燃烧器偏转-火焰原子吸收法测定水中钾钠钙镁

对采用燃烧器偏转-火焰原子吸收法测定水中钾、钠、钙、镁的仪器条件及灵敏度、检出限、测定下限、精密度、准确度进行了研究。发现该方法在没有铯盐及镧盐加入的情况下,曲线线性好、灵敏度高、精密度好、准确度高,能够满足实际分析的需要。     

氟化钙污泥处置及资源化利用

综述了现有的氟化钙污泥处理处置技术,包括浮选富集回用氟化钙,熔融焚烧实现减量化,应用于陶瓷、水泥、混凝土制作,以及利用其化学性质,作为添加剂用于飞灰的固化稳定,或者在钢铁行业中充当萤石成为助熔剂。理论分析和试验检测表明上述方法均可实现含氟污泥的减量化、无害化、资源化,在处理氟化钙污泥时可以根据实际情况选择相应的工艺技术。     

市政垃圾焚烧飞灰中添加CaO抑制PCDD/Fs生成试验探究

采用自制装置,以CaO作为PCDD/Fs生成抑制剂,对市政垃圾焚烧飞灰做热处理。通过试验考察温度、CaO添加量等因素对飞灰中PCDD/Fs生成的影响。结果表明：质量分数为5%的CaO添加可以减少80%的PCDD/Fs生成。     

High affinity binding of 3H‐verapamil to rat brain synaptic membrane is antagonized by pyrethroid insecticides

Abstract

Deltamethrin is a powerful neuroactive agent causing increased neurotransmitter release at the synapse. To understand the cause for such an action of this pyrethroid insecticide, we have studied its binding characteristics to the calcium channel by utilizing ³H‐verapamil as a specific ligand. It was found that deltamethrin is capable of competing at the same binding site as ³H‐verapamil. Also, it was found that nonlabeled verapamil could reduce the binding of ³H‐deltamethrin (tested at 1 nM) to its binding site. The EC₅₀ value of verapamil to displace 50% of ³H‐deltamethrin was in the order of 0.3 μM, which coincides with the approximate K_D value for this ligand to bind with calcium channels in the rat brain synaptosomal plasma membranes.     

A novel method to make regenerable core-shell calcium-based sorbents

A sorbent having a calcium oxide core and a clay shell was prepared and shown to be capable of reusable applications in absorption and desorption processes for carbon dioxide. The novelty of this sorbent is that only calcium carbonate and clay are used for its preparation with water as a binder. A two-step granulation procedure is used to get the core and then another step to coat the shell layer with the clay powder. A repeated wet-and-dry procedure probably makes the core porous yet strong enough to serve as a sorbent. The pellet is then calcined at 1200 degrees C for 2h to reach its final structure. The core-shell pellets have an overall diameter of 4.4mm with average shell thickness of 0.45 mm, crush load of 35 N and attrition index of 0.035 wt%/h. These results indicate that the pellets will probably be capable of withstanding the stress in future applications. Carbon dioxide absorption at or below 300 degrees C showed a maximum weight gain of 38% for our pellets. Finally, desorption in nitrogen at 800 degrees C can restore the pellet to its original state and hence it is ready for re-use as a sorbent.     

控制星湖内源性营养物质磷负荷的有效性研究

本文研究了天然沸石与石灰,铝盐,铁盐对湖水－沉积物系统中的湖水脱磷的可能性,以期在对星湖内源性营养物质磷负荷的控制方面提供科学依据。     

Alteration of shell nacre micromorphology in blue mussel Mytilus edulis after exposure to free-ionic silver and silver nanoparticles

This study describes the morphology of inner shell surface (ISS) of the blue mussel Mytilus edulis Linnaeus after short-term exposures to radiolabeled silver in free-ionic (^110mAg⁺) and engineered nanoparticulate (^110mAgNPs, <40 nm) phases. Radiolabeled silver in starting solutions was used in a similar low concentration (∼15 Bq mL⁻¹) for both treatments. After exposure experiments radiolabeled silver was leached from the ISS using HCl. It concentration for shells from both treatments was ∼0.5 Bq mL⁻¹. Whole ISS of young individuals and prismatic layer of adults showed no evidence of any major alteration process after silver uptake. However, the nacre portion of adult mussels exposed to both treatments revealed distinct doughnut shape structures (DSS) formed by calcium carbonate micrograins that covered the surface of aragonite tablets. Scanning electron microscope (SEM) imaging revealed the existence of only minor differences in DSS morphology between mussels exposed to Ag⁺ and AgNPs. From literature survey, DSS were also found in bivalves exposed to Cd²⁺. The DSS occurring in a specimen of a field-collected bivalve is also shown. Formation of distinctive DSS can be explained by a disturbance of the shell calcification mechanism. Although the occurrence of DSS is not exclusively associated with metal bioavailability to the mussels, the morphology of DSS seems to be linked to the speciation of the metal used in the uptake experiments.     

Base cation depletion, eutrophication and acidification of species-rich grasslands in response to long-term simulated nitrogen deposition

Pollutant nitrogen deposition effects on soil and foliar element concentrations were investigated in acidic and limestone grasslands, located in one of the most nitrogen and acid rain polluted regions of the UK, using plots treated for 8-10years with 35-140kg Nha(-2)y(-1) as NH(4)NO(3). Historic data suggests both grasslands have acidified over the past 50years. Nitrogen deposition treatments caused the grassland soils to lose 23-35% of their total available bases (Ca, Mg, K, and Na) and they became acidified by 0.2-0.4 pH units. Aluminium, iron and manganese were mobilised and taken up by limestone grassland forbs and were translocated down the acid grassland soil. Mineral nitrogen availability increased in both grasslands and many species showed foliar N enrichment. This study provides the first definitive evidence that nitrogen deposition depletes base cations from grassland soils. The resulting acidification, metal mobilisation and eutrophication are implicated in driving floristic changes.     

Sorption of hazardous metals from single and multi-element solutions by saltbush biomass in batch and continuous mode: interference of calcium and magnesium in batch mode

Batch studies were performed to determine the interference of calcium (Ca) and magnesium (Mg) on the sorption of Cu(II), Cd(II), Cr(III), Cr(VI), Pb(II), and Zn(II) [from CuSO(4), K(2)Cr(2)O(7), Pb(NO(3))(2), Cr(NO(3))(3), ZnCl(2), and Cd(NO(3))(2)] by saltbush (Atriplex canescens) biomass. The results demonstrated that Ca and Mg at concentrations of at least 20 times higher than the concentration of most of the target metals did not interfere with the metal binding. The data show that the batch binding capacity from a multimetal solution at pH 5.0 was (micromol/g) about 260 for Cr(III) and Pb, and about 117, 54, and 49 for Cu, Zn, and Cd, respectively. The use of 0.1M HCl allowed the recovery of 85-100% of the bound Cu, Cr(III), and Pb, and more than 37% of the bound Cd and Zn. The column binding capacity for Pb was about 49 micromol/g from both the single and multimetal solutions, while it was, respectively about 35 and 23 micromol/g for Cr(III). The binding capacity for Cu and Zn from the single and multimetal column experiments was 35 micromol/g and less than 10 micromol/g, respectively. The stripping data from the single column experiment showed that 0.1M HCl allowed the recovery of all the bound Cu and Zn, 90% and 74% of the bound Pb and Cr(VI), respectively, and less than 25% of the bound Cd and Cr(III), while the stripping from the multimetal experiment showed that 0.1M HCl allowed the recovery of all the bound Cu and about 74%, 54%, 43%, and 40% of the bound Pb, Zn, Cd, and Cr(III), respectively.     

CO2 emissions in calcium carbide industry: An analysis of China's mitigation potential

China's calcium carbide output has dominated the global market for several years, driven by the demand for PVC (polyvinyl chloride), a fundamental polymer material and also the primary downstream product of calcium carbide in China. The fast growth of this energy-intensive industry leads to an inevitable increase in CO₂ emissions. However, there is a large reduction potential with process improvement in this industry which is currently characterized by widespread outdated facilities. In this study, we attempt to assess the reduction potential of CO₂ emissions in China's calcium carbide production, based on the analysis of CO₂ emission patterns and estimation of the emission amount. Three scenarios regarding process improvement are employed to conduct this assessment. The results imply that the cumulative CO₂ abatement in the Current Policy Scenario and in the Strengthened Policy Scenario from 2008 to 2020, compared with the Baseline Scenario, are 89.0 and 107.6 million t, respectively. The specific measures and policy implications to achieve this potential are also discussed in the article.