氯乙酰胺类除草剂微生物降解研究进展

主要介绍了几种氯乙酰胺类除草剂的微生物降解机制和相关降解酶．目前没有一种纯菌培养物或混合菌群能完全矿化异丙甲草胺和甲草胺，它们只能被细菌和真菌共代谢．毒草胺能被纯菌或混合菌群完全矿化，且有几种不同的矿化途径．乙草胺是我国生产量和使用量最多的三大除草剂之一，然而关于其微生物降解方面的研究在国内外报道的非常少，因此关于乙草胺被微生物降解和矿化的研究工作还有待于进一步加强．参45     

Ferrioxalate-mediated photodegradation and mineralization of 4-Chlorophenol

INTENTION, GOAL, SCOPE, BACKGROUND: Advanced oxidation processes are powerful methods which are capable of transforming refractory, nonbiodegradable and/or toxic organic compounds into harmless end products such as carbon dioxide and water. However, one commen problem of all advanced oxidation processes is the high demand of electrical energy for ultraviolet lamps, which causes high operational costs. Minimization of the required irradiation time, and therefore the energy consumption, by optimization of other reaction conditions such as catalyst-oxidant type and concentration, pH, temperature, pollutant/oxidant ratio etc., therefore continues to gain importance. OBJECTIVE: The main objective of this study was the minimization of the required irradiation time through optimization of the use of a newly patented catalyst, ferrioxalate, and also to compare the performance of this catalyst with the performance of other AOPs. METHODS: Oxidation of 4-chlorophenol by photo-Fenton process using potassium ferrioxalate as a mediator was studied in a lab scale photoreactor. The influence of parameters such as hydrogen peroxide and ferrioxalate concentrations, initial pH, power-output, oxalate/iron ratio and different iron sources was evaluated. An upflow photoreactor equipped with a 1000 Watt high-pressure mercury vapour lamp and operating in a recirculation mode was used during photodegradation experiments. The extent of the reduction of 4-chlorophenol, Total Organic Carbon and Chemical Oxygen Demand was used to evaluate the photodegradation reaction. RESULTS AND DISCUSSION: The optimum pH range observed was found to be 2.7-3. The efficiency of 4-chlorophenol oxidation increased with increasing concentrations of hydrogen peroxide and ferrioxalate, reaching a plateau after the addition of 10 and 0.072 mM of those reagents, respectively. Using an Oxalate/iron ratio of 12 was 18% less efficient than using a ratio of 3:1. The efficiency increased with increasing radiation power. However, this increase was not linear. The UV/ferrioxalate/H2O2 process, by which complete mineralization of 100 mg l(-1) 4-chlorophenol was achieved in 20 min of total reaction time, was the most efficient process among the alternatives applied. CONCLUSIONS: The use of ferrioxalate as the catalyst was found to be more efficient than the use of Fe(II) and Fe(III) iron species. It was possible to completely mineralize 4-chlorophenol. RECOMMENDATION AND OUTLOOK: The results of this study demonstrate that the ferrioxalate-mediated degradation of 4-chlorophenol requires less irradiation times than other advanced oxidation processes. There are mainly 19 phenol isomers and other toxic and nonbiodegradable organic compounds. We recommend that similar studies should be performed on many such compounds in order to attain a clear understanding of the performance of this catalyst. Because of its light sensitivity, this catalyst should be used immediately after its preparation. The use of low pressure mercury vapour lamps in this process should also be considered, since low power outputs may be enough for the process.     

论永梅会多层、多类型成矿集中区大型铜、金、银、锡矿床成矿远景

近10多年来东南沿海找矿具突破性意义的一批矿床中，有5个各具特色的矿床及与之相类似的一批矿床（点）和矿化层位，集中分布在闽粤赣三省交界处面积约为8万km2的永定一梅县－会昌地区（简称永梅会地区），构成一成矿集中区．其特点是矿床集中且规模大、埋藏浅、多类型和多层性。该区处于不同构造单元的交接、叠置地带，自晋宁期至晚燕山期漫长的地质历史为形成多层、多类型矿床提供了良好的成矿环境；频繁的火山一侵入活动揭示了壳幔分离、地幔物质多次注入、地壳物质多次循环，特别是石炭纪以来（C1、J1、K1）三次双峰式火山活动所反映的位张环境，造就了本区成矿元素多、丰度高的地球化学场和构造应力环境；可能存在的地幔热流柱对地壳的作用是构成矿床集中的深部构造因素；区内石炭系岩相古地理特征显示本区具有与长江中下游地区石炭系铜矿含矿层位相当的合矿层位；本区中等剥蚀程度有利于寻找火山根部带或基底中的矿床。在分析该区上述成矿远景基础上，提出了该区有可能成为我国南方继德兴之后及维长江中下游地区之后的另一个铜、多金属成矿区。     

Combined effects of two sulfonylurea herbicides on soil microbial biomass and N-mineralization

ＩｎｔｒｏｄｕｃｔｉｏｎＡｇｒｏｃｈｅｍｉｃａｌｓｈａｖｅｂｅｅｎａｃｔｅｄａｖｅｒｙｉｍｐｏｒｔａｎｔｒｏｌｅｉｎａｇｒｉｃｕｌｔｕｒａｌｐｒｏｄｕｃｔｉｏｎ .Ｆｏｒａｖｏｉｄｉｎｇｄａｍａｇｅｏｆｃｒｏｐｓ,ｍａｎｙｋｉｎｄｓｏｆｐｅｓｔｉｃｉｄｅｓａｒｅａｐｐｌｉｅｄｆｏｒｔｈｅｒｅａｓｏｎｏｆｉｎｓｅｃｔ,ｄｉｓｅａｓｅｓａｎｄｗｅｅｄｃｏｎｔｒｏｌｉｎＣｈｉｎａ .Ｓｃｉｅｎｔｉｓｔｓｈａｖｅｄｏｎｅａｌｏｔｏｆｗｏｒｋｏｎｔｈｅｆａｔｅａｎｄｍｅｔａｂｏｌｉｓｍｏｆｐｅｓｔｉｃｉｄｅｓ,…     

关帝山不同海拔土壤碳矿化和微生物特征

以山西省关帝山不同海拔的8个样地土壤为研究对象,分析不同海拔土壤碳氮含量、土壤碳矿化和细菌、真菌、放线菌、固氮菌、硝化细菌和反硝化细菌6类微生物量的变化.结果表明,海拔为2163m时,土壤有机碳和活性碳1（LC1）最高,分别为74.41和6.72g/kg,在海拔2700m总氮含量最高为6.54g/kg.土壤碳矿化累积量和碳矿化速率因海拔的升高而显著增加（P<0.05）,土壤碳矿化累积量和活性碳2（LC2）之间有显著正相关.土壤细菌、放线菌和固氮菌的数量在海拔为1791m时最高,分别为3.41×10⁶、1.90×10⁶和1.21×10⁶个/g,细菌、真菌、放线菌和固氮菌的数量随着海拔的升高而逐渐下降,与海拔之间呈显著负相关;相反,硝化细菌和反硝化细菌数量却逐渐增加,在海拔为2700m时最高,分别为1.37×10⁴和6.02×10³个/g,它们与海拔和总氮之间的关系呈显著正相关（P<0.01）.总之,土壤有机碳、总氮、碳矿化累积量、硝化细菌和反硝化细菌随海拔显著增加,而细菌、真菌、放线菌和固氮菌随海拔的变化呈相反的趋势.     

氮、硫输入对河口湿地土壤有机碳矿化的实验研究

通过室内培养实验,研究了氮、硫输入对闽江河口湿地土壤有机碳矿化和土壤理化性质的影响.结果表明:NH_4Cl(N1)、NH_4NO_3(N3)、K_2SO_4(S)和NH_4Cl+K_2SO_4(NS1)处理显著促进了湿地土壤有机碳矿化速率(p0.05),较对照分别提高了76.57%、60.09%、83.20%和52.59%,并且不同处理下土壤有机碳矿化速率均表现为随培养时间的增加而递减.氮、硫输入在不同时间对湿地土壤有机碳矿化的影响不尽一致,在前6 d各处理的促进作用最明显.湿地土壤有机碳累积矿化量在不同处理下均表现为随培养时间逐渐增加,其增长速率在培养初始阶段较快,而后逐渐减慢;不同培养时间有机碳累积矿化量在N1、N3、S和NS1处理下与对照处理间均存在显著差异(p0.05).短期培养结束后,N3、NS1处理显著增加了湿地土壤DOC含量(p0.05);N1、N3、NS1和NH_4NO_3+K_2SO_4(NS3)处理均显著增加了土壤NH_4~+-N含量(p0.05);KNO_3(N2)、N3、NS2和NS3处理均显著增加了土壤NO_3~--N含量(p0.05);S、NS1、NS2和NS3处理均显著增加了土壤SO_4~(2-)含量(p0.05).不同处理下湿地土壤Cl-、pH、EC具有微弱的波动变化特征,但在不同处理组间均不存在显著差异(p0.05).多元回归分析显示,DOC、NH_4~+-N和SO_4~(2-)是氮、硫输入处理下影响闽江河口湿地土壤有机碳矿化速率的主要控制因素.     

施肥与地膜覆盖对土壤有机质平衡的影响

用田间长期定位试验法研究了施肥与地膜覆盖条件下玉米连作在壤质棕壤中有机质的矿化、积累和平衡。结果表明，土壤有机质矿化率在０．０１０７～０．０４３８／ａ之间，施肥与地膜覆盖有利于土壤有机质的积累与平衡，并加快有机质矿化；在本试验各施肥处理中土壤有机质均有所积累；在连年稳定施肥条件下，有机肥的施用会明显提高土壤有机质平衡值     

Fate of the veterinary antibiotic 14C-difloxacin in soil including simultaneous amendment of pig manure with the focus on non-extractable residues

The fate of ¹⁴C-labeled difloxacin (¹⁴C-DIF) was studied in time course experiments after application on soil (Ap horizon of silt loam) and amendment of authentic DIF containing pig manure (146 mL kg^?1; 4.17 MBq kg^?1; 0.85 mg kg^?1) or water (124 mL kg^?1; 0.42 MBq kg^?1; 0.09 mg kg^?1) for 56 and 120 days of incubation, respectively.

Mineralization of ¹⁴C-DIF was below 0.2% in both experiments after 56 days or 120 days. In the course of the experiments, portions of extractable radioactivity (Accelerated Solvent Extraction (ASE); acetonitrile-water) decreased to 19–21% depending only little on manure amendment. Non-extractable residues of ¹⁴C-DIF increased to 70–74% after 56 days and 120 days, respectively, and therefore were the main route of ¹⁴C-DIF in soil. According to radioanalytical HPLC and LC-MS/MS, only the parent compound was found in all extracts over the whole time of the experiment. According to fractionation of the non-extractable residues (NER) into particle size fractions, ¹⁴C portions were associated to the water used for fractionation, the silt and clay fractions, whereas no radioactivity was detected in the sand fraction. The majority of ¹⁴C was found within the clay fractions.

Fractionation of humic components showed that radioactivity derived from ¹⁴C-DIF was associated with humic acids, fulvic acids, humins and minerals and very little with soluble, non-humic HCl fraction. The highest portions of radioactivity were found in the fulvic acid fraction. Results obtained by size exclusion chromatography (SEC) of the purified fulvic acids were similar for every sample analyzed. One large portion of ¹⁴C co-eluted with fulvic acids of a molecular weight below 910 g mol^?1. Both fractionation methods demonstrated that the parent compound DIF or initial metabolites were rapidly integrated into humic materials and, thus, were major components of NER.     

季节性温度升高对落干期消落带土壤氮矿化影响

为揭示季节性温度升高对消落带落干期土壤氮矿化的影响,分别采集三峡支流澎溪河消落带上游和下游两个水文断面,155 m(低)、165 m(中)和175 m(高)这3个水位高程表层土壤,结合落干期气温变化特点,在25℃和35℃两个温度下进行恒温培养.结果表明,消落带土壤总氮和硝态氮在上游断面和高水位高程含量更高,而下游和低水位高程含量更低,铵态氮分布与其相反.硝态氮是无机氮的主要存在形式,占无机氮的57.4%~84.7%.相同培养温度下,氨化、硝化、净氮矿化速率均表现为随水位高程增加,随流域断面由下至上而显著增加(P0.05);总体上,在水位高程和流域断面上均表现为:温度升高使硝化速率和净氮矿化速率显著增加(P0.05),而对土壤氨化速率无显著影响(P0.05).     

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.