Effect of four experimental insecticides on enzyme activities and levels of adenosine triphosphate in mineral and organic soils

Abstract

A laboratory study was conducted to determine the effect of four experimental insecticides, DOWCO429X, DPX43898, tefluthrin and trimethacarb, on enzyme activities and levels of adenosine 5'‐triphosphate (ATP) in mineral and organic soils. DOWCO429X decreased urease activity in organic soil after 7 days while a stimulatory effect was observed with most treatments after 14 days. No inhibition on acetylene (C₂H₂) reduction by nitrogenase was evident with any of the insecticides in either soil. With the exception of DOWCO429X and tefluthrin at 7 days in organic soil, none of the insecticide treatments inhibited dehydrogenase activity in either soil. Dehydrogenase activity, measured by formazan formation, was greater in many samples in sandy loam than the control throughout the experiment. No inhibitory effect was observed on amylase activity after 2 or 3 days in sandy soil. A stimulatory effect was apparent in many samples after 2 days in organic soil. All insecticide treatments in sandy soil reduced invertase activity at 2 days. However, none of the experimental insecticides inhibited invertase activity after 3 days. A stimulatory effect in invertase activity was apparent in most cases at 2 days in organic soil and no difference was observed after 3 days. Phosphatase activity in insecticide treated samples was equal to or greater than that of control in sandy soil after 2 h. With the exception of DPX43898, the insecticides depressed phosphatase activity in most organic soil samples. The insecticides did not affect ATP levels in either soil. Results indicated that the chemical treatments at the levels tested did not significantly affect activities of enzymes or level of ATP in both soils.     

Preparation of a titanium dioxide photocatalyst codoped with cerium and iodine and its performance in the degradation of oxalic acid

A novel class of visible light-activated photocatalysts was prepared by codoping TiO(2) with cerium and iodine (Ce-I-TiO(2)). The particles were characterized using the Brunauer-Emmett-Teller method, X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Visible light absorption. Particles of Ce-I-TiO(2) had greater photoabsorption in the 400-800 nm wavelength range than iodine-doped TiO(2) (I-TiO(2)). The effects on the photocatalytic degradation of oxalic acid under visible light or UV-Visible light irradiation were investigated. The photocatalytic activity of Ce-I-TiO(2) calcined at 673 K was significantly higher than that of Ce-I-TiO(2) calcined at 773 K and I-TiO(2) calcined at 673 K in aqueous oxalic acid solution under visible light or UV-Visible light irradiation. Under visible light irradiation, oxalic acid was first adsorbed on the surface of the catalysts rather than reacted with free radicals in the bulk solution, and then oxidized by (·)OH(ads) to CO(2), which was verified by studying the effects of nitrogen purging and scavengers, as well as by gas chromatography/mass spectrometry.     

生物接触氧化处理微污染地面水的实验研究

生物接触氧化处理微污染地面水的实验结果表明,该方法处理效果显著、稳定性好、操作方便、容易实施,是解决污染给水处理问题的经济可行办法。     

内循环厌氧反应器多相流流场的三维数值分析

利用数值模拟的方法,引入欧拉双流体多相流模型及标准k-s紊流模型,模拟计算内循环厌氧反应器的三相流三维流场,并通过改变污泥颗粒密度及进水流量,针对固相流速及固含率的变化情况,分析条件的改变对流场的影响。研究结果表明,应用数值模拟方法可以获得内循环厌氧反应器内的流场特征;污泥颗粒密度及进水流量的改变对于反应器内污泥颗粒的流速及分布的均匀性有较为明显的影响。模拟结果对反应器的应用及优化设计具有一定的参考价值。     

城市污水处理厂恶臭浓度分布规律及其防治措施

城市污水处理厂的主要大气污染物之一为恶臭污染,恶臭问题已经成为环境领域的一个重要研究课题。恶臭污染物的来源主要是初沉池等水流湍动处,其成分主要是含氮化合物、含硫化合物、含氧有机物等。分析了恶臭污染物的来源、成分和浓度分布等,对确定城市污水处理厂的卫生防护距离进行了讨论,并介绍了目前国内外主要恶臭污染防治措施。湿式吸收氧化法和生物过滤法这两种技术是当前发展和应用的方向。     

改进沉淀法在溶解性无机碳稳定同位素测定中的应用研究

水体中溶解性无机碳(Dissolved inorganic carbon, DIC)的稳定碳同位素比值(δ¹³C_DIC)是揭示碳循环过程的重要技术指标。DIC的分离和富集是测定δ¹³C_DIC的基础,也是影响δ¹³C_DIC测定准确度的主要过程之一。沉淀法和气体法均为常用的DIC分离和富集方法。相比于气体法,沉淀法操作流程简单,适用性较强,在δ¹³C_DIC测定过程中具有广阔的应用前景。然而,基于沉淀法的DIC分离和富集过程中常存在碳稳定同位素分馏问题。为此,本研究在综合气体法和沉淀法优缺点的基础上,以超声时间,水浴温度和氮气吹扫速率为自变量,以δ¹³C_DIC的理论值与实测值之间绝对误差的最小化为目标,采用响应面法对传统NaOH-BaCl₂沉淀法进行了改进。基于改进沉淀法测定的δ¹³C_DIC理论值与实测值之间的...     

Fluorescence detection of phosphate in an aqueous environment by an aluminum-based metal-organic framework with amido functionalized ligands

● A novel Al-MOF was successfully synthesized by a facile solvothermal method. ● Al-MOF showed superior performance for phosphate detection. ● High selectivity and anti-interference for detection were demonstrated. ● The high coordination between Al-O and PO₄³⁻ was the key in fluorescence sensing. The on-site monitoring of phosphate is important for environmental management. Conventional phosphate detection methods are not appropriate to on-site monitoring owing to the use of complicated detection procedures, and the consequent high cost and maintenance requirements of the detection apparatus. Here, a highly sensitive fluorescence-based method for phosphate detection with a wide detection range was developed based on a luminescent aluminum-based metal-organic framework (Al-MOF). The Al-MOF was prepared by introducing amine functional groups to conventional MIL to enhance phosphate binding, and exhibited excellent fluorescence properties that originated from the ligand-to-metal charge transfer (LMCT). The detection limit was as low as 3.25 μmol/L (0.10 mg/L) and the detection range was as wide as 3–350 μmol/L (0.10–10.85 mg/L). Moreover, Al-MOF displayed specific recognition toward phosphate over most anions and metal cations, even for a high concentration of the co-existent ions. The mechanism of phosphate detection was analyzed through the characterization of the combination of Al-MOF and phosphate, and the results indicated the high affinity between Al-O and phosphate inhibited that the LMCT process and recovered the intrinsic fluorescence of NH₂-H₂BDC. The recovery of the developed detection method reached a satisfactory range of 85.1%–111.0%, and the feasibility of on-site phosphate detection was verified using a prototype sensor for tap water and lake water samples. It was demonstrated that the prepared Al-MOF is highly promising for on-site detection of phosphate in an aqueous environment.     

珠三角夏秋季节大气颗粒物与碳黑气溶胶污染特征的研究

以珠三角地区4个区域监测站2012年夏秋季节监测结果为例,分析该地区不同粒径大气颗粒物（PM10／PM2．5／PM1）和碳黑气溶胶（BC）质量浓度的变化特征。结果显示,区域内不同站点之间或站点不同粒径颗粒物之间均有显著的相关性,该地区PM,和BC质量浓度约占PM2．5的70％和8．2％,PM1,约占PM10的68％。秋季污染天气中,PM1质量浓度的增长量大于其他粒径颗粒物的增长量。颗粒物浓度与大气能见度的影响分析显示,碳黑气溶胶质量浓度增大与能见度降低关系密切。     

Recovery of platinum and synthesis of glass–ceramic from spent automotive catalyst via co-treatment process with coal fly ash

Journal of Material Cycles and Waste Management - Spent automotive catalyst (SAC) has attracted attention because of containing platinum group metals (PGMs) along with hazardous materials such as...     

Assessing the fractionation and bioavailability of heavy metals in soil–rice system and the associated health risk

Environmental Geochemistry and Health - This study developed a method to build relationships between chemical fractionations of heavy metals in soils and their accumulations in rice and estimate...