantly on degradation.
It is thus important to consider the time-dependent environmental processes when evaluating the toxicological effects of pesticides
for proper risk assessment.
Recommendations and perspectives Increasing transformation products of these contaminants are identified in the environment, although they seem to be unknown
in terms of the lacking studies on environmental behavior and ecotoxicity concerning them. Certain breakdown products probably
greatly contribute to the apparent toxicity of the parent compounds, which is ascribed to the parent compounds in general
studies ignoring the dependence of their toxicity on various transformation pathways. These studies that identify new intermediates
and assess their toxicity via the environmental processes will be helpful to distinguish the nature of toxicity of the parent
contaminants. 相似文献
14.
Background, aim and scope Toxicity testing has become a suitable tool for wastewater evaluation included in several reference documents on best available
techniques of the Integrated Pollution Prevention and Control (IPPC) Directive. The IPPC Directive requires that for direct
dischargers as well as for indirect dischargers, the same best available techniques should be applied. Within the study, the
whole effluent assessment approach of OSPAR has been applied for determining persistent toxicity of indirectly discharged
wastewater from the metal surface treatment industry. 相似文献
15.
Background, aim, and scope Acrylate and methacrylate esters are α,β-unsaturated esters that contain vinyl groups directly attached to the carbonyl carbon
(CH 2=CHCOO– and CH 2=CCH 3COO–, respectively) and are widely used in the polymer plastic and resin production. Rate coefficients for Cl reactions for
most of the unsaturated esters have not been previously determined, and a good understanding is needed of all the atmospheric
oxidation processes of these compounds in order to determine lifetimes in the atmosphere and to evaluate the impact of these
reactions on the formation of photo-oxidants and therefore on health and environment. 相似文献
16.
Purpose In this study, we investigated the effect of diphenyl diselenide [(PhSe) 2] on chlorpyrifos (CPF)-induced hepatic and hematologic toxicity in rats. Methods Rats were pre-treated with (PhSe) 2 (5?mg/kg) via the oral route (oral gavage) once a day for 7?days. On the eighth and ninth days, rats were treated with (PhSe) 2 (5?mg/kg) 30?min prior to CPF (50?mg/kg, by subcutaneous route). The aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase activities were determined in plasma of rats. Lipid peroxidation, protein carbonyl, and non-protein thiol levels as well as catalase, superoxide dismutase, glutathione peroxidase, glutathione reductase, and gluthatione S-transferase activities were determined in livers of rats. Hematological parameters were also determined. Results The results showed that CPF caused hepatic oxidative damage, as demonstrated by an increase in lipid peroxidation and protein carbonyl levels which was associated with a decrease in antioxidant defenses. CPF exposure caused a reduction in the leukocyte, indicating hematologic toxicity. (PhSe) 2 was effective in attenuating these toxic effects caused by CPF exposure in rats. Conclusions The results indicated that (PhSe) 2 was effective in protecting the hepatic and hematologic toxicity induced by acute CPF exposure in rats. 相似文献
17.
Introduction Cadmium (Cd) in plants interrupts numerous metabolic processes and reduces the water and nutrient uptake that cause chlorosis,
growth retardation, and ultimately plant death. Response of Brassica napus L. to calcium (Ca) enrichment in growth medium for reducing Cd toxicity stress by strengthening the photosynthesis organelles
and their functionality was explored in this study. 相似文献
18.
Purpose The direct aqueous photolysis of the thyroid hormone levothyroxine (T 4) has been studied. 相似文献
19.
Purpose Gamma ray irradiation is considered as an effective way to degrade diclofenac. However, due to the extensive coexisting substances
in natural waters, the use of gamma ray irradiation for degradation is often influenced by multiple factors. The various factors
that affect degradation efficiency, such as initial diclofenac concentration, initial pH, and the concentration of the additives
including H 2O 2 (·OH radical promoter), CH 3OH (·OH radical scavenger), thiourea (·OH, H·, and e aq− scavenger), humic acid, and NO 3− (coexisting substances in natural waters), are investigated. Furthermore, possible intermediate products are identified and
corresponding transformation pathways are proposed. 相似文献
20.
Background, aim and scope The applicability of the Whole Effluent Assessment concept for the proof of compliance with the “best available techniques”
has been analysed with paper mill wastewater from Germany by considering its persistency (P), potentially bio-accumulative
substances (B) and toxicity (T). 相似文献
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