Accumulation of current-use pesticides in neotropical montane forests

In Central America, chemical-intensive tropical agriculture takes place in close proximity to highly valued and biologically diverse ecosystems, yet the potential for atmospheric transport of pesticides from plantations to national parks and other reserves is poorly characterized. The specific meteorological conditions of mountain ranges can lead to contaminant convergence at high altitudes, raising particular concern for montane forest ecosystems downwind from pesticide use areas. Here we show, based on a wide-ranging air and soil sampling campaign across Costa Rica, that soils in some neotropical montane forests indeed display much higher concentrations of currently used pesticides than soils elsewhere in the country. Specifically, elevated concentrations of the fungicide chlorothalonil, the herbicide dacthal, and the insecticide metabolite endosulfan sulfate on volcanoes Barva and Poas, lying directly downwind of the extensive banana plantations of the Caribbean lowland, indicate the occurrence of atmospheric transport and wet deposition of pesticides at high altitudes. Calculations with a contaminant fate model, designed for mountain regions and parametrized to the Costa Rican environment, show that chemicals with a log K(AW) between -3 and -5 have a greater potential for accumulation at high altitudes. This enrichment behavior is quantified by the Mountain Contamination Potential and is sensitive to contaminant degradability. The modeling work supports the hypothesis suggested by the field results that it is enhanced precipitation scavenging at high elevations (caused by lower temperatures and governed by K(AW)) that causes pesticides to accumulate in tropical montane areas. By providing for the first time evidence of significant transfer of currently used pesticides to Central American montane cloud forests, this study highlights the need to evaluate the risk that tropical agricultural practices place on the region's ecological reserves.     

Atmospheric deposition of current-use and historic-use pesticides in snow at national parks in the western United States

The United States (U.S.) National Park Service has initiated research on the atmospheric deposition and fate of semi-volatile organic compounds in its alpine, sub-Arctic, and Arctic ecosystems in the Western U.S. Results for the analysis of pesticides in seasonal snowpack samples collected in spring 2003 from seven national parks are presented herein. From a target analyte list of 47 pesticides and degradation products, the most frequently detected current-use pesticides were dacthal, chlorpyrifos, endosulfan, and gamma-hexachlorocyclohexane, whereas the mostfrequently detected historic-use pesticides were dieldrin, alpha-hexachlorocyclohexane, chlordane, and hexachlorobenzene. Correlation analysis with latitude, temperature, elevation, particulate matter, and two indicators of regional pesticide use reveal that regional current and historic agricultural practices are largely responsible for the distribution of pesticides in the national parks in this study. Pesticide deposition in the Alaskan parks is attributed to long-range transport because there are no significant regional pesticide sources. The percentage of total pesticide concentration due to regional transport (%RT) was calculated for the other parks. %RT was highest at parks with higher regional cropland intensity and for pesticides with lower vapor pressures and shorter half-lives in air.     

Distribution and air-sea exchange of current-use pesticides (CUPs) from East Asia to the high Arctic Ocean

Surface seawater and marine boundary layer air samples were collected on the ice-breaker R/V Xuelong (Snow Dragon) from the East China Sea to the high Arctic (33.23-84.5° N) in July to September 2010 and have been analyzed for six current-use pesticides (CUPs): trifluralin, endosulfan, chlorothalonil, chlorpyrifos, dacthal, and dicofol. In all oceanic air samples, the six CUPs were detected, showing highest level (>100 pg/m(3)) in the Sea of Japan. Gaseous CUPs basically decreased from East Asia (between 36.6 and 45.1° N) toward Bering and Chukchi Seas. The dissolved CUPs in ocean water ranged widely from 相似文献   

Gas-phase polychlorinated biphenyl and hexachlorocyclohexane concentrations near the Great Lakes: a historical perspective

The Integrated Atmospheric Deposition Network (IADN) has been measuring gas-phase, polychlorinated biphenyl (PCB) concentrations at sites near Lakes Michigan and Superior for over a decade. Data through 2000 were used in this study to investigate PCB temporal trends in the Great Lakes atmosphere. Decreasing trends were found at both sites, and half-lives of approximately 20 yr were calculated using IADN data. However, when these data were supplemented by historical data for Lakes Michigan and Superior dating back to 1977, half-lives dropped to 10 and 6 yr, respectively. These latter half-lives agreed well with half-lives in other environmental compartments. Exponential curves fitted to the historical and IADN data indicated little decline in PCB concentrations in the basin since the mid-1990s. A similar historical analysis of alpha-and gamma-hexachlorocyclohexane (HCH) data indicated that IADN data were the best predictor of trends, resulting in half-lives of around 4 yr for both compounds. Gamma-HCH concentrations, however, have shown little decline in recent years, most likely because of its continuing use. PCB and alpha-HCH temporal trends indicated that bans on these substances have helped to remove them from the atmosphere. This work also showed that decades of data may be necessary to properly interpret long-term temporal trends in gas-phase organochlorine concentrations.     

Measuring and predicting environmental concentrations of pesticides in air after application to paddy water systems

In this study, the volatilization of five pesticides applied to an artificial flooded paddy field was assessed using the theoretical profile shape (TPS) and the integrate horizontal flux (IHF) techniques. The dataset derived was utilized to improve the volatilization routine of the rice water quality (RICEWQ) model. The masses of pesticides ethoprophos, procymidone, metalaxyl, chlorpyrifos, and chlorpyrifos methyl volatilized from paddy water and their concentrations in paddy water were determined for a period of 6 d after application. The highest and lowest volatilization losses were observed for chlorpyrifos and metalaxyl, respectively, accounting for 3.3% and 0.03% of their initially applied amount. A rapid pesticide dissipation was evident in paddy water during the study period. The RICEWQ model was used to simulate the fate of pesticides in the artificial paddy system. The Kvolat, an empiric coefficient used by the model as an input parameter, was calculated for all pesticides through model calibration. RICEWQ simulated well the fate of pesticides in paddy water. A significant regression correlation between Henry's law constant (Hk) and Kvolat of the studied compounds was established which could facilitate the parametrization of the model for describing pesticide volatilization.     

Atmospheric concentrations and air-water flux of organochlorine pesticides along the Western Antarctic Peninsula

Air, seawater, sea ice, and snow were collected during the austral winter (September-October 2001) and summer (January-February 2002) along the Western Antarctic Peninsula. Hexachlorobenzene (HCB) > heptachlor > alpha- and gamma-hexachlorocyclohexane (HCH) and heptachlor epoxide, were the most frequently detected organochlorine pesticides in air. HCB and HCH levels declined over the past 20 years, with a half-life of 3 years for sigmaHCH in Antarctic air. However, heptachlor epoxide levels have not declined in Antarctic air over the past decade, possibly due to continued use of heptachlor in the southern hemisphere. Peak heptachlor concentrations in air were measured coincident with air masses moving into the region from lower latitudes. Levels of lindane were 1.2-200 times higher in annual sea ice and snow compared to alpha-HCH, likely due to greater atmospheric input of gamma-HCH. The ratio of alpha/gamma-HCH in Antarctic air, sea ice and snow was <1, illustrative of a predominance of influx of lindane versus technical HCH to the regional environment. However, alpha/gamma-HCH in seawater was >1, likely due to more rapid microbial degradation of gamma- versus alpha-HCH. Water/air fugacity ratios for HCHs demonstrate continued atmospheric influx of HCHs to coastal Antarctic seas, particularly during late summer.     

Gas-phase reaction of phenol with NO3

The fast gas-phase reaction of NO3 radicals with phenol was found to yield 2-nitrophenol as the only relevant nitration product. The yield of this product was high and independent of the concentration of NO2 at the concentrations applied. In the presence of ozone, also significant amounts of 4-nitrophenol and p-benzoquinone were formed. The rate constant of the reaction between NO3 radicals and phenol was determined to be 5.8 x 10(-12) cm3 molecule-1 s-1. The selective formation of 2-nitrophenol (2) is suggested to derive from either the concerted keto-enol tautomerism in the reaction of a phenoxy radical with NO2 or the concerted elimination of nitric acid from a cyclohexa-3,5-diene intermediate.     

气相色谱-质谱联用法测定卷烟主流烟气气相物中挥发性有机化合物

建立了气相色谱-质谱联用(GC-MS)同时快速检测卷烟主流烟气中5种挥发性有机化合物(1,3-丁二烯,异戊二烯,丙烯腈,苯和甲苯)的分析方法。主流烟气气相物中的挥发性有机化合物被含有D6-苯内标的冷甲醇吸收,并用GC-MS 在选择离子模式下进行分析。方法的最低检出限(LOD)和最低定量限(LOQ)分别为0.01~0.81 μg/支和0.04~2.73 μg/支, 加标回收率为92.3%~98.5%,精密度为1.95%~9.21%。本方法检测限低,重复性和重现性明显优于以前报道的方法。应用此方法考察了38 种国内外卷烟样品在深度抽吸与ISO 抽吸模式下的释放量,深度抽吸模式下挥发性有机化合物的释放量是ISO 模式的两倍。     

斑马鱼在农药安全评价中的应用

主要介绍了斑马鱼的概况及其在有机氯农药、有机磷农药及杀菌剂类农药安全评价中的应用。斑马鱼作为实验模型动物,广泛应用在胚胎发育、疾病模型、药物筛选以及环境监测等方面。近年来,随着对斑马鱼了解的日趋深入,其在农药安全及环境保护中的应用也越来越被人们重视。     

Persistent organochlorine pesticides in Mexican butter

Organochlorine pesticides have been used in Mexico in malaria control programmes against ectoparasites and as seed dresser. Owing to their chemical stability, they tend to accumulate in the lipid part of the organisms. The stored pesticides are excreted with the endogenous fat during milk production. The aim was to monitor the organochlorine pesticide levels in butter manufactured in Mexico. From the pesticides, only HCB, β-HCH, pp '-DDT, op '-DDT and pp '-DDE with major frequency and levels were detected. The HCB mean level was low at 0.008 mg kg -1 on a fat basis. From the HCH isomer, only the β-HCH at 0.065 mg kg^-1 on a fat basis was determined, remaining as the main contaminant of the monitored butters. Among DDTs, pp '-DDE was the major constituent (0.043 mg kg^-1 on a fat basis) followed by pp '-DDT (0.036 mg kg^-1) and op '-DDT (0.009 mg kg^-1). Comparing the previous study (1994) and this one (2001), all organochlorine pesticides had a descendent tendency; β-HCH decreased from 0.095 to 0.065 mg kg^-1 on a fat basis, whereas the total DDT decreased from 0.056 to 0.047 mg kg^-1, pp '-DDT from 0.050 to 0.036 mg kg^-1, op '-DDT from 0.018 to 0.009 mg kg^-1, while pp '-DDE increased from 0.032 to 0.043 mg kg^-1. The decreased DDT levels in Mexican butters is caused by the substitution of organochlorine insecticides with pyrethroids used by the Mexican Ministry of Health since 1999 in sanitary programmes.     

气相聚合法制备聚吡咯导电纸

采用气相聚合法制备了导电纸,探讨了聚合反应中氧化剂浓度、处理时间、干燥时间、反应时间等因素对聚吡咯导电纸性能的影响.结果表明,将原纸在浓度为1.5mol/L的氧化剂溶液中处理1min、50℃下烘干1min后置于真空度为0.06MPa的封闭器皿中与毗咯单体进行聚合反应10min,然后在室内自然晾干,所得导电纸的导电性能良好,表面电阻率可低至20Ω/cm2.同时发现此方法不宜采用对甲苯磺酸进行掺杂.通过强度测定表明,该方法制得导电纸的定量和抗张强度均有增加,纤维零距抗张强度降低.     

Atmospherically deposited PBDEs, pesticides, PCBs, and PAHs in western U.S. National Park fish: concentrations and consumption guidelines

Concentrations of polybrominated diphenyl ethers (PBDEs), pesticides, polychlorinated biphenyls (PCBs), and polycyclic aromatic hydrocarbons were measured in 136 fish from 14 remote lakes in 8 western U.S. National Parks/Preserves between 2003 and 2005 and compared to human and wildlife contaminant health thresholds. A sensitive (median detection limit--18 pg/g wet weight), efficient (61% recovery at 8 ng/g), reproducible (4.1% relative standard deviation (RSD)), and accurate (7% deviation from standard reference material (SRM)) analytical method was developed and validated for these analyses. Concentrations of PCBs, hexachlorobenzene, hexachlorocyclohexanes, DDTs, and chlordanes in western U.S. fish were comparable to or lower than mountain fish recently collected from Europe, Canada, and Asia. Dieldrin and PBDE concentrations were higher than recent measurements in mountain fish and Pacific Ocean salmon. Concentrations of most contaminants in western U.S. fish were 1-6 orders of magnitude below calculated recreational fishing contaminant health thresholds. However, lake average contaminant concentrations in fish exceeded subsistence fishing cancer thresholds in 8 of 14 lakes and wildlife contaminant health thresholds for piscivorous birds in 1 of 14 lakes. These results indicate that atmospherically deposited organic contaminants can accumulate in high elevation fish, reaching concentrations relevant to human and wildlife health.     

卷烟主流烟气中拟除虫菊酯类农药含量的检测方法

将超声波提取法与混合层析柱净化法联合,利用气相色谱-电子捕获检测器(GC-ECD),建立了一种高效、快速的卷烟主流烟气中拟除虫菊酯类农药含量的检测方法.通过对提取条件和净化条件进行优化,最佳条件为:丙酮超声波提取捕集有卷烟主流烟气总粒相物的剑桥滤片,采用混合层析柱净化,卷烟主流烟气气相部分直接采用丙酮捕集,浓缩净化进样分析.优化条件下,方法的回收率为92.8%-97.3%,RSD为2.71%-9.02%,最低定量限为0.026-0.098μg/mL,最小检测限为0.0001-0.0009μg/mL,可满足卷烟主流烟气中拟除虫菊酯类农药含量的检测要求.     

食品中农药多残留检测新技术研究进展

食品安全是关系国计民生的大事, 发展农药残留检测新技术和开展食品中农药残留的风险评估有助于食品安全风险管理、风险交流和消费者健康。本文综述了多组分农药残留检测中最新的样品前处理方法、农药残留分析检测技术及其应用, 以期为农药残留分析检测技术的完善与发展提供参考与借鉴。