Three fish species (Carassius auratus, Pelteobagrus fulvidraco, and Squaliobarbus curriculus) were collected from Xiang River near Changsha City, Southern China. The concentrations of heavy metals including arsenic (As), cadmium (Cd), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), and zinc (Zn) in the muscle, gill, and liver of three species were determined by the inductively coupled plasma mass spectrometry method. One-way analysis of variance (ANOVA) was introduced to determine the significant variations (p < 0.05) of heavy metals. Livers were found to accumulate Cd and Cu due to the metallothionein proteins. High levels of Mn and Pb in the gills indicated that the main uptake pathway of these heavy metals was from the water. The carnivorous species, P. fulvidraco, was found to accumulate the highest levels of toxic elements (As, Cd, and Pb), while relatively high concentrations of nutrient elements (Cu, Fe, Mn, and Zn) were accumulated in omnivorous species (C. auratus and S. curriculus). According to the results of Pearson’s correlation analysis, there were few significant relationships at p < 0.01 level between the concentrations of the analyzed elements and the fish sizes. The results of risk assessment indicated that exposure to the toxic heavy metals from fish muscle consumption posed no non-carcinogenic health risk to local inhabitants.

Distribution of ten taste and odor (T&O) compounds were investigated in 135 finished water samples from 43 drinking water treatment plants (DWTPs). 2-Methylisoborneol (MIB), geosmin, and 2,4,6-trichloroanisole (2,4,6-TCA) were detected in 53.4, 41.5, and 14.1% of the samples, respectively. The corresponding concentrations were in the range of 18.0–53.1 ng L−1 for MIB, 4.2–6.4 ng L−1 for geosmin, and 0.5–6.6 ng L−1 for 2,4,6-TCA. The other seven T&O compounds, β-ionone, 2,3,6-trichloroanisole (2,3,6-TCA), 2,3,4-trichloroanisole (2,3,4-TCA), 2,4,6-tribromoanisole (2,4,6-TBA), 2-isobutyl-3-methoxypyrazine (IBMP), 2-isopropyl-3-methoxypyrazine (IPMP), and trans-2,cis-6-nonadienal (NDE) were never found in all samples. The results from finished water of DWTPs compared with associated reservoirs indicated that 2,4,6-TCA was formed in the water treatment processes. To determine the chemical formation of 2,4,6-TCA by chlorination, the concentrations of different chloroanisoles in anisole-containing water at pH 5.5–9.0 and 25 °C were measured. The results from chlorination showed that only 2-chloroanisole (2-CA), 4-chloroanisole (4-CA), and 2,4-dichloroanisole (2,4-DCA) could be detected. Their formation rates were all below 3.3% at each pH value, but the reaction was more active at pH 5.5 because of acid catalyzed effect. Accordingly, the chemical formation of 2,4,6-TCA by chlorination was not confirmed in this study, which suggested that the formation of 2,4,6-TCA was related to the methylation of 2,4,6-trichlorophenol with fungi. These findings increase our understanding on the formation of 2,4,6-TCA and provide insights into managing and controlling T&O problems in drinking water.

•Filamentous fungi were the major contributors to 2,4,6-TCA formation in drinking water.•Eleven fungal species isolated have the capability to convert 2,4,6-TCP to 2,4,6-TCA.•2,4,6-TCA was mainly distributed in extracellular environment of TCA–forming fungi.•A possible metabolic pathway of 2,4,6-TCP in TCA–forming fungi was proposed.In this study, the distribution of 2,4,6-trichloroanisole (2,4,6-TCA) in two water supply reservoirs and four associated drinking water treatment plants (DWTPs) were investigated. The 2,4,6-TCA concentrations were in the range of 1.53–2.36 ng L−1 in water supply reservoirs and 0.76–6.58 ng L−1 at DWTPs. To determine the contribution of filamentous fungi to 2,4,6-TCA in a full-scale treatment process, the concentrations of 2,4,6-TCA in raw water, settled water, post-filtration water, and finished water were measured. The results showed that 2,4,6-TCA levels continuously increased until chlorination, suggesting that 2,4,6-TCA could form without a chlorination reaction and fungi might be the major contributor to the 2,4,6-TCA formation. Meanwhile, twenty-nine fungal strains were isolated and identified by morphological and molecular biological methods. Of the seventeen isolated fungal species, eleven showed the capability to convert 2,4,6-trichlorophenol (2,4,6-TCP) to 2,4,6-TCA. The highest level of 2,4,6-TCA formation was carried out by Aspergillus versicolor voucher BJ1-3: 40.5% of the original 2,4,6-TCP was converted to 2,4,6-TCA. There was a significant variation in the capability of different species to generate 2,4,6-TCA. The results from the proportions of cell-free, cell-attached, and cell-bound 2,4,6-TCA suggested that 2,4,6-TCA generated by fungi was mainly distributed in their extracellular environment. In addition to 2,4,6-TCA, five putative volatile by-products were also identified by gas chromatography and mass spectrometry. These findings increase our understanding on the mechanisms involved in the formation of 2,4,6-TCA and provide insights into managing and controlling 2,4,6-TCA-related problems in drinking water.Download high-res image (254KB)Download full-size image

•AsB was detected in the rice roots and straws while AsC in the straws and grains.•The straw iAs% increased with straw tAs concentration in a hyperbolic pattern.•The grain iAs% was linearly and negatively dependent on grain tAs concentration.•Demethylations of MMA and DMA were predicted when translocated from straw to grain.Paddy rice (Oryza sativa L.) as the staple food in China was found to be efficient in accumulating arsenic (As) due to cultivated in flooded paddy soil. Uptake and translocation of As in rice plant depended on the As species. In this work, rice plant samples including roots, straws and grains as well as rhizosphere soils were collected from paddy fields near Changsha, a mine impacted city in Southern China. The total As concentrations in the collected samples were observed in the descending order as root > soil > straw > grain. The predominant As species detected in rice plants were inorganic forms: arsenite [As(III)] and arsenate [As(V)]. Except monomethylarsonate (MMA) and dimethylarsinate (DMA), other two organoarsenicals, arsenobetaine (AsB) and arsenocholine (AsC), were also detected in rice plants. DMA and AsB were mainly formed in rice roots with the assistance of microorganisms. MMA and AsC detected in straws might be derived from methylation and oxidation of As(III). The results of multiple linear regressions indicated that the straw As species were remarkable predictors of the corresponding grain As species. Demethylation or degradation of MMA, DMA and AsC were predicted when translocated from straw to grain.

•Research on the ozonization of IPMP and IBMP at ng L−1 level initial concentration was performed.•The intermediate by-products of IPMP and IBMP by ozonization were determined and characterized.•The possible degradation pathway of IPMP and IBMP by ozonization was for the first time proposed.2-isopropyl-3-methoxypyrazine (IPMP) and 2-isobutyl-3-methoxypyrazine (IBMP) are two of main taste and odor compounds in drinking water. The removal efficiency and possible degradation pathway of IPMP and IBMP by ozonization were studied by evaluating experimental parameters including ozonization time, initial concentration of IPMP and IBMP, and solution pH. At pH 6.8 the removal efficiency of IPMP and IBMP (100 ng L−1) were both found over 90% within 15 min ozonization, and a higher pH value (8.6) helped to accelerate the degradation in some degree. In both neutral and acidic media, the degradation followed the pseudo first order kinetics. In contrast, at lower pH range, e.g. pH 5.0, more than 10% of the title compounds were still existing even after 30 min ozonization. With increasing the initial concentration from 100 to 200 and to 400 ng L−1, the removal efficiency of the title compounds was decreased successively. The intermediate by-products of IPMP and IBMP by ozonization were mainly acid esters and carboxylic acids as identified by GC–MS, and accordingly the possible degradation pathway was proposed.

•As(III) was found to be the predominant As species in rice from Guangdong Province.•Uptake of As(III) was restricted when total As levels were elevated.•Cd, Cu and Ni in rice were derived from industrial and commercial activities.•As and Pb in rice were primarily controlled by geogenic source.•Intake of rice in Guangdong Province could cause health risk to local inhabitants.Arsenic speciation and heavy metal distributions have been investigated in locally grown rice grains from Guangdong Province, Southern China. A total of 41 polished rice grain samples were collected throughout Guangdong Province. Arsenite (As(III)), as the predominant form found in the rice, was positively correlated (p < 0.01) with total As (tAs) concentration. However, the percentage of As(III) reduced while tAs concentration increased (r = −0.361, p < 0.05), due to restricted accumulation and translocation of As(III) in rice grains at high level of tAs. Statistical and geostatistical analyses were applied to investigate potential origins of heavy metals in rice. Only Cd, Cu and Ni were identified as influenced by anthropogenic sources such as industrial and commercial activities. As and Pb were primarily controlled by natural occurrence. The results of health risk assessment implied that continuous intake of rice grown in Guangdong Province could cause considerably non-carcinogenic and carcinogenic risk to local inhabitants.

Taste and odor (T&O) problems in surface water supplies attract growing environmental and ecological concerns. In this study, 10 T&O compounds, 2-methylisoborneol (2-MIB), geosmin, β-ionone, 2-isopropyl-3-methoxypyrazine (IPMP), 2-isobutyl-3-methoxypyrazine (IBMP), 2,4,6-trichloroanisole (2,4,6-TCA), 2,3,6-trichloroanisole (2,3,6-TCA), 2,3,4-trichloroanisole (2,3,4-TCA), 2,4,6-tribromoanisole (2,4,6-TBA), and trans-2,cis-6-nonadienal (NDE) were investigated in 13 water supply reservoirs and 2 water treatment plants (WTPs) in S City of China. 2-MIB, geosmin, and β-ionone were detected in most of the reservoirs and WTPs. The highest concentrations in reservoirs reached 196.0 ng L−1 for 2-MIB, 11.4 ng L−1 for geosmin, and 39.7 ng L−1 for β-ionone. Canonical correspondence analysis (CCA) was used to examine the relationship between the 3 T&O compounds and environmental parameters of the reservoirs. The results showed that TP was strongly positively correlated with 2-MIB in wet season and negatively correlated in dry season. It was suggested that controlling nutrient (TP, TN/TP, and NH3-N) inputs was required for better management of drinking water reservoirs. Furthermore, the maximum concentrations in raw water of WTPs was kept at 82.1 ng L−1 for 2-MIB, 5.6 ng L−1 for geosmin, and 66.1 ng L−1 for β-ionone. β-Ionone could not be detected in the post-filtration and finished water of two WTPs, and both 2-MIB and geosmin significantly decreased in the water of XWTP. It was indicated that T&O compounds could be removed partly or completely by the filtration of conventional treatment processes.

•Estimating the effect of variables on arsenic species extraction by experimental designs.•Extraction of arsenic species in rice samples efficiently and simply using water as the extractant.•The proposed method provided good extraction efficiency and species stability.Statistical experimental designs were employed to optimize the extraction condition of arsenic species (As(III), As(V), monomethylarsonic acid (MMA) and dimethylarsonic acid (DMA)) in paddy rice by a simple solvent extraction using water as an extraction reagent. The effect of variables were estimated by a two-level Plackett–Burman factorial design. A five-level central composite design was subsequently employed to optimize the significant factors. The desirability parameters of the significant factors were confirmed to 60 min of shaking time and 85 °C of extraction temperature by compromising the experimental period and extraction efficiency. The analytical performances, such as linearity, method detection limits, relative standard deviation and recovery were examined, and these data exhibited broad linear range, high sensitivity and good precision. The proposed method was applied for real rice samples. The species of As(III), As(V) and DMA were detected in all the rice samples mostly in the order As(III) > As(V) > DMA.

•The QuEChERS-based method was used to detect 4-n-OP, 4-n-NP, BPA in fish.•The Plackett-Burman factorial design for screening the main factor was timesaving.•Matrix effect was reduced by matrix-matched internal standard method.The presence of endocrine disrupting chemicals such as 4-n-octylphenol, 4-n-nonylphenol and bisphenol A in environmental samples and artificial products may cause health problems for human and organisms. This developed method was efficient for monitoring of those tracing emerging contaminates and the Plackett-Burman factorial design introduced in extraction step was timesaving. Matrix effect was also considered to ensure proper quantitation. Good linearity (r2 > 0.99), low Method Detection Limits (MDL) and Method Quantitation Limits (MQL) range from 0.18 to 0.54 ng/g and 0.60 to 1.80 ng/g were obtained. Three level spiking experiment (4, 10, 15 ng/g) showed recoveries range from 74% to 113% for 4-n-octylphenol and 4-n-nonylphenol with RSD range from 2% to 11%. The method was finally applied to the analysis of real fish samples taken from Hunan Province, China, offering a reliable and effective means for monitoring of trace emerging contaminates in fishes largely consumed by residents.