Surface-mediated formation of PBDD/Fs from the high-temperature oxidation of 2-bromophenol on a CuO/silica surface

As a model brominated hydrocarbon that may form brominated dioxins, we studied the surface-mediated, oxidative thermal degradation of 2-bromophenol on a supported copper oxide catalyst in a 1 mm i.d., fused silica flow reactor at a constant concentration of 90 ppm over a temperature range from 250 to 550 degrees C. Observed products included: dibenzo-p-dioxin (DD), 1-monobromodibenzo-p-dioxin (1-MBDD), dibromodibenzo-p-dioxin (DBDD), tribromodibenzo-p-dioxin (TrBDD), 4-monobromodibenzofuran (4-MBDF), 2,4,6-tribromophenol, 2,4- and 2,6-dibromophenol, and polybrominated benzenes. The results are compared and contrasted with previous work on surface catalyzed oxidative thermal degradation of 2-chlorophenol as well as our own work with the surface-catalyzed pyrolytic thermal degradation of 2-bromophenol. Typically 20 to 200x higher yields of PBDDs are observed for 2-bromophenol than for the analogous PCDDs for 2-chlorophenol. However the anticipated PBDF, 4,6-DBDF, was not observed and 4-MBDF was observed at very low yields. Surprisingly, the maximum yields of PBDDs were observed at higher temperatures than under pyrolytic conditions. This is attributed to regeneration of the catalytic surface due to the presence of oxygen. Higher yields of polybrominated phenols and polybrominated benzenes were also observed than for the analogous chlorinated phenols and benzenes from the oxidation of 2-chlorophenol. This can be attributed to the ease of bromination over chlorination based on the higher abundance of bromine atoms present for 2-bromophenol than chlorine atoms present for 2-chlorophenol.     

Simultaneous recovery of copper and degradation of 2,4-dichlorophenoxyacetic acid in aqueous systems by a combination of electrolytic and photolytic processes

In mixed industrial effluent the presence of metal ions can retard the destruction of organic contaminants and the efficiency of recovery of the metal is reduced by the presence of the organic species. Results are presented for copper-2,4-dichlorophenoxyacetic acid (2,4-D) system in which both effects occur. An electrochemical cell alone can be used to recover copper in the pH range 1.5-4.5 but it is not capable of achieving complete disappearance of 2,4-D by anodic oxidation. A photolytic cell alone can achieve the destruction of 2,4-D at pH 3.5 but leaves copper in solution. A combined photolytic-electrochemical system using an activated carbon concentrator cathode achieves the rapid simultaneous destruction of 2,4-D and recovery of copper. Results are presented for the recovery of more than 90% copper from, and >99.9%, destruction of the organochlorine compound 2,4-D in, a solution containing 100 mg dm(-3) copper and 50 mg dm(-3) 2.4-D. The photolytic degradation of 2,4-D depends on the intensity of the UV-probe. Only 19% degradation is achieved after 8 h with the 150 W UV-probe but the corresponding value with the 400 W UV-probe is 100%. In the case of 150 W UV-probe the degradation of 2,4-D proceeds through the formation of 2,4-dichlorophenol and phenol. The concentration of these intermediates are very low in the case of 400 W UV-probe because the speed of the degradation of 2,4-D is very fast. The addition of TiO2 (1 g dm(-3)), as a semiconductor material, and H202 (1.5 g dm(-3)) as an oxidant, increases the photolytic degradation of 2,4-D.     

Kinetics of 2,4-dichlorophenol and 4-Cl-m-cresol degradation by Pseudomonas sp. cultures in the presence of glucose

Comparison of the ability of Pseudomonas sp. to degrade 2,4-dichlorophenol and 4-Cl-m-cresol in separate cultures in the presence of glucose, as a conventional carbon source, is reported. The specific growth rates at 0.1 mM 2,4-dichlorophenol and 4-Cl-m-cresol were estimated to be 0.181 and 0.154 h(-1), respectively, showing that Pseudomonas sp. is mainly inhibited by 4-Cl-m-cresol. The percentage of consumption ranges between 65% and 11% for 2,4-dichlorophenol and between 37% and 8% for 4-Cl-m-cresol, respectively, depending on its initial concentration. The dechlorination of the two compounds was investigated in the growth media and it was found that chloride liberation in the case of 2,4-dichlorophenol took place during the exponential phase of growth, followed by pH decrease from 6.1 to 5.8 at 0.1 mM. In contrast, in the case of 4-Cl-m-cresol chloride ion release was observed to a lesser extent, indicating the different metabolic pathway of 4-Cl-m-cresol. 2,4-Dichlorophenol and 4-Cl-m-cresol degradation followed a first-order kinetics model, whereas glucose consumption fitted well a zero-order kinetics model.     

Assessment of thyroid hormone activity of halogenated bisphenol A using a yeast two-hybrid assay

The thyroid hormone agonist/antagonist activities of halogenated derivatives of bisphenol A (BPA) were assessed using a yeast two-hybrid assay incorporating the human thyroid hormone α (TRα), both with and without possible metabolic activation by rat liver S9 preparation. In the absence of the rat liver S9 preparation, 3,3′,5,5′-tetrabromobisphenol A (TBBPA), 3,3′,5,5′-tetrachlorobisphenol A (TCBPA), and 3,3′,5-trichlorobisphenol A (3,3′,5-triClBPA) exhibited agonist activity, whereas 3-chlorobisphenol A (3-ClBPA), 3,5-dichlorobisphenol A (3,5-diClBPA), 3,3′-dichlorobisphenol A (3,3′-diClBPA), and BPA did not. The activities of TBBPA and TCBPA increased markedly (7.6-fold and 3.1-fold, respectively) after their metabolic activation with the rat liver S9 preparation. TBBPA, TCBPA, and 3,3′,5-triClBPA inhibited the binding of triiodothyronine (T3) to TRα at 2 × 10⁻⁵ M without rat liver S9 treatment and 4 × 10⁻⁶ M with rat liver S9 treatment, demonstrating their T3 antagonist activity. These results revealed that metabolic activation by rat liver S9 significantly increased the agonist/antagonist potential of some halogenated BPAs.     

The influence of pH on the degradation of phenol and chlorophenols by potassium ferrate

This paper presents information concerning the influence of solution pH on the aqueous reaction between potassium ferrate and phenol and three chlorinated phenols: 4-chlorophenol (CP), 2,4-dichlorophenol (DCP), 2,4,6-trichlorophenol (TCP). The redox potential and aqueous stability of the ferrate ion, and the reactivity of dissociating compounds, are known to be pH dependent. Laboratory tests have been undertaken over a wide range of pH (5.8-11) and reactant concentrations (ferrate:compound molar ratios of 1:1 to 8:1). The reactivity of trichloroethylene was also investigated as a reference compound owing to its non-dissociating nature. The extent of compound degradation by ferrate was found to be highly pH dependent, and the optimal pH (maximum degradation) decreased in the order: phenol/CP, DCP, TCP; at the optimal pH the degree of degradation of these compounds was similar. The results indicate that for the group of phenol and chlorophenols studied, the presence of an increasing number of chlorine substituent atoms corresponds to an increasing reactivity of the undissociated compound, and a decreasing reactivity of the dissociated compound.     

An unconventional approach to studying the reaction kinetics of the Fenton's oxidation of 2,4-dichlorophenoxyacetic acid

The Fenton's oxidation kinetics of herbicide 2,4-D at various [Fe(II)] and [H(2)O(2)] combinations was investigated and modelled through an unconventional approach. The reaction kinetics of 2,4-D degradation demonstrated a two-stage pattern of decay, where a very fast reactive stage was followed by a retardation stage due to the depletion of oxidants and to the competitive side-reactions of the intermediates (including 2,4-dichlorophenol, chlorohydroquinone and 2,6-dichlororesorcinol). A model characterized by two newly established constants, the initial decay rate and the maximum oxidative capacity, was proposed and proven capable of describing the two-stage process, which cannot easily be described by conventional first- or second-order kinetics approaches.     

Photoinduced transformation processes of 2,4-dichlorophenol and 2,6-dichlorophenol on nitrate irradiation

2,4-Dichlorophenol (2,4-DCP) and 2,6-dichlorophenol (2,6-DCP) undergo oxidation, nitrosation and nitration in the presence of nitrate under UV irradiation. Nitration is favoured under acidic conditions, most likely because HNO(2) is formed on nitrate photolysis. The most likely photonitration pathway is the reaction between radiation-excited dichlorophenols (DCP*) and HNO(2). HNO(2) is also able to nitrate DCP in the dark with elevated yields. Irradiation also causes DCP direct photolysis, which is more efficient for the dichlorophenolate anions. The photolysis of the dichlorophenols and that of the dichlorophenolates also produce different intermediates, by dechlorination in the former and ring contraction in the latter case.     

Ring test of a method for assessing the phototransformation of chemicals in water

Seven types of apparatus have been used to measure the quantum yields for direct phototransformation in water of 4 chemicals (pentachlorophenol; 2,4-dichlorophenol; 3,4-dichloroaniline; 4-nitrophenol) under polychromatic (12 laboratories) and monochromatic (3 laboratories) light, according to a common test protocol. The results with both types of light were in good agreement. The reproducibility and accuracy of quantum yields obtained with the ECETOC/University of Clermont-Ferrand apparatus with polychromatic light (6 laboratories) were similar to or better than those obtained with monochromatic light. A disadvantage of the method with polychromatic light is that the calculation is more complicated, but this can be overcome by the use of a desk-top computer. On the other hand experiments with polychromatic light permit the determination of quantum yields of substances of low photoreactivity.     

A standardized method for assessment of oxidative transformations of brominated phenols in water

The term persistence has been used to confusion since it is used as a conceptual parameter without a uniform definition. Work is therefore being done in order to unite ideas and describe persistence based on the chemical reactivity and chemico-physical properties of compounds via investigation of the main degradation pathways in the environment; photolysis, hydrolysis-substitution-elimination (hse), oxidation, reduction and radical reactions. The present work is focused on developing a method to determine oxidative degradation rates of chemicals and thereby measurement of their susceptibility to undergo oxidation reactions. The method based on potassium permanganate works well for water soluble compounds and is easy, robust, inexpensive and reproducible. By using the method and varying the analysed substances, the degradation rates for brominated phenols, two chlorinated phenols and high volume production compounds such as tetrabromobisphenol A (TBBPA), tetrachlorobisphenol A (TCBPA) and bisphenol A (BPA) have been determined at pH 7.6+/-0.2. The reaction rates of the two halogenated BPA's are particularly fast, giving half-lives in seconds. The other test compounds have slower reaction rates but easily measured under the reaction conditions applied. The reactions are temperature dependent. There is evidence that pK(a) and the substitution pattern of the halogens affects the rate of the reactions. The method is robust and applicable for reaction rate constant measurements of present and potential future environmental contaminants.     

Modeling the quantum yields of herbicide 2,4-D decay in UV/H2O2 process

The photodecay of herbicide 2,4-D in a hydrogen peroxide-aided photolysis process was studied and modeled. The decay rate of 2,4-D was known to be low in the natural environment, but rate improvement was achieved in an H2O2/UV system. The 2,4-D decay quantum yields under ultraviolet (UV) light at 253.7 nm increased from 4.86 x 10(-6) to 1.30 x 10(-4) as the ratio of [H2O2]/[2,4-D] increased from 0.05 to 12.5. Apparently, in the presence of UV light, the decay rate of 2,4-D could be greatly improved as the concentration of hydrogen peroxide increased. However, the efficiency of 2,4-D photodecay was retarded if the concentration of H2O2 was overdosed, because the excess hydrogen peroxide consumes the hydroxyl radicals (HO*) in the solution, resulting in a much weaker oxidant HO2*. The decay of 2,4-D was also pH dependent. A ranking of acid (highest), base (middle) and neutral (lowest) was observed owing to the property change of reactants and the shifting of dominant mechanisms among photolysis, photohydrolysis and chemical oxidation. Two mathematical models were proposed to predict the quantum yield for various [H2O2]/[2,4-D] ratios and initial pH levels, in which very good correlation was found for the ranges of regular application.     

Aerobic granulation for 2,4-dichlorophenol biodegradation in a sequencing batch reactor

Development of aerobic granules for the biological degradation of 2,4-dichlorophenol (2,4-DCP) in a sequencing batch reactor was reported. A key strategy was involving the addition of glucose as a co-substrate and step increase in influent 2,4-DCP concentration. After operation of 39d, stable granules with a diameter range of 1-2mm and a clearly defined shape and appearance were obtained. After granulation, the effluent 2,4-DCP and chemical oxygen demand concentrations were 4.8mgl(-1) and 41mgl(-1), with high removal efficiencies of 94% and 95%, respectively. Specific 2,4-DCP biodegradation rates in the granules followed the Haldane model for substrate inhibition, and peaked at 39.6mg2,4-DCPg(-1)VSS(-1)h(-1) at a 2,4-DCP concentration of 105mgl(-1). Efficient degradation of 2,4-DCP by the aerobic granules suggests their potential application in the treatment of industrial wastewater containing chlorophenols and other inhibitory chemicals.     

Toxicity of chlorinated phenoxyacetic acid herbicides in the experimental eukaryotic model Saccharomyces cerevisiae: role of pH and of growth phase and size of the yeast cell population

The inhibitory effect of the herbicides 2-methyl-4-chlorophenoxyacetic acid (MCPA) and 2,4-dichlorophenoxyacetic acid (2,4-D) in Saccharomyces cerevisiae growth is strongly dependent on medium pH (range 2.5-6.5). Consistent with the concept that the toxic form is the liposoluble undissociated form, at values close to their pK(a) (3.07 and 2.73, respectively) the toxicity is high, decreasing with the increase of external pH. In addition, the toxicity of identical concentrations of the undissociated acid form is pH independent, as observed with 2,4-dichlorophenol (2,4-DCP), an intermediate of 2,4-D degradation. Consequently, at pH values above 3.5 (approximately one unit higher than 2,4-D pK(a)), 2,4-DCP becomes more toxic than the original herbicide. A dose-dependent inhibition of growth kinetics and increased duration of growth latency is observed following sudden exposure of an unadapted yeast cell population to the presence of the herbicides. This contrasts with the effect of 2,4-DCP, which essentially affects growth kinetics. Experimental evidences suggest that the acid herbicides toxicity is not exclusively dependent on the liposolubility of the toxic form, as may essentially be the case of 2,4-DCP. An unadapted yeast cell population at the early stationary-phase of growth under nutrient limitation is significantly more resistant to short-term herbicide induced death than an exponential-phase population. Consequently, the duration of growth latency is reduced, as observed with the increase of the size of the herbicide stressed population. However, these physiological parameters have no significant effect either on growth kinetics, following growth resumption under herbicide stress, or on the growth curve of yeast cells previously adapted to the herbicides, indicating that their role is exerted at the level of cell adaptation.     

Laccase mediated biodegradation of 2,4-dichlorophenol using response surface methodology

The effects of different environmental parameters, i.e., pH, temperature, time and enzyme concentration on the biodegradation of 2,4-dichlorophenol (2,4-DCP) in aqueous phase was evaluated with laccase from Pleurotus sp. using response surface methodology (RSM) in the present investigation. The Box-Behnken design of experiments was used to construct second order response surfaces with the investigated parameters. It was observed that the maximum degradation efficiency of approximately 98% was achieved at pH 6, temperature of 40 degrees C, time 9h and an enzyme concentration of 8IUml(-1). The adequacy of the model was confirmed by the coefficient of multiple regression, R(2) and adjusted R(2) which were adjudged to be 87.9% and 73.6%, respectively indicating a reasonably good model for practical implementation. Despite the fact that many successful attempts have been taken in the past for biodegradation of 2,4-DCP using whole cells, the present study emphasizes the fastest biodegradation of 2,4-DCP, a potent xenobiotic compound.     

Degradation of chlorophenols in aqueous media using UV XeBr excilamp in a flow-through reactor

2-Chlorophenol (2-CP), 4-chlorophenol (4-CP) and 2,4-dichlorophenol (2,4-DCP) at initial concentrations of 10, 20, 50 and 100mg l(-1) were degraded in aqueous media by direct UV photolysis using dielectric barrier discharge XeBr( *) excilamp (283nm) in a flow-through photoreactor. The pseudo-first order rate constants were highest and half-life times were lowest for 4-CP. The rates of photolysis under the experimental conditions increased in the order: 2-CP<2,4-DCP<4-CP. The intermediates of photolysis were identified by GC-MS and HPLC. The evolution of hydroquinone and p-benzoquinone as major intermediates of 4-CP photolysis was monitored.     

Coupling of 2,4,6-trinitrotoluene (TNT) metabolites onto humic monomers by a new laccase from Trametes modesta

During degradation of trinitrotoluene (TNT) by Trametes modesta, addition of humic monomers prevented the accumulation of all major stable TNT metabolites (aminodinitrotoluenes [AMDNT]) by at least 92% in the presence of 200 mM ferulic acid and guaiacol. Acute toxicity tests with individual TNT metabolites and in T. modesta cultures supplemented with 200 microM TNT demonstrated that the TNT biodegradation process lead to less toxic metabolites. Toxicity decreased in the order TNT>4-HADNT (4-hydroxylaminodinitrotoluene)>2-HADNT>2,6-DNT (2,6-dinitrotoluene)>2',2',6,6-azoxytetranitrotoluene>4-AMDNT>2-AMDNT>2,4-diamninonitrotoluene (2,4-DAMNT) while 2,4-DNT and 2,6-DAMNT were the least toxic. Ferulic acid is the best candidate for immobilization TNT biodegradation metabolites since it prevented the accumulation of AMDNTs in cultures during TNT biodegradation and its products were less toxic. All humic monomers were very effective in immobilizing 2-HADNT [100%], 4-HADNT [100%] and 2,2,6,6-azoxytetranitrotoluene [100%]. Two distinct laccase isoenzymes (LTM1 and LTM2) potentially involved in immobilization of TNT degradation products were purified to electrophoretic homogeneity. LTM1 and LTM2 have molecular weights of 77.6 and 52.5 kDa, are 18% and 24% glycosylated, have pI values of 3.6 and 4.2, respectively. Both enzymes oxidized all the typical laccase substrates tested. LTM1 showed highest kinetic constants (K(m)=0.03 microM; K(cat)=8.8 4x 10(7)s(-1)) with syringaldazine as substrate.     

Reductive transformation of 2,4-dichlorophenoxyacetic acid by nanoscale and microscale Fe3O4 particles

Reductive transformation of 2,4-dichlorophenoxyacetic acid (2,4-D) by nanoscale and microscale Fe₃O₄ was investigated and compared. Disappearance of the parent species and formation of reaction intermediates and products were kinetically analyzed. Results suggest that the transformation of 2,4-D followed a primary pathway of its complete reduction to phenol and a secondary pathway of sequential reductive hydrogenolysis to 2,4-dichlorophenol (2,4-DCP), chlorophenol (2-CP, 4-CP) and phenol. About 65% of 2,4-D with initial concentration of 50 μ M was transformed within 48 h in the presence of 300 mg L^?1 nanoscale Fe₃O₄, and the reaction rates increased with increasing dosage of nanoscale Fe₃O₄. The decomposition of 2,4-D proceeded rapidly at optimum pH 3.0. Chloride was identified as a reduction product for 2,4-D in the magnetite–water system. Reductive transformation of 2,4-D by microscale Fe₃O₄ was slower than that by nanoscale Fe₃O₄. The reactions apparently followed pseudo-first-order kinetics with respect to the 2,4-D transformation. The degradation rate of 2,4-D decreased with the increase of initial 2,4-D concentration. In addition, anions had a significant adverse impact on the degradation efficiency of 2,4-D.     

Anaerobic degradation of brominated flame retardants in sewage sludge

Tetrabromobisphenol A (TBBPA), hexabromocyclododecane (HBCD), and decabromodiphenyl ether (DecaBDE) are high production volume chemicals used as flame retardants in plastics for products such as electronic equipment, insulation panels, and textiles. The environmental safety of brominated flame retardants, especially their persistence, bioaccumulation, and toxicity is a controversial topic. Here, we studied and compared the degradation of TBBPA, HBCD, and DecaBDE under anaerobic conditions in digested sewage sludge. The half-lives of TBBPA and a technical HBCD mixture were 0.59 and 0.66 d, respectively. The fact that (+/-)-alpha-HBCD exhibited an almost doubled half-life compared to (+/-)-beta-HBCD and (+/-)-gamma-HBCD is an important finding with respect to the discussion on the persistence of individual HBCD stereoisomers and the recent reports on strong relative enrichment of alpha-HBCD in biota. We found no statistically significant enantioselective degradation of alpha-, beta-, or gamma-HBCD. Half-lives of TBBPA and a technical HBCD mixture were not dependent on the presence of additional nutrients or primers. Concentrations of TBBPA and a technical HBCD mixture decreased also in sterile control samples, however, at a rate that was more than a factor of 50 smaller than in incubations under non-sterile conditions. Compared to TBBPA and a technical HBCD mixture, DecaBDE exhibited a much longer half-life of 7 x 10(2)d in the same system. Pseudo-first-order degradation rate constants decreased according to the following sequence: TBBPA congruent with(+/-)-gamma-HBCD congruent with(+/-)-beta-HBCD>(+/-)-alpha-HBCD>DecaBDE. Preliminary investigations suggest that degradation of TBBPA, HBCD, and DecaBDE occurs in full-scale anaerobic digesters, as well.     

Removal of 2,4-dichlorophenol by suspended and immobilized Bacillus insolitus

In this experiment, Bacillus insolitus was isolated and selected from a mixed culture that have been acclimated to chlorophenols. Decomposition of chlorophenolic compounds will be studied using this pure culture in both suspended and immobilized form. The results are: at lower initial concentrations of 2,4-dichlorophenol (10-50 mg/l), immobilized Bacillus insolitus shows a higher removal of 2,4-dichlorophenol than Bacillus insolitus in suspended growth. When the 2,4-dichlorophenol concentration becomes higher (50-200 mg/l), both immobilized and suspended Bacillus insolitus have approximately the same efficiency for removal of 2,4-dichlorophenol. Higher concentrations of 2,4-dichlorophenol are inhibitive to the growth of either suspended or immobilized Bacillus insolitus. At lower concentrations of 2,4-dichlorophenol, immobilized mixed culture may have the same removal efficiency of 2,4-dichlorophenol as immobilized pure culture of Bacillus insolitus. But with regard to the overall 2,4-dichlorophenol removal efficiency, immobilized pure culture is considered to be superior to immobilized mixed culture.     

Removal of dinitrotoluenes from water via reduction with iron and peroxidase-catalyzed oxidative polymerization: a comparison between Arthromyces ramosus peroxidase and soybean peroxidase

A two-step process for the removal of dinitrotoluene from water is presented: zero-valent iron reduction is coupled with peroxidase-catalyzed polymerization of the resulting diaminotoluenes (DAT). The effect of pH was examined in the reduction step: at pH 6 the reaction occurred much more rapidly than at pH 8. In the second step, optimal pH and substrate ratio, minimal enzyme concentration and effect of polyethylene glycol (PEG) as an additive for greater than 95% conversion of DAT, over a 3h reaction period were determined using high performance liquid chromatography. Two enzymes were investigated and compared: Arthromyces ramosus peroxidase (ARP) and soybean peroxidase (SBP). The optimal pH values were 5.4 and 5.2 for ARP and SBP, respectively, but SBP was more resistant to mild acid whereas ARP was more stable in neutral solutions. SBP was found to have a greater hydrogen peroxide demand (optimal peroxide/DAT molar ratio for SBP: 2.0 and 3.0 for 2,4-diaminotoluene (2,4-DAT) and 2,6-diaminotoluene (2,6-DAT), respectively; for ARP: 1.5 and 2.75 for 2,4-DAT and 2,6-DAT, respectively) but required significantly less enzyme (0.01 and 0.1 U ml(-1) for 2,4-DAT and 2,6-DAT, respectively) to convert the DAT than ARP (0.4 and 1.5 U ml(-1) for 2,4-DAT and 2,6-DAT, respectively). PEG was shown to have no effect upon the degree of substrate conversion for either enzyme.     

Levels and spatial distribution of chlorophenols - 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol in surface water of China

The chlorophenol pollutants (CPs) have been reported to occur at relatively high concentrations in some Chinese waters. To map the distribution of CPs in the surface water throughout China, samples were collected from over 600 sites in the seven major watersheds and three drainage areas. The samples were analyzed for the representative CPs including 2,4-dichlorophenol, 2,4,6-trichlorophenol, and pentachlorophenol. In general, it was observed that 2,4-dichlorophenol and 2,4,6-trichlorophenol were more frequently detected at higher concentrations in the rivers of North China compared with those of South China. High concentration sites of 2,4-dichlorophenol and 2,4,6-trichlorophenol mainly occurred in the Yellow River, Huaihe River, and Haihe River watersheds, while pentachlorophenol contamination mainly occurred in the Yangtze River watershed. The pentachlorophenol was the most ubiquitous CPs being detected in 85.4% of samples (median=50.0ngl(-1); range <1.1-594.0ngl(-1)), 2,4-dichlorophenol was detected in 51.3% (median=5.0ngl(-1); range <1.1-19960.0ngl(-1)) and the 2,4,6-trichlorophenol was detected in 54.4% of water samples (median=2.0ngl(-1), range <1.4-28650.0ngl(-1)). The results of this investigation indicated that 2,4-dichlorophenol and 2,4,6-trichlorophenol contaminations of Yellow River, Huaihe River, and Haihe River watersheds were of particular concern, while the pentachlorophenol contamination mainly occurred in the Yangtze River watershed. These results showed that CPs contamination in the surface water of China was similar to other places of the world.