Benzotriazole (BTA) is an emerging contaminant that also is a recalcitrant compound. Sequential and intimate coupling of UV-photolysis with biodegradation were investigated for their impacts on BTA removal and mineralization in aerobic batch experiments. Special attention was given to the role of its main photolytic products, which were aminophenol (AP), formic acid (FA), maleic acid (MA), and phenazine (PHZ). Experiments with sequential coupling showed that BTA biodegradation was accelerated by photolytic pretreatment up to 9 min, but BTA biodegradation was slowed with longer photolysis. FA and MA accelerated BTA biodegradation by being labile electron-donor substrates, but AP and PHZ slowed the rate because of inhibition due to their competition for intracellular electron donor. Because more AP and PHZ accumulated with increasing photolysis time, their inhibitory effects began to dominate with longer photolysis time. Intimately coupling photolysis with biodegradation relieved the inhibition effect, because AP and PHZ were quickly biodegraded and did not accumulate, which accentuated the beneficial effect of FA and MA.
The IMPROVE thermal/optical reflectance (TOR) method, commonly used for EC quantification in atmospheric aerosols, is applied to soils and sediments and compared with a thermochemical method commonly applied to these non-atmospheric samples. TOR determines elemental carbon (EC) by an optical method, but it also yields thermally defined EC fractions in a 2% O2/98% He oxidizing atmosphere at 550 degrees C (EC1), 700 degrees C (EC2), and 800 degrees C (EC3). Replicate TOR TC, OC, and EC values exhibited precisions of approximately +/-10% as determined from multiple analyses of the same samples. EC abundances relative to total mass concentrations were within the ranges reported by other methods for diesel exhaust soot, n-hexane soot, wood and rice chars, and coals, as well as for environmental matrices. A direct comparison with the chemothermal (CTO) method of Gustafson et al. for ten soil and sediment samples demonstrated that almost all of the OC and EC1 are eliminated, as is part of the EC2. The CTO soot carbon is bounded by the EC3 and EC2+EC3 fractions of the IMPROVE TOR analysis. It might be possible to adjust these fractions to obtain better agreement between atmospheric aerosol and soil/sediment analysis methods. Given its linking the EC measurement in the atmosphere to sediments, the TOR method will not only provide useful information on the explanation and comparison between different environmental matrices, but also can be used to derive information on global cycling of EC. 相似文献
The effects of copper (Cu) on the yield and Cu uptake of three ecotypes of Elsholtzia splendens and one of Elsholtzia argyi were studied using solution culture. Three Cu concentrations were compared: 0.31 (control), 50 and 100 micromol L(-1). Although E. argyi took up more Cu in the aboveground parts, typical visual symptoms of Cu toxicity appeared when the plants grew in 50 and 100 micromol Cu L(-1). In contrast, plants from all three populations of E. splendens showed high Cu tolerance and substantial shoot Cu accumulation of 58-144 mg kg(-1). Shoot Cu concentrations were about 16-27 times higher than root Cu concentrations. Root-to-shoot ratio of the E. argyi ecotype was halved when Cu was supplied at a level of 100 mg L(-1) compared to the control (0.31 mg L(-1)) but the ratio increased by 6-47% in the three E. splendens ecotypes. The increase in root-to-shoot ratio in E. splendens may be a mechanism by which the plants can tolerate high Cu concentrations. There were few differences in morphology among the three E. splendens ecotypes in response to added Cu. The results are discussed in relation to the possible use of E. splendens as a pioneer species in the phytostabilization of Cu-contaminated soils. 相似文献
For enhanced phytoextraction, mobilization of heavy metals (HMs) from the soil solid phase to soil pore water is an important
process. A pot incubation experiment mimicking field conditions was conducted to investigate the performance of three soil
additives in mobilizing HMs from contaminated paddy soil (Gleyi-Stagnic Anthrosol): the [S, S]-isomer of ethylenediamine disuccinate
(EDDS) with application rates of 2.3, 4.3, and 11.8 mmol kg−1 of soil, ethylenediamine tetraacetate (EDTA; 1.4, 3.8, and 7.5 mmol kg−1), and elemental sulfur (100, 200, and 400 mmol kg−1). Temporal changes in soil pore water HM and dissolved organic carbon concentrations and pH were monitored for a period of
119 days. EDDS was the most effective additive in mobilizing soil Cu. However, EDDS was only effective during the first 24
to 52 days, and was readily biodegraded with a half-life of 4.1 to 8.7 days. The effectiveness of EDDS decreased at the highest
application rate, most probably as a result of depletion of the readily desorbable Cu pool in soil. EDTA increased the concentrations
of Cu, Pb, Zn, and Cd in the soil pore water, and remained effective during the whole incubation period due to its persistence.
The highest rate of sulfur application led to a decrease in pH to around 4. This increased the pore water HM concentrations,
especially those of Zn and Cd. Concentrations of HMs in the soil pore water can be regulated to a large extent by choosing
the proper application rate of EDDS, EDTA, or sulfur. Hence, a preliminary work such as our pot experiment in combination
with further plant experiments (not included in this study) will provide a good tool to evaluate the applicability of different
soil additives for enhanced phytoextraction of a specific soil. 相似文献
Pyrite is the most abundant sulfide semiconductor mineral with excellent optical properties. However, few reports have investigated its photocatalytic activity because of the low photogenerated carrier separation efficiency. In this work, a Z-scheme FeS2/Fe2O3 composite photocatalyst was fabricated in situ via structural transformation of pyrite through heat treatment. A remarkably enhanced photocatalytic performance was observed over the FeS2/Fe2O3 composite photocatalyst. Compared with the pristine pyrite, the degradation efficiency of carbamazepine (CBZ) reached 65% at the added hexavalent chromium (Cr(Ⅵ)) concentration of 20 mg/L and the Cr(Ⅵ) was nearly completely reduced in the mixed system using FeS2/Fe2O3 within 30 min under simulated solar light irradiation. The enhanced photocatalytic activity can be attributed to the efficient separation and transfer of photogenerated carriers in the FeS2/Fe2O3 composite photocatalyst. This facilitated the generation of ?OH, hole (h+) and ?O2? species, which participated in the photocatalytic reaction with CBZ. Based on the measurement of the active species and electric properties, a Z-scheme electron transfer pathway was proposed for the FeS2/Fe2O3 composite photocatalyst. This work broadens the application potential of pyrite in environmental remediation. 相似文献
The coastal area of the East China Sea has experienced rapid urbanization and industrialization in China since 1980 s, resulting in severe pollution of its environments.Antibiotic resistance genes(ARGs) are regarded as a kind of emerging pollutant with potential high risk. The sediment samples were collected from Hangzhou Bay(HB),Xiangshan Bay(XB), and Taizhou Bay(TB) to investigate the spatial occurrence and distribution of 27 ARGs and class I integron–integrase gene(intI1) in the coastal area of the East China Sea. The PCR results showed the frequent presence of 11 ARGs and intI1 in the sediments of the three bays. The qPCR results further showed that sulfonamide resistance was the most prevalent ARG type and antibiotic target replacement and protection were the most important resistance mechanisms in the sediments. Regarding the subtype of ARGs, sulI, tetW, and dfrA13 were the most abundant ARGs, in which sulI was higher in TB(based on both the absolute and relative abundances) and dfrA13 was higher in HB(based on the relative abundances). The network analysis revealed that intI1 had significant correlations with tetC, sulI, sulII, and blaPSE-1. Oil was the key connected factor, which had positive connections with sulI, sulII, and blaPSE-1. In addition, the joint effect of heavy metals and nutrients organic pollutants might be crucial for the fate of ARGs in the coastal sediments. 相似文献