Photochemical Behavior of Parathion in the Presence of Humic Acids from Different Origins

This paper reports the effect of ultraviolet radiation on the degradation of pesticide ethyl parathion in the presence of humic acids. Ethyl parathion was completely degraded in 300 min using an artificial lamp of 7.41 × 10^{? 10} einstein/s. Humic acid from peat did not influence the photochemical rate (k = 8.92 × 10^?3 min). However, in the presence of aquatic humic acid, the photochemical rate was higher (11.5 × 10^?3 min). The analytical determinations show the presence of p-nitrophenol and aminophenol in the reaction medium during the photochemical experiments. The kinetic of degradation in all experiments obeyed a first-order reaction pattern.     

Natural resistance of rose petals to microbial attack

Petals of red, yellow and white roses (Rosa damascene Mill.) of the family Rosaceae were extracted with (1:1) methylene chloride/methanol and tested for their antimicrobial activities against four species of Gram-positive bacteria (Bacillus cereus, Bacillus subtilis, Micrococcus luteus and Staphylococcus aureus), five species of Gram-negative bacteria (Enterobacter aerogenes, Escherichia coli, Klebsiella pneumonia, Pseudomonas aeruginosa and Serratia marcescens) and five species of fungi (Penicillium notatum, Aspergillus niger, Rhizopus stolonifer, Saccharomyces cerevisiae and Fusarium oxysporum). All of the crude extracts showed a wide range of antimicrobial activities according to the tested organism and rose's type. Micrococcus luteus was found to be the most susceptible bacteria to all crude extracts. Red and yellow petal extracts showed much higher antibacterial activity than the white petals extract. Bacillus subtilis was found to be the least susceptible to all extracts. The fungus, Penicillium notatum was found to be the most susceptible with white petal extract being the most effective. Saccharomyces cerevisiae and Fusarium oxysporum were the least susceptible to all extracts. White roses extract showed much higher antifungal activities against Penicillium notatum than red or yellow roses, therefore, it was subjected to several bioassay guided chromatographic fractionations and purification to isolate the active chemical(s) responsible for the antifungal activity. Chemical structure of the isolated antifungal compounds were identified by spectroscopy techniques and found to be a γ-sitosterol and (Z,Z)-9,12-octadecadienoic acid. Antibacterial activity of the various types of rose extracts were due to complex mixtures of organic compounds which are still under chemical investigation and will be published later.     

Species of Trace Metals, Organic Residues and Humic Substances in Sediments From the Taiwan Erhjin River and Coastal Areas

Total organic carbon, humic substances, and the species of trace metals (including Cu, Zn, Pb, Cd, Cr, Mn and Fe) in six and seven phases, such as bioexchangeable (P1), skeletal (carbonates, P2), easily reducible (Fe and Mn oxides, P3), moderately reducible (crystalline Mn oxides, P4), organic matters with sulphides (P5), and detritus with minerals (P6) as well as organic with humic substances (PB4) and organic residues (PB6), were analyzed in sediments from the Taiwan Erhjin coastal (including river and estuarine) area, where places we found the copper pollution. Results indicate that higher percentages of P1 and P2 for copper, zinc, lead, cadmium and manganese in samples collected in March and September of 1990 were much higher than those in P3-P6. High percentages of chromium and iron in samples respectively collected in March and September of 1990 were found in P6. for the seven phase analysis, higher percentages of copper species in PB4 and PB6 as well as iron species in PB7 were observed. On the other hand, purified humic acid with the high contents of manganese and iron in humic acid as well as purified fulvic acids were generally found at the upstream stations; and low values at coastal stations. However, extremely high copper (as high as 1750μg g^-1, dry weight in fulvic acid and 820μg g^-1 in humic acid) and lead (821μg g^-1 in humic acid) concentrations with relatively high manganese and iron concentrations were observed in humic substances from the station near the copper recycling area. Comparing the results obtained from the Antarctic Ocean sediments with those from the Taiwan Erhjin Chi coastal sediments, the human impacts on the latter are evaluated.     

Zeolites relieves inhibitory stress from high concentrations of long chain fatty acids

Protein and fat rich slaughterhouse waste is a very attractive waste stream for the production of biogas because of the high biochemical methane potential of the substrate. The material has however some drawbacks as the sole material for biogas production due to the production of several process disturbing metabolites such as ammonia, sulfides and long chain fatty acids. We can in this work present results that show that zeolites have the potential to relieve inhibitory stress from the presence of long chain fatty acids. Moreover, the results strongly indicate that it is mainly acetic acid consumers that are most negatively affected by long chain fatty acids and that the mechanism of stress relief is an adsorption of long chain fatty acids to the zeolites. In addition to this, it is shown that the effect is immediate and that only a small amount of zeolites is necessary to cancel the inhibitory effect of long chain fatty acids.     

无磷缓蚀阻垢剂CETSA的合成与缓蚀阻垢机理分析

针对工业循环水处理系统中使用磷系缓蚀阻垢剂带来的磷排放问题,以马来酸酐和3-巯基丙酸为主要原料,在催化剂作用下应用“一步法”合成S-羧乙基硫代琥珀酸(CETSA)无磷缓蚀阻垢剂,通过红外(IR)、核磁共振(13CNMR)等方法对其结构进行了表征.采用碳酸钙沉积法、旋转挂片法对CETSA的阻垢缓蚀性能进行评价,考察了加药量、水温、pH值、水流转速等对CETSA阻垢缓蚀性能的影响.结果表明,当加药量为110mg/L、循环水温度低于50℃、pH值为6～8、水流转速低于100 r/min时,CETSA对A3碳钢的腐蚀率小于0.25mm/a,最大缓蚀率可达61.3％,最大阻垢率达88.4％.CETSA是一种小分子多羧酸结构,其具有较高的缓蚀阻垢性能可能是因为与水中的钙镁离子发生了螯合,生成了稳定的络合物抑制结垢,同时非极性键、烷基等亲水基吸附于金属表面,电负性较高的O、S元素与Fe产生强吸附,形成的致密保护膜有效抑制了金属腐蚀.经测算,10％水剂的CETSA生产成本约为3 047元/t,总磷减排量可达3～5g/m3循环水排水.研究表明,CETSA可替代传统磷系缓蚀阻垢剂,适于电力、钢铁、化工、油田等行业的循环冷却水系统.     

利用巨藻发酵联产氢气与挥发性有机酸的研究

通过批式实验探讨了巨藻生物质厌氧发酵过程中巨藻的预处理方法、接种比、初始p H值等条件对累积产氢和挥发性脂肪酸(VFA)的影响,结果发现,巨藻可以用来发酵联产氢气与VFA;热碱预处理比较适于巨藻发酵产氢与产酸,在4 g·L-1的Na OH和100℃处理后,接种比为0.3,初始p H值为6时,单位挥发性固体(VS)最大累积产氢量可达到36.21 m L·g-1,比未经处理巨藻提高了77.82%;同时,巨藻在最佳的预处理条件下单位VS的总挥发性脂肪酸TVFA的产率为0.15 g·g-1,且以乙酸和丁酸为主.     

短链氯化石蜡暴露对HepG2细胞代谢的影响

短链氯化石蜡(short-chain chlorinated paraffins,SCCPs)是一组成分复杂的氯代正构烷烃,在环境中普遍存在。然而有关其毒性机理的信息十分有限,限制了对其健康风险的评估。本研究采用液相色谱–串联质谱(LC-MS/MS)分析技术,研究了不同剂量的SCCPs暴露(0、1.0、10.0和100.0μg·L-1;C13-CPs;55.0%Cl)对人体肝癌细胞Hep G2的糖代谢、氨基酸代谢和脂肪酸代谢的影响。通过偏最小二乘判别分析(PLS-DA)鉴别各组代谢产物谱差异,发现3个SCCPs暴露剂量组均能够与对照组完全分开,表明SCCPs短期暴露能够引起细胞代谢活动的显著改变。SCCPs的低剂量暴露可明显刺激Hep G2细胞对氨基酸的吸收。与对照组相比,SCCPs低剂量暴露组(1.0μg·L-1)培养基中谷氨酰胺、色氨酸和丝氨酸的含量显著(P0.05)降低。而高剂量SCCPs(100.0μg·L-1)暴露抑制了细胞对氨基酸和葡萄糖吸收,但促进了乳酸、丙氨酸、半胱氨酸的生成。氨基酸吸收的抑制不可避免地会影响蛋白质的合成。同时,SCCPs的暴露使饱和脂肪酸代谢紊乱,使不饱和脂肪酸水平上调。为确定SCCPs的毒性作用方式,有必要从转录组和蛋白组层面进一步研究其毒性机制。     

Variation in soil organic carbon mineralization and microbial community structure induced by the conversion from double rice fields to drained fields北大核心CSCD

Land use conversion is an important factor influencing the carbon gas exchange between land and atmosphere. The effect of land use conversion on soil organic carbon mineralization and microbial function is important for soil organic carbon sequestration and stability. This research studied the effects of land use conversion on soil chemical properties, organic carbon mineralization and microbial community structure after two years of conversion from double rice cropping (RR) to maize-maize (MM) and soybean-peanut (SP) double cropping systems in southern China. The results showed that soil pH significantly decreased by 0.50 (MM) and 0.52 (SP, P = 0.002), and dissolved organic carbon significantly increased by 23%- 35% (P = 0.016). No significant difference was found in soil organic carbon mineralization rate with the land use conversion, though the accumulated mineralization decreased after 13 days of incubation (P = 0.019). Land use conversion from paddy to upland significantly changed soil microbial community structure. The total PLFAs, bacterial, gram-positive bacterial (G+), gram-negative bacterial (G-) and actinomycetic PLFAs decreased significantly (P < 0.05), the ratio of fungal PLFAs to bacterial PLFAs (F/B) increased significantly (P = 0.006). But no significant differences in microbial groups were found between MM and SP. The accumulated mineralization at the beginning period of the incubation were significantly positively correlated with soil actinomycetic PLFAs (P = 0.034). After 13 days of incubation, soil F/B showed a positive correlation with the accumulated mineralization (P = 0.004). However, soil microbial community structure(P = 0.014)and total PLFAs(P = 0.033)showed a positive correlation with the accumulated mineralization after 108 days of incubation. Our results indicated that after conversion from paddy soils to drained soils, soil pH and total nitrogen are the key factors regulating the variations in soil microbial community structure and biomass, and then influencing soil organic carbon mineralization.     

Enhanced anaerobic fermentation with azo dye as electron acceptor： Simultaneous acceleration of organics decomposition and azo decolorization

Accumulation of hydrogen during anaerobic processes usually results in low decomposition of volatile organic acids（VFAs）. On the other hand, hydrogen is a good electron donor for dye reduction, which would help the acetogenic conversion in keeping low hydrogen concentration. The main objective of the study was to accelerate VFA composition through using azo dye as electron acceptor. The results indicated that the azo dye serving as an electron acceptor could avoid H2 accumulation and accelerate anaerobic digestion of VFAs. After adding the azo dye, propionate decreased from 2400.0 to 689.5 mg/L and acetate production increased from 180.0 to 519.5 mg/L. It meant that the conversion of propionate into acetate was enhanced. Fluorescence in situ hybridization analysis showed that the abundance of propionate-utilizing acetogens with the presence of azo dye was greater than that in a reference without azo dye. The experiments via using glucose as the substrate further demonstrated that the VFA decomposition and the chemical oxygen demand（COD） removal increased by 319.7 mg/L and 23.3% respectively after adding the azo dye. Therefore, adding moderate azo dye might be a way to recover anaerobic system from deterioration due to the accumulation of H2 or VFAs.