石灰—硫酸亚铁法处理高浓度砷和氟酸性废水试验研究

采用二级石灰－硫酸亚铁法处理砷和氟浓度分别高达１１０ｍｇ／Ｌ和６５０ｍｇ／Ｌ以上的酸性废水。当一、二级控制条件分别为ｐＨ９．５和９．０、Ｆｅ／Ａｓ比为２．５和１５时，一级砷和氟去除率分别可达９９．５％和９４％，二级出口砷和氟残余浓度分别可低至０．１ｍｇ／Ｌ和１３．８ｍｇ／Ｌ，Ｃｕ、Ｚｎ和Ｐｂ等重金属离子均达检不出水平。     

光催化氧化-混凝工艺处理化工废水

探索了光催化氧化－混凝工艺处理废水的工艺条件,最佳光催化氧化处理条件为ＰＨ＝３,催化剂为铁盐,氧化剂Ｈ２Ｏ２,低压汞灯,光照时间１．５ｈ,废水温度４５℃,温凝剂选用ＰＡＣ和ＰＡＭ（混凝剂的投加量为原水ＣＯＤｃｒ：ＰＡＣ：ＰＡＭ＝７：１．５：０．０１）,混凝ＰＨ６,沉降时间０．５ｈ,在该工艺条件对ＣＯＤｃｒ为１７３－７０１４４ｍｇ／Ｌ的十二烷基苯磺酸钠废水、苯酐废水、富马酸废水、邻苯二甲酸二辛酯废水     

垃圾渗滤液中的氨氮对微生物活性的抑制作用

研究了合成废水和垃圾滤渗滤中氨氮对活性污泥微生物活性的抑制作用。当合成废水的氨氮浓度从５０ｍｇ／Ｌ依次成倍递增至８００ｍｇ／Ｌ时,脱氢酶活性由１１．０４μｇＴＦ／ｍｇＭＬＳＳ下降至４．２２,此时ＣＯＤ的去除率相应由９５．１％降低到７９．１％。     

炼铜烟灰制取高纯度硫酸锌

采用炼钢烟灰制取高纯度硫酸锌,研究了制取条件对收率和产品质量的影响,试验结果表明,控制适宜的酸浸条件,锌浸取率≥９８％,铁浸取率可控制在０．０２％以下,当酸浸工艺条件液固比为３：１,温度８０－９０℃,硫酸加入量３９ｇ／Ｌ（酸浸液）滴酸时间１．５ｈ浸取时间２ｈ,再用空气和过氧化氢氧化除去溶液中的铁,产品中硫酸锌含量≥９９％,铁含量可降至０．５ｍｇ／Ｌ以下。     

厌氧—好氧法处理渗滤液与城市污水混合废水的可行性

彩厌氧－好氧工艺对不同浓度的垃圾填埋场渗滤液与城市污水在不同混合比（ＶＳＨ：ＶＣＨ）时的处理效果及可行性进行了研究,厌氧段采用新型ＡＢＲ反应器并将控制在水解酸化阶段。研究表明,当原渗滤液ＣＯＤ〈５５００ｍｇ／Ｌ时,ＶＳＨ：ＶＣＨ达４：６是可行的,其稳定运行时的ＣＯＤ和ＢＯＤ５去除率可分别达８８．９％和９６．８％当原渗滤液ＣＯＤ≥６５００～８８００ｍｇ／Ｌ时,须将ＶＳＨ：ＶＣＨ控制在２．８以内。     

SBR法处理化学药物制剂废水

采用 ＳＨＲ法处理化学药物制剂废水． 调节 ｐＨ至７．５,进水 ＣＯＤｃｒ ２２４～１５３０ ｍｍ／Ｌ,曝气１０ ｈ, ＣＯＤｃｒ容积负荷达２．５８ｋｇ／ｍ~３·ｄ,ＣＯＤｃｒ的去除率高达９４．２％,处理后出水ＣＯＤｃｒ＜１００ｍｇ／Ｌ,达到综合排放标准（ＧＢ８９７－９６）一级标准。ＣＯＤｃｒ容积负荷至３．８４ ｋｇ／ｍ~３·ｄ, ＣＯＤｃｒ去除率仍＞８５．９％。     

太湖微囊藻对哺乳动物毒性影响的研究

首先通过血凝实验证实太湖的微囊藻具有蓝藻毒素，在此基础上给小白鼠进行染毒。结果发现湖的微囊藻对小白鼠急性中毒的半致死浓度ＬＤ５０（２ｈ）为２５０ｍｇ／ｋｇ，ＬＤ５０（２４ｈ）对１４０ｍｇ／ｋｇ，说明太湖微囊藻是属于中等毒性的蓝藻。病理检查结果为肝肿大充血，小白鼠的肝体重比较未染毒的小白鼠高３．１４％￣３．４４％。     

铁—草酸盐络合物的光解对水溶性染料脱色作用的研究

进行了铁－草酸盐络合物在紫外光照射下，对水溶性染料的光解脱色研究。结果表明，在ｐＨ＝４．Ｆｅ／Ｃ２Ｏ＾２－４＝２０μｍｏｌ．Ｌ＾－１／２４０μｍｏｌ．Ｌ＾－１的条件下，铁－草酸盐络合物／ＵＶ对２０ｍｇ／Ｌ染料的混合溶液的脱色率为４３．１％，有一定的脱色效果。     

活性硅酸混凝剂PFASSC处理造纸废水

利用硅酸钠、硫酸铝、三氯化铁和硫酸为主要原料制备了复合型活性硅酸混凝剂ＰＦＡＳＳＣ并对造纸废水进行了处理，得到活性硅酸混凝剂ＰＦＡＳＳＣ最佳配方为：ＰＨ＝２．０（Ｆｅ＾３＋＋Ａｌ＾２）／ＳｉＯ２（摩尔比）＝１．５，Ｆｅ＾３＋／Ａｌ＾３＋（摩尔比）＝１．０，与常用混凝剂相比，ＰＦＡＳＳＣ混凝剂处理造纸废水对除浊、脱色和去除ＣＤＤＣｒ有更加优良的性能。     

光度法测定高浓度化学需氧量

在建立了低浓度化学需氧量光度测定法的基础上，进一步摸索了高浓度ＣＯＤ光度测定法的测试条件，实验证明，在波长６１０ｎｍ，重铬酸钾浓度（１／６Ｋ２Ｃｒ２Ｏ７）０．５５ｍｏｌ／Ｌ的条件下，可以测定２００～２０００ｍｇ／Ｌ范围内的ＣＯＤ，结果令人满意，用该光度法测定的ＣＯＤ与标准滴定法的ＣＯＤ比值在０．９７～１．０３之间。     

Mercaptobenzothiazole-on-gold organic phase biosensor systems: 1. Enhanced organosphosphate pesticide determination

This paper reports the construction of the gold/mercaptobenzothiazole/polyaniline/acetylcholinesterase/polyvinylacetate (Au/ MBT/PANI/AChE/PVAc) thick-film biosensor for the determination of certain organophosphate pesticide solutions in selected aqueous organic solvent solutions. The Au/MBT/PANI/AChE/PVAc electrocatalytic biosensor device was constructed by encapsulating acetylcholinesterase (AChE) enzyme in the PANI polymer composite, followed by the coating of poly(vinyl acetate) (PVAc) on top to secure the biosensor film from disintegration in the organic solvents evaluated. The electroactive substrate called acetylthiocholine (ATCh) was employed to provide the movement of electrons in the amperometric biosensor. The voltammetric results have shown that the current shifts more anodically as the Au/MBT/PANI/AChE/PVAc biosensor responded to successive acetylthiocholine (ATCh) substrate addition under anaerobic conditions in 0.1 M phosphate buffer, KCl (pH 7.2) solution and aqueous organic solvent solutions. For the Au/MBT/PANI/AChE/PVAc biosensor, various performance and stability parameters were evaluated. These factors include the optimal enzyme loading, effect of pH, long-term stability of the biosensor, temperature stability of the biosensor, the effect of polar organic solvents, and the effect of non-polar organic solvents on the amperometric behavior of the biosensor. The biosensor was then applied to detect a series of 5 organophosphorous pesticides in aqueous organic solvents and the pesticides studied were parathion-methyl, malathion and chlorpyrifos. The results obtained have shown that the detection limit values for the individual pesticides were 1.332 nM (parathion-methyl), 0.189 nM (malathion), 0.018 nM (chlorpyrifos).     

Fipronil toxicity in northern bobwhite quail Colinus virginianus: reduced feeding behaviour and sulfone metabolite formation

Fipronil is a phenyl pyrazole insecticide registered for agricultural use in many countries. Avian exposure to fipronil occurs mainly by ingesting contaminated insects or seeds. There is little information regarding the toxicological effects of fipronil in avian species and even less research documenting avian behavioural responses to fipronil ingestion. We examined the effects of a single oral dose of fipronil in northern bobwhite quail, the most fipronil-sensitive species tested to date, in respect to signs of intoxication and the metabolic fate of fipronil. Fipronil-treated birds did not eat or drink following pesticide administration, and as a result lost a significant amount of body mass. Treated birds also appeared withdrawn and did not respond to disturbance within the first hour after treatment. Identifiable signs of fipronil toxicity were not observed until at least 2d after treatment. Chemical analyses indicated a difference between fipronil and fipronil-sulfone residue distribution and bioaccumulation, with significantly higher (30- to 1000-fold) tissue concentrations of the sulfone detected at all time points from 8 to 96 h post-dose in brain, liver and adipose tissues. Tissue sulfone concentrations increased significantly in fipronil-treated birds, peaking at 72 h post-dose. Body mass decreased at all time points in dosed birds. The coincidence of the particular intoxication symptoms with the time course of rise in brain sulfone levels after fipronil dosing gives insight into possible mechanisms of toxicity in this highly sensitive species.     

Photodegradation of organophosphorus insecticides - investigations of products and their toxicity using gas chromatography-mass spectrometry and AChE-thermal lens spectrometric bioassay

Four organophosphorus compounds: azinphos-methyl, chlorpyrifos, malathion and malaoxon in aqueous solution were degraded by using a 125 W xenon parabolic lamp. Gas chromatography-mass spectrometry (GC-MS) was used to monitor the disappearance of starting compounds and formation of degradation products as a function of time. AChE-thermal lens spectrometric bioassay was employed to assess the toxicity of photoproducts. The photodegradation kinetics can be described by a first-order degradation curve C=C0e(-kt), resulting in the following half lives: 2.5min for azinphos-methyl, 11.6 min for malathion, 13.3 min for chlorpyrifos and 45.5 min for malaoxon, under given experimental conditions. During the photoprocess several intermediates were identified by GC-MS suggesting the pathway of OP degradation. The oxidation of chlorpyrifos results in the formation of chlorpyrifos-oxon as the main identified photoproduct. In case of malathion and azinphos-methyl the corresponding oxon analogues were not detected. The formation of diethyl (dimethoxy-phosphoryl) succinate in traces was observed during photodegradation of malaoxon and malathion. Several other photoproducts including trimethyl phosphate esters, which are known to be AChE inhibitors and 1,2,3-benzotriazin-4(3H)-one as a member of triazine compounds were identified in photodegraded samples of malathion, malaoxon, and azinphos-methyl. Based on this, two main degradation pathways can be proposed, both result of the (P-S-C) bond cleavage taking place at the side of leaving group. The enhanced inhibition of AChE observed with the TLS bioassay during the initial 30 min of photodegradation in case of all four OPs, confirmed the formation of toxic intermediates. With the continuation of irradiation, the AChE inhibition decreased, indicating that the formed toxic compounds were further degraded to AChE non-inhibiting products. The presented results demonstrate the importance of toxicity monitoring during the degradation of OPs in processes of waste water remediation, before releasing it into the environment.     

Effects of malathion and chlorpyrifos on acetylcholinesterase and antioxidant defense system in Oxya chinensis (Thunberg) (Orthoptera: Acrididae)

The study was undertaken to evaluate the effects of malathion and chlorpyrifos on acetylcholinesterase (AChE), esterase (EST) activity and antioxidant system after topical application with different concentration to Oxya chinensis. The results showed that malathion and chlorpyrifos inhibited EST, AChE activity and increased malondialdehyde (MDA) contents. A change in superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), glutathione peroxidase (GPx), and glutathione reductase (GR) activity combined with reduced glutathione (GSH) and total glutathione (tGSH) contents was found in O. chinensis after malathion and chlorpyrifos treatments. Malathion and chlorpyrifos increased SOD and CAT activity compared with the control. With the concentrations increasing, SOD and CAT activity showed the similar tendency, namely, SOD and CAT activity increased at the lower concentrations and decreased at the higher concentrations. The results showed that malathion and chlorpyrifos decreased significantly GR activity. GST and GPx activity at the studied concentrations of chlorpyrifos was lower than that of the control. However, no significance was observed. GPx and GST activity in malathion treated grasshoppers showed a biphasic response with an initial increase followed by a decline in its activity. Malathion and chlorpyrifos decreased GSH contents and the ratio of GSH/GSSG. The present findings indicated that the toxicity of malathion and chlorpyrifos might be associated with oxidative stress.     

Organophosphorus pollutants (OPP) in aquatic environment at Damietta Governorate, Egypt: implications for monitoring and biomarker responses

The study was carried out from spring 1999 to spring 2001 to monitor the residue levels of organophosphorus pollutants (OPP) in aquatic environment of the drainage canal surrounding a pesticide factory at Damietta Governorate. Water, sediment, and fish samples were collected at six different seasonal periods. OPPs were analyzed by GLC and confirmed using GC-MS. Chlorpyrifos, chlorpyrifos-methyl, malathion, diazinon, pirimiphos-methyl and profenofos were detected in most samples. Chlorpyrifos was dominant in all water and sediment samples. It was ranged from 24.5 to 303.8 and 0.9 to 303.8 ppb in water and sediment samples, respectively. Diazinon level was slightly similar to chlorpyrifos in fish samples. Data based on the grand total concentration of OPP showed that the most polluted samples were collected either at spring 1999 or autumn 2000. They were 675.5 and 303.8 ppb in water samples and 43.0 and 52.2 ppb in fish collected at spring 1999 and autumn 2000, respectively. The obtained results are in parallel to that found in case of cholinesterase activity where the activity of both acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) was declined at these seasonal period. The activity levels of AChE and BuChE were found to be 77.18% and 59.67% of control at spring 1999 and 78.62% and 85.80% of control, at autumn 2000, respectively. Thus, AChE and BuChE could be used as biomarkers for tracing and biomonitoring OPP pollution.     

Optimization of a methodology for the simultaneous determination of deltamethrin,permethrin and malathion in stored wheat samples using dispersive liquid–liquid microextraction with solidification of floating organic drop and HPLC-UV

The purpose of this study was to investigate common pesticides in stored wheat at Kermanshah province's silos in Iran. A simple, inexpensive, reliable and environmentally friendly method based on dispersive liquid–liquid microextraction with solidification of floating organic drop was developed. The analytical characteristics of the method were determined. Also, various parameters such as the materials of the silos, types of ownerships of the silos, geographic orientation of silo locations and climatic conditions of silo locations on pesticide residues in studied wheat samples were investigated. Among all the studied parameters, the climatic conditions of silo locations showed the highest influence on pesticide residues in wheat samples. Generally, 61.2% of the samples had pesticide levels below the method detection limits and 38.8% of the total samples had at least one of the understudied pesticides. Also, 13.9% of the samples had deltamethrin residues, 16.7% of the samples had permethrin, 22.2% of the samples had malathion, 11.1% of the samples had both permethrin and malathion and 2.8% of the samples had both deltamethrin and malathion. The results revealed that the residues of deltamethrin and malathion were lower than the standard level announced by European Union regulation and only three samples contained permethrin higher than Europe standard level.     

Growth,photosynthesis and removal responses of the cyanobacteria Chroococcus sp. to malathion and malaoxon

Abstract

Malathion is an organophosphorus pesticide widely used in agricultural crops, despite its toxicity. In addition, malaoxon occurs by oxidation of malathion being more toxic. The toxic effects of malathion and malaoxon in humans include hepatoxicity, breast cancer, genetic damage and endocrine disruption. The aim of this study involved assessing the effect of malathion commercial grade on Chroococcus sp., and its potential as an alternative to the removal of this pesticide and its transformation product such as malaoxon. We evaluated the effect of malathion at different concentrations (1, 25, 50, 75 and 100?ppm) on the biomass of the cyanobacteria Chroococcus sp. grown in medium BG-11; also, we analyse its ability to degrade both malathion and malaoxon into a temperature of 28?±?2?°C and at pH 6. The results showed that 50?ppm of malathion the cyanobacteria Chroococcus sp. reached the highest removal efficiency of malathion and malaoxon (69 and 65%, respectively); also, the growth rate of Chroococcus sp. increased without inhibiting the production of chlorophyll “a”, this can be explained by the hormesis phenomenon. Therefore, we consider that the cyanobacteria Chroococcus sp. may be a good candidate for bioremediation of aquatic systems contaminated with organophosphorus pesticides such as malathion and its transformation product such as malaoxon.     

Histopathology of gills in mosquitofish,Gambusia affinis after long-term exposure to sublethal concentrations of malathion

The histopathological effects of malathion, an organophosphate pesticide, on the gill tissues in mosquitofish, Gambusia affinis, were determined by light microscope. The fish were exposed to sublethal concentrations (0.01 and 0.02 mg/L) of malathion for 10, 20 and 30 days. Histological examination of the gills treated with malathion showed a variety of histopathological effects. The gill lesions included necrosis and desquamation of secondary lamellar epithelium, lifting up of epithelium, intraepithelial oedema, fusion of adjacent secondary lamellae, haemorrhage at primary lamellae, disorganization and rupture in seconder lamellae, hypertrophy and hyperplasia of epithelial cells. These alterations were time- and dose-dependent.     

Recovery of acetylcholine esterase activity of Drawida willsi (Oligochaeta) following application of three pesticides to soil

The recovery of acetylcholine esterase (AChE) activity of a dominant crop field earthworm (Drawida willsi, Michaelsen) was investigated under laboratory conditions following the application of two recommended agricultural (single and double) doses of butachlor (1.1 and 2.2 mga.i.kg(-1) dry soil), malathion (2.2 and 4.4 mga.i.kg(-1) dry soil) and carbofuran (1.1 and 2.2 mga.i.kg(-1) dry soil) to the soil. A sharp decline in the AChE activity of D. willsi was observed up to 9 and 12 days following treatment of carbofuran and malathion in both single and double doses, respectively, whereas very little inhibition was noticed in case of butachlor. D. willsi worms took 45 and 75 days to resume normal AChE activity after exposure to both single and double doses of malathion and carbofuran, respectively. Earlier [Soil Biol. Biochem. 31 (1999) 363-366], [Ph.D. thesis, Sambalpur University, Orissa, India, 2003] and [Pedobiologia (spl. issue), in press] reported that D. willsi takes 75-90 days and 90-105 days to resume normal growth and reproduction following application of both single and double agricultural doses of malathion and carbofuran, respectively. On the basis of the present and previous studies, we strongly suggest that the time gap between the first and second application of malathion, irrespective of single and double dosage, should be at least 90 days, whereas it should be at least 105 days for carbofuran. Butachlor was found to be very toxic, suppressing growth, sexual maturation and cocoon production of D. willsi at both single and double doses [Ph.D. thesis, Sambalpur University, Orissa, India, 2003]. We therefore suggest that application of organochlorine pesticides like butachlor should be avoided as far as possible to ensure maintenance of good soil health.     

The mobility of thiobencarb and fipronil in two flooded rice-growing soils

The mobility of the rice pesticides thiobencarb (S-[(4-chlorophenyl) methyl] diethylcarbamothioate) and fipronil ([5-amino-3-cyano-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]pyrazole) were investigated in the glasshouse under flooded conditions using two Australian rice-growing soils. When using leakage rates of 10 mm day(-1), less than 20% of applied thiobencarb and fipronil remained in the water column after 10 days due to rapid transfer to the soil phase. Up to 70% and 65% of the applied thiobencarb and fipronil, respectively, were recovered from the 0-1 cm layer of soils. Only 5-7% of each pesticide was recovered from the 1-2 cm layer, and less than 2% was recovered from each 1 cm layer in the 2-10 cm region of the soils. Analysis of the water leaking from the base of the soil cores showed between 5-10% of the applied thiobencarb and between 10-20% of the applied fipronil leaching from the soil cores. The high levels of pesticide in the effluent was attributed to preferential flow of pesticide-laden water via soil macropores resulting from the wetting and drying process, worm holes and root channels.