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The construction of semiconductor heterojunction photocatalysts that improve the separation and transfer of photoinduced charge carriers is an effective and widely employed strategy to boost photocatalytic performance. Herein, we have successfully constructed a CdS/Ag/Bi2WO6 Z-scheme heterojunction with an Ag-bridge as an effective charge transfer channel by a facile process. The heterostructure consists of both CdS and Ag nanoparticles anchored on the surface of Bi2WO6 nanosheets. The photocatalytic efficiency of the CdS/Ag/Bi2WO6 system was studied by the decontamination of tetracycline (TC) and Rhodamine B (RhB) under visible light irradiation (λ ≥ 420). The results exhibited that CdS/Ag/Bi2WO6 shows markedly higher photocatalytic performance than that of CdS, Bi2WO6, Ag/Bi2WO6, and CdS/Bi2WO6. The trapping experiment results verified that the •O2− and h+ radicals are the key active species. The results of photoluminescence spectral analysis and photocurrent responses indicated that the CdS/Ag/Bi2WO6 heterojunctions exhibit exceptional efficiency in separating and transferring photoinduced electron−hole pairs. Based on a series of characterization results, the boosted photocatalytic activity of the CdS/Ag/Bi2WO6 system is mostly due to the successful formation of the Ag-bridged Z-scheme heterojunction; these can not only inhibit the recombination rate of photoinduced charge carriers but also possess a splendid redox capacity. The work provides a way for designing a Z-scheme photocatalytic system based on Ag-bridged for boosting photocatalytic performance. [ABSTRACT FROM AUTHOR]

The work investigated the concentration of perfluorinated compounds (PFCs) in surface water, sediments and aquatic plants of Nansi Lake, China. The total concentration of 12 PFCs was in the range of 34.07–153.39 ng/L in surface water. The short-chain PFCs were dominant PFC homologs, and the concentration of PFOA was higher than that of PFOS in water samples. The total concentration of 12 PFCs was in the range of 0.63–1.62 ng/g (dry weight, DW) in the sediments. There were more long-chain PFCs (PFOA and PFOS) than short-chain PFCs in sediments, with no apparent connection according to the concentration of PFCs in water and sediments. Moreover, the bioaccumulation factors (BAF) indicated the aquatic plants had significant absorption for long-chain PFCs (PFOA and PFOS), especially PFOS. The log BAF value of Ceratophyllum demersum Linn for PFOS was the highest in all aquatic plants. Risk assessment indicated that the water environment of Nansi Lake was at a safe level. [ABSTRACT FROM AUTHOR]

The work investigated the distribution of twelve perfluorinated compounds (PFCs) in surface water and soil in the partial areas of Shandong Province, China. The total concentration of PFCs was in the range of 36.1–1,236.21 ng/L in surface water and 4.23–48.72 ng/g dw (dry weight) in the soil. The concentration of PFOA is higher than that of PFOS in all the surface water and soil. There was a positive correlation between PFOS and PFOA. The ratio method and principal component analysis (PCA) were used to identify the potential source of PFCs in surface water. The results showed that atmospheric precipitation, industrial emissions and domestic sewage were the main reasons for PFCs pollution in the surface water of partial areas of Shandong Province, China. [ABSTRACT FROM AUTHOR]

The concentrations of polycyclic aromatic hydrocarbons (PAHs) were analyzed in water, sediment, and biota (aquatic plant, shrimp, and fish) of Nansi Lake by gas chromatography-mass spectrometry (GC-MS). The concentrations of total PAHs were 27.54-55.04 ng L in water, 80.31-639.23 ng g dry weight (dw) in sediments, 20.92-192.78 ng g dw in aquatic plants, and 67.3-533.9 ng g dw in fish and shrimp muscles. The ratios of phenanthrene to anthracene (Ph/An), fluoranthene to pyrene (Flu/Pyr), and low molecular weight to high molecular weight (LMW/HMW) in sediment indicated that the sources of the PAHs were a mixture of pyrolytic and petrogenic contamination at most sampling sites in Nansi Lake. The composition profile of PAHs in plants was similar to that in water and animals with 2-3 ring PAHs being dominant. The 4-6 ring PAHs were the dominant PAH compounds in sediment. There is a positive correlation between sediment and aquatic plants, but their PAH composition profiles were different, implying that aquatic plant absorption of PAHs from sediment is selective and the accumulation of PAHs in aquatic plants is different. The concentration of PAHs in fish showed a positive correlation with plants, reflecting that the PAHs in fish are mainly absorbed from aquatic plants rather than directly from the water. Bioaccumulation of LMW PAHs in aquatic biota was higher than HMW PAHs. The biota-sediment accumulation factor (BSAF) values of total PAHs in the plants Potamogeton lucens Linn and Ceratophyllum demersum Linn were higher than that in most animals. The BSAF values of total PAHs in animals were in the following order: Cyprinus carpio > Macrobrachium nipponense > Carassius auratus > Channa argus. There was no significant relationship between PAH bioaccumulation and trophic levels in Nansi Lake. Risk assessment of PAHs in water, sediment, and animals indicated that the water environment of Nansi Lake is safe at present. It is worthwhile to note that benzo [ a] anthracene (BaA), benzo [ a] pyrene (BaP), indeno [1,2,3- cd] pyrene (InP), dibenz [ a, h] anthracene (DBA), and benzo [ ghi] perylene (BghiP) were detected in sediment, plants, and animals at all sampling sites, and they have potential carcinogenicity to the organisms of Nansi Lake. [ABSTRACT FROM AUTHOR]

The concentrations of heavy metals (As, Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were investigated in water, sediment and biota (aquatic plant, fish and shrimp) of Nansi Lake by an inductively coupled plasma-atomic emission spectrometry. The lower concentrations of heavy metals in lake water and the higher concentrations of heavy metals in sediment implied that there were low-level, persistent inputs of heavy metals in the Nansi Lake. The concentrations of Cr and Fe in aquatic plants exceeded their corresponding toxic concentrations. The correlations among the concentrations of heavy metals in water, sediment, aquatic plants and animals were lower. The factor analysis and the correlation analysis of different heavy metals in water, sediment and aquatic biota samples showed that most heavy metals had the same source except As. This finding implied that As was of different source compared to the other heavy metals in Nansi Lake. The comparison of heavy metals in different samples from upper lake and lower lake showed that the contamination of heavy metals in upper lake was more serious than that in lower lake. The intensive coal mining and more coal thermal plants were an important reason leading to contamination of heavy metals in Nansi Lake. The heavy metals in aquatic organisms were not accumulated along food web except As and Zn. There was a positive correlation between the accumulation of As and Zn and food web based on bioaccumulation factors value in Nansi Lake. Risk assessment of heavy metals in water, sediment and animals indicated that the water environment of Nansi Lake is safe at present. However, people should pay more attention to the intake of As and Zn. [ABSTRACT FROM AUTHOR]

The concentration of 12 organochlorine pesticides (OCPs) were measured in water, sediment, aquatic plant, and animal (shrimp and fish) of Nansi Lake by gas chromatography equipped with an electron capture detector. The total OCPs concentrations were 65.31-100.31 ng L in water, 2.9-6.91 ng g dry weight (dw) in sediments, 1.29-6.42 ng g dw in aquatic plants and 7.57-17.22 ng g dw in animals. The OCPs composition profiles showed that heptachlor compounds was also the predominant OCPs contaminants in addition to hexachlorocyclohexanes (HCHs) and dichlorodiphenyltrichloroethanes (DDTs) in Nansi Lake. According to the source of HCHs and DDTs in sediment samples, there was no new input and the HCHs pollution mainly came from the use of Lindane in Nansi Lake. Bioaccumulation of OCPs in aquatic biota indicated that DDTs and heptachlor compounds had a strong accumulation, followed by HCHs and drins. The accumulation abilities of fish for OCPs were higher than those of plants and shrimps. The OCPs biota-sediment accumulation factor values of Channa argus was the highest in fish samples, followed by Carassius auratus, and Cyprinus caspio. Risk assessment of sediment showed that heptachlor epoxide had a higher occurrence possibility of adverse ecological effects to benthic species. Based on the calculation of acceptable daily intake and hazard ratio, HCHs in fish and shrimps from Nansi Lake had a lifetime cancer risk of greater than one per million. The risk assessment of water, sediment, and fish indicated the water environment of Nansi Lake is at a safe level at present. [ABSTRACT FROM AUTHOR]

Novel Bi2W2O9 and Bi2Mo2O9 with irregular polyhedron structure were successfully synthesized by a hydrothermal method. Compared to ordinary Bi2WO6 and Bi2MoO6, the modified structure of Bi2W2O9 and Bi2Mo2O9 were observed, which led to an enhancement of photocatalytic performance. To investigate the possible mechanism of enhancing photocatalytic efficiency, the crystal structure, morphology, elemental composition, and optical properties of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9 were examined. UV-Vis diffuse reflectance spectroscopy revealed the visible-light absorption ability of Bi2WO6, Bi2MO6, Bi2W2O9, and Bi2Mo2O9. Photoluminescence (PL) and photocurrent indicated that Bi2W2O9 and Bi2Mo2O9 pose an enhanced ability of photogenerated electron–hole pairs separation. Radical trapping experiments revealed that photogenerated holes and superoxide radicals were the main active species. It can be conjectured that the promoted photocatalytic performance related to the modified structure, and a possible mechanism was discussed in detail. [ABSTRACT FROM AUTHOR]