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791.
人口膨涨、资源短缺是人类21世纪面临的两大难题,合理开发和利用农业后备资源缓解人口与资源矛盾的重要途径。笔者根据农业区划成果和农业后备资源调查资料,分析了远安县农业后备资源的现状及开发潜力,提出了农业后备资源开发利用的设想,并针对性地提出了措施及建议. 相似文献
792.
Baloch Zulfiqar Ali Tan Qingmei Fahad Shah 《Environmental science and pollution research international》2022,29(38):57306-57316
Environmental Science and Pollution Research - Poor agricultural communities are particularly more disruptive to changes in climate. In southeast Asian countries, Pakistan is extremely vulnerable... 相似文献
793.
研究了低强度紫外线对活性艳红X 3B溶液的处理效果 ,考察了紫外线波长、溶液pH、起始浓度、催化剂用量、温度及曝气条件对染料降解的影响。结果表明 ,36 5nm紫外线 (UV3 65nm)的处理效果明显优于 2 5 4nm紫外线 (UV2 54nm) ,反应最适pH为 3 0~ 5 0 ,最佳TiO2 投加量为 2 0g/L ,最适温度为 4 0℃ ,通入空气或氧气均能加速活性艳红X 3B的降解。在上述条件下 ,起始浓度为 5 0mg/L的活性艳红X 3B在 1 5 0min内可完全分解 相似文献
794.
应用改进分光光度法测定多组分水样的COD 总被引:1,自引:0,他引:1
提出改进分光光度法测定多组分水样的化学需氧量(COD)。以多种物质的吸光曲线回归方程,将实时测得的水样吸光度分解成多种物质的吸光度,利用多元一次方程进行求解并计算出COD的方法。新方法对含邻苯二甲酸氢钾和丙烯酰胺水样测量的COD,误差平均值为+5.0%,对更多组分的水样测量紫外吸光度误差较大,通过引入修正系数修正后误差大幅下降,10次测量的变异系数约0.5%,精密度较好。通过分析新方法实际运用时存在的优劣之处,提出综合高锰酸盐指数(CODMn)来弥补其测量上不足的新型废水监测模式,以实现监测的快速测量、低耗能、低污染和实时性。 相似文献
795.
796.
Kun Xu Haiwei Wang Xuechen Liang Ying Tan Xianping Yao Pixin Wang 《Journal of Polymers and the Environment》2018,26(7):2782-2792
Cationic hyperbranched oligomer poly(N-acryloyl-1,2-diaminoethane hydrochloride) (HADE) was firstly synthesized by Michael addition reaction. And then, a series of cationic flocculants poly(acrylamide/N-acryloyl-1,2-diaminoethane hydrochlorides) (PAM-HADEs) with hyperbranched structure was prepared from HADE as macro-monomer and acrylamide (AM). The structures of PAM-HADEs were characterized by Fourier transform infrared spectrometry, 1H and 13C nuclear magnetic resonance spectroscopy, gel permeation chromatography (GPC) and matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF). And the properties were systematically evaluated by intrinsic viscosity, zeta potential and hydrodynamic radius. The mechanism of the cationic hyperbranched copolymer used in water treatment was extensively studied via a jar test in which the transmittance of the supernatant, settling time, and average floc size were used to evaluate the flocculability. Compared with the linear flocculant poly (acrylamide/liner-N-acryloyl-1,2-diaminoethane hydrochloride) (PAM-LADE), the novel hyperbranched polymeric flocculants exhibited outstanding flocculability which were reflected by shorter settlement time, high transmittance and large floc size. The primary cause that PAM-HADEs owned excellent flocculability is the more stretching configuration and less chains entanglement of PAM-HADEs in waste-water due to their hyperbranched structure compared with that of the linear PAM-LADE which exhibited curly coil configuration. On the other hand, abundant and exposed cationic terminal groups of PAM-HADEs originated from their hyperbranched structure also hint higher flocculation capacity. At optimum dosages of the polymer, the transmittance of the supernatant is less at low and high pH values, indicating that the natural pH (pH 7.29) of the suspension is the most appropriate pH for the flocculation. 相似文献
797.
Thomalla Frank Lebel Louis Boyland Michael Marks Danny Kimkong Ham Tan Sinh Bach Nugroho Agus 《Regional Environmental Change》2018,18(4):1211-1222
Regional Environmental Change - Most studies of major disasters focus on the impacts of the event and the short-term responses. Some evaluate the underlying causes of vulnerability, but few... 相似文献
798.
It has been widely reported that heavy metal contamination in coastal waters can modify the allozyme profiles of marine organisms. Previous studies have recorded elevated metal concentrations in sediments and mussel tissues off Peninsular Malaysia. In the present study, horizontal starch gel electrophoresis was carried out to estimate the levels of allelic variation of the green-lipped mussel, Perna viridis, collected from one contaminated and three relatively uncontaminated sites off Peninsular Malaysia. Fourteen polymorphic loci were observed. In addition, the concentrations of cadmium, copper, lead, mercury and zinc were determined in the sediments and in the soft tissues of the mussels. Mussels from contaminated site, evidenced by high metal pollution indices (MPI) of the sediment and the mussel tissues, showed the highest percentage of polymorphic loci (78.6%), while those collected from the uncontaminated sites had lower MPI of the sediment and mussel tissue, and exhibited lower percentages of polymorphic loci (35.7-57.1%). The population from the contaminated site showed the highest excess of heterozygosity (0.289) when compared to that of the populations from the three uncontaminated sites (0.108-0.149). Allozyme frequencies at the phosphoglucomutase (PGM; E.C. 2.7.5.1) locus also differed between the contaminated and uncontaminated populations. Previous studies have shown that exposure to heavy metals can select or counter-select for particular alleles at this locus. The present results suggest that allozyme polymorphism in P. viridis is a potential biomonitoring tool for heavy metal contamination but further validation is required. 相似文献
799.
800.
改性TiO2光催化降解三苯甲烷类污染物 总被引:1,自引:0,他引:1
以硫酸钛为原料采用水热法制备了掺Fe3+TiO2晶体粉末,采用X射线衍射仪(XRD)对样品的结构进行了表征。在可见光条件下,用溴酚蓝、甲基绿、甲基蓝、孔雀石绿、甲基紫和碱性品红等6种典型三苯甲烷类化合物为目标降解物,研究了以自制的掺Fe3+TiO2晶体粉末对它们的催化降解作用。实验结果表明,制备的掺Fe3+TiO2晶体属于锐钛矿型。6种化合物的光催化降解反应遵循拟一级动力学规律,且可用Langmuir-Hinshelwood(L-H)动力学模型描述,其表观反应速度常数(k)的大小顺序为:溴酚蓝<甲基绿<甲基蓝<孔雀石绿<甲基紫<碱性品红,大小变化次序与其半衰期t1/2成反比,并从分子结构上对它们的降解规律进行定性解释。 相似文献