Research Progress on the Mechanism of Groundwater Arsenic Contamination Caused by Animal Feed Additives with Roxarsone

Firstly, the general situation of arsenic pollution caused by livestock and poultry industry at home and abroad was introduced, and then the transformation and adsorption of roxarsone in the environment were analyzed, finally the control measures of roxarsone pollution was discussed,

实际野外条件下的污染场地土壤和地下水污染限值计算(英文)

加拿大联邦及Alberta省级环境导则为石油烃污染场地提供了多级环境标准及评价方法。其中二级环境标准评价,准许根据污染场地的实际条件计算土壤和地下水污染限值。环境导则限定了计算污染限值的模型和方法。这些模型大都是基于十分简化的野外条件的解析解模型,并根据导则规定的方法使用,以简化应用与审批程序。这些模型的用途和方法与一般通用地下水和土壤污染物运移模型有所不同,在实际运用时这些差别常常被忽略。同时,在复杂野外条件下运用这些模型时,经常遇到确定模型输入参数的困难。介绍了加拿大环境导则中计算污染场地土壤和地下水污染限值以保护地表水环境的模型方法,强调这些模型方法只适用于计算污染限值的特殊目的,不适用于预测污染物运移或套用一般模型拟和调参方法。结合具体计算实例,探索运用Monte Carlo方法评价与表示模型输入参数带来的不确定性。这种方法用参数变化区间(或概率分布)来表示输入参数的变化或不确定性,以求得具有统计意义的保险污染限值。这种方法简单易行,却将二级环境标准评价方法推广到较为复杂(更真实)的野外条件。

Mechanistic insight into Cr(Ⅵ)retention by Si-containing ferrihydrite

Hexavalent chromium[Cr(Ⅵ)]causes serious harm to the environment due to its high toxicity,solubility,and mobility.Ferrihydrites(Fh)are the main adsorbent and trapping agent of Cr(Ⅵ)in soils and aquifers,and they usually coexist with silicate(Si),forming Si-containing ferrihydrite(Si-Fh)mixtures.However,the mechanism of Cr(Ⅵ)retention by Si-Fh mixtures is poorly understood.In this study,the behaviors and mechanisms of Cr(Ⅵ)adsorption onto Si-Fh with different Si/Fe molar ratios was investigated.Transmission electron microscope,Fourier transform infrared spectroscopy,X-ray diffraction,X-ray photoelectron spectroscopy,and other techniques were used to characterize Si-Fh and Cr(Ⅵ)-loading of Si-Fh.The results show that specific surface area of Si-Fh increases gradually with increasing Si/Fe ratios,but Cr(Ⅵ)adsorption on Si-Fh decreases with increasing Si/Fe ratios.This is because with an increase in Si/Fe molar ratio,the point of zero charge of Si-Fh gradually decreases and electrostatic repulsion between Si-Fh and Cr(Ⅵ)increases.However,the complexation of Cr(Ⅵ)is enhanced due to the increase in adsorbed hydroxyl(A-OH-)on Si-Fh with increasing Si/Fe molar ratio,which partly counteracts the effect of the electrostatic repulsion.Overall,the increase in the electrostatic repulsion has a greater impact on adsorption than the additional complexation with Si-Fh.Density functional theory calculation further supports this observation,showing the increases in electron variation of bonding atoms and reaction energies of inner spherical complexes with the increase in Si/Fe ratio.

miR-146a impedes the anti-aging effect of AMPK via NAMPT suppression and NAD^(+)/SIRT inactivation

Nicotinamide adenine dinucleotide(NAD^(+))is indispensable for the anti-aging activity of the sirtuin(SIRT)family enzymes.AMPactivated protein kinase(AMPK)upregulates NAD^(+)synthesis and SIRT activity in a nicotinamide phosphoribosyltransferase(NAMPT)-dependent manner.However,the molecular mechanisms that affect AMPK-driven NAMPT expression and NAD^(+)/SIRT activation remain unclear.In this study,we tried to identify senescence-associated microRNAs(miRNAs)that negatively regulate the cascade linking AMPK and NAMPT expression.miRNA-screening experiments showed that the expression of miR-146a increased in senescent cells but decreased following AMPK activation.Additionally,miR-146a overexpression weakened the metforminmediated upregulation of NAMPT expression,NAD^(+)synthesis,SIRT activity,and senescence protection,whereas treatment with the miR-146a inhibitor reversed this effect.Importantly,these findings were observed both in vitro and in vivo.Mechanistically,miR146a directly targeted the 3′-UTR of Nampt mRNA to reduce the expression of NAMPT.AMPK activators metformin and 5-aminoimidazole-4-carboxamide(AICAR)hindered miR-146a expression at the transcriptional level by promoting IκB kinase(IKK)phosphorylation to attenuate nuclear factor-kappaB(NF-κB)activity.These findings identified a novel cascade that negatively regulates the NAD^(+)/SIRT pathway by suppressing miR-146a-mediated NAMPT downregulation.Furthermore,our results showed that miR-146a impedes the anti-aging effect of AMPK.This mutual inhibitory relationship between miR-146a and AMPK enriches our understanding of the molecular connections between AMPK and SIRT and provides new insight into miRNA-mediated NAD^(+)/SIRT regulation and an intervention point for the prevention of aging and age-related diseases.

Overpressure Evolution Recorded in Fluid Inclusions in the Dongpu Depression,Bohai Bay Basin,North China

The Dongpu depression,like other depressions in the Bohai Bay Basin,is characterized by overpressure,however,the published studies have not clearly given the overpressure formation mechanism and paleo-pressure evolution history in the Dongpu depression.In addition,the current researches are mainly focused on the northern Dongpu depression,while rare investigation has been conducted in the southern part.In this context,it is urgent to explore the comprehensive overpressure evolution and formation mechanism in the Dongpu depression in academic and industrial fields.This paper provided a systematic analysis of fluid inclusions,including fluid inclusion petrography,microthermometry,vapor phase filling degree measurement and PVT-x modeling.By using homogenization temperature-burial history projection,the trapping time of the oil inclusions are determined.Four pressure evolution stages are identified in both the northern and the southern Dongpu depression.The results indicate that the pressure accumulation stage is derived by disequilibrium compaction and hydrocarbon generation in the northern part because of the salt rock distribution,while the stage is only derived by hydrocarbon generation in the southern part because of no salt rock distribution.The pressure release stages are mainly caused by the tectonic uplifting movements at the end of Dongying and Minghuazhen Formation.The overpressure in most areas in the northern part has been preserved till now,which is considered as a result of the good plasticity and sealing ability of salt rock that prevent the pressure leakage by smearing on the fault.Areas without salt rock distribution show normal pressure,which means the salt rock is an important factor that contributes to the overpressure preservation.However,there are exceptions that in Baimiao and Qiaokou,the overpressure still exists even without salt rock distribution,which is due to fault closure.

Mixing Characteristics of Oil Inclusions with Different Thermal Maturities in the Wenliu Uplift,Dongpu Depression,Bohai Bay Basin,North China

Multiple types of oil inclusions with different fluorescence colors have been detected in the northern Dongpu depression.Recent evidences show that these inclusions may have been trapped simultaneously or during a very short period.Therefore,whether these oils were mixed before trapping is unknown.In this study,we analyzed the petrography and fluorescence spectral characteristics of oil inclusions in the Wenliu uplift in the northern Dongpu depression,and assessed the data with the oil mixing ratio curve obtained in the previous experiment.The results show that there are three types of oil inclusions(type I,type II and type III)with yellow,green and blue fluorescence colors,corresponding to low-mature,medium-mature and high-mature oil,respectively.The"pure"oil inclusions,do exist in type II and type III group of oil inclusions,showing the medium-mature oil was generated from the source rock rather than being formed by the mixture of high-mature and low-mature end oils.Most of the oil inclusions are mixtures of high-mature and medium-mature end oils from the sub-sags to the Wenliu uplift,the mixing degree increases to close to 50%.The oil between the Qianliyuan sub-sag and the Wenliu uplift was mainly mixed by medium mature oils,whereas the oil between the Liutun sub-sag and the Wenliu uplift was mainly mixed by high mature oil.

Evolution Characteristics and Influence Factors of Deep Groundwater Depression Cone in North China Plain,China——A Case Studyin Cangzhou Region

The North China Plain（NCP） is one of the global hotspots of groundwater depletion, groundwater is almost the only source of water for agricultural, industrial and drinking water in this region. After long-term＇s over-exploitation of deep groundwater, there appeared several deep groundwater depression cones, such as Cangzhou cone, Dezhou cone, Hengshui cone, Tianjin cone, etc., in which the Cangzhou cone is one of the typical cones for its special geography and hydrogeology conditions. In this study, the authors intended to analyze the evolution characteristics and influence factors of deep groundwater depression cone in Cangzhou region, especially the No. III aquifer depression cone, which is the main exploitation zone in this region. Analysis of the evolution of the groundwater depression cone of the No. III aquifer group in Cangzhou region showed that this process can be divided into four stages, namely, development, stable development, rapid expansion, and gradual recovery. The shape and evolution characteristics of the depression cone at different stages are described by analyzing the evolution of the-30,-40, and-50 contours of the groundwater table, for example the closed area of water table contour of-50 m has been enlarged from 95 km2 in 1985 to 6 528.5 km2 in 2005. The dominant factors that affect the evolution characteristics at different stages are proposed. The results showed that relatively long dry periods with less precipitation, special geological and hydrogeological conditions, and sharply increased water consumption for industrial and agricultural development are the main factors that cause the formation of deep groundwater depression cones. Meanwhile, an environmental response against groundwater exploitation is presented, and rational solutions are suggested to avert water crisis.

Soil-Air Partitioning of Polychlorinated Biphenyls and Total Dichloro-Diphenyl-Trichloroethanes

Soil-air partitioning is an important diffusive process that affects the environmental fate of organic compounds and human health. In this review, factors affecting the soil-air partitioning of polychlorinated biphenyls （PCBs） and total dichloro-diphenyl-trichloroethanes （p,p＇- and o,p＇- isomers of DDT, DDD, and DDE） are discussed. Hydrophobicity is an important factor that influences soil-air partition coefficients （KsA）, and its effect can be explained through enthalpy of phase change for soil-air partitioning transfer （AHsA）. For more hydrophobic compounds, a sharp increase in the KSA of PCBs and organochlorines can be seen in the early aging period. During the aging period, the temperature has a significant effect on the more hydrophobic organic compounds. The content and properties of soil or- ganic matter influence the KSA of the target compounds. Generally, KSA decreases with increasing rela- tive humidity in soils. The linear trend between KSA and temperature （T） changes at 0 ~C. Freezing the air or soil in experiments would change the research results. On the basis of factors influencing soil-air partitioning, a multipleparameter （T, organic carbon fraction （foe）, and octanol-air partition coefficient （KoA）） model is put forward to predict the KSA values for PCBs and total DDTs.

SeHed,a novel gene expression system with stress-evoked hydrogen peroxide elimination property and anti-aging effect

Dear Editor,The moderate level of reactive oxygen species(ROS)contributes to cellular functions such as proliferation,differentiation,and infection resistance,but the excessive level of ROS causes oxidative damage which underlies the basic mechanism for aging and geriatric diseases.1 Therefore,precisely managing cellular ROS levels,meaning to keep redox homeostasis properly,stands as an aim for health and longevity.Actually,this aim is challenging,as it asks not only to restrain excessive ROS accumulation at the right time and right place but also to guarantee proper ROS levels for fitting physiological requirements.Traditional ways for eliminating ROS put more attention on the efficiency and identified a variety of drugs and enzymes with antioxidant properties,known as enzymatic and non-enzymatic ROS scavengers,respectively.However,how to accurately manage the integrative effect of ROS scavengers in vivo remains a problem.Actually,the effectiveness of non-enzymatic antioxidants in vivo is controversial,explained mostly by the uncertainty to reach a given organ with the appropriate concentration or to work there persistently.2 As to enzymatic ROS scavengers,although their overexpression in a given place can be achieved,this mode is often unwieldy or harmful to intrinsic physiologic functions in cases.3 For this reason,we attempt to develop new ways for in vivo antioxidation,for establishing a high-quality balance between efficiency and safety.As the consequence,we innovated a gene expression system that can limit the excessive ROS accumulation but keep the physiological level of ROS.