A batch kinetic study on decolorization and inhibition of Reactive Black 5 and Direct Brown 2 in an anaerobic mixed culture

Decolorization and inhibition kinetic characteristics of two azo dyes namely Reactive Black 5 (RB 5) and Direct Brown 2 (DB 2) were investigated with partially granulated anaerobic mixed culture using glucose (3000 mg l(-1) COD) as carbon source and electron donor during batch incubation. Monod, zero-, first-, and second-order reaction kinetic models were tested in order to determine the most suitable rate model of substrate and color removal kinetic. The course of the decolorization and substrate removal process approximates to first-order kinetic model under batch conditions. Decolorization, and substrate removal were achieved effectively under test conditions but ultimate removal of azo dyes and substrate were not observed at high dye concentrations. Aromatic amine and volatile fatty acid accumulation were observed proportionally at a higher azo dye concentration. A competitive kinetic model that describes the anaerobic co-metabolism of increasing RB 5 and DB 2 dye concentrations with glucose as co-substrate has been developed based on the experimental data.     

漆酶对活性黑KN-B和直接大红染料的脱色性能

利用白腐真菌漆酶对活性黑KN-B和直接大红2种偶氮染料进行脱色实验。考察反应时间、加酶量、pH值、染料浓度、温度对脱色率的影响,研究了ABTS介体以及金属离子存在下的脱色效果,并分析了漆酶脱色的动力学性能以及其对偶氮染料的降解规律。结果表明,活性黑KN-B和直接大红脱色适宜条件为：反应时间为30 min,加酶量8 U/mL,pH=7,染料浓度分别为50 mg/L和80 mg/L,温度40~45℃。ABTS介体对酶促偶氮染料脱色没有明显促进作用。Fe²⁺对漆酶脱色有较强的抑制作用;Cu²⁺对漆酶催化活性黑KN-B促进作用较大,对直接大红影响较小。漆酶对2种染料的脱色反应符合米氏方程,其催化活性黑KN-B和直接大红染料的K_m值分别为114.81 mg/L,317.5 mg/L,v_max值分别为6.57 mg/（L·min）和26.0 mg/（L·min）。     

Evidence of acid–base interactions between amines and model indoor surfaces by ATR-FTIR spectroscopy

Molecular associations of pyridine with cellulose and gypsum, surrogates for common indoor surface materials, were studied using an attenuated total reflection (ATR)-Fourier transform infrared (FTIR) spectrophotometric method. The purpose of this study was to gain insight into the molecular interactions of amines with well-characterized materials that affect their partitioning between indoor air and surfaces. The experimental results suggest the presence of at least two sorptive states for volatile and semivolatile amines, attributed to the chemisorbed species and to a more labile surface state (i.e., physisorbed pyridine). Both exhibited spectroscopic signatures corresponding to aromatic C–H stretching modes (2950–3100 cm⁻¹) in the studied spectral region. Chemisorbed pyridine could be identified by the presence of additional IR signals in the N–H and O–H stretching region of the spectrum (2900–3600 cm⁻¹). During desorption under a stream of N₂, surface enrichment in the chemisorbed species was evidenced by a slower reduction of the absorbance of the broad band at 2900–3600 cm⁻¹ in relation to the total pyridine absorbance change. This spectroscopic evidence for acid–base interactions between amines and surfaces is consistent with the desorption behavior observed in previous work for nicotine from model surfaces.     

Direct spectral analysis and determination of high content of carcinogenic bromine in bread using UV pulsed laser induced breakdown spectroscopy

Laser induced breakdown spectroscopy (LIBS) was applied for the detection of carcinogenic elements like bromine in four representative brands of loaf bread samples and the measured bromine concentrations were 352, 157, 451, and 311 ppm, using Br I (827.2 nm) atomic transition line as the finger print atomic transition. Our LIBS system is equipped with a pulsed laser of wavelength 266 nm with energy 25 mJ pulse^?1, 8 ns pulse duration, 20 Hz repetition rate, and a gated ICCD camera. The LIBS system was calibrated with the standards of known concentrations in the sample (bread) matrix and such plot is linear in 20–500 ppm range. The capability of our system in terms of limit of detection and relative accuracy with respect to the standard inductively coupled plasma mass spectrometry (ICPMS) technique was evaluated and these values were 5.09 ppm and 0.01–0.05, respectively, which ensures the applicability of our system for Br trace level detection, and LIBS results are in excellent agreement with that of ICPMS results.     

A comprehensive review on the carcinogenic potential of bisphenol A: clues and evidence

Environmental Science and Pollution Research - Bisphenol A [BPA; (CH3)2C(C6H4OH)2] is a synthetic chemical used as a precursor material for the manufacturing of plastics and resins. It gained...     

Synthesis and pesticidal activity of new N-alkyl-N-[1-(2-hydroxyphenyl) ethyl]amines

A series of novel N-alkyl-N-[1-(2-hydroxyphenyl) ethyl]amines were synthesized as potential new agents to control pests. Their structures were confirmed on the basis of IR, NMR and elemental analyses. Six new N-alkyl-N-[1-(2-hydroxyphenyl) ethyl]amines were prepared by reduction of corresponding Schiff bases using sodium borohydride in 80–87 % yields. These compounds were tested for their antifungal activity against two pathogenic fungi viz., Rhizoctonia bataticola ITCC 0482 and Sclerotium rolfsii ITCC 5226 and for insecticidal activity against insects of stored grain pest Callosobruchus analis. Fungicidal bioassay revealed that compound N-Decyl-N-[1-(2-hydroxyphenyl)ethyl]amine, was highly effective against R. bataticola (ED₅₀ 6.86 mg L^?1) which was comparable with that of commercial fungicide hexaconazole (ED₅₀ 6.35 mg L^?1). Also compounds N-Heptyl-N-[1-(2-hydroxyphenyl)ethyl]amine, N-Octyl-N-[1-(2-hydroxyphenyl)ethyl]amine and N-Nonyl-N-[1-(2-hydroxyphenyl)ethyl]amine displayed promising fungitoxicity against same pathogen. However, compound N-Heptyl-N-[1-(2-hydroxyphenyl)ethyl]amine was also found to be effective against S. rolfsii (ED₅₀ 4.92 mg L^?1 as against 1.27 mg L^?1 for hexaconazole). Compound N-Hexyl-N-[1-(2-hydroxyphenyl)ethyl]amine was most effective as insecticide followed by compound N-Octyl-N-[1-(2-hydroxyphenyl)ethyl]amine. LC₅₀ values for these compounds were 155.0 and 275.0 mg L^?1 respectively as against 36.70 mg L^?1 for commercial insecticide dichlorovos. The results obtained from bioassays indicate that this class of compounds can be utilized for the design of new substances endowed with pesticidal activities.     

Influence of tobacco smoke on carcinogenic PAH composition in indoor PM10 and PM2.5

Because of the mutagenic and/or carcinogenic properties, Polycyclic Aromatic Hydrocarbons (PAH), have a direct impact on human population. Consequently, there is a widespread interest in analysing and evaluating the exposure to PAH in different indoor environments, influenced by different emission sources. The information on indoor PAH is still limited, mainly in terms of PAH distribution in indoor particles of different sizes; thus, this study evaluated the influence of tobacco smoke on PM₁₀ and PM_2.5 characteristics, namely on their PAH compositions, with further aim to understand the negative impact of tobacco smoke on human health. Samples were collected at one site influenced by tobacco smoke and at one reference (non-smoking) site using low-volume samplers; the analyses of 17 PAH were performed by Microwave Assisted Extraction combined with Liquid Chromatography (MAE–LC). At the site influenced by tobacco smoke PM concentrations were higher 650% for PM₁₀, and 720% for PM_2.5. When influenced by smoking, 4 ring PAH (fluoranthene, pyrene, and chrysene) were the most abundant PAH, with concentrations 4600–21 000% and 5100–20 800% higher than at the reference site for PM₁₀ and PM_2.5, respectively, accounting for 49% of total PAH (Σ_PAH). Higher molecular weight PAH (5–6 rings) reached concentrations 300–1300% and 140–1700% higher for PM₁₀ and PM_2.5, respectively, at the site influenced by tobacco smoke. Considering 9 carcinogenic PAH this increase was 780% and 760% in PM₁₀ and PM_2.5, respectively, indicating the strong potential risk for human health. As different composition profiles of PAH in indoor PM were obtained for reference and smoking sites, those 9 carcinogens represented at the reference site 84% and 86% of Σ_PAH in PM₁₀ and PM_2.5, respectively, and at the smoking site 56% and 55% of Σ_PAH in PM₁₀ and PM_2.5, respectively. All PAH (including the carcinogenic ones) were mainly present in fine particles, which corresponds to a strong risk for cardiopulmonary disease and lung cancer; thus, these conclusions are relevant for the development of strategies to protect public health.     

Role of pH in partitioning and cation exchange of aromatic amines on water-saturated soils

Predicting the reversible interactions between aromatic amines and soil is essential for assessing the mobility, bioavailability and exposure from contaminated sites. Reversible sorption mechanisms of aniline and alpha-naphthylamine were investigated by using single and binary solute sorption to five soils at several pH values, and by applying a distributed parameter (DP) model. The DP model assumes linear partitioning of the neutral species into soil organic matter domains and organic cation binding on negative-charged sites with the exchange coefficients represented by a Gaussian probability distribution. Sorption nonlinearity was attributed to cation exchange with varying site affinities, which was adequately simulated using the DP model. Greater uptake by hydrophobic partitioning and selectivity for cation exchange sites was observed for alpha-naphthylamine compared to aniline. Sorption of alpha-naphthylamine was not impacted quantitatively by aniline under those conditions examined; however, aniline sorption was reduced by alpha-naphthylamine with the largest reduction occurring in the soil with the lowest pH. DP model simulations showed that although hydrophobic partitioning increases with soil-solution pH, cation exchange still contributes significantly to the total sorption even at soil-solution pH values greater than pKa + 2.     

Effect of five insecticides on microbial and enzymatic activities in sandy soil

Abstract

A laboratory study was conducted to examine the effects of five insecticides on microbial and enzymatic activities important to fertility in sandy soil. Cyfluthrin significantly increased bacterial populations after 2 wks. Imidacloprid showed an inhibitory effect on fungal numbers after 2 wks incubation while the others did not affect fungal population. No inhibitory effect was observed on nitrification of soil indigenous nitrogen. All treatments stimulated S‐oxidation after 4 wks. With the exception of cyfluthrin and imidacloprid after 2 wks, denitrification in sandy soil indicated that all treatment inhibited denitrification throughout the experiment. No inhibitory effects on biomass‐c were observed during 2‐wk periods. An inhibitory effect was observed on amylase after 1 wk while significant recovery was observed after 3 wks. With the exception of HgCl₂, no effect was observed on reducing sugar formation for 2 wks with all treatments. Formazan formation resulting from dehydrogenase activity was significantly greater with tebupirimphos and Aztec for 1 wk. All treatments supressed phosphatase activity for 1 wk, while none of the treatments suppressed phosphatase activity after 2 wks. Amitraz, tebupirimphos and Aztec inhibited urease activity for 1 wk. With the exception of tebupirimphos, no treatments affected N₂‐fixation in soil. Although short‐lived inhibitory effects on activities of microbes and enzymes were caused by the insecticides, the soil indigenous microbes can tolerate the chemicals used for control of soil pests.     

The effects of residual tetracycline on soil enzymatic activities and plant growth

A pot trial was carried out to investigate the adverse effects of tetracycline (TC) on soil microbial communities, microbial activities, and the growth of ryegrass (Lolium perenne L). The results showed that the presence of TC significantly disturbed the structure of microbial communities and inhibited soil microbial activities in terms of urease, acid phosphatase and dehydrogenase (p < 0.05). Plant biomass was adversely influenced by TC, especially the roots with a reduction of 40% when compared with the control. Furthermore, TC decreased the assimilation of phosphorus by the plant although the concentration of phosphorus was increased by 20% due to decreased plant biomass. TC seemed to increase the concentration of dissolved organic carbon (by 20%) in soil. The findings implied that the agricultural use of animal manure or fishpond sediment containing considerable amounts of antibiotics may give rise to ecological risks.     

Effects of six selected antibiotics on plant growth and soil microbial and enzymatic activities

The potential impact of six antibiotics (chlortetracycline, tetracycline and tylosin; sulfamethoxazole, sulfamethazine and trimethoprim) on plant growth and soil quality was studied by using seed germination test on filter paper and plant growth test in soil, soil respiration and phosphatase activity tests. The phytotoxic effects varied between the antibiotics and between plant species (sweet oat, rice and cucumber). Rice was most sensitive to sulfamethoxazole with the EC10 value of 0.1 mg/L. The antibiotics tested inhibited soil phosphatase activity during the 22 days' incubation. Significant effects on soil respiration were found for the two sulfonamides (sulfamethoxazole and sulfamethazine) and trimethoprim, whereas little effects were observed for the two tetracyclines and tylosin. The effective concentrations (EC10 values) for soil respiration in the first 2 days were 7 mg/kg for sulfamethoxazole, 13 mg/kg for sulfamethazine and 20 mg/kg for trimethoprim. Antibiotic residues in manure and soils may affect soil microbial and enzyme activities.     

Influence of short-time imidacloprid and acetamiprid application on soil microbial metabolic activity and enzymatic activity

The influence of two neonicotinoids, i.e., imidacloprid (IMI) and acetamiprid (ACE), on soil microbial activities was investigated in a short period of time using a combination of the microcalorimetric approach and enzyme tests. Thermodynamic parameters such as Q _T (J g^?1 soil), ?H _met (kJ mol^?1), J _Q/S (J g^?1 h^?1), k (h^?1), and soil enzymatic activities, dehydrogenase, phosphomonoesterase, arginine deaminase, and urease, were used to evaluate whole metabolic activity changes and acute toxicity following IMI and ACE treatment. Various profiles of thermogenic curves reflect different soil microbial activities. The microbial growth rate constant k, total heat evolution Q _T (expect for IMI), and inhibitory ratio I show linear relationship with the doses of IMI and ACE. Q _T for IMI increases at 0.0–20 μg g^?1 and then decreases at 20–80 μg g^?1, possibly attributing to the presence of tolerant microorganisms. The 50 % inhibitory ratios (IC₅₀) of IMI and ACE are 95.7 and 77.2 μg g^?1, respectively. ACE displays slightly higher toxicity than IMI. Plots of k and Q _T against microbial biomass-C indicate that the k and Q _T are growth yield-dependent. IMI and ACE show 29.6; 40.4 and 23.0; and 23.3, 21.7, and 30.5 % inhibition of dehydrogenase, phosphomonoesterase, and urease activity, respectively. By contrast, the arginine deaminase activity is enhanced by 15.2 and 13.2 % with IMI and ACE, respectively. The parametric indices selected give a quantitative dose-response relationship of both insecticides and indicate that ACE is more toxic than IMI due to their difference in molecular structures.     

Effects of azinphos-methyl exposure on enzymatic and non-enzymatic antioxidant defenses in Biomphalaria glabrata and Lumbriculus variegatus

Azinphos-methyl is an organophosphate insecticide used for pest control on a number of food crops in many parts of the world. The oligochaete Lumbriculus variegatus and pigmented and non-pigmented specimens of the gastropod Biomphalaria glabrata are freshwater invertebrates that have been recommended for contamination studies. Recently, it has been shown that L. variegatus worms exhibit a higher cholinesterase (ChE) activity and a greater sensitivity to in vivo ChE inhibition by azinphos-methyl than pigmented B. glabrata snails. The aims of the present study were (1) to investigate if, in addition to its anticholinesterase action, azinphos-methyl has also pro-oxidant activity in L. variegatus and B. glabrata, and (2) to examine if species that are highly susceptible to the neurotoxic effects of organophosphates also suffer a greater degree of oxidative stress. Therefore, total glutathione (t-GSH) levels and activities of cholinesterase (ChE), superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and glucose 6-phosphate dehydrogenase (G6PDH) were measured in the whole body soft tissue of organisms exposed for 48 and 96 h to a level of azinphos-methyl that produces 50% of inhibition on ChE. Results showed different patterns of antioxidant responses between the gastropods and the oligochaetes, and even between the two phenotypes of gastropods: (1) in exposed L. variegatus t-GSH levels increased and CAT and SOD activities decreased with respect to control organisms, (2) in pigmented gastropods, SOD decreased while CAT transiently diminished, and (3) in non-pigmented gastropods, SOD activity showed a biphasic response. GST and G6PDH were not altered by azinphos-methyl exposure. Of note, t-GSH levels were 4-fold times higher in L. variegatus than in both phenotypes of B. glabrata. This may suggest that GSH could play a more important role in antioxidant defense in L. variegatus than in B. glabrata.     

Influence of soil properties on heavy metal sequestration by biochar amendment: 1. Copper sorption isotherms and the release of cations

The amendment of carbonaceous materials such as biochars and activated carbons is a promising in situ remediation strategy for both organic and inorganic contaminants in soils and sediments. Mechanistic understandings in sorption of heavy metals on amended soil are necessary for appropriate selection and application of carbonaceous materials for heavy metal sequestration in specific soil types. In this study, copper sorption isotherms were obtained for soils having distinct characteristics: clay-rich, alkaline San Joaquin soil with significant heavy metal sorption capacity, and eroded, acidic Norfolk sandy loam soil having low capacity to retain copper. The amendment of acidic pecan shell-derived activated carbon and basic broiler litter biochar lead to a greater enhancement of copper sorption in Norfolk soil than in San Joaquin soil. In Norfolk soil, the amendment of acidic activated carbon enhanced copper sorption primarily via cation exchange mechanism, i.e., release of proton, calcium, and aluminum, while acid dissolution of aluminum cannot be ruled out. For San Joaquin soil, enhanced copper retention by biochar amendment likely resulted from the following additional mechanisms: electrostatic interactions between copper and negatively charged soil and biochar surfaces, sorption on mineral (ash) components, complexation of copper by surface functional groups and delocalized π electrons of carbonaceous materials, and precipitation. Influence of biochar on the release of additional elements (e.g., Al, Ca) must be carefully considered when used as a soil amendment to sequester heavy metals.     

3种污泥对活性黑KN-B的生物吸附及降解研究

对比研究了好氧污泥、厌氧污泥和厌氧颗粒污泥对染料活性黑KN-B的吸附和降解。结果表明,这3种污泥对活性黑的吸附均符合Freundlich模型(R~2为0.9665～0.9859)和Langmuir模型(R~2为0.9460～0.9906),但3种污泥对活性黑这种染料的吸附量较小;并且厌氧污泥对活性黑的吸附能力优于好氧污泥和厌氧颗粒污泥。实验还发现,3种污泥对活性黑的脱色主要是生物降解作用,而不是吸附作用。     

曝气对黑臭河道污染物释放的影响

利用黑臭河道模拟装置,对比研究了在静置和人工曝气2种方式下底泥污染释放特征及对上覆水水质的影响。结果表明,与静置释放相比,人工曝气促使实验前期底泥污染物快速释放,使得上覆水体中的各项污染物指标上升;随着水体中DO浓度的增加,硝化细菌、嗜磷菌等好氧细菌的活性增强,水体中的COD、氨氮、TN和TP得到降解或转化,浓度快速下降。实验期内,人工曝气底泥中TN、TP的平均释放速率分别为:-0.11 g/(m2·d)和-0.02 g/(m2·d),并且TP由最初的0.96 mg/L降到最终的0.48 mg/L,去除率达到50.00%。人工曝气在前期对水体中各污染指标有升高的影响,但增加了水体中的DO浓度,可以有效地抑制底泥中氮和磷的释放,对水体有机污染物、TN及TP有一定的削减作用,因此,该技术适合黑臭河道的水体修复。     

Calcium-lead interactions involving earthworms. Part 1: The effect of exogenous calcium on lead accumulation by earthworms under field and laboratory conditions

Earthworms (Lumbricus rubellus and Dendrodrilus rubidus) were collected from several acidic and calcareous abandoned ferrous metalliferous mine sites. Tissue lead concentrations were substantially lower than the total soil lead concentrations, except at one site (Cwmystwyth) where the tissue lead concentrations of both species were approximately 5 to 10 times higher than that of the soil. Soil lead was the major factor in determining the tissue lead concentration, although it was demonstrated that both soil pH and soil calcium concentration could markedly increase the % variance in tissue lead concentration. These findings help explain the apparent anomaly in tissue lead concentrations of earthworms from Cwmystwyth, where the soil is acidic and has exceptionally low calcium concentrations. Soil-liming experiments provided supportive evidence that soil pH, coupled with soil calcium, influences lead accumulation by earthworms, but a filter paper feeding experiment provided unequivocal evidence that soil calcium concentration alone can influence lead accumulation by earthworms. It is concluded that, although lead accumulation by earthworms is influenced by both physico-chemical and biochemical mechanisms, the latter over-rides the former, i.e. soil calcium is more important factor in determining the accumulation of lead earthworms than is soil pH.     

Influence of plant-earthworm interactions on SOM chemistry and p,p'-DDE bioaccumulation

Laboratory experiments assessed how bioaccumulation of weathered p,p′-DDE from soil and humic acid (HA) chemistry are affected by interactions between the plants Cucurbita pepo ssp. pepo and ssp. ovifera and the earthworms Eisenia fetida, Lumbricus terrestris, and Apporectodea caliginosa. Total organochlorine phytoextraction by ssp. pepo increased at least 25% in the presence of any of the earthworm species (relative to plants grown in isolation). Uptake of the compound by ssp. ovifera was unaffected by earthworms. Plants influenced earthworm bioaccumulation as well. When combined with pepo, p,p′-DDE levels in E. fetida decreased by 50%, whereas, in the presence of ovifera, bioconcentration by L. terrestris increased by more than 2-fold. Spectral analysis indicated a decrease in hydrophobicity of HA in each of the soils in which both pepo and earthworms were present. However, HA chemistry from ovifera treatments was largely unaffected by earthworms. Risk assessments of contaminated soils should account for species interactions, and SOM chemistry may be a useful indictor of pollutant bioaccumulation.