Concentration Of TCP Research Articles

Photochemical reactions between superoxide ions and 2,4,6-trichlorophenol in atmospheric aqueous environments

The superoxide anion radical (O2•−) is an important reactive oxygen species (ROS), and participates in several chemical reactions and biological processes. In this report, O2•− was produced by irradiating riboflavin in an O2-saturated solution by ultraviolet light with a maximum emission at 365 nm. And the contribution of O2•− to 2, 4, 6-trichlorophenol (2, 4, 6-TCP) was investigated by a combination of laser flash photolysis (LFP) and UV light steady irradiation technique. The results of steady-state experiments showed that the photochemical decomposition efficiency of 2, 4, 6-TCP decreased with the increase of the initial concentration of TCP, while the increase of pH and riboflavin concentration promoted the photochemical reaction. The second-order rate constant of the reaction of the superoxide anion radical with 2, 4, 6-TCP phenoxyl radical (TCP•) was (9.9 ± 0.9) × 109 L mol−1 s−1 determined by laser flash photolysis techniques. The dechlorination efficiency was 61.5% after illuminating the mixed solution with UV light for 2 h. The conversion of 2, 4, 6-trichlorophenol was accompanied by the reductive dechlorination process induced by superoxide ions. The main steady products of the photochemical reaction of 2, 4, 6-TCP with O2•− were 2, 6-dichlorophenol (DCP), 2, 6-dichloro-1, 4-benzoquinone (DCQ) and 2, 6-dichlorohydroquinone (DCHQ). The addition process was the preferred process in the total reaction of superoxide ions with 2, 4, 6-TCP phenoxyl radical. These results indicated that the reaction of 2, 4, 6-TCP with O2•− was a potential conversion pathway and contribute to atmospheric aqueous phase chemistry.

Temporal and Spatial Characteristics of Total Phosphorus in the Middle and Lower Yangtze River Mainstem Under New Water and Sediment Conditions

After the completion of the Three Gorges Reservoir and the upstream reservoir group of the Yangtze River, new water and sediment conditions appeared in the middle and lower reaches of the Yangtze River, and its influence on the phosphorus concentrations in water has attracted much attention. Therefore, the spatial and temporal distributions of total phosphorus (TP) concentrations in the middle and lower reaches of the mainstem under the new water and sediment conditions were studied. The results show that:① after the construction of the Three Gorges Reservoir, the concentrations of TCP (samples were allowed to settle for 30 min) in the middle and lower reaches of the Yangtze River fluctuates between 0.10 and 0.15 mg·L-1, and generally increased during 2004-2010 and then decreased during 2014-2019, and increases along the flow direction. The concentrations of dissolved total phosphorus (TDP) have slowly increased with time. ② The settleable solids influence the phosphorus content to varying degrees. The median values of TCP/TP ratio in Nanjinguan, Hankou, and 23 km below Wusongkou, are 0.900, 0.720, and 0.609, respectively, which decreases successively from upstream to downstream. The proportion of TPP (total particulate phosphorus)/TP shows an increasing trend along the flow direction. The median values of TPP/TP ratios in Nanjinguan, Hankou, and 23 km below Wusongkou were 0.439, 0.567, and 0.738, respectively. ③ According to the "Environmental quality standard for surface water GB 3838-2002", the water quality was assessed using TCP concentrations, and the assessment results showed that the water quality of the middle and lower reaches of the Yangtze River was generally good. However, considering the influence of settleable solids, the water quality categories assessed based on TP concentrations would be worse, especially near estuaries. ④ In the middle and lower reaches of Yangtze River, there is little difference in the phosphorus concentration of different monitoring sites in the upper section of main stream; however, the difference is obvious near the estuary. ⑤ The concentration of TCP in the coastal waters of the urban river section of the middle and lower reaches of the Yangtze River is significantly higher than that of the main channel, and there are obvious coastal pollution zones in the coastal waters of the urban river section.

Enhancing photodegradation of 2,4,6 trichlorophenol and organic pollutants in industrial effluents using nanocomposite of TiO2 doped with reduced graphene oxide

The present study investigated the applicability of synthesized TiO2@rGO photocatalyst for degradation of organic pollutants from industrial wastewater and photodegradation of 2,4,6 trichlorophenol (2,4,6 TCP) under UV irradiation. The results showed a high reduction in COD and TOC values of industrial effluents reaching 85% and 82%, respectively. Effects of several factors on the photodegradation process such as pH of the solution, TCP initial concentration, irradiation time and catalyst dose were studied. The results proved a high relationship between pH of the solution and the adsorption capacity. The maximum degradation ratio reached up to 90% at pH 6 at the initial concentration of TCP of 50 mg/l when exposed to UV irradiation for 180 min and 0.4 g/L catalyst dose. Kinetic studies indicated that the adsorption process obeyed pseudo-second order model with qe values ranging between 22.0 and 22.7 mg/L and R2 > 0.99. Isotherm model studies showed a good fit with the Langmuir model better than Freundlich model.

Two Step Electrochemical Deposition Of Palladium And Polyaniline On Graphene Dispersed Glassy Carbon electrode For Electrochemical Analysis Of Pesticide

Herein we reported graphene (Gr) was firstly fabricated on glassy carbon electrode (GCE) by drop casting method, subsequently polyaniline (PAN) and Palladium (Pd) nanocomposite were fabricated by two-step electrochemical depositing process on graphene dispersed glassy carbon electrode (Gr/GCE) and used as an electrochemical sensor for determination of Tetrachlorvinphos (TCP < /span>) pesticide in vegetables. Here most of the work has been focused on the preparation and characterization of modified electrode with cyclic voltammetry (CV) and scanning electron microscopy (SEM). The modified composite electrode unveiled significantly good voltammetric response on TCP. Square wave voltammetry (SWV) was used for determination of TCP at optimized conditions such as square wave frequency, step potential, pH of buffer, applied sample volume, accumulation potential and accumulation time. The well-defined reduction (C=C) peaks were acquired over the potential maximum around at -1.3V in acidic medium in Briton-Robinson (B-R) buffer solution at low current values. The low current peaks were obtained over the concentration of TCP at 1.5×10 -6 M with lower detection limit and limit of quantifications are 5.62×10 -10 M and 2.65×10 -8 respectively. The composite modified electrode showed good stability and reproducibility. The proposed method was successfully applied for the present investigation with a great assure as an economical and simple sensor with furthermore a shorter analysis time and further the sensor also used for heavy metal detection in real samples.

Multilayer coatings formed on titanium alloy surfaces by plasma electrolytic oxidation-electrophoretic deposition methods

Tricalcium phosphate was deposited on the surface of anodized titanium alloys (Ti-6Al-7Nb, Ti-13Nb-13Zr and Ti-15Mo) using the electrophoretic technique (EPD). The multilayer coatings were formed by a three-step experiment. The influences of voltage (step I), time (step II) and concentration of TCP in the suspensions (step III) on the ceramic particle deposition was investigated. The appropriate conditions were determined for each titanium alloy surface modification. The total thickness of the anodized titanium alloys increased, the surface roughness decreased and the wettability increased after TCP particle deposition. A TL-XRD investigation showed that the multilayer coatings were mainly amorphous. All the coatings adhered well to the substrate. The surface modifications increased the corrosion resistance in Ringer’s solution, particularly for the Ti-15Mo alloy. In addition, the multilayer coatings formed on this titanium alloy exhibited the best cytocompatibility with MG-63 osteoblast-like cells.

Photochemical fate and photocatalysis of 3,5,6-trichloro-2-pyridinol, degradation product of chlorpyrifos.

In this study we have focused on 3,5,6-trichloro-2-pyridinol (TCP), degradation product of chlorpyrifos. Photolysis experiments were conducted in order to elucidate its degradation mechanism. Identification of products was performed using the LC-MS technique. To evaluate the mineralization efficiency, TiO2 photocatalytic study was performed. Under photolytic experimental conditions, the concentration of TCP after 120 min of irradiation reached 5.9 ± 1.5% of the initial concentration, while chloride concentration reached approximately 73% of total chloride concentration. The TOC measurements after 120 min of photocatalytic degradation experiment revealed high mineralization rate, i.e. 53.6 ± 1.9%, while chloride concentration reached 26.6 mg L(-1) what means almost quantitative transformation of organic chlorine into chloride. TIC chromatogram (ESI, negative ion mode) of the reaction mixture after 30 min of irradiation revealed the presence of several peaks. One of them has already been reported previously. Two other products have been identified in this study for the first time. They have been formed by radical attack of the reactive OH(•) species on the carbonyl group followed by the corresponding N-C or C-C bond cleavages and recyclization with formation of the pyrrol structures substituted with carboxylic groups. Both deprotonated molecules easily lose CO2 in ESI conditions.

Nano Sized C-doped TiO2 As A Visible-light Photocatalyst For The Degradation Of 2,4,6- Trichlorophenol

Nanosized bare and carbon (C)-doped TiO2 were prepared using reverse micro-emulsion method. Synthesized powders were characterized with the help of X-ray diffractometer (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscope (EDX) and UV-visible spectrophotometer. EDX study reveals that as calcination temperature increases amount of C on TiO2 decreases. SEM and TEM images show that TiO2 particles are spherical in shape and after increasing the calcination temperature size of particle increases. Particle size of TiO2 obtained from TEM data varies between 10 to 17nm. Visible light photocatalytic degradation of 2,4,6-trichlorophenol (TCP) aqueous solution was carried out using nanosized bare as well as C-doped TiO2. UV-visible spectrophotometer and high pressure liquid chromatography (HPLC) techniques were used to analyze the concentration of TCP during the degradation process. In presence of visible light C-doped TiO2 obtained after calcination of precursor at 300°C shows better photocatalytic activity. Parameters affecting the photocatalytic process such as calcination temperature, amount of catalyst and TCP concentration are investigated. TCP photocatalytic degradation process was optimized. It is observed that to get better photocatalytic activity optimum amount of photocatalyst and concentration of TCP solution required are 1.0 gL -1 and 20 mg L -1 respectively. Reusability study indicates that C doped TiO2 prepared in the present work is highly stable and reusable photo catalyst.

Impact of chlorophenols on microbiota of an unpolluted acidic soil: microbial resistance and biodegradation

The impact of 2-monochlorophenol (MCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP) on the microbial community of an acidic forest soil was studied under controlled laboratory conditions by spiking microcosms with the pollutants at concentrations ranging from 0.1 to 5000 mg kg(-1). A decrease in the cumulative respirometric values and changes in the bacterial and fungal community composition were detected at 1000 mg MCP kg(-1), 100 mg TCP kg(-1) and 100 and 1000 mg PCP kg(-1). However, drastic effects on the microbial community were revealed only at higher concentrations of MCP and TCP, although the toxicity of PCP was expected to be stronger. The acidic condition of the soil presumably reduces bioavailability of PCP, leading to less pronounced effects than the other pollutants. This finding highlights the consideration of pollutant bioavailability in each environment to adequately assess contamination effects. Twenty-two different chlorophenol-resistant and potentially degrading microorganisms were isolated from highly polluted microcosms. The most resistant isolates were related to Burkholderia arboris, Bacillus circulans, Paenibacillus taichungensis, Luteibacter rhizovicina and Janibacter melonis. These isolates also showed the capacity to reduce the concentration of TCP or PCP between 15% and 35% after 5 days of incubation (initial concentration of 50 mg L(-1)). The isolate related to B. circulans is an atypical case of a member of the Firmicutes group for which chlorophenol-degrading capacities have been described.

Modulation of steroidogenic gene expression and hormone synthesis in H295R cells exposed to PCP and TCP

Chlorophenols (CPs) have been suspected to disrupt the endocrine system and thus affect human and wildlife reproduction but less is known about the underlying mechanism. In this study, we investigated the effects of pentachlorophenol (PCP) and 2,4,6-trichlorophenol (TCP) on human adrenocortical carcinoma cell line (H295R). The H295R cells were exposed to environmentally relevant concentration (0.0, 0.4, 1.1, 3.4 μM) of PCP and TCP for 48 h, and expression of specific genes involved in steroidogenesis, including cytochrome P450 ( CYP11A, CYP17, CYP19), 3βHSD2, 17βHSD4 and StAR was quantitatively measured using real-time polymerase chain reaction. The selected gene expressions were significantly down-regulated compared with those in the control group. Exposure to PCP and TCP significantly decreased production of both testosterone (T) and 17β-estradiol (E2). Furthermore, a dose-dependent decrease of cellular cAMP was observed in H295R cells exposed to both PCP and TCP. A time-course study revealed that the observed selected steroidogenic gene expressions and protein abundance ( StAR) are consistent with reduced cellular cAMP concentrations. The results showed that PCP and TCP may inhibit steroidogenesis by disrupting cAMP signaling. The research indicates that H295R cells can be used as an in vitro model for endocrine disruption assay for chlorophenols and the mechanism involvement of disturbing cAMP signaling.

The microbiota of an unpolluted calcareous soil faces up chlorophenols: Evidences of resistant strains with potential for bioremediation

To highlight the effects of a variety of chlorophenols (CP) in relation to the response of an indigenous bacterial community, an agricultural Mediterranean calcareous soil has been studied in microcosms incubated under controlled laboratory conditions. Soil samples were artificially polluted with 2-monochlorophenol (MCP), 2,4,6-trichlorophenol (TCP) and pentachlorophenol (PCP), at concentrations ranging from 0.1 up to 5000 mg kg −1. Both activity and composition of the microbial community were assessed during several weeks, respectively, by respirometric methods and PCR-DGGE analysis of extracted DNA and RNA. Significant decreases in soil respirometric values and changes in the bacterial community composition were observed at concentrations above 1000 mg kg −1 MCP and TCP, and above 100 mg kg −1 PCP. However, the persistence of several active bacterial populations in soil microcosms contaminated with high concentration of CP, as indicated by DGGE fingerprints, suggested the capacity of these native bacteria to survive in the presence of the pollutants, even without a previous adaptation or contact with them. The isolation of potential CP degraders was attempted by culture plating from microcosms incubated with high CP concentrations. Twenty-three different isolates were screened for their resistance to TCP and PCP. The most resistant isolates were identified as Kocuria palustris, Lysobacter gummosus, Bacillus sp. and Pseudomonas putida, according to 16S rRNA gene homology. In addition, these four isolates also showed the capacity to reduce the concentration of TCP and PCP from 15% to 30% after 5 d of incubation in laboratory assays (initial pollutant concentration of 50 mg L −1). Isolate ITP29, which could be a novel species of Bacillus, has been revealed as the first known member in this bacterial group with potential for CP bioremediation applications, usually wide-spread in the soil natural communities, which has not been reported to date as a CP degrader.

Sensitivity of Different Cytotoxic Responses of Vero Cells Exposed to Organic Chemical Pollutants and their Reliability in the Bio-toxicity Test of Trace Chemical Pollutants

To find a sensitive cytotoxic response to reflect the bio-toxicity of trace organic pollutants, the sensitivity and reliability of morphological change and proliferation inhibition of Vero cells exposed to 2, 4, 6-trichlorophenol (TCP) and the leachate from products related to drinking water (PRDW) were compared, and the mechanism of the morphological change in Vero cells exposed to chemical pollutants was studied. Vero cells were treated by different concentration of TCP and the leachate from PRDW. Methylthiazol-2-yl-2, 5-diphenyl tetrazolium bromide (MTT) assay was carried out for proliferation inhibition. Bioluminescence method was carried out as another method to test the toxicity of TCP. Flow Cytometry assay was used to test cell Apoptosis and damage of cell-membrane. 0.25 mg/L TCP had an effect on cell morphology, and the proportion of morphologically changed cells increased with increasing TCP concentration. At low TCP concentrations, inhibition of cell proliferation did not seem to correlate to TCP concentration, and was negative when TCP concentration was <1.0 mg/L. After exposure to leachate from PRDW extracted at different temperatures, the percentage of morphologically changed cells increased with extracting temperature, but the inhibition of cell proliferation failed to reflect the correlation between extracting temperature and proliferation inhibition of Vero cells. Although the Sensitivity of bioluminescence method seems to be similar to morphological change in Vero cells, the bacterial in this method is not homologous enough with human body cells to reflect the toxicity to human body. These imply cell morphological change is a more sensitive and reliable method to reflect bio-toxicity of organic pollutants than proliferation inhibition. Flow cytometry analysis and cell rejuvenation experiments indicated cell membrane damage, which results in cell morphological change, was an early and sensitive cytotoxic response comparing with necrosis. These results indicated that the cell membrane toxicity represented by morphological changes is a more sensitive and reliable method to indicate the composite bio-toxicity of trace chemicals than proliferation inhibition, inhibition on bioluminescence and necrosis. Nevertheless, the quantification of morphological change should be studied further.

Reaction Kinetics and Mechanisms for Hydrolysis and Transesterification of Triglycerides on Tungstated Zirconia

Hydrolysis and transesterification are two reactions which can occur during the synthesis of biodiesel. An Investigation of the mechanistic pathways in hydrolysis and transesterification were carried out at a relatively high temperature (100–130 °C) and moderate pressures (120–180 psi) with tricaprylin and water for hydrolysis or methanol for transesterification using a tungstated zirconia catalyst in a batch reactor. It was found that upon increasing the concentration of TCp, the reaction rates for both hydrolysis and transesterification increased at all conditions. In contrast, water inhibited the reaction rate of hydrolysis by poisoning the active sites. For transesterification, the apparent reaction order of methanol evolved from positive to negative as the concentration of methanol relative to TCp increased. Using a reaction model discrimination procedure, it was found that hydrolysis on WZ could be successfully described by an Eley–Rideal single site mechanism with adsorbed TCp reacting with bulk phase water. The mechanistic pathway for transesterification also seems to follow a similar mechanism, identical to the one previously proposed for transesterification on a solid acid catalyst (SiO2-supported Nafion-SAC-13) at lower temperature (60 °C).

Adsorption of 2,4,6-trichlorophenol by multi-walled carbon nanotubes as affected by Cu(II)

Adsorption equilibrium of 2,4,6-trichlorophenol (TCP) on multi-walled carbon nanotubes (MWCNTs) was investigated to explore the possibility of using MWCNTs for concentration, detection and removal of TCP from contaminated water. The adsorption of TCP on MWCNTs at pH 4 was nonlinear, reversible and best fit by a Polanyi–Manes model. Oxidation treatment increased surface area and introduced hydrophilic carboxylic groups to the defect sites of MWCNTs, hence increased the sorption of TCP and Cu(II) individually. Cu(II) suppressed the sorption of TCP on oxidized MWCNTs15A, but had little effect on as-grown MWCNTs15. TCP had no influence on Cu(II) sorption to either. The mechanisms of Cu(II) suppression effect on TCP adsorption are ascribed to the formation of surface complexes of Cu(II), which was verified by X-ray absorption spectroscopy. Cu(II) exerts a cross-linking effect of functional groups on adjacent tubes, creating a more tightly knit bundle and suppressing the condensation of TCP in the pore spaces between the tubes. The large hydration sphere around surface complexes of Cu(II) may also intrude or shield hydrophilic sites, leading to the “crowding out” of TCP around the Cu(II)-complexed sites.

Kinetics of the aqueous‐phase reaction between ozone and 2,4,6‐trichlorophenol

AbstractA wetted‐sphere absorber was used to measure absorption rates of ozone into aqueous‐buffered solutions of 2,4,6‐trichlorophenol (TCP). Gas consisting of approximately 2.5% ozone in oxygen was contacted with aqueous‐buffered TCP solution flowing over a sphere in a laminar liquid film. Absorption data were obtained by measuring the change in the liquid‐phase concentration of TCP from the inlet to the outlet of the absorber. A rigorous numerical model for this diffusion/reaction process was used to analyze the absorption data to determine the second‐order rate constant of the reaction between ozone and TCP at 15–35°C and pH 2 and 7. The kinetic data indicate that the rate‐limiting step for the reaction of aqueous TCP with ozone is the same at pH 2 and 7. Four reaction products that occur early in the reaction of ozone with aqueous TCP were identified by GCMS, including: 2,3,4,6‐tetrachlorophenol (TRCP), 4,6‐dichlorocatechol (DCC), 2,6‐dichlorohydroquinone (DCHQ), and 2,6‐dichloroquinone (DCQ). Only DCHQ and DCQ occurred in significant concentrations. Over the pH range of 2 to 5, both DCHQ and DCQ were detected in the reacted solutions, while for pH 6 and 7 only DCHQ was detected. Carbon‐13 NMR analysis shows that over longer ozone exposure times short‐chain carboxylic acids are the dominant species in the reacted TCP solutions.

Gestational Exposure to Chlorpyrifos: Comparative Distribution of Trichloropyridinol in the Fetus and Dam

Chlorpyrifos (O,O′-diethyl O-[3,5,6-trichloro-2-pyridyl] phosphorothionate) is a commonly used anticholinesterase insecticide, and therefore the potential for human exposure is high. The present time course and dose response studies were conducted to delineate the toxicokinetics of chlorpyrifos and its metabolites in the pregnant rat and fetus. Time-pregnant, Long–Evans rats were treated orally with chlorpyrifos during late gestation (Gestational Days 14–18). Following euthanasia the level of chlorpyrifos and its metabolites, chlorpyrifos-oxon and 3,5,6-trichloro-2-pyridinol (TCP), were measured in both fetal and maternal brain and liver (limits of quantitation: 59.2, 28.8, and 14.0 ng/g tissue, respectively). In addition, cholinesterase inhibition was also measured in the same tissues for comparison. TCP was the only component detected. The highest level of TCP and the lowest level of cholinesterase activity showed the same time of peak effect: 5 h after the last dose. The concentration of TCP in the maternal liver was approximately fivefold higher than the TCP concentration in fetal liver, but, paradoxically, the concentration of TCP in the fetal brain was two- to fourfold higher than the TCP concentration in the maternal brain. The half-life of the TCP was identical in all tissues examined (12–15 h). These toxicokinetic results suggest that the fetal nervous system may be exposed to a higher concentration of chlorpyrifos than the maternal nervous system when the dam is orally exposed to chlorpyrifos during late gestation.

Body residues and responses of the midge chironomus riparius to sediment-associated 2,4,5-trichlorophenol in subchronic and chronic exposures

Subchronic and chronic toxicity of sediment-associated 2,4, 5-trichlorophenol to the midge Chironomus riparius was determined by conducting a 10-day growth and a 50-day emergence tests with spiked lake sediment (nominal initial TCP concentrations were 25, 51, 101, 203, 304 and 405 &mgr;mol kg-1 dry weight in the growth test and 25, 76, 152 and 304 &mgr;mol kg-1 dry weight the emergence test). In addition, we measured the residue of chlorophenol in larval tissue and made an attempt to relate it with the observed adverse biological responses. The larvae were exposed individually to avoid density-dependent effects of mortality on food ration and growth of the surviving larvae. In the growth test, mortality was low at sediment concentrations </=193 &mgr;mol TCP kg-1, but it increased sharply at the higher concentrations being 37 and 94% at 334 and 441 &mgr;mol kg-1 DW, respectively. The effect of sediment TCP concentration on larval mortality was highly significant (10-day LC50 337 &mgr;mol TCP kg-1 dry sediment) in the growth test. In the emergence test, however, mortality was low (3-13%) at all concentrations. TCP did not affect larval growth at the concentrations used. The concentration of TCP in the whole larvae after the 10-day exposure was proportional to sediment concentration, being at highest 160 &mgr;mol kg-1 fresh weight. When the average body residues of TCP were below 80 &mgr;mol kg-1, mortality was low, but it increased when the body residue approached 100 &mgr;mol kg-1. After the 10-day exposure, the body residue, at which 50% of the larvae survived (CBR50) was 113 &mgr;mol g-1. TCP exposure accelerated larval development and the midges exposed to 171 and 324 &mgr;mol TCP kg-1 emerged earlier than those in the other concentrations or in the control sediment. In natural environments, sediment-associated chlorophenolics are probably not a major environmental problem to benthic fauna because concentrations similar to that which we observed to cause adverse effects to C. riparius (>60 mg kg-1 dry sediment) are rare.http://link.springer-ny. com/link/service/journals/00244/bibs/37n1p42.html

Uncertainty and transient contamination of river water by agricultural use of industrial products: Release and run-off of hazardous chemicals from agricultural plastic film

An organophosphoric acid triester, tricresyl phmphate (TCM was detected in the Kurose river. Hiroshima, Japan. The concentration was low during dry weathcr and increased after rainy days suggesting typical contamination originating from non-point sources. However, precipitation did not always increase the concentration of TCP in the river. Some rainevents increased TCP in river water and bottom sediments, whereas others did not. To clarify the uncertainty and mechanism of the transient contamination, we carried out an intensive survey both in the river and catchment area. Small amounts of TCP were dctaud both in domestic and industrW waste waters. Also, urban run-oft dry and wet procrpitation and other possible non-point sources did not eonWn significant amounts of TCP. Occasionally, we could detect high concentration of TCP in agricultural runoff from greenhouses. Must greenhouses in the region are covered by plastic films for insulation. Although TCP used in many industrial products in the basin, it seemed most likely that the major sources of TCP were plastic films for agricultural purposes. Release of TCP from an agricultural plastic film by rainwater was confirmed. However, the release did not always reach the river or its tributaries. Most of the released TCP seemed to be transported to the soil and was decomposed in the soil. This mean that run-off of TCP from the field was not associated with rainfall. Only a part of the TCP seemed ot be released from the film to be transported to soil and finally to the river with surface run-off of soils.