Arsenic dynamics in the rhizosphere and its sequestration on rice roots as affected by root oxidation

A pot experiment was conducted to investigate the effects of root oxidation on arsenic （As） dynamics in the rhizosphere and As sequestration on rice roots. There were significant differences （P 〈 0.05） in pH values between rhizosphere and non-rhizosphere soils, with pH 5.68-6.16 in the rhizosphere and 6.30-6.37 in non-rhizosphere soils as well as differences in redox potentials （P 〈 0.05）. Percentage arsenite was lower （4%-16%） in rhizosphere soil solutions from rice genotypes with higher radial oxygen loss （ROL） compared with genotypes with lower ROL （P 〈 0.05）. Arsenic concentrations in iron plaque and rice straw were significantly negatively correlated （R = -0.60, P 〈 0.05）. Genotypes with higher ROL （TD71 and Yinjingmanzhau） had significantly （P 〈 0.001） lower total As in rice grains （1.35 and 0.96 mg/kg, respectively） compared with genotypes with lower ROL （IAPAR9, 1.68 mg/kg; Nanyangzhan 2.24 mg/kg） in the As treatment, as well as lower inorganic As （P 〈 0.05）. The present study showed that genotypes with higher ROL could oxidize more arsenite in rhizosphere soils, and induce more Fe plaque formation, which subsequently sequestered more As. This reduced As uptake in aboveground plant tissues and also reduced inorganic As accumulation in rice grains. The study has contributed to further understanding the mechanisms whereby ROL influences As uptake and accumulation in rice.     

基于CFD的防风抑尘网非均匀孔隙率的优化研究

孔隙率是影响抑尘网防护效果的最主要因素,不同孔隙率抑尘网对料堆表面的显著作用区域不同,高孔隙率(ε30.3)网后料堆中下部扬尘得到明显抑制,低孔隙率(ε < 0.3)网的抑尘作用则于料堆上部突显.基于均匀孔隙率的抑尘区域提出不同孔隙率组合的非均匀抑尘网,选取6种典型非均匀工况,应用Fluent6.3对网和料堆周围流场进行数值模拟,结果显示:网下部孔隙率(ε_L)相同,上部孔隙率(ε_H)由0增至0.1时,网后气流扰动减弱,基于湍流结构和料堆受力判定ε_H取0.1较好;网上部孔隙率(ε_H)相同,下部孔隙率(ε_L)由0.3增至0.6时,紧贴料堆表面风速随ε_L增大而增大,ε_L为0.3时最优.比较非均匀抑尘网最佳工况(ε_H=0.1/ε_L=0.3)与均匀网(ε=0.1和ε=0.3)的料堆表面受力显示:ε_H=0.1/ε_L=0.3非均匀网可使起尘量最大的迎风面的各个区域剪切力均显著减小,中下部比ε=0.1时减小85.2%,上部比ε=0.3时减小84.3%,料堆表面剪切力总和的减少量可达均匀网时的50%左右.     

China''s energy, environment and policy perspective

Ｗｉｔｈｔｈｅｈｕｇｅｐｏｐｕｌａｔｉｏｎａｎｄｒａｐｉｄｅｃｏｎｏｍｉｃｇｒｏｗｔｈ ,Ｃｈｉｎａｂｅｃａｍｅｔｈｅｗｏｒｌｄ’ｓｓｅｃｏｎｄｌａｒｇｅｒｃｏｎｓｕｍｅｒｏｆｅｎｅｒｇｙ .Ｃｏａｌｄｏｍｉｎａｔｅｓｔｈｅｐｒｉｍａｒｙｅｎｅｒｇｙｕｓｅｄ ,ｆｏｌｌｏｗｅｄｂｙｏｉｌ,ｐｒｉｍａｒｙｅｌｅｃｔｒｉｃｉｔｙａｎｄｎａｔｕｒａｌｇａｓ.Ｗｈａｔｓｔｒａｔｅｇｉｅｓａｎｄ ｐｏｌｉｃｉｅｓａｄｏｐｔｅｄｂｙＣｈｉｎａｔｈｅｒｅｆｏｒｅｗｉｌｌｎｏｔｏｎｌｙｈａｖｅｉｍｐｌｉｃａｔｉｏｎｓｔ…     

China''''s energy, environment and policy perspective

This paper discusses the specific features of the energy in China, and addresses those key challenges in China is that the coexist of (1) higher total energy production and lower per capita level; (2) lower per capita energy resources level with unrational energy consumption structure; (3) lower energy utilization efficiency and higher energy conservation potential; and (4) unequal distribution of energy resources. It reviews the key environmental problems related to the feature of energy production and consumption. Based on the analysis, the author furthers addresses the policy and actions needed.     

Real-world gaseous emission characteristics of natural gas heavy-duty sanitation trucks

As compared to conventional diesel heavy-duty vehicles, natural gas vehicles have been proved to be more eco-friendly due to their lower production of greenhouse gas and pollutant emissions, which are causing enormous adverse effects on global warming and air pollution. However, natural gas vehicles were rarely studied before, especially through on-road measurements. In this study, a portable emission measurement system (PEMS) was employed to investigate the real-world emissions of nitrogen oxides (NOx) (nitrogen monoxide (NO), nitrogen dioxide (NO₂)), total hydrocarbons (THC), carbon monoxide (CO), and carbon dioxide (CO₂) from two liquified natural gas (LNG) China V heavy-duty cleaning sanitation trucks with different weight. Associated with the more aggressive driving behaviors, the vehicle with lower weight exhibited higher CO₂ (3%) but lower NOx (48.3%) (NO₂ (78.2%) and NO (29.4%)), CO (44.8%), and THC (3.7%) emission factors. Aggressive driving behaviors were also favorable to the production of THC, especially those in the medium-speed range but significantly negative to the production of CO and NO₂, especially those in the low-speed range with high engine load. In particular, the emission rate ratio of NO₂/NO decreased with the increase of speed/scaled tractive power in different speed ranges.     

Groundwater arsenic removal by coagulation using ferric(III) sulfate and polyferric sulfate: A comparative and mechanistic study

Elevated arsenic (As) in groundwater poses a great threat to human health. Coagulation using mono- and poly-Fe salts is becoming one of the most cost-effective processes for groundwater As removal. However, a limitation comes from insufficient understanding of the As removal mechanism from groundwater matrices in the coagulation process, which is critical for groundwater treatment and residual solid disposal. Here, we overcame this hurdle by utilizing microscopic techniques to explore molecular As surface complexes on the freshly formed Fe flocs and compared ferric(III) sulfate (FS) and polyferric sulfate (PFS) performance, and finally provided a practical solution in As-geogenic areas. FS and PFS exhibited a similar As removal efficiency in coagulation and coagulation/filtration in a two-bucket system using 5 mg/L Ca(ClO)₂. By using the two-bucket system combining coagulation and sand filtration, 500 L of As-safe water (< 10 μg/L) was achieved during five treatment cycles by washing the sand layer after each cycle. Fe k-edge X-ray absorption near-edge structure (XANES) and As k-edge extended X-ray absorption fine structure (EXAFS) analysis of the solid residue indicated that As formed a bidentate binuclear complex on ferrihydrite, with no observation of scorodite or poorly-crystalline ferric arsenate. Such a stable surface complex is beneficial for As immobilization in the solid residue, as confirmed by the achievement of much lower leachate As (0.9 μg/L–0.487 mg/L) than the US EPA regulatory limit (5 mg/L). Finally, PFS is superior to FS because of its lower dose, much lower solid residue, and lower cost for As-safe drinking water.     

GPM卫星降水数据在天山山区的适用性分析

卫星降水产品在山区的适用性具有较高的不确定性。论文基于天山山区2014-2015年167个气象站点数据,应用较为广泛的两套卫星降水产品--TRMM与CMORPH,选用均方根误差（RMSE）、相关系数（R）、相对误差（PB）,以及分类统计分析指标（错报率FAR、探测率POD、公正先兆评分ETS、频率偏差BIAS）等,评估了新一代卫星降水产品--Global Precipitation Measurement（GPM）在天山山区的适用性。结果表明：相对于以上两种产品,GPM在山区的精度最高。具体表现在：1）3套产品在降水较多的夏秋季均表现较好,相对于TRMM与CMORPH,GPM与观测数据的相关系数最高（R≥0.6）,相对误差最小（PB≈10%）;2）在整个天山山区,GPM相对于其他两套产品表现出较低的误差范围（-55%~55%）;3）GPM在不同的高程带内,均表现出同观测站点较低的误差与较高的相关系数;4）3套降水产品均表现出对探测弱降水事件较高的准确性（POD≈0.58）和较低的错误率（FAR≈0.63）,但综合分析4种指数,GPM表现最佳,能够以较准确的精度和较低的误差估测降水系统。     

Salinity influence on soil microbial respiration rate of wetland in the Yangtze River estuary through changing microbial community

Estuarine wetland, where freshwater mixes with salt water, comprises different regions（rivers and marine ecosystems） with significantly varying tidal salinities. Two sampling areas, ZXS and JS, were selected to investigate the effect of tidal salinity on soil respiration（SR）. ZXS and JS were located in Zhongxia Shoal and Jiangyanan Shoal of Jiuduansha Wetland respectively, with similar elevation and plant species, but significantly different in salinity. The results showed that with almost identical plant biomass, the SR and soil microbial respiration（SMR） of the tidal wetland with lower salinity（JS） were significantly higher than those of the tidal wetland with higher salinity（ZXS）（p 〈 0.05）. However, unlike SMR and SR, the difference in the soil microbial biomass（SMB） was not significant（p 〉 0.05）with the SMB of ZXS a little higher than that of JS. The higher SMR and SR of JS may be closely connected to the soil microbial community structures and amount of dominant bacteria. Abundant β- and γ-Proteobacteria and Actinobacteria in JS soil, which have strong heterotrophic metabolic capabilities, could be the main reason for higher SMR and SR,whereas a high number of ε-Proteobacteria in ZXS, some of which have carbon fixation ability, could be responsible for relatively lower carbon output. Path analysis indicated that soil salinity had the maximum negative total influencing coefficient with SMR among the various soil physical and chemical factors, suggesting that higher soil salinity, restricting highly heterotrophic bacteria, is the principle reason for lower SMR and SR in the ZXS.     

Distribution of rare earth elements in PM10 emitted from burning coals and soil-mixed coal briquettes

Emission from burning coals is one of the major sources of the airborne particles in China. We carried out a study on the rare earth elements(REEs) in the inhalable particulate matter(PM₁₀) emitted from burning coals and soil-coal honeycomb briquettes with different volatile contents and ash yields in a combustion-dilution system. Gravimetric analysis indicates that the equivalent mass concentration of the PM₁₀ emitted from burning the coals is higher than that emitted from...     

镉处理对大豆幼苗生长及激素含量的影响

采用室内培养试验,通过测定植株生理生化指标,研究了不同浓度Cd²⁺处理对大豆幼苗生长及激素含量的影响.结果表明:①不同浓度Cd²⁺处理对大豆幼苗地下部生长素(IAA)和赤霉素(GA₃)的合成有抑制效应,对地上部生长素(IAA)和赤霉素(GA₃)的合成具有低浓度下的刺激效应和高浓度下的抑制效应;对地下部、地上部玉米素(Z)和脱落酸(ABA)的合成均有刺激效应.②Cd²⁺处理84h对大豆幼苗根系活力、叶绿素a和叶绿素b的合成有刺激效应,对类胡萝卜素的合成无影响.③Cd²⁺处理对过氧化物酶(POD)活性和丙二醛(MDA)含量具有低浓度下的抑制效应和高浓度下的激活效应,且随着Cd²⁺浓度的增加激活效应逐渐加强.④短时间、低浓度Cd²⁺胁迫可刺激大豆幼苗的生理活性,以Cd²⁺处理浓度为0.50 mg/L时,大豆幼苗根系活力最大,IAA和GA₃含量最高,POD活性最低,植物生理活性最强.     

ATP as an indicator of biomass activity in thermophilic upflow anaerobic sludge blanket reactor

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅ ｑｕａｎｔｉｔｙａｎｄａｃｔｉｖｉｔｙｏｆｍｉｃｒｏｏｒｇａｎｉｓｍｓ ｐｒｅｓｅｎｔｅｄｉｎａｂｉｏｒｅａｃｔｏｒａｒｅｔｗｏｃｒｉｔｉｃａｌｐａｒａｍｅｔｅｒｓｔｈａｔｄｅｔｅｒｍｉｎｅｔｈｅｒｅａｃｔｏｒｐｅｒｆｏｒｍａｎｃｅｉｎｗａｓｔｅｗａｔｅｒｔｒｅａｔｍｅｎｔ.Ｔｈｅｃｏｎｖｅｎｔｉｏｎａｌｐａｒａｍｅｔｅｒｆｏｒｂｉｏｍａｓｓｑｕａｎｔｉｔｙｍｅａｓｕｒｅｓｉｓｔｏｔａｌｓｕｓｐｅｎｄｅｄｓｏｌｉｄ (ＴＳＳ)ｏｒｖｏｌａｔｉｌｅｓｕｓｐｅｎｄｅｄｓｏｌ…     

Organic matter and pH affect the analysis efficiency of P-NMR

Solution ³¹P nuclear magnetic resonance spectroscopy (³¹P-NMR) is a useful method to analyze organic phosphorus (Po), but a general procedure for the analysis method is lacking. The authors used solution ³¹P-NMR, which was found to be an effective method for analysis of Po in Haihe River sediment, to analyze the Po in the surface sediment in Eastern China at the regional scale, and found that the NaOH-ethylenediaminetetraacetic acid (EDTA) extraction rate was affected by environmental factors. At the regional scale, the extraction rate showed a positive relationship with loss on ignition, when the extraction rate was lower than 60%. The extraction rate had no relationship with the loss on ignition when the extraction rate was higher than 60%. The extraction rate showed a negative relationship with pH, which means that the extraction rate was higher in acidic sediment and lower in alkaline sediment. The ratio of TC/TN (the ratio of total carbon to total nitrogen) was considered to represent the origin of organic matter in the sediment. The extraction rate was high when the TC/TN ratio was lower than 20, meanwhile the extraction rate decreased as the TC/TN ratio increased. The results show that the origin of organic matter in sediment significantly affects the NaOH-EDTA extraction rate. This study will give theoretical support for building an effective and general solution ³¹P-NMR analysis method.     

三峡库区典型消落带土壤及沉积物中溶解性有机质(DOM)的紫外-可见光谱特征

溶解性有机质(DOM)是陆地生态系统的重要组成部分,在环境地球化学中扮演着重要角色.在测定三峡库区典型消落带土壤及沉积物DOM的紫外-可见光谱基础上,通过特征参数及光谱模型来获取DOM的地化特征和信息.紫外-可见光谱特征参数表明土壤DOM的芳香性、疏水组分及腐殖化程度都明显低于上层沉积物,与高程和土地利用类型无关;而所选择的4种吸收光谱模型中以模型2为最优.同时,不同模型和不同拟合波段均对DOM光谱曲线斜率(S)有影响:S值随波长增加而减小;而不同波段S值相关性存在差异,表明各波段S值仅反映DOM部分信息,而非全部.此外,特征斜率之比(SR)反映出表层沉积物所受降解程度(光漂白或生物降解)小于土壤和往年沉积物,其芳香性更高,分子量更大,参与降解的反应活性也更大;这表明DOM越新鲜,其受到的光照和生物作用相对较小,降解潜力越大.     

ATP as an indicator of biomass activity in thermophilic upflow anaerobic sludge blanket reactor

This work investigated the biomass activity in a thermophilic upflow anaerobic sludge blanket (UASB) reactor of wastewater treatment. Synthetic textile wastewater with pH 10-11, COD level of 2000-3000 mg/L was tested. Cellular adenosine triphosphate (ATP) in volatile solids (VS; mg ATP/gVS) was measured and expressed as specific ATP content to compare the biomass activity in up zone and lower zone in UASB reactor. The result shows that the specific ATP content based on total volatile solids (VS)in lower zone (0. 046 mgATP/gVS average) is much lower than that in up zone (0.62 mgATP/gVS average) due to high content of inactive biomass and high pH in lower zone. The SATP in up zone increases as HRT increases and approaches to a maximum value of 0.85 mgATP/gVS at HRT of 7h, then decreases. It shows most of the total VS in up zone represent active bacterial biomass at HRT of 7h. Rate of subtract utilization is directly related to the activity of microorganisms in the reactor. The effect of HRT on SATP in lower zone is not as significant as on SATP in up zone. The buffer capacity of the thermophilic UASB reactor is very good. It is the activity of sludge granules in lower zone that give the UASB reactor such a good buffer capacity to the inlet high pH.     

菌根和间作对滇池流域红壤磷素迁移的影响

为了研究菌根和间作对滇池流域红壤磷迁移的减控影响,根据2013年5—10月采集的6次径流水样,通过田间小区试验,选取玉米/大豆间作的红壤径流区,以单作玉米、单作大豆为对照,并设置抑菌处理(施用苯菌灵)和未抑菌处理,模拟分析间作和菌根处理复合作用下的径流磷迁移特征. 结果表明:除7月19日外,整个雨季各处理下径流中ρ(TP)、ρ(可溶性磷)和ρ(颗粒态磷)随采样时间均无明显变化;所有组合处理中,未抑菌-间作处理下径流中ρ(TP)最低,比单作玉米、单作大豆分别降低25.6%、12.2%;无论是否抑菌,玉米/大豆间作处理可使径流中ρ(可溶性磷)较单作玉米处理降低约24.7%;未抑菌处理下,玉米/大豆间作处理径流中ρ(颗粒态磷)比单作玉米、单作大豆分别降低约14.3%、20.2%,并且在玉米/大豆间作条件下,未抑菌处理径流中ρ(颗粒态磷)显著低于抑菌处理. 另外,无论是何种种植模式,抑菌处理下土壤中w(TP)均显著高于未抑菌处理,增幅在9.0%以上;抑菌条件下,间作玉米处理下土壤中w(TP)、w(速效磷)较单作玉米处理显著降低;与抑菌-单作玉米处理相比,未抑菌-间作玉米处理下土壤中w(TP)和w(速效磷)也分别降低了0.25 g/kg和2.56 mg/kg. 研究显示,菌根真菌协同玉米/大豆间作体系可在一定程度上减少坡耕地红壤磷的径流流失,对滇池流域农业非点源污染具有一定削减潜力.      

First-trimester maternal serum alphafetoprotein and chorionic gonadotropin in aneuploid pregnancies

First-trimester maternal serum alpha-fetoprotein (AFP) and human chorionic gonadotropin (HCG) levels were measured in samples from 29 women with cytogenetically abnormal pregnancies and 145 women with cytogenetically normal pregnancies matched for gestational age, race, and sample storage time. All patients had a risk of fetal aneuploidy greater than or equal to that of a mother 35 years of age. AFP was significantly lower in samples from pregnancies affected with trisomy 21 (0.67 MoM;p <0.05), while HCG values were no different from those of matched controls. Trisomies 13 and 18 could not be distinguished from matched controls by AFP. However, levels of HCG were significantly lower in such pregnancy samples, with median values of 0.65 MoM in trisomy 13 and 0.32 MoM in trisomy 18 (p<0.05). Variations in AFP and HCG levels suggest that expressed differences between autosomal aneuploidies include differences in fetal and placenta! protein production in the first trimester.     

膜萃取处理水溶液中镉、锌离子的工艺

以P204+正庚烷为萃取剂,将中空纤维膜萃取技术用于处理水溶液中镉离子、锌离子.研究了两相流速、初始浓度及溶液pH等因素对传质系数和萃取率的影响,计算了膜萃取器的传质单元高度(HTU)_w,同时还研究了萃取剂的再生问题.实验结果表明,在低浓度下(＜500 mg/L),平衡分配系数较大,传质阻力主要是在水相;在初始浓度较高时(＜2000mg/L),由于分配系数较小,三项传质阻力均不可忽略;在初始浓度很高时(＞2000mg/L),传质由有机相和膜相阻力控制.实验还表明通过膜器串联可以实现萃取剂的再生.对于稀溶液(＜200mg/L),中空纤维膜萃取可以使水溶液中金属离子浓度减小2个数量级,通过计算,中空纤维膜萃取器(HTU)_w在15～30cm之间,大大低于传统的萃取塔.     

氮沉降与生物炭对土壤可溶性有机质的影响

利用盆栽实验,探讨氮沉降与生物炭（BC）施用对杉木幼苗土壤可溶性有机碳（DOC）含量和可溶性有机质（DOM）光谱学特征的短期影响.氮沉降处理为0（对照）、40（低氮）和80kgN/（hm²·a）（高氮）,在不同氮沉降下BC施用水平分别为0（对照）、12（低量BC）和36t/hm²（高量BC）.结果表明：相比对照处理,单独低氮与单独高氮处理3个月后土壤pH值分别下降了0.06和0.09（P<0.05）,但单独施用BC和氮沉降背景下施用BC处理的土壤pH值均呈上升趋势,增加了0.32~0.94（P<0.05）.与对照处理相比,单独低氮处理的土壤DOC含量显著降低,单独高氮处理的则显著升高且DOM结构趋于简单;单独施用BC和氮沉降背景下施用BC处理中,低量BC处理的土壤DOC含量无明显变化,但高量BC处理的显著提高了30.1%~95.6%,并且DOM结构趋于复杂.冗余分析发现,土壤pH值是导致不同处理DOM存在差异的关键因素.因此,氮沉降背景下施用高量BC短期内可以减缓土壤酸化,提高土壤DOC含量并使DOM更加稳定.     

南京北郊工业乡村混合区秋季边界层VOCs垂直分布特征

利用2020年秋季南京北郊低对流层(0～1 000 m)VOCs探空实验数据,分析了该地区VOCs垂直廓线分布及其日变化、光化学反应性等特征.结果表明,φ(VOCs)随高度升高而降低(72.1×10^-9±28.1×10^-9～56.4×10^-9±24.8×10^-9).各高度上烷烃占比最大(68%～75%),其次为芳香烃(10%～12%)、卤代烃(10%～11%)、烯烃(3%～7%)和乙炔(2%).边界层日变化对VOCs廓线影响较大,早晚较低的边界层致使VOCs在近地面累积,而在上部体积分数较低;午后VOCs的垂直分布则较均匀.上午光化学反应性强(弱)的烯烃(烷烃)等的体积分数占比随高度升高而减小(增加),说明高层的VOCs光化学老化显著.午后VOCs各组分占比及其OFP在低对流层内垂直分布则较均匀.受周边不同来源气团影响,各高度φ(VOCs)及组分占比差异明显,工业气团在200～400 m;高度间φ(VOCs)随高度升高,芳香烃占比增大;城区气团φ(VOCs)垂直负梯度最大,近地面φ(VOCs)较高,...     

氮沉降与生物炭对土壤可溶性有机质的影响

利用盆栽实验,探讨氮沉降与生物炭（BC）施用对杉木幼苗土壤可溶性有机碳（DOC）含量和可溶性有机质（DOM）光谱学特征的短期影响.氮沉降处理为0（对照）、40（低氮）和80kgN/（hm²·a）（高氮）,在不同氮沉降下BC施用水平分别为0（对照）、12（低量BC）和36t/hm²（高量BC）.结果表明：相比对照处理,单独低氮与单独高氮处理3个月后土壤pH值分别下降了0.06和0.09（P<0.05）,但单独施用BC和氮沉降背景下施用BC处理的土壤pH值均呈上升趋势,增加了0.32~0.94（P<0.05）.与对照处理相比,单独低氮处理的土壤DOC含量显著降低,单独高氮处理的则显著升高且DOM结构趋于简单;单独施用BC和氮沉降背景下施用BC处理中,低量BC处理的土壤DOC含量无明显变化,但高量BC处理的显著提高了30.1%~95.6%,并且DOM结构趋于复杂.冗余分析发现,土壤pH值是导致不同处理DOM存在差异的关键因素.因此,氮沉降背景下施用高量BC短期内可以减缓土壤酸化,提高土壤DOC含量并使DOM更加稳定.