Determination of octylphenol and nonylphenol in aqueous sample using simultaneous derivatization and dispersive liquid-liquid microextraction followed by gas chromatography-mass spectrometry.

A simple and fast sample preparation method for the determination of nonylphenol (NP) and octylphenol (OP) in aqueous samples by simultaneous derivatization and dispersive liquid-liquid microextraction (DLLME) was investigated using gas chromatography-mass spectrometry (GC/MS). In this method, a combined dispersant/derivatization catalyst (methanol/pyridine mixture) was firstly added to an aqueous sample, following which a derivatization reagent/extraction solvent (methyl chloroformate/chloroform) was rapidly injected to combine in situ derivatization and extraction in a single step. After centrifuging, the sedimented phase containing the analytes was injected into the GC port by autosampler for analysis.

One-step extraction and derivatization liquid-phase microextraction for the determination of chlorophenols by gas chromatography-mass spectrometry.

A sample pretreatment method for the determination of 18 chlorophenols (CPs) in aqueous samples by derivatization liquid-phase microextraction (LPME) was investigated using gas chromatography-mass spectrometry. Derivatization reagent was spiked into the extraction solvent to combine derivatization and extraction into one step. High sensitivity of 18 CPs derivatives could be achieved after optimization of several parameters such as extraction solvent, percentage of derivatization reagent, extraction time, pH, and ionic strength.

Organophosphorus pesticide ozonation and formation of oxon intermediates.

In the present study, organophosphorus pesticides (OPs) (diazinon, methyl parathion, and parathion) were oxidized by bubbling ozone into a glass reactor. OP residues were detected using HPLC and ozonation intermediates were identified using GC-MS. The degradation of OPs followed pseudo-first-order kinetics through direct ozone oxidation and indirect hydroxyl radical oxidation.

Culturable and molecular phylogenetic diversity of microorganisms in an open-dumped, extremely acidic Pb/Zn mine tailings.

A combination of cultivation-based and molecular-based approaches was used to reveal the culturable and molecular diversity of the microbes inhabiting an open-dumped Pb/Zn mine tailings that was undergoing intensive acid generation (pH 1.9). Culturable bacteria found in the extremely acidic mine tailings were Acidithiobacillus ferrooxidans, Leptospirillum ferriphilum, Sulfobacillus thermotolerans and Acidiphilium cryptum, where the number of acidophilic heterotrophs was ten times higher than that of the iron- and sulfur-oxidizing bacteria.

Copper and Zinc in a paddy field and their potential ecological impacts affected by wastewater from a lead/zinc mine, P. R. China.

As well known, at normal levels, copper and zinc are essential micronutrients for plants, animals, and humans. However, excessive Cu and Zn are toxic and disturb a wide range of biochemical and physiological processes. Using Atomic Absorption Spectrophotometer (AAS; Perkin-Elmer 3030, USA), soil and rice plant (Oryza sativa L.

Determination of hydroxy metabolites of polycyclic aromatic hydrocarbons by fully automated solid-phase microextraction derivatization and gas chromatography-mass spectrometry.

A fully automated sample pretreatment method was developed for the detection of mono and dihydroxy metabolites of polycyclic aromatic hydrocarbons (PAHs) by gas chromatography-mass spectrometry in the selected ion monitoring mode. Direct immersion solid-phase microextraction for the extraction of target compounds and the headspace on-fiber silylation with N,O-bis(trimethylsilyl)trifluoroacetamide were performed automatically by a multipurpose autosampler (MPS2). The operating conditions including extraction time, derivatization time, ionic strength, pH, and incubation temperature were optimized.

Distribution patterns of octylphenol and nonylphenol in the aquatic system at mai po marshes nature reserve, a subtropical estuarine wetland in Hong Kong.

Spatial and temporal distribution of octylphenol (OP) and nonylphenol (NP) in Mai Po Marshes, a subtropical estuarine wetland in Hong Kong, were investigated. Surface water samples were collected every month from 11 sites during the period of September-December 2004. Concentrations of OP and NP ranged from 11.

Effects of landfill leachate effluent and bisphenol A on glutathione and glutathione-related enzymes in the gills and digestive glands of the freshwater snail Bellamya purificata.

Environmental contaminants with estrogenic activity have recently attracted attention due to their potential detrimental effects on the reproduction of human and wildlife. The aim of this study was to evaluate the use of endogenous glutathione and glutathione-related enzymes as biomarkers of exposure to landfill leachate effluent and bisphenol A (BPA) in the freshwater snail, Bellamya purificata. Following exposure to 1%, 5% and 10% landfill leachate effluent and 1, 10, 50 and 100mugl(-1) BPA for 0, 2, 7 and 15d, activities of glutathione S-transferase (GST), selenium-dependent glutathione peroxidase (SeGPx) and glutathione reductase (GR) and levels of total glutathione were measured in the gills and digestive glands of the snails.

Effects of organophosphorus pesticides and their ozonation byproducts on gap junctional intercellular communication in rat liver cell line.

The effects of organophosphorus pesticides (OPs), oxons and their ozonation byproducts on gap junctional intercellular communication (GJIC) on cultured BRL cell line were investigated using scrape loading and dye transfer (SL/DT) technique. The neutral red uptake assay was used to identify the non-cytotoxic levels of diazinon, parathion and methyl-parathion applied to GJIC assay. The concentration-dependent inhibition of GJIC was observed over a range of 50-350 mg/l diazinon, parathion and methyl-parathion after 90 min incubation compared with the vehicle control.

Influence of growth medium on cometabolic degradation of polycyclic aromatic hydrocarbons by Sphingomonas sp. strain PheB4.

The influence of growth medium on cometabolic degradation of polycyclic aromatic hydrocarbons (PAHs) was investigated when Sphingomonas sp. strain PheB4 isolated from surface mangrove sediments was grown in either phenanthrene-containing mineral salts medium (PMSM) or nutrient broth (NB). The NB-grown culture exhibited a more rapid cometabolic degradation of single and mixed non-growth substrate PAHs compared to the PMSM-grown culture.

Metabolite production in degradation of pyrene alone or in a mixture with another polycyclic aromatic hydrocarbon by Mycobacterium sp.

Degradation of pyrene (PYR) alone and in the presence of phenanthrene or fluoranthene by Mycobacterium sp. strain A1-PYR isolated from mangrove sediments was investigated. When PYR was the only polycyclic aromatic hydrocarbon compound and the sole carbon source, only 33% of the added PYR was slowly degraded during 7 d of incubation.

Dependence of bisphenol A photodegradation on the initial concentration of oxalate in the lepidocrocite-oxalate complex system.

To understand the degradation of endocrine disrupting chemicals (EDCs) in natural environment with existence of iron oxides and carboxylic acids, the dependence of bisphenol A (BPA) photodegradation on the initial concentration of oxalate (COX) in lepidocrocite (gamma-FeOOH) aqueous suspension was investigated under both UV and visible lights in this study. Lepidocrocite powder was home-prepared by a hydrothermal process. It was found that BPA degradation was promoted greatly in the presence of oxalate owing to the formation of lepidocrocite-oxalate complex.

Field released transgenic papaya effect on soil microbial communities and enzyme activities.

Soil properties, microbial communities and enzyme activities were studied in soil amended with replicase (RP)-transgenic or non-transgenic papaya under field conditions. Compared with non-transgenic papaya, significant differences (P<0.05) were observed in total nitrogen in soils grown with transgenic papaya.

Cultivation-dependent and cultivation-independent characterization of the microbial community in acid mine drainage associated with acidic Pb/Zn mine tailings at Lechang, Guangdong, China.

Cultivation-based and molecular approaches were used to characterize the phylogenetic composition and structure of the microbial community in an extremely acidic (pH 2.0) acid mine drainage (AMD) associated with Pb/Zn mine tailings that were undergoing vigorous acid generation. Acidophilic bacteria were isolated and enumerated on solid media, and were found to be restricted to isolates related to Acidithiobacillus ferrooxidans and Acidiphilium cryptum.

Full automation of solid-phase microextraction/on-fiber derivatization for simultaneous determination of endocrine-disrupting chemicals and steroid hormones by gas chromatography-mass spectrometry.

A fully automated method using direct immersion solid-phase microextraction (DI-SPME) and headspace on-fiber silylation for simultaneous determinations of exogenous endocrine-disrupting chemicals (EDCs) and endogenous steroid hormones in environmental aqueous and biological samples by gas chromatography-mass spectrometry (GC-MS) was developed and compared to a previously reported manual method. Three EDCs and five endocrine steroid hormones were selected to evaluate this method. The extraction and derivatization time, ion strength, pH, incubation temperature, sample volume, and extraction solvent were optimized.

Solid-phase microextraction with on-fiber silylation for simultaneous determinations of endocrine disrupting chemicals and steroid hormones by gas chromatography-mass spectrometry.

Based on solid-phase microextraction (SPME) and on-fiber silylation, a method for simultaneous determinations of exogenous endocrine disrupting chemicals (EDCs) and endogenous steroid hormones in environmental aqueous and biological samples by gas chromatography-mass spectrometry (GC-MS) was developed. The selected target compounds were: octylphenol (OP), technical grade nonylphenol (t-NP), diethylstilbestrol (DES), dehydroisoandrosterone (DEHA), estrone (E1), 17beta-estradiol (E2), testosterone (T) and pregnenolone (PREG). The optimization of operating conditions influencing the performances of SPME and derivatization were studied in detail.

Distribution of polychlorinated biphenyls in the water, sediment and fish from the Pearl River estuary, China.

The concentrations and distribution of polychlorinated biphenyls were determined in water, surface sediments and fishes from the estuaries of Pearl River, PR China. The results showed that the concentrations ranged from 2.47 ng l-1 to 6.

[Oligotrophic bacteria and their applications in environmental science].

Oligotrophic bacteria are a group of microbes living in oligotrophic environments. Their diversity and biomass are dominant in biosphere, and thus, play an important role in biogeochemical cycles. Since 1980s, their oligotrophic mechanisms, responses to starvation, and roles in ecosystems have been one of the most advanced subjects in microbial ecological research.

[Analyses of virus resistance and transgenes for transgenic papaya].

Virus resistance in field and molecular biological characterizations of the transgenes were analyzed for two lines of T(1) generation of transgenic papaya with the replicase mutant gene from papaya ringspot virus (PRV). The transgenic plants showed highly resistant or immune against PRV. Results indicated that the transgenes inherited to and expressed at RNA level in the progenies.

Accumulation of heavy metals in four grasses grown on lead and zinc mine tailings.

A field experiment was conducted to compare the growth and metal accumulation of Vetiveria zizanioides, Paspalum notatum, Cynodon dactylon and Imperata cylindraca var. major on the tailings, amended with 10 cm domestic refuse + complex NPK fertilizer(Treatment A), 10 cm domestic refuse(Treatment B) and complex NPK fertilizer (Treatment C) respectively, and without any amendment used as control (Treatment D). The results indicated that V.

Characterization of methanogenic Archaea in the leachate of a closed municipal solid waste landfill.

Cultivation-independent molecular approaches were used to investigate the phylogenetic composition of Archaea and the relative abundance of phylogenetically defined groups of methanogens in the leachate of a closed municipal solid waste landfill. Cloning and phylogenetic analysis of archaeal 16S rRNA gene sequences (16S rDNA) revealed that the landfill leachate harbored a diverse Archaea community, with sequence types distributed within the two archaeal kingdoms of the Euryarchaeota and the Crenarchaeota. Of the 80 clones examined, 51 were phylogenetically associated with well-defined methanogen lineages covering two major methanogenic phenotypes; 20 were related to Thermoplasma and were grouped with some novel archaeal rRNA gene sequences recently recovered from various anaerobic habitats; finally, five belonged to Crenarchaeota and were not closely related to any hitherto cultivated species.

Diversity and structure of the archaeal community in the leachate of a full-scale recirculating landfill as examined by direct 16S rRNA gene sequence retrieval.

The diversity and structure of the archaeal community in the effluent leachate from a full-scale recirculating landfill was characterized by direct 16S rRNA gene (16S rDNA) retrieval. Total-community DNA was extracted from the microbial assemblages in the landfill leachate, and archaeal 16S rDNAs were amplified with a universally conserved primer and an Archaea-specific primer. The amplification product was then used to construct a 16S rDNA clone library, and 70 randomly selected archaeal clones in the library were grouped by restriction fragment length polymorphism (RFLP) analysis.

[Effects of copper on rhizobia-Acacia auriculaeformis symbiotic association].

The effects of different levels of Cu2+ were studied individually on the growth of two Rhizobium strains and host plant growth, nodulation(%) and nitrogen fixation activity in A. auriculaeformis under solution culture conditions so as to explore a probability of utilization of the genus Acacia in revegetation of Cu(2+)-contaminated land. The results shows that Rhizobium sp.