保护性耕作下小麦田土壤呼吸及碳平衡研究

为了研究小麦农田生态系统土壤碳排放与作物碳蓄积特征,采用LI6400-09在重庆北碚西南大学教学试验农场对平作(T)、垄作(R)、平作+覆盖(TS)、垄作+覆盖(RS)这4种处理下的西南紫色土丘陵区小麦/玉米/大豆套作体系中小麦生长季节的土壤呼吸及植株生长动态进行了观测.利用根系生物量外推法(root biomass regression,RBR)和根排除法(root exclusion,RE)这2种方法比较分析根系呼吸对土壤总呼吸的贡献,并估算小麦农田碳收支状况.结果表明,土壤呼吸介于0.62~2.91μmol·(m2·s)-1,平均值为1.71μmol·(m2·s)-1.T、R、TS、RS各处理日均土壤呼吸速率分别为1.29、1.59、1.99、1.96μmol·(m2·s)-1,表现为T相似文献   

农业现代化、信息化与农业面源污染研究

利用2003年-2013年中国30个省份的面板数据,检验了农业现代化、信息化与农业面源污染之间的关系.研究发现,农业现代化对农业面源污染有着一定的加重作用;信息化能够有效缓解因农业现代化所导致的农业面源污染,这一现象在粮食主产省同样存在,说明信息化能够发挥减污增绿的作用;农业环境库兹涅茨曲线(EKC)也得到验证.因此,应进一步推进信息化发展,有效利用信息化对农业现代化所致农业面源污染的缓解作用,还应多措并举促进农民增收,加快农民收入越过EKC曲线拐点.     

Heavy Metal Contents and Magnetic Properties of Playground Dust in Hong Kong

This study examined the levels of seven heavy metals (namelyzinc, copper, cadmium, chromium, lead, manganese and iron) andtheir associations with magnetic properties in playground dustof Hong Kong. Results showed that the playground dust containedhigh concentrations of Zn (mean = 1883 g g^-1), Cu(mean = 143 g g^-1) and Cr (mean = 263 g g^-1).Qualitative examination of dust samples under microscope indicated local traffic as one of the important pollutant sources. Magnetic measurements indicated that these anthropogenicpollutants mainly consisted of coarse-grained multidomain (MD) ferrimagnetic minerals. Superparamagnetic (SP), stable single domain (SSD) ferrimagnetic grains and non-ferrimagnetic mineralswere present in relatively small amounts. Significant correlations between heavy metals and various magnetic parametersindicated a strong affinity of heavy metals to magnetic minerals hence pointed out the potential of magnetic properties for simpleand rapid proxy indications of heavy metal pollution in playground dust.     

超高压液相色谱/质谱联用法测定地表水中特定污染物

采用超高压液相色谱/质谱联用法测定地表水特定项目中包括微囊藻毒素-LR在内的13种污染物,对测定条件进行优化,使得各目标化合物均能在3min内检测完毕.试验表明,方法在各测定范围内线性良好,相关系数均〉0.99,各目标化合物的方法检出限为0.12μg/L～8.40μg/L,地表水样的加标回收率在62.0% ～104%之间,6次平行测定的RSD〈6%.用该方法测实际水样,阿特拉津和马拉硫磷被检出,质量浓度分别为0.6μg/L和0.7μg/L.     

Microbial degradation characteristics and kinetics of novel pyrimidynyloxybenzoic herbicide ZJ0273 by a newly isolated Bacillus sp. CY

ZJ0273 (propyl 4-(2-(4,6-demethoxy pyrimidin-2-yloxy)benzylamino)benzoate) is a novel herbicide developed in China for oilseed crop. Sixteen bacteria capable of utilizing ZJ0273 as the sole carbon source were isolated from soils. One of the isolates was designated as Bacillus sp. CY based on its physiological and biochemical characteristics and phylogenetic analysis of 16S rDNA sequences. The present study aimed to investigate the ZJ0273 degradation characteristics and kinetics by Bacillus sp. CY which has the ability to utilize ZJ0273 as the sole source of carbon and energy under aerobic conditions. The optimum biodegradation temperature, pH, and ZJ0273 initial concentration were 20–40 °C, 5.0–9.0, and 50–400 mg/l, respectively. Strain CY degraded 65 % of ZJ0273 (initial concentration of 50 mg/l) during 30 days of incubation in basal mineral medium at pH 8.0 and 35 °C. DT50 (half-life value), k (degradation rate constant of ZJ0273), and R ² are 19.20 days, 0.0361 day^?1, and 0.9464, respectively.     

同步硝化反硝化工艺中DO浓度对N2O产生量的影响

采用序批式生物膜反应器(SBBR),在连续曝气全程好氧的运行条件下,考察不同溶解氧浓度对同步硝化反硝化脱氮性能及N2O产量的影响.控制溶解氧浓度恒定在1、2、2.5和3 mg/L.结果表明,DO为2 mg/L和2.5 mg/L时,氨氮去除率分别为97.9%和98.5%,同步硝化反硝化率均为99%.DO为2 mg/L时,...     

Concentrations of formaldehyde and other carbonyls in environments affected by incense burning

Burning incense to pay homage to deities is common in Chinese homes and temples. Air samples were collected and analyzed for carbonyls from a home and a temple in Hong Kong where incense burning occurs on a daily basis. Carbonyls in the air were trapped on a solid sorbent coated with O-(2,3,4,5,6-pentafluorobenzyl)-hydroxylamine, followed by thermal desorption and subsequent GC/MS analysis. The carbonyls identified include formaldehyde, acetaldehyde, acrolein, 2-furfural, benzaldehyde, glyoxal, and methylglyoxal. The levels of the above carbonyls correlate with the intensity of the incense-burning activities. The total mixing ratios of the carbonyls in the temple exceed those in the ambient air outside the temple by 11-23 times. Formaldehyde is the most abundant species, contributing to approximately 55% of the total carbonyl mixing ratios in both the temple and the home environments during incense burning. The mixing ratio of formaldehyde ranges from 108 to 346 ppbv in the temple and averages 103 ppbv in the home during incense burning. These values exceed the World Health Organization (WHO) air quality guideline of 100 microg m(-3) (88 ppbv) for formaldehyde. The highest formaldehyde level in the temple exceeds the WHO guideline by 3 times at peak incense burning hours. The mixing ratio of acrolein in the temple ranges from 20 to 99 ppbv, approaching or exceeding the WHO air quality guideline of 50 microg m(-3) (22 ppbv) for acrolein. Our measurements indicate that incense burning significantly elevates the concentrations of a number of carbonyls, most notably formaldehyde and acrolein, in the surrounding environments. This study provides preliminary insights on indoor air quality problems created by incense burning.     

采暖锅炉氧腐蚀的原因与防腐对策

热水锅炉及其采暖系统在运行和停运期间都存在较严重的氧腐蚀,但由于主客观原因的限制,并没有引起人们的高度重视.氧腐蚀对锅炉及其采暖系统运行的安全性和经济性造成重大影响,严重时引起爆管,被迫停炉等危害.大力提倡节能减排的今天,延长锅炉的寿命,促进安全经济生产意义重大.本论文分析总结采暖锅炉目前的水质与防腐工作的现状,同时提出了对采暖锅炉今后锅炉及热力管网防腐的对策.     

循环硫化床锅炉脱硫率主要影响因素

循环流化床锅炉添加石灰石脱硫技术近年来得到了很大的发展,它具有脱硫效率高,脱硫成本低,操作简单、无水污染等特点.本文分析概括了循环流化床锅炉添加石灰石脱硫工艺脱硫率的主要影响因素.