硫丹在茶叶中的残留动态与用药安全性评价

硫丹在茶叶中的消解动态符合一级动力学方程,在茶叶中的残留量随着施用剂量的增加而增加。硫丹在乌龙茶中的消解速率显著低于绿茶,同一环境下,35％硫丹乳油500倍、1000倍、1500倍、2000倍液处理在乌龙茶和绿茶中的半衰期分别为2．15-2．84d和1．65-1．98d,药后7d残留量分别为4．21mg／kg-12．04mg／kg和2．81mg／kg～8．98mg／kg。同时,由于气候差异,同一浓度处理的残留量和半衰期不同地区间的差异也较大。不同茶区,无论乌龙茶或绿茶品种,药后7d,1000倍、1500倍、2000倍液处理的残留量均在10．0mg／kg以下,而500倍的个别超过10．0mg／kg,但在20．0mg／kg以下,所以,按欧盟最高限量30．0mg／kg标准计,目前茶园施用该药安全间隔期为7d是合理的。本分析方法采用微型层析柱法净化,具有操作时间短,试剂用量省、净化效果好的优点,最低检出量为0．0006ng,最小检出浓度为0．0064g／g,该技术指标完全满足残留分析的要求。     

氰戊菊酯在香蕉及蕉园土壤中的残留动态与安全性评价

采用气相色谱(GC-ECD)及田间试验方法,研究氰戊菊酯在香蕉及蕉园土壤中的残留降解动态。结果表明,氰戊菊酯在香蕉上的原始残留沉积量因不同施药处理有所差异,香蕉及蕉园土壤上的降解速度较缓慢,降解规律符合“C＝C₀·^e-kt”一级动力学关系。在香蕉上,相关系数r = 0.9722～0.9980(P＜0.01),降解系数k = 0.0703～0.0767,半衰期T_1/2 = 9.1～9.9 d,降解99%所需要时间T_0.99 = 60.1～65.6 d;在土壤中,k = 0.0821,T_1/2 = 8.5 d,T_0.99 = 56.1 d。距第2次施药后62～68 d,最终香蕉的残留量＜0.01 mg·kg^-1,土壤中为0.015～0.020 mg·kg^-1。在福建蕉区,氰戊菊酯的常规施药方法是间隔期7 d连续2次施用有效剂量112.50 g·hm^-2,采样前安全间隔期可推荐为＞13.6 d,产品质量最终可符合GB/T 2763-2012、NY/T 750-2011的要求。     

氯氰菊酯在香蕉、土壤上的残留动态及安全性评价

采用气相色谱法及田间试验法研究氯氰菊酯在香蕉及蕉园土壤上的残留降解动态。结果表明,氯氰菊酯在香蕉上的原始沉积量较低,不同施药剂量有明显的差异。氯氰菊酯在香蕉及蕉园土壤上降解速度较缓慢,残留降解规律均符合一级动力学关系,在香蕉上两种施药剂量的降解速率相接近,半衰（T1/2）为12.1～12.8 d、降解99%需时（T0.99）为80.3～85.1 d;在蕉园土壤上T1/2、T0.99分别为8.0 d、52.9 d。在香蕉上距第2次施药后62～70 d最终产品残留量＜0.01 mg/kg。在福建蕉区氯氰菊酯按常规施药方法,间隔期7 d连续施用有效剂量56.25 g/hm2两次,施药安全间隔期可推荐为＞7 d,最终产品质量符合NY/T 750-2011规定的MRL要求。     

水胺硫磷在香蕉及土壤中的残留动态

通过田间试验,采用气相色谱法检测水胺硫磷在香蕉及其土壤中的残留消解动态。结果表明,水胺硫磷在香蕉中的原始沉积量及残留量与施药剂量密切相关,施用加倍剂量处理的原始沉积量为推荐剂量的148%。水胺硫磷在香蕉及土壤中的消解规律符合一级动力学关系,在香蕉中的相关系数︱r︱= 0.9465～0.9490(P＜0.01),消解系数(︱k︱) = 0.1606±0.0035,半衰期(T1/2)为4.3～4.5 d,消解99%所需要时间(T0.99)为28.1～29.4 d;在土壤上︱r︱= 0.9552(P＜0.01),︱k︱= 0.2107,T1/2为3.3 d、T0.99为21.9 d。距末次施药后58~65d,在香蕉最终产品及蕉园土壤均未检出水胺硫磷残留。     

辛硫磷在柚园土壤中的残留动态研究

按沙田柚园上桔实雷瘿蚊的防治期适期喷施40%辛硫磷乳油(3.75kg/hm2),其在不同果园土壤中的原始沉积量为81.65～132.96mg/kg,半衰期为2.7～4.5d,药后7d各处理点辛硫磷的消解率均在90%以上.     

茚虫威在豇豆中残留动态及安全使用技术研究

采用气相色谱(GC-ECD)分析法,研究15%茚虫威(安打)乳油在豇豆中的残留消解动态和安全使用技术。该方法最小检出量为0.01ng,最低检出浓度为0.005mg/kg;添加回收率分别为84.7%~92.8%,RSD为3.43%~5.27%。残留消解动态表明,茚虫威在豇豆中的原始沉积量间隔7d连续施用2次>施用1次;残留消解动态均符合一级动力学方程,茚虫威施用1次的消解动态方程为C=2.7180·e^-0.2500t,半衰期(DT₅₀)为2.8d,消解99%所需时间T_0.99为18.4d;施用2次的消解动态方程为C=2.3712·e^-0.2404t,DT₅₀为2.9d,T_0.99为19.2d。在豇豆采收期施用茚虫威有效成分48.21g/hm² 1次,或间隔7d连续施用2次,在末次施药后11d采集豆荚样品检测,残留量均<0.2mg/kg,平均残留量分别为0.103mg/kg和0.111mg/kg,产品质量安全水平符合日本最高残留限量(MRL)的要求。     

基于Maxent和ArcGIS预测川贝母潜在分布及适宜性评价

川贝母(Fritillaria cirrhosa D.Don)为百合科(Liliaceae)贝母属(Fritillaria L.)多年生草本植物,其干燥鳞茎为名贵中药材,具有重要的药用价值,但目前野生资源几近枯竭。本文结合川贝母108个地理分布记录和16项环境因子,应用最大熵模型(Maxent)和地理信息系统(ArcGIS 9.3),预测了川贝母在我国的潜在适生区及其适生等级。结果显示,川贝母的潜在适生区主要分布在四川的西南、云南的西北和西藏的东南等地区,贵州的西北和甘肃的西南部分地区有零星分布。其中,川贝母最适宜分布区集中在四川(凉山和阿坝)、云南(楚雄、大理和迪庆)和西藏(林芝、山南和日喀则)等地区(适生指数0.5)。等温性(模拟贡献率,20.2%)、年均降水量(16.6%)、海拔(14.3%)、温度季节性变化的标准差(14.2%)、1月最低气温(10.9%)和土壤pH值(7.9%)是影响川贝母分布最主要的6个环境因子。综合分析表明,川贝母最适宜生长在年温差小而日温差大的高原或山区,海拔2500~3500 m、年均降水量为850~950 mm、1月份最低温度在-3.5~4.7℃和土壤偏酸性(pH=6.66)是川贝母最适宜生长的生态位参数。上述研究结果对于适生区开展川贝母野生抚育和种植区划及标准化栽培具有重要的指导意义。     

基于MaxEnt和ArcGIS对太白米的潜在分布预测及适宜性评价

利用最大熵生态位模型(MaxEnt)与地理信息系统(ArcGIS),结合89个太白米地理分布数据、28个气候因子以及6个与太白米生长相关的土壤因子,对太白米在我国的潜在分布和适宜等级进行了预测。结果表明:太白米的最适生区(适宜系数0.5)主要集中分布在四川(阿坝、甘孜和凉山,51813 km2)、云南(迪庆和丽江,15889 km2)、陕西(太白,16131 km2)、西藏(林芝、山南和日喀则,17748 km2)和甘肃(陇南,12184 km2)等地区。ROC曲线的AUC=0.979,表明预测结果可信度高。影响太白米分布的主要环境因素有年均降水量(贡献率38%)、海拔(32.1%)、1月最低温(7.6%)、1月降水量(6.8%)、土壤pH值(3.9%)等,太白米最适宜区环境参数为:年均降水量870 mm,海拔2550 m,1月最低温-6.3℃,1月降水量5.3 mm,土壤pH=6.77。     

3%噻霉酮水分散粒剂在烟草和土壤中的残留检测方法

建立了一种超高效液相色谱法(UPLC)测定烟草基质中茚虫威残留量的方法。土壤用乙酸乙酯直接萃取;烟草经乙腈溶液提取,旋转蒸发去乙腈后水相经二氯甲烷液液分配浓缩后采用UPLC-PDA检测茚虫威残留量。仪器的最小检出量为2.0×10-14g,土壤的添加水平为0.01~1.0 mg/kg,烟草的添加水平为0.1~1.0mg/kg,茚虫威的平均回收率为73.34~84.90%,相对标准偏差为3.81~5.64%。该方法适合于水稻基质中茚虫威含量的快速准确测定。     

Monitoring and Risk Assessment of Pesticide Residues in Tea Samples from China

In the present study an effort was made to monitor the residue levels of 32 pesticides in tea samples collected from three representative tea districts of China during 2010 to 2012. A total of 223 samples of green tea, pu-erh tea, black tea, and oolong tea were determined using gas chromatography with mass spectrometry (GC-MS). Among 223 samples, 198 samples contained pesticide residues, and 39 samples had residue levels that were more than the European Union (EU) maximum residue limits (MRLs). The most positive and violated MLRs were observed in Oolong tea. The highest detection rates and the most often exceeding the MRLs were observed for the residues of bifenthrin. Ten pesticides were not found in the 223 tea samples. The potential health risks to consumers due to tea consumption in three representative cities were estimated. The results suggested that non-cancer hazards of organophosphorus, organochlorines, and pyrethroids and the cancer risks from exposure to hexachlorobenzene, heptachlor, chlordane, and pp’-DDT were clearly below the safe limit. Nevertheless, an investigation into continuous monitoring and tighter regulation of pesticide residues in tea samples are almost always desirable or even necessary for public health protection.     

Residue aspects of disinfectants used in the food industry

Disinfectants are frequently used in the food industry against harmful (micro-)organisms on equipment (surfaces, pipelines etc.) which can come into contact with food. In The Netherlands, such uses of disinfectants are only allowed when registered according to the provisions of our national Pesticide Law. In most cases, (registered) uses require an operating procedure consisting of 3 consecutive steps: cleaning, disinfection and rinsing the equipment with clean water, thus avoiding contamination of food as much as possible. However, in some cases traces of the used compound(s) in food are inevitable. Therefore, Maximum Residue Limits (MRLs) for the disinfectants involved are established in food in the Netherlands. As remaining residues must be safe when ingested by the public, intake must be well below the Acceptable Daily Intake (ADI) for the respective chemicals. Also, sensitive and easy-to-operate methods of residue analysis, capable of detecting low levels of the compounds in food, must be available for enforcement purposes. In the Netherlands, experience with the existing legislation was gained over the past 25 years, resulting in the establishment of some 15–20 MRLs for residues of disinfectants in food.Harmonisation of the use of disinfectants (and other biocides) in the EU will be achieved in a draft ‘Biocide Directive’ in which the residue aspects of disinfectants are also covered, in a more-or-less comparable way as has been layed down in the Dutch legislation.Recent developments include the use of disinfectants in food as such, to reduce micro-organisms and to prolong the shelf-life of food products. Although in some surrounding countries this technique may already have become common practice. The Netherlands is reluctant to register those uses, and restricts it to cases where there is an inevitable technical need for disinfection, to minimize the exposure of the consumer to residues of (potentially) dangerous chemicals.     

Concentrations of organophosphorus pesticides in rice (Oryza sativa) and human health risk assessment from Songhua River,Northeast China

The aim of this study was to investigate organophosphorus pesticides (OPs) concentrations in rice grains and estimate potential health risk to inhabitants. A total of 102 rice samples were collected from the Irrigated Area of Songhua River, located in Jilin province, one of the most important rice production areas and a key agricultural area in China. The twelve OPs were determined by gas chromatography coupled with flame photometric detector. Results showed that OPs concentrations in rice grains did not exceed maximum residue limit. The mean concentrations obtained for the detected twelve OPs in µg kg^?1 were as follows: omethoate (0.60), diazinon (0.56), parathion-methyl (0.54), dimethoate (0.38), isocarbophos (0.38), phorate (0.31), fenitrothion (0.24), parathion (0.23), fenthion (0.23), malathion (0.13), dichlorvos (0.13), and methamidophos (0.08). Diazinon (39.2%), omethoate (31.4%), and parathion-methyl (25.5%) had the highest frequency in the detected twelve OPs. 69.6% of samples contained more than one OP, 24.5% of samples detected one OP, and only 5.9% samples did not find any OPs. The average target hazard quotients were all less than one and average hazard index for adults and children were 0.273 and 0.238, respectively. Overall, results indicated that the intake of rice may be safe for consumers.     

最大似然法和贝叶斯推论与似然比检验探讨泽泻目系统发育关系

应用最大似然法(ML)、贝叶斯推论(BI)、邻接法(NJ)和似然比检验(hLRTs)进行泽泻目分子系统学研究。所用的rbcL基因序列代表了泽泻目14科46属以及作为外类群的6相关属。研究结果表明,*等级制似然比检验表明泽泻目rbcL序列最适合的DNA进化模型为GTR+I+G,最大似然法、贝叶斯法和邻接法构建的系统发育树拓扑结构相似,没有显著的差异,但贝叶斯树支持率较高;泽泻目为一单系类群,由两个主要谱系分支构成,深层分布格局由5个主要分支构成。基于分子系统发育树,文中对泽泻目科间、水鳖科+茨藻科、泽泻科+花蔺科+黄花蔺科、和"Cymodoeaceae complex"的系统发育关系进行了讨论。研究结果还表明,泽泻目系统发育关系可能还需要更多的证据进一步的澄清。     

茶树水通道蛋白基因的克隆与表达分析

从茶树中克隆了6个水通道蛋白(aquaporin,AQP)基因的cDNA全长序列,根据序列相似性和系统进化分析结果,分别命名为CsNIP1;1、CsNIP5;1、CsPIP2;1、CsPIP2;2、CsTIP1;1和CsTIP2;2。氨基酸序列特征分析表明,6个基因的编码氨基酸序列长度在250~301个氨基酸残基,分子量在25.186~30.728kD之间;均为疏水性蛋白,并都含有6个跨膜螺旋;6个基因均含有MIP蛋白家族的特征序列HF/I/VNPA/SI/L/VTI/FA/G和NPA(Asn-Pro-Ala)基序,以及类似沙漏状的跨膜三级结构。荧光定量PCR分析显示:这6个基因在根、茎、叶和花中均表达,且在根中的表达水平最高,表明它们与茶树根系的物质转运密切相关;CsAQPs基因的表达受ABA、高盐、干旱和低温胁迫的调控,表明它们可能参与茶树抗逆响应。     

Heavy metals in wetland soils along a wetland-forming chronosequence in the Yellow River Delta of China: Levels,sources and toxic risks

Surface soil (0–20 cm) samples were collected from four chronological sequences of wetlands (i.e., >50-yr-old wetlands, 40-yr-old wetlands, 30-yr-old wetlands and 10-yr-old wetlands) in the Yellow River Delta of China in May and June of 2007. Total contents of Al, As, Cd, Cr, Cu, Ni, Pb and Zn were determined using inductively coupled plasma atomic absorption spectrometry (ICP-AAS) to investigate the levels, sources and toxic risks of heavy metals in these wetlands. Our results showed an increasing trend for Pb, Cu and Zn along the wetland-forming chronosequence although their pollution levels were low. Both As and Cd exhibited significant enrichment due to their high enrichment factor (EF) values (EF > 5), especially in older wetlands (i.e., >50-yr-old and 40-yr-old wetlands), whereas other heavy metals were minimally or moderately enriched in this region. The results of principal component analysis showed that 83.09% of total variance based on eigenvalues (eigenvalue > 1) could be explained by three principal components (PCs) in four wetlands. The source of Al, Cu, Pb and Zn was different from Cd, Cr and Ni. According to the sediment quality guidelines (SQGs) of China, soil samples in the younger wetlands, especially the 10-yr-old wetlands, were moderately polluted by As, Cd and Ni. According to the SQGs of US EPA, all soil samples were heavily polluted by As and moderately polluted by Ni and soil samples in the older wetlands were moderately polluted by Cr. However, with the exception of As and Ni, the contents of other heavy metals in the four wetlands did not exceed the probable effect level (PEL) values. As, Cd and Ni were identified as heavy metals of primary concerns in four wetlands, Cr were of moderate concern in older wetlands, and Pb, Cu and Zn should be paid more attention in younger wetland (i.e., 10-yr-old and 30-yr-old wetlands). A new and sensitive toxic risk index (TRI) is developed for the accurate assessment of toxic risk for heavy metals in wetland soils compared with the sum of the toxic units (∑TUs), and As, Cr, Ni and Cd showed higher contributions to TRI.     

茉莉酸甲酯和机械损伤对茶树叶片多酚氧化酶时序表达的影响

以温室中培养的龙井43茶树2年生扦插苗为实验材料,采用分光光度计法测定了正常茶树叶片中多酚氧化酶(PPO)活性变化的日节律,以及茉莉酸甲酯(MeJA)处理和机械损伤诱导不同叶位叶片PPO活性的时序变化.结果表明:正常茶树叶片中PPO活性高峰出现在4:00;MeJA处理茶树30 h后,其叶片PPO活性与对照间呈现显著差异,于处理后174 h达到最高峰;半定量RT-PCR检测结果发现,MeJA诱导茶树叶片PPO基因表达量最高峰出现在处理后126 h,比生化测定结果提前了48 h.机械损伤可诱导处理叶及其下叶位叶片PPO活性迅速升高,表现出一定系统性;机械损伤叶片与系统诱导叶片间PPO活性随时间变化的趋势基本平行,但机械损伤叶片中PPO活性始终高于系统诱导叶片.本研究证明,MeJA和机械损伤均可诱导茶树叶片中PPO活性的显著增强,进一步证实茉莉酸(JA)信号转导途径在茶树的直接防御反应中具有重要作用.