Arbuscular mycorrhizal fungi involvement in zinc and cadmium speciation change and phytoaccumulation

Over the past few years, there has been a greater study and understanding of the application of phytoremediation to remediate contaminated soil. The enhancement of phytoaccumulation of heavy metals—zinc (Zn), cadmium (Cd), arsenic (As), and selenium (Se)—in plants has been shown by inoculation of roots using arbuscular mycorrhizal fungi (AMF). This article presents the results of in vitro lab experiments conducted to verify the effects of AMF ( Glomus intraradices) hyphae on speciation of essential Zn and nonessential Cd heavy metals in order to change these metals from a water‐ insoluble carbonate to a soluble and phytoavailable form. Results show that in the presence of heavy metals in a nonavailable form to plants, endomycorrhizal hyphae can change the metal from carbonate to a water‐ soluble species. This phenomenon is more apparent with a nonessential (Cd) than with an essential metal (Zn). Zn saturation is reached in the G. intraradices colonized roots at around 400 ppm, independently of initial ZnCO₃ concentrations. Cd saturation is not reached; in the lower Cd treatment, the plant/media metal ratio is 3:1, and in the higher treatment, the ratio is 1:1. © 2005 Wiley Periodicals, Inc.     

Prenatal diagnosis of female monozygotic twins discordant for Turner syndrome: implications for prenatal genetic counselling

We describe a set of monozygotic (MZ) female twins, one of whom presented with a typical Turner syndrome (TS) phenotype and the other a normal female phenotype. Prenatal fetal ultrasonographic examination showed a monochorial diamniotic pregnancy with a hygroma colli and growth delay in Twin A and no anomalies in Twin B. Karyotypic analysis performed on fetal blood samples demonstrated a 46,XX/45,X (23/2) mosaicism in Twin A and a normal 46,XX chromosome constitution in Twin B. At birth, Twin A presented with a typical TS and Twin B had a normal female phenotype. Postnatal cytogenetic investigation of blood lymphocytes showed the same 46,XX/45,X mosaicism in both twins: 46,XX/45,X (40/7) in Twin A and 46,XX/45,X (40/5) in Twin B. Further investigations at the age of 10 months showed in Twin A a 46,XX/45,X (98/2) mosaicism in lymphocytes and 100% of 45,X (50 analysed cells) in fibroblasts, and in Twin B a normal 46,XX (100 analysed cells) chromosome constitution in lymphocytes but a mild 46,XX/45,X (78/2) mosaicism in fibroblasts. Monozygosity was confirmed by molecular analysis. To our knowledge, this is the first report of prenatal diagnosis of MZ female twins discordant for TS. Review of reported sets of MZ female twins (eight cases) or triplets (one case) discordant for TS shows, as in the present case, that the phenotype correlates better with the chromosomal distribution of mosaicism in fibroblasts than in lymphocytes. In the blood of MZ twins chimerism may modify the initial allocation of the mosaicism. These results suggest that, in cases of prenatal diagnosis of MZ female twins discordant for TS, the phenotype of each twin would be better predicted from karyotype analysis of cells from amniotic fluid than from fetal blood. Copyright © 2002 John Wiley & Sons, Ltd.     

Prenatal diagnosis of primary anophthalmia with a 3q27 interstitial deletion involving SOX2

We report an interstitial deletion of chromosome 3q26-q28 in a fetus in which anophthalmia had been detected prenatally. FISH analysis, using BAC clones encompassing the SOX2 locus, showed that SOX2 gene was involved in the chromosomal breakpoint of the deletion. This case confirms that haploinsufficiency for SOX2 plays a crucial role in human eye development and emphasizes the necessity of careful chromosomal analysis, including FISH analysis of the 3q region, in case of prenatal discovery of anophthalmia. Copyright © 2004 John Wiley & Sons, Ltd.     

The African electric power sector in the context of an acute financial crisis

There has been a sharp downturn in the building of electricity production and distribution facilities in sub-Saharan Africa due to economic and financial constraints. In part this was due to the steady decline in GDP in sub-Saharan Africa throughout the 1980s. The slackening growth of demand and the continuing decline in existing generating capacity have led to a shift in emphasis towards the restructuring of electricity companies, management improvements and the rehabilitation of existing plants rather than new investment in production and distribution facilities. Nevertheless, valid doubts remain as to the ability of the African electricity sector to mobilize sufficient resources in the medium term to ensure its development.     

Monochorionic and dichorionic twin pregnancies discordant for fetal anencephaly: a systematic review of prenatal management options

The aim of this study was to evaluate the effect of selective feticide (SF) compared to expectant management (EM) on perinatal outcome in dichorionic and monochorionic twins discordant for anencephaly. For this purpose, we conducted a systematic review of literature and added ten unpublished cases. As a result, we found that in dichorionic twins, mean gestational age (GA) at birth in the SF group was 38.0 weeks versus 34.9 weeks (P = 0.0002). Mean birth weight was 2922 g in the SF group versus 2474 g (P = 0.03). In monochorionic twins, mean GA at birth was 35.2 weeks versus 32.7 weeks (P = 0.1). Mean birth weight was 2711 g versus 1667 g (P = 0.0001). We conclude that while SF does not reduce perinatal mortality, it does result in significantly longer gestations and higher birth weight, and appears to be the management of choice in dichorionic twins discordant for anencephaly. In monochorionic twins, SF also increases birth weight, but in view of the complexity of this group, no clear recommendations can be made. Copyright © 2008 John Wiley & Sons, Ltd.     

Efficiency and degradation products elucidation of the photodegradation of mefenpyrdiethyl in water interface using TiO2 P-25 and Hombikat UV100

The photodegradation of mefenpyrdiethyl (MFD), an herbicide safener, was investigated in aqueous suspensions by using Degussa P-25 and Hombikat UV100 titanium oxide under simulated sunlight irradiation. The effects of initial concentration of the herbicide, pH, catalysts and hydrogen peroxide doses as well as their combinations were studied and optimized. Accordingly, the kinetic parameters were determined and the effectiveness of the processes was assessed by calculating the rate constants. A pseudo first-order kinetics was observed. Under experimental conditions, the degradation rate constants were strongly influenced using P-25 and no noticeable effect was observed for Hombikat UV100. DFT calculations with B3LYP/6-311+G(2d,p)//B3LYP/6-31+G(d,p) level of theory were performed to check whether significant conformational changes occur when the charge state of the MFD substrate changes and whether these changes could play a role in the dependency of photodegradation rate constant on the studied pH. High resolution mass spectrometry (FT-ICR/MS) was implemented to identify the main degradation products.     

五种水生植物对水中铀的去除作用

采用水培实验,研究了浮叶植物野生水葫芦(Eichhornia crassipes)、漂浮植物浮萍(Lemna minor L)、满江红(Azolla imbircata)、沉水植物菹草(Potamogeton crispus)、挺水植物空心莲子草(Alligator Alternanthera Herb)在初始铀浓度分别为0.15、1.50和15.00 mg·L^-1水中的生长状况及它们对水中铀的去除能力.结果表明,在21 d的水培试验期内,满江红对铀表现出了最强的抗性,0.15、1.50和15.00 mg·L^-1的铀对满江红的生长抑制率分别只有4.56%、2.48%和6.79%,而满江红对水中铀的去除率分别达到了94%、97%和92%.进一步的试验表明,每1 L水中种植7.5 g满江红,可以获得最大的铀去除率,将初始铀浓度为1.25、2.50、5.00和10.00 mg·L^-1的水体降至国家排放标准(GB 23727—2009)规定值(0.05 mg·L^-1)以下分别需要17、19、23和25 d.研究结果为进一步开展铀污染水体植物修复的研究打下了基础.     

改性生物质电厂灰钝化修复南方镉污染土壤及其长效性研究

选取我国南方生物质发电厂的灰渣为原料,经物理和化学改性制成重金属钝化剂,针对我国南方重金属Cd污染的土壤开展钝化修复研究.底灰中Cd等重金属含量明显低于其对应的飞灰,这是选择底灰作原料的重要原因.用其制备的BFA型钝化剂在水中对Cd的吸附量可达16mg/g以上.室内盆栽试验中,添加土壤干重1%的钝化剂,第一季稻米Cd含量降低80%以上,从超标2.8倍降至达标;第二季小麦籽粒Cd降低70%,从超标0.9倍降至达标.在我国南方Cd重度污染的农田中开展的原位修复试验表明,添加1%的钝化剂,稻米和小麦籽粒中Cd降低70%~90%,其中稻米Cd持续降低,2017年降低率相较2016年继续提升10%~20%,最终从超标20倍降至达标;Ni降低60%以上,且保留有益的Cu、Zn元素不受明显影响;此BFA型钝化剂还能促进作物生长,第一季稻米产量提高40%~60%,第二季仍有一定的增长效果.综合安全性考虑,我国南方生物质电厂的灰渣重金属含量很低,经过改性加工可制成安全高效的重金属钝化剂.可为钝化修复我国南方重金属污染农田提供一种经济有效的方法,也为现阶段难以处置的灰渣提供一个重要的利用途径.     

泰安市冬季一次严重空气污染过程分析

为揭示泰安市空气污染形成原因,选取泰安市2016年12月一次严重空气污染过程,利用泰安市2016年12月地面和探空资料及NCEP/NCAR（美国国家环境预报中心/美国国家大气研究中心）提供的FNL资料,对泰安市严重污染期间大气环流形势、边界层条件、污染源及传输路径进行分析.结果表明:在泰安市霾污染期间,500 hPa大气环流形势呈"两槽一脊"的特征,850 hPa泰安市处于南支槽前,受西南暖湿气流影响,为ρ（PM_2.5）的升高提供了有利条件;泰安市近地面处于高压控制下的弱风区（平均风速约为1.2 m/s）且边界层有逆温层存在,阻碍了PM_2.5的垂直输送,造成近地面ρ（PM_2.5）急剧升高.此外,泰安市及周边地区污染严重,聚类分析结果表明此次过程本地输送占比约为34%,其余均为外来传输,即污染物主要通过外来源传输,本地污染源贡献比率较小.污染物的高、低空传输路径不一致,低空污染物主要从安徽省水平输送至泰安市,高空污染物则先由河北省、河南省向南传输至安徽省、湖北省等地,再随南风气流向北输送至泰安市.研究显示,外来污染源传输作用配合本地静稳天气形势是造成此次泰安市空气污染的主要原因.      

植物根系质外体溶液的提取方法研究:以多环芳烃为例

根系质外体溶液中多环芳烃(PAHs)的分析对于阐明植物根系PAHs吸收运移机制及阻控意义重大.然而,迄今鲜有便捷成熟的植物根系质外体溶液提取方法的报道.为此,本研究以小麦为材料,菲为PAHs的代表,探究了植物根系质外体溶液的真空渗透离心提取方法.结果表明,小麦根系质外体菲提取量随真空度、真空时间、离心速率、离心时间的增加而增大;小麦根系质外体六磷酸葡萄糖脱氢酶(G6PDH)活性随真空度、真空时间、离心速率、离心时间的增加而升高.依据质外体溶液受原生质污染程度小于1%且尽量提取完全的原则,真空渗透离心提取法的最佳真空度为70 k Pa,最佳真空时间为10 min,最佳离心速率为3 068 r·min-1,最佳离心时间为15 min.研究结果可为污染物的植物根系质外体运输研究提供有效、简便的方法支撑.