新型杀菌剂氟吡菌胺对9种环境生物的急性毒性及其在斑马鱼体内的生物富集

为评价新型杀菌剂氟吡菌胺对环境生物的毒性风险,避免其在使用过程中对我国特有的环境生物产生危害,测定了氟吡菌胺对意大利蜜蜂、日本鹌鹑、斑马鱼、家蚕、斜生栅藻、大型溞、玉米螟赤眼蜂、赤子爱胜蚓和黑斑蛙蝌蚪等9种代表性环境生物的急性毒性,并以斑马鱼为试材,研究了氟吡菌胺的生物富集性,即根据鱼类急性毒性结果 LC50(96 h)=1.489 mg·L~(-1),设计生物富集试验水样浓度为LC50的1/2、1/10和1/100,即0.745 mg·L~(-1)、0.149 mg·L~(-1)和0.0149 mg·L~(-1),连续暴露8 d,采用液相色谱法测定3个浓度下氟吡菌胺在斑马鱼体内的富集量。结果表明,氟吡菌胺对斑马鱼、斜生栅藻和大型溞3种水生生物的急性毒性为中毒级,对黑斑蛙蝌蚪急性毒性为高毒级,其对蜜蜂、鸟类、家蚕、蚯蚓和天敌赤眼蜂等环境生物均为低毒或低风险;斑马鱼在0.745、0.149和0.0149 mg·L~(-1)的氟吡菌胺水溶液中暴露192 h时,生物富集系数BCF分别为33.65、26.39和193.25;根据化学农药环境安全评价试验准则评价标准,10BCF≤1000,氟吡菌胺属于中等富集性农药。     

Cysteine-enhanced reductive degradation of nitrobenzene using nano-sized zero-valent iron by accelerated electron transfer

As an aliphatic amino acid, cysteine (CYS) is diffuse in the living cells of plants and animals. However, little is known of its role in the reactivity of nano-sized zero-valent iron (NZVI) in the degradation of pollutants. This study shows that the introduction of CYS to the NZVI system can help improve the efficiency of reduction, with 30% more efficient degradation and a reaction rate constant nine times higher when nitrobenzene (NB) is used as probe compound. The rates of degradation of NB were positively correlated with the range of concentrations of CYS from 0 to 10 mmol/L. The introduction of CYS increased the maximum concentration of Fe(III) by 12 times and that of Fe(II) by four times in this system. A comparison of systems featuring only CYS or Fe(II) showed that the direct reduction of NB was not the main factor influencing its CYS-stimulated removal. The reduction in the concentration of CYS was accompanied by the generation of cystine (CY, the oxidized form of cysteine), and both eventually became stable. The introduction of CY also enhanced NB degradation due to NZVI, accompanied by the regeneration of CYS. This supports the claim that CYS can accelerate electron transfer from NZVI to NB, thus enhancing the efficiency of degradation of NB.     

采用商业混合菌种测定BOD5的可行性

通过实验,对比研究了采用商业混合菌种（Polyseed）改进传统方法测定BOD5的可行性。研究结果表明,相比于采用地表水作为接种水的传统方法,采用进口商业混合菌种配制接种稀释水BOD5（空白值）更稳定,可以改进传统BOD5测定方法,使得日常监测工作更为便捷。     

Automatic habitat classification methods based on satellite images: A practical assessment in the NW Iberia coastal mountains

Although remote sensing is increasingly in use for habitat mapping, traditional image classification methods tend to suffer shortcomings due to non-normality of spectral signatures, as well as overlapping and heterogeneity in radiometric responses of natural and semi natural vegetation. Methods using non-parametric classifiers and object-oriented analysis have been suggested as possible solutions for overcoming these limitations. In this paper, we aimed at evaluating the performance of some of these techniques for the European Natura 2000 network of protected areas habitats mapping. For this purpose, we tested different methods of supervised image classification in the Northern Mountains of Galicia, Spain, an area included in the Natura 2000 network, which is characterized by a highly heterogeneous landscape. Methods involved the use of maximum likelihood and nearest neighbour decision rules in per-pixel and per-object classification analyses on Landsat TM imagery. Per-object classifications were completed using the segment mean and segment means plus standard deviation feature spaces. The results showed the existence of significant differences in the accuracies for the different methodologies, their strengths and weaknesses and identified the most adequate approach for habitat mapping. Analyses pointed out that significant improvements in accuracy were achieved only under certain combinations of per-object analysis, non-parametric classifiers and high dimensionality feature space.     

高职高专计算机专业考试改革思路与措施探析

高职教育以技术为核心,以能力为本位,不仅要调整和改革教学计划,还要改革考试方法。本文分析了目前高校考试存在的问题,从学校考试改革的实际出发,总结出计算机专业考试改革应遵循的四点原则。依据高职高专院校的人才培养目标,结合计算机专业教学特点,提出了形成式考核、能力考核和职场模拟考核等多项考试改革措施。     

Ranking potential impacts of priority and emerging pollutants in urban wastewater through life cycle impact assessment

Life cycle impact assessment (LCIA), a feature of the Life cycle assessment (LCA) methodology, is used in this work outside the LCA framework, as a means to quantify the potential environmental impacts on ecotoxicity and human toxicity of wastewater containing priority and emerging pollutants. In order to do this, so-called characterisation factors are obtained for 98 frequently detected pollutants, using two characterisation models, EDIP97 and USES-LCA. The applicability of this methodology is shown in a case study in which wastewater influent and effluent samples from a Spanish wastewater treatment plant located in the Mediterranean coast were analysed. Characterisation factors were applied to the average concentration of each pollutant, obtaining impact scores for different scenarios: discharging wastewater to aquatic recipient, and using it for crop irrigation. The results show that treated wastewater involves a substantially lower environmental impact when compared to the influent, and pharmaceuticals and personal care products (PPCPs) are very important contributors to toxicity in this wastewater. Ciprofloxacin, fluoxetine, and nicotine constitute the main PPCPs of concern in this case study, while 2,3,7,8-TCDD, Nickel, and hexachlorobenzene are the priority pollutants with highest contribution. Nevertheless, it must be stressed that the new characterisation factors are based on very limited data, especially with regard to toxicology, and therefore they must be seen as a first screening to be improved in the future when more and higher quality data is available.     

一日三餐,吃什么最健康?

一日三餐,我们每天都在吃,而吃什么最安全,吃什么最健康,聪明的您,又有多少了解呢?这是一份世界卫生组织公布的经过约三年时间研究得出的最佳食品榜.     

Fertilizer residence time affects nitrogen uptake efficiency and growth of sweet corn

Understanding plant N uptake dynamics is critical for increasing fertilizer N uptake efficiency (FUE) and minimize the risk of N leaching. The objective of this research was to determine the effect of residence time of N fertilizer on N uptake and FUE of sweet corn. Plants were grown in 25 L columns during the fall and spring to mimic short-term N uptake dynamics. Nitrogen was applied either 1, 3, or 7 d before a weekly leaching event, using KNO3 solution (total of 393 kg N ha(-1)). Residence times (tR) were tR-1, tR-3, and tR-7 d before weekly removal of residual soil N. Plant N uptake was calculated by comparing weekly N recovery from planted with non-planted columns. During the fall, N uptake values at 70 d after emergence were 59, 73, and 126 kg N ha(-1). During the spring, corresponding values were 54, 108, and 159 kg N ha(-1). A linear response of plant growth and yield to the tR was observed under cooler conditions, whereas a quadratic response occurred under warmer conditions. There was correlation between root length density and yield. It is concluded that increasing N fertilizer residence time, which is indicative of better irrigation practices, enhanced overall sweet corn growth, yield, N uptake, and FUE, consequently reduced the risk of N being leached below the root zone before complete N uptake.     

Nitric oxides and nitrous oxide fluxes from typical vegetables cropland in China: Effects of canopy,soil properties and field management

In China, vegetable croplands are characterized by intensive fertilization and cultivation, which produce significant nitrogenous gases to the atmosphere. In this study, nitric oxides (NO_X) and nitrous oxide (N₂O) emissions from the croplands cultivated with three typical vegetables had been measured in Yangtze River Delta of China from September 2 to December 16, 2006. The NO fluxes varied in the ranges of 1.6–182.4, 1.4–2901 and 0.5–487 ng Nm^?2 s^?1 with averages of 33.8 ± 44.2, 360 ± 590 and 76 ± 112 (mean ± SD) ngNm^?2 s^?1 for cabbage, garlic, and radish fields (n = 88), respectively. N₂O fluxes from the three vegetable fields were found to occur in pulses and significantly promoted by tillage with average values of 5.8, 8.8, and 4.3 ng Nm^?2 h^?1 for cabbage, garlic, and radish crops, respectively. Influence of vegetables canopy on the NO emission was investigated and quantified. It was found that on cloudy days the canopy can only shield NO emission from croplands soil while on sunny days it cannot only prevent NO emission but also assimilate NO through the open leaves stomas. Multiple linear regression analysis indicated that soil temperature was the most important factor in controlling NO emission, followed by fertilizer amount and gravimetric soil water content. About 1.2%, 11.56% and 2.56% of applied fertilizers N were emitted as NO–N and N₂O–N from the cabbage, garlic and radish plots, respectively.     

地块尺度城市土地质量地球化学调查方法:以雄安新区起步区为例

以土地质量地球化学调查评价成果服务于城市土地资源精准管护为目标,选择中国城镇化探路者的雄安新区起步区为研究对象,采用差异化分类布设样点,开展不同采样密度条件下地块尺度土壤元素空间插值精度、地块（图斑）插值精度和地球化学预测评价等级准确度的定量评估研究.结果表明：①采用差异化分类布设样点方法使平面上随机分布的区域地球化学量变值在每一个地块（图斑）都有明确的量值反映,能满足城市土地资源精准管护对单一地块（图斑）具有质量属性的基本需求;②研究区土壤元素指标空间变异性以轻中度为主;其中Hg、Pb、Cd、Cu、Zn、N、P和Se受人类生产活动影响,具有较高的空间变异性;③相同采样密度条件下,元素含量空间变异性越大,其空间插值精度和图斑插值精度越低;同一种元素插值精度受采样密度的影响,但采样密度的增大并不一定能够识别土壤元素含量的结构性连续组分;区内土壤环境本底清洁,重金属含量低于GB15618-2018标准,其插值评价等级和实测评价等级结果基本一致;养分指标N、P和K含量区间变化大,受人为扰动和空间变异性等因素影响,其预测等级和实测等级差异较大;④采用16点·km^-2的采样密度开展地块尺度城市土地质量地球化学调查评价可以满足研究区及类似地区城市土地资源精准管控的需求.