Accumulation of Heavy Metals in Maga-Pouss Rice Fields (Far-North Region, Cameroon) and Transfer to Rice Grains

Monitoring of heavy metals contamination of agricultural products and their transfer and bioaccumulation in crops like rice has become a hot topic worldwide over the last two decades. The present study was carried out to determine the accumulation of heavy metals in rice fields and their transfer to rice grains. Soil, irrigation water and rice grains samples were gathered in Maga-Pouss, Far-North, Cameroon. Concentrations of six heavy metals (lead, cadmium, zinc, copper, iron and mercury) were evaluated by Atomic Absorption Spectrophotometer (AAS). Mercury was not detected in this study. Average concentrations of metals were in this order (in mg/kg): Fe (188.60 ± 97.06) > Pb (63.63 ± 7.11) > Cd (2.59 ± 0.29) > Zn (1.10 ± 1.05) > Cu (0.80 ± 0.73) in water and Pb (105.50 ± 31.11) > Fe (105.50 ± 31.11) > Cu (45.93 ± 14.39) > Zn (22.52 ± 6.40) > Cd (3.15 ± 0.49) in soil. Water in Maga-Pouss rice fields appears to be more harmful than the soil, notably for lead, cadmium and copper. In rice grains, heavy metals were found in this order (mg/kg): Fe (188.01 ± 82.62) > Cu (27.20 ± 0.00) > Zn (23.61 ± 12.42) > Pb (19.50 ± 19.91) > Cd (2.02 ± 1.05). The mean bioconcentration factor (BCF) of metals from soil to rice grains was in the following order: Fe (2.60) > Zn (1.05) > Cd (0.64) > Cu (0.59) > Pb (0.18). From water to rice grains, the order is: Cu (37.26) > Zn (22.49) > Cd (6.97) > Pb (2.74) > Fe (1.94). Rice field pH and electrical conductivity favored the uptake of lead, copper and cadmium by rice grains. The findings of this study will be good documentation for risk assessment, and decision-making by environmental managers in this region.

Novel quantum phenomena induced by strong magnetic fields in heavy-ion collisions

The relativistic heavy-ion collisions create both hot quark–gluon matter and strong magnetic fields, and provide an arena to study the interplay between quantum chromodynamics and quantum electrodynamics. In recent years, it has been shown that such an interplay can generate a number of interesting quantum phenomena in hadronic and quark–gluon matter. In this short review, we first discuss some properties of the magnetic fields in heavy-ion collisions and then give an overview of the magnetic fieldinduced novel quantum effects. In particular, we focus on the magnetic effect on the heavy flavor mesons, the heavyquark transports, and the phenomena closely related to chiral anomaly.

Heavy fermions in high magnetic fields

Heavy fermion materials are prototypical strongly correlated electron systems, where the strong electron–electron interactions lead to a wide range of novel phenomena and emergent phases of matter. Due to the low energy scales, the relative strengths of the Ruderman–Kittel–Kasuya–Yosida(RKKY) and Kondo interactions can often be readily tuned by non-thermal control parameters such as pressure, doping, or applied magnetic fields, which can give rise to quantum criticality and unconventional superconductivity. Here we provide a brief overview of research into heavy fermion materials in high magnetic fields, focussing on three main areas. Firstly we review the use of magnetic fields as a tuning parameter,and in particular the ability to realize different varieties of quantum critical behaviors. We then discuss the properties of heavy fermion superconductors in magnetic fields, where experiments in applied fields can reveal the nature of the order parameter, and induce new novel phenomena. Finally we report recent studies of topological Kondo systems, including topological Kondo insulators and Kondo–Weyl semimetals. Here experiments in magnetic fields can be used to probe the topologically non-trivial Fermi surface, as well as related field-induced phenomena such as the chiral anomaly and topological Hall effect.

Development Strategies for Achieving High Production with Fewer Wells in Conventional Offshore Heavy Oil Fields in Bohai Bay,China

Development strategy for heavy-oil reservoirs is one of the important research interests in China National Offshore Oil Corp. （CNOOC） that plans a highly effective development for heavy oil fields in multilayered fluvial reservoirs because of their significant influence on marine oil and even on China＇s petroleum production. The characteristics analysis of multilayered fluvial reservoirs in the heavy oil fields in Bohai Bay indicates that large amounts ofoil were trapped in the channel, point bar and channel bar sands. The reserves distribution of 8 oilfields illustrates that the reserves trapped in the main sands, which is 20%-40% of all of the sand bodies, account for 70%-90% of total reserves of the heavy oil fields. The cumulative production from high productivity wells （50% of the total wells） was 75%-90% of the production of the overall oilfield, while only 3%-10% of the total production was from the low productivity wells （30% of the total wells）. And the high productivity wells were drilled in the sands with high reserves abundance. Based on the above information the development strategy was proposed, which includes reserves production planning, selection of well configuration, productivity design, and development modification at different stages.

Biotransfer of heavy metals along a soil-plant-insect-chicken food chain:Field study

The accumulation and transfer of Pb,Zn,Cu,and Cd along a soil-plant-insect-chicken food chain at contaminated sites were investigated.The study site nearing the Pb/Zn mine had been contaminated by heavy metals severely.Cadmium and Pb concentrations steadily declined with increasing trophic level（p 〈 0.01）,but concentrations of Zn and Cu slightly increased from plant to insect larva（p 〉 0.05）.The concentrations of heavy metals were the highest in chicken muscle,with lower values in liver and blood.The bioaccumulation of Pb was observed in chicken livers.The eliminations of Pb,Zn,Cu,and Cd via insect and chicken feces avoid metal bioaccumulation in insect and chicken body.These results suggest that the accumulation of heavy metals in specific animal organ of tissues could not be neglected,although transfer of metals to chicken from plant and insect was limited.

Electromagnetic field effects on nucleon transverse momentum for heavy ion collisions around 100 A MeV

With taking electromagnetic field into account for the transport model of Boltzmann-Uehling-Uhlenbeck,electromagnetic effects are studied for ^(208)Pb +^(208)Pb collisions around 100A MeV. Electromagnetic field evolution during the collisions was estimated. It was found that the electric field has an obvious effect on the transverse momentum(p_T) spectra of nucleons during heavy ion collisions, and leads to different minimum position for the peak of p_T spectra of nucleons versus beam energy when the electric field is switched on. For the magnetic field, it affects the z-axis direction distributions of nucleons for central heavy ion collisions at lower energy.

Evaluation of Heavy Metal Pollution in Dazhai Mellow-soil Field

In order to determine the pollution condition of heavy metal in Dazhai mellow-soil field,the content of Zn,Cr,Cu,Ni,Pb,As,Cd and Hg in this area were analyzed,the content of heavy metals in soils in Shanxi Soil Environment Quality Standard and the secondary standard of National Soil Environment Quality Standard were used as evaluation standard. Based on the single factor index method,the result showed that the content of 8 heavy metals in soil didn't exceed the secondary standard of National Soil Environment Quality Standard,while the content of As,Hg,Ni,Pb exceeded Shanxi Soil Environment Quality Standard. The soil in the study areas reached high pollution of As,Hg,Pb,and the pollution index of Cu,Ni,Zn,Cd reached a high level. The potential ecological risk index order was Hg ﹥ Cd ﹥ As ﹥ Pb ﹥ Ni﹥ Cu ﹥ Zn ﹥ Cr. The pollution level risk intensity was mild. The correlation analysis indicated that Cr,Ni,Zn,Cu,Cd and As were probably from the same source,while Hg and other heavy metals were not correlated. Heavy metals with high levels of pollution were closely related to agricultural fertilization,tourism,transportation,construction,daily life and production activities.

The Longmen Cloud Physics Field Experiment Base, China Meteorological Administration

Aiming at the needs of mechanism analysis of rainstorms and development of numerical prediction models in south China, the Guangzhou Institute of Tropical and Marine Meteorology of China Meteorological Administration and the Chinese Academy of Meteorological Sciences jointly set up the Longmen Cloud Physics Field Experiment Base,China Meteorological Administration. This paper introduces the instruments and field experiments of this base, provides an overview of the recent advances in retrieval algorithms of microphysical parameters, improved understanding of microphysical characteristics, as well as the formation mechanisms and numerical prediction of heavy rainfalls in south China based on the field experiments dataset.

Preparation and Field Application of a Novel Micro-emulsion as Heavy Oil Displacement Agent

A novel micro-emulsion was prepared by mixing an oil-soluble viscosity reducer,which was screened to aim at improving the heavy oil properties of Shengli oilfield with water-soluble surfactant and co-surfactant.The static viscosity reduction and oil washing performance of the micro-emulsion were investigated,and the field application of the microemulsion used as heavy oil displacement agent was also reported.Results showed that the micro-emulsion exhibited excellent viscosity reduction performance for the studied heavy oil samples.When heavy oil was mixed with 0.5%of the micro-emulsion,a stable oil-in-water heavy oil emulsion could be formed.After the content of the micro-emulsion was increased to 3.0%,the oil removing rate reached up to 80%.Field application of the micro-emulsion to the Pai-601-Ping-115 well and the Pai-601-Ping-123 well was shown to be effective by increasing the periodic oil production up to 203 tons.

Effects of heavy metals on soil microbial community of different land use types

To evaluate soil environmental quality of introduced new crops and other traditional crops,and to understand the importance of response of soil microbial community to heavy metal stress,rhizosphere soil samples of different land use types(Sphagnum farming,rice field,grassland and bare land) in Dading Village,Duyun City,Guizhou Province of China were selected as research objects.The differences of soil chemical properties,heavy metal concentration and microbial community among different land use types were compared.The abundance and structural diversity of microbial communities in soil samples were analyzed by 16S rDNA sequencing,the relationship between soil pollution characteristics and microbial community in farmland was studied.The results showed that the different land use types planting different agricultural products under the same growing environment were subject to different heavy metal pollution.Soil chemical properties and heavy metals had significant effects on the soil microbial community.Proteobacteria,Actinobacteriota and Acidobacteriota were the most dominant groups of bacteria.The soil microorganisms responded more actively to the variability of pH,SOM and AK contents,although the variability was not high.With the increase of pH value,the abundance of the dominant species Proteobacteria also increased.Verrucomicrobiota had a better tolerance to the heavy metal Hg.Verrucomicrobiota and Firmicutes had strong resistance to the heavy metal Cd.These results deepen our understanding of the changes and aggregation of microorganisms under different land use patterns in heavy-metal contaminated farmland soils.

Evolution of Meteorological Conditions during a Heavy Air Pollution Event under the Influence of Shallow Foehn in Urumqi, China

The air pollution in Urumqi which is located on the northern slope of the Tianshan Mountains in northwestern China,is very serious in winter.Of particular importance is the influence of terrain-induced shallow foehn,known locally as elevated southeasterly gale(ESEG).It usually modulates atmospheric boundary layer structure and wind field patterns and produces favorable meteorological conditions conducive to hazardous air pollution.During 2013-17,Urumqi had an average of 50 d yr-1 of heavy pollution(daily average PM2.5 concentration>150μg m-3),of which 41 days were in winter.The majority(71.4%)of heavy pollution processes were associated with the shallow foehn.Based on microwave radiometer,wind profiler,and surface observations,the surface meteorological fields and boundary layer evolution during the worst pollution episode in Urumqi during 16-23 February 2013 are investigated.The results illustrate the significant role of shallow foehn in the building,strengthening,and collapsing of temperature inversions.There were four wind field patterns corresponding to four different phases during the whole pollution event.The most serious pollution phase featured shallow foehn activity in the south of Urumqi city and the appearance of an intense inversion layer below 600 m.Intense convergence caused by foehn and mountain-valley winds was sustained during most of the phase,resulting in pollutants sinking downward to the lower boundary layer and accumulating around urban area.The key indicators of such events identified in this study are highly correlated to particulate matter concentrations and could be used to predict heavy pollution episodes in the feature.

Influence of Chiral Mean Field on Kaon In-plane Flow in Heavy Ion Collisions

The influence of the chiral mean field on the K+ in-plane flow in heavy ion collisions at SIS energy is investigated within covariant kaon dynamics. For the kaon mesons inside the nuclear medium a quasi-particle picture including scalar and vector fields is adopted and compared to the standard treatment with a static potential. It is confirmed that a Lorentz force from spatial component of the vector field provides an important contribution to the inmedium kaon dynamics and strongly counterbalances the influence of the vector potential on the K+ in-plane flow. The calculated results show that the new FOPI data can be reasonably described using the Brown & Rho parametrization,which partly takes into account the correction of higher order contributions in the chiral expansion. This indicates that one can abstract the information on the kaon potential in a nuclear medium from the analysis of the K+ in-plane flow.

稠油井内衬保温油管热损失分析及开采参数优化

针对塔河油田稠油开采过程中原油热量损失大、资源浪费的问题,开展内衬保温油管开采技术研究。基于井筒稳态热传递与地层非稳态热传递理论,建立了稠油井井筒热传递数学模型,评价了不同内衬材料油管的保温性能,揭示了含水率、日产液量及内衬保温油管下深对井筒温度的影响规律。研究表明:内衬聚酮防腐层与气凝胶保温层的保温油管保温性能最佳,日产液量和保温油管下深对井口温度影响较大,含水率对井口温度的影响较小;日产液量大于72 t/d且保温油管下深大于3 500 m时,可满足稠油开采的温度要求。该研究明确了内衬保温油管保温的可行性,可为油田保温油管内衬的选材、稠油开采工艺参数的制订提供技术依据。

重载铁路双柱式桥墩加固技术优化研究

为探索基于性能提升的桥墩加固优化设计方法,以重载铁路中数量较多的分离式双柱式桥墩为对象,基于数值模拟分析和桥墩加固运营性能试验,开展3种常用方法加固条件下的桥墩静力性能对比分析和动力性能对比试验研究,并进行加固技术优化研究.结果表明,设计荷载作用下,墩身外包加固抑制墩顶水平位移效果较好,而"增大基础和增补桩基"组合加固则能有效减少基底截面应力;运营列车作用下,3种方法加固条件的墩顶横向振幅较加固前均有不同程度降低,但也有部分桥墩受施工等因素影响出现振幅增大的情况.采用优化提出的"增大基础+增补桩基+墩身外包"三重加固法,墩顶横向振幅降低幅度超过50%,能够很好地满足重载铁路双柱式桥墩强化改造需求.

外源秸秆对污染土壤氧化还原过程水分散性胶体态重金属的影响

土壤胶体尤其是水分散性胶体,作为一种重要的污染物载体,在重金属吸附、迁移以及生物吸收过程起着重要作用。通过土壤培养试验探讨了外源添加水稻秸秆在氧化还原波动条件下如何影响土壤液相中及水分散性胶体中重金属的分布。结果表明,外源秸秆增加厌氧过程液相中溶解性有机碳(DOC)、砷(As)、铁(Fe)、锰(Mn)、钙(Ca)、钾(K)、硅(Si)、铝(Al)、镁(Mg)等浓度,降低了厌氧过程氧化还原电位(Eh)及铜(Cu)、铅(Pb)等浓度,提高了好氧过程Pb浓度。利用非对称流场流分馏-紫外可见-电感耦合等离子体-质谱联用技术(AF4-UV-ICP-MS),测得水分散性胶体颗粒主要分布在0.3~3 kDa、3~40 kDa和130 kDa~450 nm三个粒径范围,各粒径颗粒的组成有所差异,主要含有机质、无机黏土矿物和铁矿物等。外源秸秆促进液相中Fe和As由胶体态向溶解态转化,促进镉(Cd)和Cu由溶解态向胶体态转化。本研究有助于揭示农业活动影响重金属迁移转化及有效性的界面机制。

贵州青黄泥田重金属元素低积累水稻品种筛选

以贵州中部地区近年主栽的10个水稻品种为试验材料,在中轻度重金属复合污染农田土壤上开展田间原位小区试验,探究不同水稻品种对镉(Cd)、铬(Cr)、铅(Pb)、镍(Ni)、铜(Cu)和锌(Zn)的吸收累积能力差异,并筛选出适宜贵州中部青黄泥田种植的重金属低累积水稻品种。结果表明,不同水稻品种根区土壤重金属含量存在一定的田间异质性,且同一品种的重复之间也具有一定的田间异质性;不同水稻品种糙米对不同重金属元素累积具有显著性差异,参试水稻品种糙米对重金属的富集能力强弱整体表现为Zn>Cd>Cr>Cu>Ni>Pb。水稻品种间对同一典型有害重金属元素的累积存在显著差异,按照糙米中重金属含量进行聚类分析,可以把水稻品种划分为较高值类、中间值类和较低值类3个类别。10个水稻品种糙米综合污染指数(P_(Z))(0.94~3.34)介于无污染至重度污染之间,Cr为主要污染贡献者,其单项污染指数(P_(i))在0.47~1.94之间。供试水稻品种产量在8242.8~13434.0 kg/hm^(2)之间,平均产量为10843.8 kg/hm^(2),极差相差较大,为47.9%。筛选出宜香优800为适宜该地种植的重金属低积累水稻品种。

CO_(2)响应型β-环糊精材料用于稠油降黏

制备了一种环境友好型马来酸酐改性β-环糊精(MAH-β-CD),温和条件下将其与聚醚胺(JD230)通过静电作用合成了具有CO_(2)响应性的表面活性剂(MJD230)。MJD230能与稠油形成稳定的水包油乳液,进而有效降低溶液的表面张力。在CO_(2)调控下,MJD230可重复用于稠油的乳化降黏和破乳。利用FTIR对MJD230结构进行了表征。通过观察降黏率和乳液粒径优化MJD230的合成条件,同时对降黏效果和乳液的稳定性进行了考察。将在反应温度为60℃,反应时间为60min,MAH-β-CD与JD230物质的量比为2∶1条件下制备的MJD230配成质量分数为0.5%的MJD230水溶液,其与稠油按照体积比为3∶7乳化后,稠油降黏率可达99.19%。反应体系pH和电导率的可逆变化证明了MJD230溶液对CO_(2)的响应性,这为表面活性剂驱油和CO_(2)捕集相结合提高稠油采收率提供了可行的途径。

基于Meta分析的华东地区菜田土壤重金属污染评价

基于2000—2023年发表的92篇文献,文章对华东地区菜田土壤不同重金属污染(Cd、Cr、Hg、Pb、As、Cu、Zn、Ni)进行了Meta分析。结果显示,华东地区菜田土壤普遍存在重金属积累,其中Cd污染尤为严重。土壤中Cd、Cr、Cu、Zn和Ni含量明显偏高,相较于背景值分别提高了120%、10.5%、26.5%和16.6%和6.8%。此外,菜田土壤重金属积累与当地经济发展水平有一定关联。值得注意的是,重金属积累区域通常伴随土壤酸化,导致重金属生物有效性增加。文章通过Meta分析综合评估了华东地区菜田土壤重金属污染现状、驱动因素和变化特征,以期为菜田土壤重金属污染评估提供参考,并为土壤环境质量改善和食品安全提供数据支撑。

电场调控激光诱导石墨烯基重金属电化学检测装置的研制

为了快速、精准分析农田重金属,该文设计了一款基于施加电场与激光诱导石墨烯(laser-inducedgraphene,LIG)电极阵列的功能核酸比率电化学检测装置,用于农田中典型重金属离子Hg^(2+)、Pb^(2+)的分析。该装置主要包括电场施加模块与LIG电极阵列传感器两个部分,前者以AT89S52单片机作为主控芯片、DAC0832作为电压输出端口,设计单片机控制电压输出的电场施加装置,实现了可编程电压的稳定输出;后者则通过结合CO_(2)激光直写和环氧树脂转印技术,提出了LIG电极阵列的快速制备方法,并进一步构建了LIG基功能核酸比率电化学传感器。在检测过程中,通过调控施加电场的性质,该装置实现了Hg^(2+)、Pb^(2+)在传感器表面的快速特异性富集以及响应信号的稳定获取,其对Hg^(2+)、Pb^(2+)检测限分别低至8.5×10^(-12)mol/L(4.25×10^(-11)mg/L)和4.6×10^(-13)mol/L(2.22×10^(-12)mg/L),实现了农田灌溉用水中Hg^(2+)、Pb^(2+)的现场精准检测。该装置利用施加电场与LIG阵列传感器,实现了重金属离子的快速、精准、现场分析需求,对于农田环境重金属污染的监测及治理具有重要意义。

重载列车车速对隧道入口段扬尘特征的影响模拟

为掌握重载列车车速对隧道入口段风流运移及扬尘特征的影响,为铁路隧道抑尘提供技术支持,以梁家山隧道为研究对象,模拟分析了重载列车以不同车速进入隧道时入口段压力场、风流场的演变规律,探究了隧道入口段煤尘颗粒运移轨迹及其浓度分布规律。结果表明:重载列车驶入隧道过程中,车速越大,列车运行前方正压场及车身周边的负压场越强,隧道入口段产生的涡流区及风速越大;重载列车完全驶入隧道后,空间内的煤尘颗粒以内旋和外旋两种运移方式呈高速无序地扩散,同一尾流区断面上,列车不同位置处监测点的煤尘浓度和最大煤尘浓度对应的时间分布有差异。该研究成果有助于理解重载列车运行速度对隧道入口段风流运移及扬尘特征的影响,对梁家山隧道入口段的煤尘防治有指导意义。