水土匹配、空间效应及区域农业经济增长——基于中国2003-2013的经验分析

水资源和土地资源是非常重要的自然资源,是农业经济发展不可或缺的物质要素。水资源与土地资源的合理匹配能够促进区域的资源优势转化为经济增长,从而促进区域农业经济发展。我国是一个人口众多的农业大国,同时也存在水资源与土地资源短缺的问题。本文结合我国农业水土资源自然禀赋与实际利用情况,首先利用中国2003-2013年的分省数据,选取单位耕地面积的广义农业水资源量测度方法和当量系数描述了我国农业水土资源匹配的现实,发现我国农业水资源与土地资源在空间上匹配程度不高,农业生产受到水土资源约束较强,农业水土资源的形成区域与消耗区域在空间上不相匹配;然后,在邻接权重矩阵下采用Moran’s I指数验证我国区域农业经济增长的空间关联性,结果显示我国各省农业经济增长存在显著的空间关系,呈现出高度的集聚性和非均质性。为避免估计结果有偏,本文在此基础上采用空间计量建模及估计方法,加入农业生产人、财、物等控制变量,测度水土匹配度对区域农业经济增长的空间溢出效应。结果显示,水土匹配度对区域农业经济发展的区域内和区域间的溢出效应都显著为正,总体上水土匹配度对区域农业经济发展具有正向的溢出效应,即水土匹配度对本地区农业经济增长具有促进作用;同时,由于相邻区域的水土资源自然禀赋条件类似,而且农业生产中存在"示范效应"和"模仿效应",水土匹配度对相邻地区农业经济增长也具有一定的促进作用。因此,采取相关措施优化农业水土资源匹配关系,对促进我国区域农业经济增长,保障我国粮食安全非常重要。     

农地流转对农地与劳动力资源利用效率的影响——基于甘肃省农户调查数据的实证研究

本研究采用倾向得分匹配法（PSM）分别就农地流转对农地、农业劳动力、非农劳动力和总劳动力资源利用效率的影响进行了分析。结果表明,农户的农地转入和转出行为都能有效提高总劳动力资源利用效率,而农地转出行为在一定程度上降低了农地资源利用效率。农地转入户的总劳动力和农业劳动力资源利用效率比未参与流转的农户分别高2026.153元/人和4844.289元/人,两组农户间的农地资源利用效率差异不显著;农地转出户的总劳动力和非农劳动力资源利用效率比未参与流转的农户分别高3315.577元/人和2581.883元/人,其农地资源利用效率比未参与流转的农户低466.488元/亩。因此,农地流转不一定会提高农地资源利用效率,但有利于促进农村劳动力专业化,从而提高农村总劳动力资源利用效率。     

黄浦江上游优先控制有机物的筛选

参考国内外同行有关控制物的筛选方法，通过黄浦江上游饮用水源保护区内水质的污染现状分析，确立了黄浦江上游水源保护区优先控制污染物的筛选原则和筛选程序，建立了黄浦江上游工业废水和地面水中的优先控制的名单。     

三江平原水土资源空间匹配格局

三江平原是我国重要的商品粮生产基地,其水土资源的空间匹配格局对保障区域粮食安全具有举足轻重的作用。近年来,由于水稻的大面积种植,三江平原水土资源数量、质量及其空间匹配状况均发生了明显的变化。为了客观地评价三江平原水土资源空间匹配现状,该研究在分析水土资源空间分布格局的基础上,引入水资源可利用量作为水资源量的表征参数,从水资源的可利用量与耕地资源的匹配角度,构建了区域水土资源匹配测算模型,并对其匹配程度进行了划分。分析结果表明,2000年以来,三江平原水土资源整体表现出"土地资源丰富,水资源欠缺"的态势,并且其空间分布格局存在明显的错位现象,已非惯称的"水土资源丰富和匹配";2008年三江平原水土资源匹配系数为0.35×10⁴ m³/hm²,远低于同期全国平均水平(0.56×10⁴ m³/hm²),水土资源匹配较差;水土资源匹配程度空间差异性较为显著,总体呈现出"南北优于东西,边缘优于腹地,林区优于农区,山丘区优于平原区"的格局。针对三江平原水土资源空间匹配程度差、区域差异明显的特点,应在水利设施建设的同时,兼顾水土资源的优化配置,以此提高三江平原水土资源空间匹配程度,为三江平原的粮食生产提供保障。     

An inventory of N(2)O emissions from agriculture in China using precipitation-rectified emission factor and background emission

Fertilized agricultural soils are a major anthropogenic source of atmospheric N₂O. A credible national inventory of agricultural N₂O emission would benefit its global strength estimate. We compiled a worldwide database of N₂O emissions from fertilized fields that were consecutively measured for more than or close to one year. Both nitrogen input (N) and precipitation (P) were found to be largely responsible for temporal and spatial variabilities in annual N₂O fluxes (N₂O–N). Thus, we established an empirical model (N₂O–N = 1.49 P + 0.0186 P · N), in which both emission factor and background emission for N₂O were rectified by precipitation. In this model, annual N₂O emission consists of a background emission of 1.49 P and a fertilizer-induced emission of 0.0186 P · N. We used this model to develop a spatial inventory at the 10 × 10 km scale of direct N₂O emissions from agriculture in China. N₂O emissions from rice paddies were separately quantified using a cropping-specific emission factor. Annual fertilizer-induced N₂O emissions amounted to 198.89 Gg N₂O–N in 1997, consisting of 18.50 Gg N₂O–N from rice paddies and 180.39 Gg N₂O–N from fertilized uplands. Annual background emissions and total emissions of N₂O from agriculture were estimated to be 92.78 Gg N₂O–N and 291.67 Gg N₂O–N, respectively. The annual direct N₂O emission accounted for 0.92% of the applied N with an uncertainty of 29%. The highest N₂O fluxes occurred in East China as compared with the least fluxes in West China.     

原子吸收光谱仪的背景校正

介绍了原子吸收光谱仪的５种主要的背景校正技术（邻近谱线技术，连续光源法，塞曼法，自吸法及连续光源单色器波长调节法ＣＥＷＭ）及其主要产品，分析评述了各种校正技术的原理，特点及其应用状况。     

企业厂界噪声监测问题的探讨

在厂界噪声测量中，由于国家标准测量方法——《工业企业厂界噪声测量方法》中介绍的不够详细，给分析人员在实际工作中带来许多不便，特别是临界状况时背景值的修正、周期性噪声测量方法的选择及厂界噪声测点的布设等问题，结合多年的工作经历针对这些问题谈谈看法。     

Comparing urban air quality in Europe in real time a review of existing air quality indices and the proposal of a common alternative

The EU directives on air quality force member states to inform the public on the status of the ambient air quality. The Internet is commonly used for this purpose and often air quality is being presented as an index ranging from good to bad. A review of existing websites and air quality indices shows that the way air quality is interpreted differs considerably. The paper presents a new air quality index. The index is part of a project to develop a website dedicated to comparing air quality in European cities. The common air quality index (CAQI) is not aimed at replacing existing local indices. The CAQI is a set of two indices: one for roadside monitoring sites and one for average city background conditions. Differentiating between roadside and general city conditions is a first step in assuring consistence in the parameters that are being compared.     

National baseline survey of soil quality in the Netherlands

To determine background values of the 252 chemical compounds listed in Dutch legislation, a survey was designed with the aim of estimating percentiles of the cumulative frequency distributions and areal fractions exceeding the former, legislative reference values. Sampling locations were selected by probability sampling, so that in estimating the target quantities no model assumptions on the spatial variation were required, and valid estimates could be obtained by design-based inference. Strata in random sampling were formed by overlaying an aggregated soil map and land use map. For most of the heavy metals the areal fraction with concentrations in the topsoil (0-10 cm) exceeding the reference value was smaller than the allowable maximum of 5%. For these compounds a background value was determined smaller than the reference value. Exceptions were V, Co, Ba and Cu, for which a background value was defined (slightly) larger than the reference value.     

Are soil conservation technologies “win‐win?” A case study of Anjeni in the north‐western Ethiopian highlands

This study measures the impact of fanya juu terraces on the net value of crop income in a high‐rainfall area in the Ethiopian highlands using cross‐sectional multiple plot observations. Using propensity score matching methods we find that the net value of crop income for plots with fanya juu terraces is lower than for plots without fanya juu terraces. This finding makes it difficult to avoid concluding that while the technologies might reduce soil erosion and associated off‐site effects, they do so at the expense of poor farmers in the Ethiopian highlands. Therefore, fanya juu terraces cannot be characterized as a “win‐win” measure to reduce soil erosion. New agricultural technologies need to be profitable to the farmer if they are to be adopted and sustained.