镉胁迫对向日葵幼苗生长和生理特性的影响

采用溶液培养方法,研究了不同浓度镉(0、0.05、0.1、0.5和1 mg/L)处理7 d对向日葵幼苗生长和生理特性的影响。结果表明：随着镉处理浓度的增加,向日葵幼苗对镉的吸收显著增加。1 mg/L镉浓度处理时,叶、茎和根中镉浓度分别为0.05 mg/L镉处理时的16.3、19.2和581倍;根中积累的镉含量明显高于叶和茎, 各浓度根部积累的镉分别为叶和茎的37.8～63倍和29.4～41倍。镉胁迫显著抑制向日葵幼苗生长和叶绿素合成,当镉浓度达1 mg/L时,整株植物生物量和总叶绿素含量分别为对照的55.9%和52.6%。镉胁迫下向日葵幼苗游离脯氨酸和丙二醛（MDA）含量显著增加,1 mg/L镉浓度时,根中含量分别为对照的4和5.8倍。向日葵幼苗可溶性蛋白含量和过氧化物酶(POD)活性变化与镉胁迫浓度呈明显的倒U字型关系,可溶性蛋白含量在0.05 mg/L镉浓度时达到最大值,叶、茎、根中的POD活性分别在0.1、0.1和0.05 mg/L镉浓度时达到最大值。     

钙对李氏禾富集和耐受铬的调控作用

通过水培实验,研究钙对铬胁迫下李氏禾幼苗生理生化、草酸分泌及铬吸收量的影响,考察钙对李氏禾体内草酸合成的调控,进而促进李氏禾的铬耐性富集能力的作用。结果显示,不同浓度Cr³⁺胁迫下缺钙处理,李氏禾生长受抑制及质膜过氧化作用加剧,体内总草酸含量为对照处理的113%~169%,且主要表现为水溶性草酸含量显著高于对照,水溶性草酸含量为对照处理的135%~197%;高钙处理,李氏禾细胞膜透性、丙二醛（MDA）含量低于对照,李氏禾叶部总草酸含量为对照处理的125%~155%,且主要表现为不溶性草酸含量显著高于对照,其含量为对照处理的181%~270%。低浓度（0.2、0.4 mmol/L）铬胁迫下,高钙处理总铬含量分别为对照处理的175%和215%,高浓度（0.8、1.0 mmol/L）铬胁迫下,总铬含量与对照处理无显著差异（P>0.05）。可见,添加Ca²⁺能在一定Cr³⁺浓度胁迫下,有效缓解铬对李氏禾的毒害,且能通过提高植物体内不溶性草酸含量达到促进植物富集和耐受铬的能力。     

巯基化合物在万寿菊镉解毒中的作用

采用水培实验方法研究了万寿菊体内镉积累和解毒与巯基化合物含量的关系。万寿菊植株分别在镉浓度为0、0.1、0.5、2和8 mg/L的营养液中暴露7 d,测定了根、茎、叶中镉、非蛋白巯基(NPT)、半胱氨酸(Cys)、γ-谷氨酰半胱氨酸(γ-EC)、谷胱甘肽(GSH)和植物络合素(PCs)的含量。植物根、茎、叶中镉含量都随着镉暴露浓度的增加而增加。当溶液中镉浓度较低(0.1～2 mg/L)时,茎叶中NPT、PCs、Cys和γ-EC含量随着镉浓度增加而增大;当镉浓度较高(8 mg/L)时,茎叶中PCs含量迅速降低,GSH含量大幅度增高。在根部,这些巯基化合物的含量几乎不受镉处理影响,且含量较低。以上研究结果表明:PCs在万寿菊镉的解毒机制中发挥一定的作用,暴露于高浓度的镉,GSH比PCs起着更为重要的解毒作用。     

不同化肥品种对水稻铬吸收和分配的影响

采用盆栽试验,研究在300mg/kg铬污染水稻土中分别施加氮肥(NH4Cl、NH4NO3、Ca(NO3)2和CO(NH2)2)、钾肥(K2SO4和KCl)、磷肥(Ca(H2PO4)2和NaH2PO4)对水稻生长以及吸收和分配铬的影响。结果表明:(1)施肥处理虽然增加了水稻的产量,但也改变了水稻植株对土壤铬的吸收和积累。从总体上看,不同施肥处理对水稻植株总铬的影响达到显著水平(p0.05);氮肥、钾肥处理的水稻植株总铬比对照处理增加了1.7%~72.9%,磷肥处理的水稻植株总铬比对照处理降低了2.1%~21.9%。(2)不同施肥处理明显影响了铬在水稻植株内的分配与迁移。受试的氮肥、钾肥不仅促进水稻根部对铬的吸收和累积,也促进了铬向地上部分迁移;而磷肥则降低了水稻根部对铬的吸收和累积以及铬向地上部分迁移。(3)受试8种不同施肥处理均显著提高了水稻糙米总铬,施肥处理后水稻成熟期糙米总铬为1.10~1.32mg/kg,均超过《食品中污染物限量》(GB 2762—2005)中铬的限量(粮食1.0mg/kg),比对照处理提高了139.1%~187.0%,增加了铬通过食物链威胁人体健康的风险。     

不同营养条件对薏苡人工湿地去除Cr(Ⅵ)的影响

为研究不同营养水平下薏苡人工湿地对Cr(Ⅵ)的净化与形态转变化的影响,以生活污水(W)、1/2(体积比)Hoagland营养液(Y)、1/2Hoagland营养液+生活污水(Y+W)为灌溉水源,构建微型模拟垂直流薏苡人工湿地,采取间歇进水方式,进水分别以0、10、30mg/L左右Cr(Ⅵ)(以K2Cr2O7形式加入)进行处理。结果表明:(1)根、茎、叶中总铬均随处理时间的延长和Cr(Ⅵ)浓度的提高而提高;不同器官之间相比较,总铬依次为根叶茎。(2)在不同营养条件下,基质中可交换态、铁锰氧化物结合态、有机物结合态、残渣态铬含量均随着Cr(Ⅵ)浓度的增加而提高,而碳酸盐结合态铬则先升高后降低。(3)Y处理出水Cr(Ⅵ)较高,W、(Y+W)处理均能提高人工湿地对含铬污水的处理效果。     

黑麦草间作对镉在小麦中积累和转运的影响

利用镉(Cd)污染土壤进行盆栽试验,设置黑麦草(Lolium perenne L.)单作、小麦(Triticum aestivum L.)单作和小麦与黑麦草间作3个处理,研究间作对小麦各器官Cd积累和转运的影响。结果显示,间作模式对小麦不同生育期的根、茎、叶Cd含量基本都有降低作用,但对产量几乎没有影响。与单作模式相比,间作模式降低了收获期小麦根向地上部器官的转运系数和节向籽粒的转运系数,从而使籽粒的Cd含量下降,为同时满足Cd污染土壤的植物修复与农业生产进行提供理论支持。     

8种植物对铀和镉的富集特性

研究8种植物在铀镉复合污染土壤条件下的吸收、富集和转运特性具有重要意义。在每千克土中施用铀、镉的浓度分别为150、15 mg·kg-1,采用主成分分析法对植物富集特性进行综合性评价。结果表明:白皮菜铀镉综合评价值最高,地上部、地下部、单株铀镉总含量、单株铀镉总积累量均最大,分别为90.03 mg·kg-1DW(干质量)、477.00 mg·kg-1DW、150.26 mg·kg-1DW和1 168.52μg;花椰菜铀综合评价值最高,地上部、地下部铀含量分别为42.16、444.83 mg·kg-1DW,单株铀积累量达到255.42μg;南瓜综合评价最低,单株铀镉积累量仅为58.47μg;供试植物地上部铀含量均显著小于地下部铀含量,转运系数均小于1,根系是植物富集铀镉的主要器官。     

水葱修复土壤镉污染潜力的研究

野外观察与研究发现水葱(Scirpus tabernaemontani G.)可以耐受土壤中高浓度的重金属污染,并对镉(Cd)有很高的生物富集量.实验室水培试验研究了两个主要因素,营养液pH与Cd含量,对水葱生物量以及Cd富集效果的影响.结果表明,它可耐受高浓度Cd (30 mg/L)和大范围pH变化 (3.7～7.7).当营养液pH为4.7, Cd为25 mg/L时,水葱富集的Cd达到最大值:地上部分264.71 mg/kg,地下部分234.39 mg/kg,平均转运系数1.13.这显示了它用于植物修复Cd污染土壤的潜力.     

生物菌肥与石灰配施对水稻吸收积累Cd的影响

采用田间随机区组试验的方法,研究了基施生物菌肥(Bi处理)与追施石灰(L处理)及其配合施用(Bi+L处理)对晚稻湘晚籼12号生物量、水稻对土壤Cd的富集情况、4个生育期内各部位间转运系数以及各部位中Cd含量的影响。结果表明,水稻各部位间Cd含量从大到小依次为根部、茎鞘、穗部、叶片,随不同生育期对营养物质的需求而改变,各处理不会影响水稻生物量及转运系数,并能降低水稻各部位富集Cd能力,使水稻糙米中Cd含量显著降低,其中以生物菌肥与石灰配施的降Cd效果最佳。     

Pb超富集植物金丝草（Pogonatherum crinitum）、柳叶箬（Lsache globosa）

重金属超富集植物是植物修复技术的核心和前提,但目前国内发现的Pb超富集植物较少,本研究通过野外调查和室内胁迫模拟实验相结合的方法,在国内首次发现并证实金丝草和柳叶箬为Pb的超富集植物。野外调查结果表明;金丝草地上部分Pb含量1 231.80 mg/kg,转运系数达到1.32,柳叶箬地上部分Pb含量1 818.40 mg/kg,转运系数6.5。室内模拟胁迫实验表明：在Pb胁迫浓度为5 000 mg/kg时金丝草和柳叶箬对Pb的转运系数均大于1,而且其地上部分Pb含量也超过1 000 mg/kg的水平。在Pb胁迫浓度为18 000 mg/kg时2种植物体内Pb含量达到最大值,金丝草地上部分和地下部分Pb含量分别达3 789.84 mg/kg和4 964.76 mg/kg,柳叶箬地上部分和地下部分Pb含量分别达3 411.56 mg/kg和1 523.02 mg/kg。     

Meta-analysis of time-series studies of air pollution and mortality: effects of gases and particles and the influence of cause of death,age, and season

A comprehensive, systematic synthesis was conducted of daily time-series studies of air pollution and mortality from around the world. Estimates of effect sizes were extracted from 109 studies, from single- and multipollutant models, and by cause of death, age, and season. Random effects pooled estimates of excess all-cause mortality (single-pollutant models) associated with a change in pollutant concentration equal to the mean value among a representative group of cities were 2.0% (95% CI 1.5-2.4%) per 31.3 microg/m3 particulate matter (PM) of median diameter < or = 10 microm (PM10); 1.7% (1.2-2.2%) per 1.1 ppm CO; 2.8% (2.1-3.5%) per 24.0 ppb NO2; 1.6% (1.1-2.0%) per 31.2 ppb O3; and 0.9% (0.7-1.2%) per 9.4 ppb SO2 (daily maximum concentration for O3, daily average for others). Effect sizes were generally reduced in multipollutant models, but remained significantly different from zero for PM10 and SO2. Larger effect sizes were observed for respiratory mortality for all pollutants except O3. Heterogeneity among studies was partially accounted for by differences in variability of pollutant concentrations, and results were robust to alternative approaches to selecting estimates from the pool of available candidates. This synthesis leaves little doubt that acute air pollution exposure is a significant contributor to mortality.     

Sources and fate of PCDD and PCDF

PCDD and PCDF were found in urban air particulates from St. Louis and Washington, D.C., and in sediments from the Great Lakes and Siskiwit Lake, Isle Royale. The similarity between the PCDD and PCDF found in air particulates and sediment samples and the presence of PCDD and PCDF in sediment from Siskiwit Lake (a location which can receive only atmospheric inputs) suggest that these compounds are emitted to the atmosphere from combustion sources. The historical input of PCDD and PCDF to dated sediment cores shows a strong increase since 1940, and this suggests that the incineration of chlorinated organic compounds is an important source of PCDD and PCDF to the environment.     

Field and laboratory studies of the fate and enantiomeric enrichment of venlafaxine and O-desmethylvenlafaxine under aerobic and anaerobic conditions

The stereoselectivity of R,S-venlafaxine and its metabolites R,S-O-desmethylvenlafaxine, N-desmethylvenlafaxine, O,N-didesmethylvenlafaxine, N,N-didesmethylvenlafaxine and tridesmethylvenlafaxine was studied in three processes: (i) anaerobic and aerobic laboratory scale tests; (ii) six wastewater treatment plants (WWTPs) operating under different conditions; and (iii) a variety of wastewater treatments including conventional activated sludge, natural attenuation along a receiving river stream and storage in operational and seasonal reservoirs. In the laboratory and field studies, the degradation of the venlafaxine yielded O-desmethylvenalfaxine as the dominant metabolite under aerobic and anaerobic conditions. Venlafaxine was almost exclusively converted to O-desmethylvenlafaxine under anaerobic conditions, but only a fraction of the drug was transformed to O-desmethylvenlafaxine under aerobic conditions. Degradation of venlafaxine involved only small stereoisomeric selectivity. In contrast, the degradation of O-desmethylvenlafaxine yielded remarkable S to R enrichment under aerobic conditions but none under anaerobic conditions. Determination of venlafaxine and its metabolites in the WWTPs agreed well with the stereoselectivity observed in the laboratory studies. Our results suggest that the levels of the drug and its metabolites and the stereoisomeric enrichment of the metabolite and its parent drug can be used for source tracking and for discrimination between domestic and nondomestic wastewater pollution. This was indeed demonstrated in the investigations carried out at the Jerusalem WWTP.     

Meta-Analysis of Time-Series Studies of Air Pollution and Mortality: Effects of Gases and Particles and the Influence of Cause of Death,Age, and Season

Abstract

A comprehensive, systematic synthesis was conducted of daily time-series studies of air pollution and mortality from around the world. Estimates of effect sizes were extracted from 109 studies, from single- and multipollutant models, and by cause of death, age, and season. Random effects pooled estimates of excess all-cause mortality (single-pollutant models) associated with a change in pollutant concentration equal to the mean value among a representative group of cities were 2.0% (95% CI 1.5-2.4%) per 31.3 μg/m³ particulate matter (PM) of median diameter <10 μm (PM₁₀); 1.7% (1.2-2.2%) per 1.1 ppm CO; 2.8% (2.1-3.5%) per 24.0 ppb NO₂; 1.6% (1.1-2.0%) per 31.2 ppb O₃; and 0.9% (0.7-1.2%) per 9.4 ppb SO₂ (daily maximum concentration for O₃, daily average for others). Effect sizes were generally reduced in multipollutant models, but remained significantly different from zero for PM₁₀ and SO₂. Larger effect sizes were observed for respiratory mortality for all pollutants except O₃. Heterogeneity among studies was partially accounted for by differences in variability of pollutant concentrations, and results were robust to alternative approaches to selecting estimates from the pool of available candidates. This synthesis leaves little doubt that acute air pollution exposure is a significant contributor to mortality.     

Sorption and desorption of Cu and Cd by macroalgae and microalgae

The sorption and desorption of Cu and Cd by two species of brown macroalgae and five species of microalgae were studied. The two brown macroalgae, Laminaria japonica and Sargassum kjellmanianum, were found to have high capacities at pHs between 4.0 and 5.0 while for microalgae, optimum pH lay at 6.7. The presence of other cations in solution was found to reduce the sorption of the target cation, suggesting a competition for sorption sites on organisms. Sorption isotherms obeyed the Freundlich equation, suggesting involvement of a multiplicity of mechanisms and sorption sites. For the microalgae tested, Spirulina platensis had the highest capacity for Cd, followed by Nannochloropsis oculata, Phaeodactylum tricornutum, Platymonas cordifolia and Chaetoceros minutissimus. The reversibility of metal sorption by macroalgae was examined and the results show that both HCl and EDTA solutions were very effective in desorbing sorbed metal ions from macroalgae, with up to 99.5% of metals being recovered. The regenerated biomass showed undiminished sorption performance for the two metals studied, suggesting the potential of such material for use in water and wastewater treatment.     

骆马湖富营养化和生态状况调查与评价

为了了解骆马湖水质状况，在2005年对骆马湖富营养化状态和生态特性进行了调查，并结合“十五”期间的监测资料进行了分析。2005年骆马湖水体中总氮和总磷的平均值超《地表水环境质量标准》（GB3838-2002）中Ⅲ类，超标情况分别为0．78倍和0．54倍，达到湖库特定项目Ⅳ类水标准，骆马湖处于轻度富营养化状态。对骆马湖生态特征分析表明，由于该湖泊的形态以及“藻型浊水状态”和“泥沙型浊水状态”交替出现，遏制了湖水从高营养盐含量向全面富营养化状态演变，保障了底栖动物的良好生长环境，从而形成了骆马湖独特的环境生态平衡。     

剩余污泥浓缩脱水投药量优化和模型建立

应用高分子阳离子絮凝剂（CPF-100）和聚丙烯酰胺（PAM）对污水厂剩余污泥进行浓缩脱水实验,研究表明：CPF-100的浓缩脱水效果优于PAM;当CPF-00投加量为1．16‰时,污泥沉降性能改善程度为37．51％;且在CPF-100投加量逐渐增大的初始阶段,污泥沉降性能改善程度随投加量的增加而增大,但CPF-100投加量也不宜过大,当CPF-100投加量超过1．16‰后,反而会使浓缩脱水效果变差。同时,建立了污泥沉降性能改善程度与絮凝剂CPF-100投加量、沉降时间之间的数学模型,其能较好地反映污水厂剩余污泥的浓缩脱水效果。     

Copper-catalyzed chlorination and condensation of acetylene and dichloroacetylene

The chlorination and condensation of acetylene at low temperatures is demonstrated using copper chlorides as chlorinated agents coated to model borosilicate surfaces. Experiments with and without both a chlorine source and borosilicate surfaces indicate the absence of gas-phase and gas-surface reactions. Chlorination and condensation occur only in the presence of the copper catalyst. C₂ through C₈ organic products were observed in the effluent; PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed that is consistent with the observed product distributions. Similar experiments with dichloroacetylene indicate greater reactivity in the absence of the copper catalyst. Reaction is observed in the gas-phase and in the presence of borosilicate surfaces at low temperatures. The formation of hexachlorobenzene is only observed in the presence of a copper catalyst. PCDD/F were only observed from extraction of the borosilicate surfaces. A global reaction model is proposed for the formation of hexachlorobenzene from dichloroacetylene.     

Aerobic and anaerobic degradation of profluralin and trifluralin

Abstract

The degradation of profluralin [N‐(cyclopropylmethyl)‐α,α,α‐trifluoro‐2,6‐dinitro‐N‐propyl‐]p‐toluidine] and trifluralin (α,α,α‐trifluoro‐2,6‐dinitro‐N,N‐dipropyl‐p‐toluidine) was studied under aerobic and anaerobic soil conditions. Three soils (Goldsboro loamy sand, Cecil loamy sand, Drummer clay loam) were each treated with 1 ppmw herbicide; anaerobic conditions were maintained by flooding. Soil samples were extracted monthly and subjected to TLC analysis. No degradation was detected in sterile controls. Aerobic degradation of both herbicides was greatest in the Cecil loamy sand soil over the entire incubation period. Degradation of profluralin in Cecil soil under aerobic conditions was 86 percent after 4 months with three products detected; 83 percent of the trifluralin was degraded with two products detected. Anaerobic degradation accounted for 72 percent of the profluralin and 78 percent of the trifluralin after 4 months. Degradation of both herbicides increased with incubation time for the first 3 months and decreased slightly thereafter. Generally there was more extensive degradation (percent and in number of products formed) of profluralin than trifluralin under the conditions tested. More degradation products were detected for both herbicides under aerobic conditions than under anaerobic conditions.