Changing chemical composition of precipitation in Wilmington, North Carolina, U.S.A.: implications for the Continental U.S.A

The H+(aq) concentration in Wilmington, NC, precipitation has decreased by approximately 50% during the preceding two decades, similar to trends seen nationwide. The decrease in acidity is important because solution pH plays a key role in atmospheric reactions, and because the change is so large. This study presents the first long-range study of dissolved organic carbon (DOC) levels in precipitation which demonstrates that DOC concentrations have decreased by approximately half in Wilmington, NC, precipitation. The concentrations of H+(aq) and DOC are highly correlated primarily because small organic acids contribute to both DOC and H+(aq) in precipitation. Ammonium ion concentrations in precipitation have increased due to increased agricultural activities, and this also affects precipitation pH. The reduction of SO2 emissions in 1995 imposed by the Clean Air Act Amendment, better control of emissions of volatile organic compounds, and the increase in ammonia emissions all contribute to the decreasing H+(aq) in precipitation nationwide. These compositional changes in precipitation have many environmental implications, such as decreased acid deposition to lakes, changing speciation for trace metals in precipitation, increased ammonium deposition to coastal waters, and decreased DOC transport to the open ocean.     

Effect of storage on the isotopic composition of nitrate in bulk precipitation

Stable isotopic analysis of atmospheric nitrate is increasingly employed to study nitrate sources and transformations in forested catchments. Large volumes have typically been required for delta18O and delta15N analysis of nitrate in precipitation due to relatively low nitrate concentrations. Having bulk collectors accumulate precipitation over an extended time period allows for collection of the required volume as well as reducing the total number of analyses needed to determine the isotopic composition of mean annual nitrate deposition. However, unfiltered precipitation left in collectors might be subject to microbial reactions that can alter the isotopic signature of nitrate in the sample. Precipitation obtained from the Turkey Lakes Watershed was incubated under conditions designed to mimic unfiltered storage in bulk precipitation collectors and monitored for changes in nitrate concentration, delta15N, and delta18O. Results of this experiment indicated that no detectable nitrate production or assimilation occurred in the samples during a two-week incubation period and that atmospheric nitrate isotopic ratios were preserved. The ability to collect unfiltered precipitation samples for an extended duration without alteration of nitrate isotope ratios is particularly useful at remote study sites where daily retrieval of samples may not be feasible.     

美国大豆食品

大豆是一种重要的农产品，近年来，其产量在美国和全世界都稳定增长。它具有很高的营养价值，其蛋白质和脂肪的含量很高，而且质量也很好。大豆还含有许多微量成分，其健康价值也是独一无二的。总体上讲，美国市场上的大豆食品可分为六个主要部分：豆油、传统大豆食品、大豆蛋白制品中，新一代大豆食品、大豆强化食品和功能性大豆成分。由于意识到了大豆食品的市场潜力，越来越多的大豆食品生产厂家和大豆的相关产品出现了，大豆食品有望成为21世纪世界上最普遍流行的食品。     

Exposure estimates of nitrite and nitrate from consumption of cured meat products by the U.S. population

The dietary exposures of nitrite and nitrate from consumption of cured meat products were estimated for the U.S. population aged 2 years and older, and children aged 2 to 5 years, using both 2-day food consumption data from the publicly available combined 2009–2012 National Health and Nutrition Examination Survey (NHANES) and 10–14-day food consumption data from the 2009 and 2012 NPD Group, Inc. National Eating Trends-Nutrient Intake database (NPD NET-NID), and residual nitrite and nitrate levels in cured meat products available from the recent American Meat Institute Foundation/National Pork Board (AMIF/NPB) national market survey of the nitrite and nitrate levels in cured meat products in the U.S.A. The dietary exposure for consumers of cured meat products (eaters-only) was estimated at the mean and 90th percentile for three exposure scenarios: low exposure, average exposure, and high exposure, to account for the range in the amount of nitrite and nitrate in a given cured meat product category. In addition, a cumulative exposure that takes into account all cured meat product categories containing nitrite and nitrate was determined, and the relative percent contribution of each cured meat product category to the cumulative exposure was estimated. Cured, cooked sausages and whole-muscle brine-cured products were the two major contributing categories to dietary exposure of nitrite and nitrate for both U.S. population aged 2 years and older and children aged 2–5 years.     

Impacts of land use change on nitrogen cycling archived in semiarid unsaturated zone nitrate profiles, southern High Plains, Texas

Nitrate (NO3) profiles in semiarid unsaturated zones archive land use change (LUC) impacts on nitrogen (N) cycling with implications for agricultural N management and groundwater quality. This study quantified LUC impacts on NO3 inventories and fluxes by measuring NO3 profiles beneath natural and rainfed (nonirrigated) agricultural ecosystems in the southern High Plains (SHP). Inventories of NO3-N under natural ecosystems in the SHP normalized by profile depth are extremely low (2-10 kg NO3-N/ha/m), in contrast to those in many semiarid regions in the southwestern U.S. Many profiles beneath cropland (9 of 19 profiles) have inventories at depth that range from 28-580 kg NO3--N/ha/m (median 135 kg/ha/m) that correspond to initial cultivation, dated using soil water Cl. These inventories represent 74% (median) of the total inventories in these profiles. This NO3 most likely originated from cultivation causing mineralization and nitrification of soil organic nitrogen (SON) in old soil water (precultivation) and is attributed to enhanced microbial activity caused by increased soil wetness beneath cropland (median matric potential -42 m) relative to that beneath natural ecosystems (median -211 m). The SON source is supported by isotopes of NO3 (delta15N: +5.3 to +11.6; delta18O: +3.6 to +12.1). Limited data in South Australia suggest similar processes beneath cropland. Mobilization of the total inventories in these profiles caused by increased drainage/ recharge related to cultivation in the SHP could increase current NO3-N levels in the underlying Ogallala aquifer by an additional 2-26 mg/L (median 17 mg/L).     

Perfluorinated compounds in human milk from Massachusetts, U.S.A

Perfluorinated compounds (PFCs), notably perfluorooctanesulfonate (PFOS) and perfluorooctanoic acid (PFOA), have been reported in human blood. Furthermore, the occurrence of PFCs in the blood of newborn babies, coupled with the need to study the potential association of PFC exposure with birth outcomes in neonates, suggests the need for determining the sources and magnitude of exposure in infants. In this study, nine PFCs were measured in 45 human breast milk samples collected in 2004 from Massachusetts, U.S.A. PFOS and PFOA were the predominant PFCs found at mean concentrations of 131 and 43.8 pg/mL, respectively. Comparison of the ratio of PFOS to PFOA in human milk with the ratios published for human serum from the U.S. female population suggested preferential partitioning of PFOA to milk. Concentrations of PFOA were significantly higher in the milk of mothers nursing for the first time (n = 34) than in the milk of mothers who have previously nursed (n = 8). Based on the estimated body weight and milk intake, the average and highest daily intakes of total PFCs by infants were 23.5 and 87.1 ng/kg bw, respectively. We found that the daily ingestion rates of PFOS and PFOA did not exceed the tolerable daily intake recommended by the U.K. Food Standards Agency. This is the first study to measure the occurrence of PFCs in human milk from the U.S.A.     

Mercury distribution across 14 U.S. Forests. Part I: spatial patterns of concentrations in biomass, litter, and soils

Results from a systematic investigation of mercury (Hg) concentrations across 14 forest sites in the United States show highest concentrations in litter layers, strongly enriched in Hg compared to aboveground tissues and indicative of substantial postdepositional sorption of Hg. Soil Hg concentrations were lower than in litter, with highest concentrations in surface soils. Aboveground tissues showed no detectable spatial patterns, likely due to 17 different tree species present across sites. Litter and soil Hg concentrations positively correlated with carbon (C), latitude, precipitation, and clay (in soil), which together explained up to 94% of concentration variability. We observed strong latitudinal increases in Hg in soils and litter, in contrast to inverse latitudinal gradients of atmospheric deposition measures. Soil and litter Hg concentrations were closely linked to C contents, consistent with well-known associations between organic matter and Hg, and we propose that C also shapes distribution of Hg in forests at continental scales. The consistent link between C and Hg distribution may reflect a long-term legacy whereby old, C-rich soil and litter layers sequester atmospheric Hg depositions over long time periods. Based on a multiregression model, we present a distribution map of Hg concentrations in surface soils of the United States.     

美国冰淇淋见闻

本文介绍了美国冰淇淋市场及其品种，进而指出厂其生产的发展趋向和新原辅料的使用情况。     

美国生物质燃料产业的机遇和挑战

总结了美国在生物质燃料方面采取的一系列政策和措施,阐述了生物质燃料的应用趋势,重点指出通过加大研发力度以促进第二代生物质燃料的发展和商业化。目前,研发工作已经在许多领域同时开展,主要有生物质资源评价、开发新的生物质原料、提高转化技术以及系统的整体化等。其他需考虑的重要因素还包括燃料的质量和规格,对燃料混合、分配和储存的要求等。大量的研发、政策及制度的实施和开展都必须考虑生物质燃料对能源和环境产生的影响。这些影响不仅包括车辆使用的直接排放量,还包括与燃料生命周期相关的能源的总使用量、温室气体排放量等的影响。由于生物质原料、转化技术和系统整体化方法都具有多样性,所以生物质燃料生命周期的影响也可以有很大差异。     

美国企业是如何实施名牌战略的

介绍了美国成功企业创立名牌、保护名牌、发展名牌、以名牌为支撑的发展战略，为我国企业在市场经济条件下实施名牌战略提供借鉴。     

Saturated zone denitrification: potential for natural attenuation of nitrate contamination in shallow groundwater under dairy operations

We present results from field studies at two central California dairies that demonstrate the prevalence of saturated-zone denitrification in shallow groundwater with 3H/ 3He apparent ages of < 35 years. Concentrated animal feeding operations are suspected to be major contributors of nitrate to groundwater, but saturated zone denitrification could mitigate their impact to groundwater quality. Denitrification is identified and quantified using N and O stable isotope compositions of nitrate coupled with measurements of excess N2 and residual NO3(-) concentrations. Nitrate in dairy groundwater from this study has delta15N values (4.3-61 per thousand), and delta18O values (-4.5-24.5 per thousand) that plot with delta18O/delta15N slopes of 0.47-0.66, consistent with denitrification. Noble gas mass spectrometry is used to quantify recharge temperature and excess air content. Dissolved N2 is found at concentrations well above those expected for equilibrium with air or incorporation of excess air, consistent with reduction of nitrate to N2. Fractionation factors for nitrogen and oxygen isotopes in nitrate appear to be highly variable at a dairy site where denitrification is found in a laterally extensive anoxic zone 5 m below the water table, and at a second dairy site where denitrification occurs near the water table and is strongly influenced by localized lagoon seepage.     

Bisphenol A (BPA) in U.S. food

Bisphenol A (BPA) is a chemical used for lining metal cans and in polycarbonate plastics, such as baby bottles. In rodents, BPA is associated with early sexual maturation, altered behavior, and effects on prostate and mammary glands. In humans, BPA is associated with cardiovascular disease, diabetes, and male sexual dysfunction in exposed workers. Food is a major exposure source. We know of no studies reporting BPA in U.S. fresh food, canned food, and food in plastic packaging in peer reviewed journals. We measured BPA levels in 105 fresh and canned foods, foods sold in plastic packaging, and in cat and dog foods in cans and plastic packaging. We detected BPA in 63 of 105 samples, including fresh turkey, canned green beans, and canned infant formula. Ninety-three of these samples were triplicates which had similar detected levels. Detected levels ranged from 0.23 to 65.0 ng/g ww and were not associated with type of food or packaging but did vary with pH. BPA levels were higher for foods of pH 5 compared to more acidic and alkaline foods. Detected levels were comparable to those found by others. Further research is indicated to determine BPA levels in U.S. food in larger, representative sampling.     

美国学校营养膳食及启示

美国学校供餐已有百余年,经历了四次重大变革,迄今仍在不断改进和完善,其中许多做法和经验值得我们借鉴.     

Verifiable metamodels for nitrate losses to drains and groundwater in the Corn Belt, USA

Nitrate leaching in the unsaturated zone poses a risk to groundwater, whereas nitrate in tile drainage is conveyed directly to streams. We developed metamodels (MMs) consisting of artificial neural networks to simplify and upscale mechanistic fate and transport models for prediction of nitrate losses by drains and leaching in the Corn Belt, USA. The two final MMs predicted nitrate concentration and flux, respectively, in the shallow subsurface. Because each MM considered both tile drainage and leaching, they represent an integrated approach to vulnerability assessment. The MMs used readily available data comprising farm fertilizer nitrogen (N), weather data, and soil properties as inputs; therefore, they were well suited for regional extrapolation. The MMs effectively related the outputs of the underlying mechanistic model (Root Zone Water Quality Model) to the inputs (R(2) = 0.986 for the nitrate concentration MM). Predicted nitrate concentration was compared with measured nitrate in 38 samples of recently recharged groundwater, yielding a Pearson's r of 0.466 (p = 0.003). Predicted nitrate generally was higher than that measured in groundwater, possibly as a result of the time-lag for modern recharge to reach well screens, denitrification in groundwater, or interception of recharge by tile drains. In a qualitative comparison, predicted nitrate concentration also compared favorably with results from a previous regression model that predicted total N in streams.     

中美两国烤烟育种比较与分析

美国烤烟育种历史悠久,经验丰富,常规育种程序设计合理。美国把F₂~F₄种在需要的病圃里,主要进行抗性筛选,自F₅才进行农艺性状鉴定。抗病性是由少数基因乃至单基因控制的,在分离后代中表现为显性或部分显性,并可遗传,早代选择效率是高的,所以有种成绩也大。中国烤烟育种起步晚。目前虽已具有了培育优良品种的基本条件,但成绩仍不理想。这可能与育种程序设计不够完美有关。中国把F₂~F₄种在一般田间,先进行农艺性状的筛选,到第5代才抗性鉴定。农艺性状是由多基因控制的,在分离后代中表现为隐性效应,不能遗传,早代选择的效率是低的。因此,中国烟草育种程序需要改进。      

《中美纺织品谅解备忘录》评估

北京时间2005年11月8日,美国贸易代表波特曼和中国商务部部长薄熙来在英国伦敦共同签署了《中华人民共和国政府与美利坚合众国政府关于纺织品和服装贸易的谅解备忘录》(下文简称《备忘录》),长达数月的纺织品谈判暂告段落。一《、备忘录》基本内容1《、备忘录》涵盖21大类产品(共计34个TC码),见表1。其中有18类(共计31个TC码)为2003￣2005年美国对华纺织品特保设限产品或2005年美方特保调查阶段产品,占总数的85.7%。2《、备忘录》规定2007￣2008年相关产品可出口量均以上年出口量为计算基数(2006年可出口量以2005年出口量为基数)。3《、备…     

A consumption-based GHG inventory for the U.S. state of Oregon

Many U.S. states conduct greenhouse gas (GHG) inventories to inform their climate change planning efforts. These inventories usually follow a production-based method adapted from the Intergovernmental Panel on Climate Change. States could also take a consumption-based perspective, however, and estimate all emissions released to support consumption in their state, regardless of where the emissions occur. In what may be the first such comprehensive inventory conducted for a U.S. state, we find that consumption-based emissions for Oregon are 47% higher than those released in-state. This finding implies that Oregon's contribution to global greenhouse gas emissions (carbon footprint) is considerably higher than traditional production-based methods would suggest. Furthermore, the consumption-based inventory helps highlight the role of goods and services (and associated purchasing behaviors) more so than do production-based methods. Accordingly, a consumption-based perspective opens new opportunities for many states and their local government partners to reduce GHG emissions, such as initiatives to advance lower-carbon public sector or household consumption, that are well within their sphere of influence. State and local governments should consider conducting consumption-based GHG inventories and adopting consumption-based emission reductions targets in order to broaden the reach and effectiveness of state and local actions in reducing global GHG emissions. Consumption-based frameworks should be viewed as a complement to, but not a substitute for, production-based (in-state) GHG emissions inventories and targets.