A bottom-up assessment and review of global bio-energy potentials to 2050

In this article, a model for estimating bioenergy production potentials in 2050, called the Quickscan model, is presented. In addition, a review of existing studies is carried out, using results from the Quickscan model as a starting point. The Quickscan model uses a bottom-up approach and its development is based on an evaluation of data and studies on relevant factors such as population growth, per capita food consumption and the efficiency of food production. Three types of biomass energy sources are included: dedicated bioenergy crops, agricultural and forestry residues and waste, and forest growth. The bioenergy potential in a region is limited by various factors, such as the demand for food, industrial roundwood, traditional woodfuel, and the need to maintain existing forests for the protection of biodiversity. Special attention is given to the technical potential to reduce the area of land needed for food production by increasing the efficiency of food production. Thus, only the surplus area of agricultural land is included as a source for bioenergy crop production. A reference scenario was composed to analyze the demand for food. Four levels of advancement of agricultural technology in the year 2050 were assumed that vary with respect to the efficiency of food production. Results indicated that the application of very efficient agricultural systems combined with the geographic optimization of land use patterns could reduce the area of land needed to cover the global food demand in 2050 by as much as 72% of the present area. A key factor was the area of land suitable for crop production, but that is presently used for permanent grazing. Another key factor is the efficiency of the production of animal products. The bioenergy potential on surplus agricultural land (i.e. land not needed for the production of food and feed) equaled 215–1272 EJ yr⁻¹, depending on the level of advancement of agricultural technology. The bulk of this potential is found in South America and Caribbean (47–221 EJ yr⁻¹), sub-Saharan Africa (31–317 EJ yr⁻¹) and the C.I.S. and Baltic States (45–199 EJ yr⁻¹). Also Oceania and North America had considerable potentials: 20–174 and 38–102 EJ yr⁻¹, respectively. However, realization of these (technical) potentials requires significant increases in the efficiency of food production, whereby the most robust potential is found in the C.I.S. and Baltic States and East Europe. Existing scenario studies indicated that such increases in productivity may be unrealistically high, although these studies generally excluded the impact of large scale bioenergy crop production. The global potential of bioenergy production from agricultural and forestry residues and wastes was calculated to be 76–96 EJ yr⁻¹ in the year 2050. The potential of bioenergy production from surplus forest growth (forest growth not required for the production of industrial roundwood and traditional woodfuel) was calculated to be 74 EJ yr⁻¹ in the year 2050.     

Exploring farmer's knowledge as a source of information on past and present cultural landscapes: A case study from NW Spain

The primary goal of this research was to explore the potential of farmer's knowledge as a source of information on the past and present cultural landscapes, focusing on the land-use system, the cultural heritage, and the farmer's perception of landscape changes, from the 1950s to the present day. For this purpose, 42 semi-structured interviews were conducted from a random sample of 10% of the villages in an area of the Northern Mountains of Galicia (NW Spain). As shown in farmers’ reports, the main crops in the 1950s were wheat or rye, potatoes or maize (only near the coast) and turnips. Scrubland areas were an essential resource for pasture, litter, temporary crops and charcoal, whereas deciduous forest was mainly used as a source of wood for carpentry, firewood and litter. Agriculture was the main economic activity, whereas crafts and other activities in the fisheries or forestry industry were secondary. Granaries, watermills and stone laundry basins were the most frequent elements of built heritage that was mentioned in the interviews. Farmers were also comprehensively aware of the broad changes that occurred in the landscape. The results indicate that farmer's knowledge is a valuable source of information for documenting past and present land-use practices, local cultural heritage and changes in the landscape, all of which are helpful for the design of landscape-orientated policies. Moreover, observed ancestral cultural practices, such as extensive grazing in scrubland areas, may be promoted as strategies for helping the sustainability of cultural landscapes in the study area and in other areas with similar characteristics.     

Performance Indices for Surface N Fertigation

The application of N fertilizers mixed with a surface irrigation stream (surface N fertigation) is widely practiced in the southwestern United States. Procedures for the optimal design and management of surface N fertigation systems are needed. The purpose of this work is to identify and define a set of performance indices that can be used to assess the relative merits of alternative design and management scenarios. Equations and solutions for quantifying the performance indices are proposed. Sample performance calculations are presented for a fertigation field experiment in which bromide ion was used as a tracer to simulate the movement of nitrate on the surface and through the soil profile.     

Mechanisms of metal adsorption from aqueous solutions by waste tyre rubber

The mechanisms of adsorption of cadmium(II), mercury(II) and lead(II) on to shredded rubber from old automobile types have been studied and it is shown that at least two distinct processes can be involved depending upon the metal being adsorbed. Mercury and cadmium uptake are accompanied by displacement of zinc and therefore probably involve an ion exchange type mechanism. Lead adsorption, in contrast, involves no zinc displacement and is not competitive with cadium or mercury uptake, suggesting that a completely separate mechanism and site of binding are used by lead(II).     

农产品电子商务发展中的问题与对策

我国农产品电子商务主要有两种类型即政府办的供求信息服务型和各经济实体办的商务服务型，目前还处于初期阶段。本文简述了农产品电子商务发展过程中的几点技术、观念问题，并提出相关解决对策。     

光纤免疫传感器在环境检测中的应用

综合介绍了光纤免疫传感器的基本原理、种类、结构及其发展现状，文章着重指出，该传感器适用于毒素及其它有毒有害物质的分析检测，在环境保护等领域有着广泛的应用前景。     

无滴农用薄膜生产新工艺

本文论述了国内外无滴农用薄膜的应用和生产状况及其发展前景，同时介绍了涂敷性无滴技术，防雾滴涂料的性能与合成工艺。     

Determination of chromium in human milk, serum and urine by electrothermal atomic absorption spectrometry without preliminary ashing

In the present study a Perkin-Elmer 5000 atomic absorption spectrometer equipped with a tungsten--iodide lamp for improved background correction at the 357.9 nm chromium absorption line and an HGA 500 graphite furnace were employed for the direct determination of chromium in human serum, milk and urine. The method of standard additions was used: 0.25-0.75 ng Cr was added to 1 ml samples. Except for urine samples, a dilution of 1 + 1 to 1 + 2 with H2O was necessary in order to obtain correct calibration curves. The average concentration of chromium in all the samples of normal subjects was less than 0.5 ng Cr ml-1. The day-to-day variation for all of the pooled samples was around 10% (relative standard deviation). For urine, the accuracy of the method was tested by comparing the results of another laboratory for the same two round robin samples. Excellent agreement was found between the present method and those of the other laboratory that had used isotope dilution--mass spectrometry and continuum source wavelength modulated echelle--atomic absorption spectrometry to define the chromium concentration in the samples. The detection limit of the method, 0.05 ng Cr ml-1 for urine and serum and 0.1 ng Cr ml-1 for human milk, was sufficient for the biological fluids analyzed. The method was employed for the determination of chromium in 24-h urine samples of maturity onset diabetics supplemented with 20 or 200 micrograms Cr3+ d-1 for six weeks. It was shown that the 24-h urinary chromium excretion accurately indicates the daily dietary chromium intake of these patients.     

Assessment of Algerian sorghum protein quality [Sorghum bicolor (L.) Moench] using amino acid analysis and in vitro pepsin digestibility

To assess the protein quality and the nutritive value of seven Algerian local sorghum cultivars, the in vitro pepsin digestibility was determined, which ranged from 25.0% to 65.0%, and the amino acid composition of each cultivar was compared with other sorghum cultivars. In addition, the amino acid scores (AAS) and the protein digestibility-corrected amino acid scores (PDCAAS) were calculated. Relative to the WHO protein standard, most of the sorghum cultivars tested, scored very high AAS, with values ranging between 0.9 and 2.6 except for lysine, methionine and cysteine. The PDCAAS were high for Ain Salah cultivars AS1 and AS3, however, all other cultivars showed low values except for leucine. This study confirmed that in terms of both quantity and quality, sorghum proteins could serve as a source of essential amino acids and as a potential source of proteins in the future.     

某金属冶炼厂区周围农村居民膳食无机砷暴露评估

目的对广西某金属冶炼厂区周围农村居民膳食无机砷暴露情况进行风险性评估,为预防控制慢性砷危害提供依据。方法在广西某金属冶炼厂周围农村村屯,按照随机抽样的原则对该村屯居民自种自供的大米、蔬菜和养殖的鸡、鸭等食品采样,用GB/T5009.11—2003《食品中总砷及无机砷的测定》方法检测上述食品无机砷的含量,按照国家标准进行评价;同时结合当地居民膳食摄入量(食物频次法),并参考2002年广西营养与健康调查得出的农村居民各类食物每日消费量分别计算出当地居民膳食无机砷暴露量,利用JECFA提出的无机砷每公斤体重每周允许摄入量[PTWI为0.015mg/(kgBW·week)]进行风险性评估。结果该村种植的食用植物性农产品无机砷总体超标率为60.29%,其中大米超标率高达87.10%,平均含量为0.65mg/kg,最大超标15.5倍;蔬菜超标68.42%,平均含量0.16mg/kg;饲养家禽类食物总体无机砷超标率54.76%。每标准人每日平均、P90、P97.5膳食无机砷摄入量分别为0.2149mg、0.3900mg、0.4642mg,分别是JECFA提出的无机砷每日允许摄入量(ADI)的1.66倍、3.02倍、3.60倍(其中参考2002年农村居民食物摄入量计算为ADI的2.0倍)。结论该厂区周围村屯食用农产品无机砷污染严重,居民尤其是高消费人群膳食无机砷暴露量明显超过ADI值,存在危害健康风险。