Potential ecological and health risk assessment of different kiwifruit orchards in Qianjiang district,Chongqing city,China

Environmental Science and Pollution Research - Heavy metal (HM) pollution in orchards is becoming serious in many countries, and some fruit HMs exceed the safety limits. In this study, contents of...     

Effects of synthesis methods on catalytic activities of CoOx–TiO2 for low-temperature NH3-SCR of NO

A series of cobalt doped TiO_2(Co-TiO_2) and Co Oxloaded TiO_2(Co/TiO_2) catalysts prepared by sol–gel and impregnation methods respectively were investigated on selective catalytic reduction with NH_3(NH_3-SCR) of NO. It was found that Co-TiO_2 catalyst showed more preferable catalytic activity at low temperature range. From characterization results of XRD,TEM, Raman and FT-IR, Co species were proved to be doped into TiO_2 lattice by replaced Ti atoms. After being characterized and analyzed by NH_3-TPD, PL, XPS, EPR and DRIFTS, it was found that the better NH_3-SCR activities of Co-TiO_2 catalysts, compared with Co/TiO_2 catalyst, were ascribed to the formation of more oxygen vacancies which further promoted the production of more superoxide ions(O-2). The superoxide ions were crucial for the formation of low temperature SCR reaction intermediates(NO-3) by reacting with adsorbed NO molecule. Therefore, these aspects were responsible for the higher low temperature NH_3-SCR activity of Co-TiO_2 catalysts.     

Keep swimming but stop peeing in the pools

正Swimming is excellent exercise and offers many health benefits.However,the"chlorine smell"in swimming pools may be a turn-off for some people.Although this smell is often thought to be of chlorine,it actually comes from volatile compounds that are produced from unintended reactions between disinfectants(e.g.,chlorine)and organic matter in     

Adsorption–desorption behavior of atrazine on agricultural soils in China

Adsorption and desorption are important processes that affect atrazine transport,transformation,and bioavailability in soils.In this study,the adsorption–desorption characteristics of atrazine in three soils(laterite,paddy soil and alluvial soil) were evaluated using the batch equilibrium method.The results showed that the kinetics of atrazine in soils was completed in two steps:a"fast" adsorption and a "slow" adsorption and could be well described by pseudo-second-order model.In addition,the adsorption equilibrium isotherms were nonlinear and were well fitted by Freundlich and Langmuir models.It was found that the adsorption data on laterite,and paddy soil were better fitted by the Freundlich model;as for alluvial soil,the Langmuir model described it better.The maximum atrazine sorption capacities ranked as follows:paddy soil alluvial soil laterite.Results of thermodynamic calculations indicated that atrazine adsorption on three tested soils was spontaneous and endothermic.The desorption data showed that negative hysteresis occurred.Furthermore,lower solution pH value was conducive to the adsorption of atrazine in soils.The atrazine adsorption in these three tested soils was controlled by physical adsorption,including partition and surface adsorption.At lower equilibrium concentration,the atrazine adsorption process in soils was dominated by surface adsorption;while with the increase of equilibrium concentration,partition was predominant.     

电锅炉技术及其应用对环境影响的分析研究

针对电锅炉技术及其应用对环境影响,以绿色电力能源代替煤、油、气等常规化石能源,减少因化石能源在城镇人群聚集区终端使用造成"雾霾"类大气污染,已经成为一种新的发展趋势.本文系统分析了电锅炉的常用技术,分别阐述了不同种类电锅炉的技术原理、技术特点、工艺流程、应用领域,并通过实际应用案例,分析了电锅炉技术推广应用对城镇人口聚集区环境污染改善的效果,最后提出电锅炉技术的应用建议,为推行电锅炉技术选型提供依据,保证绿色环境的生成.     

简析页岩气开发对水资源的破坏

页岩气的开发主要采用水平井水力压裂的方法,压裂过程中压裂液的大量使用以及对返排压裂液的处理不当,会造成页岩气开发过程中对水资源的破坏,主要表现在导管破裂污染、返排液地面污染、大量消耗水资源等方面。通过总结对比返排压裂液的几种处理方法,认为废液处理后循环使用的方法在节约成本的同时,可最大程度地减小对水资源的破坏。     

桩土刚度比及布桩位置对桩身内力分布的影响研究

桩土刚度比及布桩位置直接影响抗滑桩的桩身内力分布及边坡加固效果。采用数值模拟的方法,考虑不同桩土刚度比和布桩位置,分别进行了计算分析。结果表明:(1)桩身剪力近似呈反"S"型分布,弯矩呈现向桩后的凸型分布,且桩身剪力和弯矩均随桩土刚度比的增加而增大,呈现先陡后缓的变化趋势;(2)桩位一定时,桩身正负最大剪力分别出现在桩身1/2和1/4高度位置,对应位置应加强抗剪箍筋的配置;桩身弯矩最大的位置出现在桩身1/3高度位置,即边坡滑带所在的位置,对应位置应加强抗弯钢筋的配置;(3)布桩于边坡中部及两侧时,加固后边坡的安全系数提高明显,桩身剪力和弯矩较大,而且对塑性区有明显的隔断作用。考虑到一般边坡中部的滑体厚度较深,在坡体中部位置布桩无论在技术上还是经济上都不太合适,因此,建议布桩于边坡中部两侧的位置,可取得较好的加固效果。     

Response of three dominant shrubs to soil water and groundwater along the oasis-desert ecotone in Northwest China

The ecotone from oasis to desert is an important area for combating sandy desertification. Three dominant desert shrubs (Nitraria tangutorum, Calligonuum mongolicum, Haloxylon ammodendrori) were selected in Minqin Oasis, Northwest China, to determine the groundwater level; soil water potential; and change of the three shrubs in density, coverage, and biomass along the natural and seminatural oasis-desert ecotone (ODE), respectively. The results indicated that traits of desert plant interaction with the topsoil water and groundwater depth along the ODE play an important role in generating complex desert vegetation spatial dynamics. Some natural desert plant species with shallow root systems will distribute themselves according to distribution of topsoil water. Thus, the distribution of Nitraria tangutorum had a decreasing trend in distribution along ODE. Calligonuum mongolicum occurs in different trends in natural and seminatural ODE due to utilizing groundwater as well as topsoil water. Some plant species with deep roots, such as Haloxylon ammodendron, will show more degradation near oases and will exhibit an ascending trend along ODE. Therefore, it is of primary importance to protect the integrity of groundwater depth in order to protect the stability of the oasis-desert ecotones. The text was submitted by the authors in English.