Abundance and distribution of ammonia-oxidizing archaea in Tibetan and Yunnan plateau agricultural soils of China

As low oxygen and high ultraviolet （UV） exposure might significantly affect the microbial existence in plateau, it could lead to a specialized microbial community. To determine the abundance and distribution of ammonia-oxidizing archaea （AOA） in agricultural soil of plateau, seven soil samples were collected respectively from farmlands in Tibet and Yunnan cultivating the wheat, highland-barley, and colza, which are located at altitudes of 3200-3800 m above sea level. Quantitative PCR （q-PCR） and clone library targeting on amoA gene were used to quantify the abundances of AOA and ammonia-oxidizing bacteria （AOB）, and characterize the community structures of AOA in the samples. The number of AOA cells （9.34 × 10^7-2.32× 10^8 g^-1 soil） was 3.86-21.84 times greater than that of AOB cells （6.91 × 10^6-1.24 × 10^8 g^-1 soil） in most of the samples, except a soil sample cultivating highland- barley with an AOA/AOB ratio of 0.90. Based Kendall＇s correlation coefficient, no remarkable correlation between AOA abundance and the environmental factor was observed. Additionally, the diversities of AOA community were affected by total nitrogen and organic matter concentration in soils, suggesting that AOA was probably sensitive to several environmental factors, and could adjust its community structure to adapt to the environmental variation while maintaining its abundance.     

闽西北马尾松人工林营养元素的积累与分配格局

通过定位监测与取样分析,研究了41 a生马尾松人工林生态系统中的林木、林下植被、地被物及土壤等各组分营养元素含量、积累及分配特征.对林木的养分含量分析显示,除Ca元素外,针叶的养分含量最高,其次是枝、根、皮,树干的养分含量最低.林下植被层的养分含量比较高,其养分含量大小排列顺序为Ca＞N＞K＞Mg＞P;凋落物中各元素的含量与林木养分含量基本一致;土壤中K含量最高,其次是Mg,而Ca、N、P的含量则比较低.通过对林木生产力的分析表明,马尾松的养分年积累量为110.79 kg·hm-2·a-1,其中叶占34.47%,树干占22.56%,皮、枝和根分别占21.43%、10.91%和10.63%.马尾松林生态系统养分总贮量为187864.77 kg hm-2,其中土壤占98.70%,林木占1.18%,林下植被和凋落物养分元素总贮量较低,仅占总贮量的0.12%.     

腐植酸臭氧氧化和过氧化氢催化氧化处理特性比较

以TOC和UV254为指标,比较了不同条件下腐植酸的臭氧氧化和过氧化氢催化氧化效果,运用HPLC和热裂解-GC-MS分析考察了氧化前后有机物分子量分布和官能团构造的变化情况．研究结果表明：过氧化氢和臭氧单独作为氧化剂对水中TOC基本上没有去除作用,但均能导致水中UV254浓度的降低;在几种催化剂的作用下,过氧化氢对TOC和UV254的去除效果明显提高,其中以O3作为催化剂的效果最好,Fe^2＋次之,而Mn^2＋和Cu^2＋的催化效果较差;过氧化氢催化氧化和臭氧化均导致有机物分子量分布向小分子的方向转移,氧化后水中以羧酸、醇、胺、酯、醚、烷烃为代表的含氧基团和饱和构造基团明显增多;过氧化氢催化氧化和臭氧氧化均有助于改善混凝处理和活性炭吸附处理的效果．关键词腐植酸,臭氧,过氧化氢,催化氧化．     

大冶龙角山矿区几种植物的重金属吸收特征

通过调查采样和化学测试,对大冶龙角山矿区小麦、油菜、莴苣、白菜苔、豌豆等几种主要农作物中的重金属Cu、Pb、Cd及类金属As的质量分数进行分析。结果表明,供试农作物中,莴苣的重金属(包括As)质量分数显著高于其它作物的,其中以Cd质量分数最高,而豌豆的重金属质量分数最低,其它作物重金属质量分数由高到低的顺序为油菜、腌菜、白菜苔、小麦;小麦中的重金属质量分数依次是w(Cd) > w(As) > w(Pb) > w(Cu) > w(Cr),油菜中为w(Cd) > w(As) > w(Pb) > w(Cr) > w(Cu),莴苣中为w(Cd) > w(Cu) > w(Pb) > w(As)> w(Cr);随河流向下,作物中重金属含量变化规律与相应土壤中重金属累积量基本一致,如油菜含铜量在上游为0.61 g/g,在下游为0.37 g/g。     

复合型人工湿地模型对污水厂尾水的深度净化效果

采用由一级垂直流湿地、连续的4级沉水植物氧化塘和二级垂直流湿地组成的复合型人工湿地处理小城镇污水处理厂尾水。结果表明,在0.13 m3.m-2.d-1水力负荷条件下,模型出水仅ρ(CODCr)和ρ(氨氮)(以NH4+-N计)达到地表Ⅲ类水标准(GB 3838—2002);但当进水ρ(TP)达到《城镇污水处理厂污染物排放标准》(GB18918—2002)一级B标准时,出水ρ(TP)亦达到地表Ⅲ类水标准。当二级垂直流湿地水力负荷调整为0.06 m3.m-2.d-1时,出水ρ(TP)和ρ(TN)最终都达到地表Ⅲ类水标准。认为水体中TN主要通过一级垂直流湿地的过滤吸附和二级垂直流湿地的反硝化作用去除,而TP则主要以一级垂直流湿地中石灰石的吸附沉降方式来去除。     

油菜秸秆还田对水稻根系分布及稻谷产量的影响

根系健康是水稻正常生长及高产的前提,为明确油菜秸秆还田方式和还田量对水稻生长及产量的影响,以秸秆不还田作为对照,设置秸秆半量还田(1.5 t/hm2)、全量还田(3.0 t/hm2)、超量还田(4.5 t/hm2)3个还田量以及秸秆覆盖还田(FG)、秸秆翻埋还田(FM)两种还田方式,通过盆栽和大田试验相结合,研究秸秆处...     

水体中高氯酸盐（ClO-4）污染控制技术

系统介绍了现阶段水体中高氯酸盐(ClO4-)污染控制技术;分析了各种技术的优点与局限性;指出离子交换、生物降解与修复是目前处理水体中ClO4-的主要技术,认为探寻有效的组合处理工艺,开发更经济、高效的新处理技术,将是今后控制水体ClO4-污染的研究重点.     

Dissolved organic matter with multi-peak fluorophores in landfill leachate

Dissolved organic matter (DOM) sampled from municipal landfill leachate of different ages with/without anoxic or aerobic treatment, was intensively fractionated via size exclusion chromatography (SEC) and hydrophobic resins, and was studied with fluorescence excitation and emission matrix (EEM). Six fluorophores with multiple EEM peaks (fluorophore A-F) were identified based on the collected EEM spectra and validated by bi-variate analysis, principal component analysis, and parallel factor analysis, as follows (excitation wavelength Ex and emission wavelength Em): (Ex 240, 310, 360 nm, Em 460 nm), (Ex 220, 280 nm, Em 340 nm), (Ex 220, 270 nm, Em 300 nm), (Ex 220, 280 nm, Em 360 nm), (Ex 230, 320 nm, Em 420 nm) and (Ex 220, 310 nm, Em 400 nm). The spectral characteristics of these fluorophores were discussed using fractional EEM and apparent molecular weight (AMW) data obtained via SEC analysis. The triple peak flurophore A was pointed at a hydrophobic acid or hydrophobic neutral compound with a pyrenyl functional group of AMW 2500-3500 Da, which displayed an excitation wavelength at 360 nm and a fluorescence intensity ratio of 6.70(+/-1.79):1.70(+/-0.41):1 (fluorescent intensities of Ex 240:Ex 310:Ex 360 nm at Ex 460 nm). This compound is observed to be refractory in landfilling or in anoxic/aerobic treatments, and is specific to this leachate contamination. This paper revealed that the coupling of SEC and EEM can be useful to track the fluorescent DOM fraction in landfill leachate.     

Residual concentrations of micropollutants in benthic mussels in the coastal areas of Bohai Sea, North China

Studies of heavy metals and organic pollutants in different benthic mussel species from Bohai Sea show that concentrations of Cd in mussels commonly exceed national biological quality standards. In addition, a site located in Laizhou Bay exhibits higher average concentrations of As, Hg and Pb with respect to the other sites. Residual levels of petroleum hydrocarbons at several sites in Liaodong Bay also exceed quality guidelines. Contents and compositional characteristics of DDT and its metabolites in mussels suggest the probability of recent inputs and potential ecological risks to the local benthic environment.     

Atmospheric distribution of particulate- and gas-phase phthalic esters (PAEs) in a Metropolitan City, Nanjing, East China

Phthalic acid esters (PAEs) are used in many branches of industry and are produced in huge amounts throughout the world. An investigation on particulate- and gas-phase distribution of PAEs has been conducted in Nanjing (China). The 12-h daily sampling program (from 8:00 am to 8:00 pm) for ten consecutive days was conducted in April, July and October 2005, and in January 2006 at about 1.5m above the ground level. For comparative purposes, sampling events were simultaneously conducted at two stations, one at the urban center and the other about 12 km from city center for suburban background monitoring. It was observed that the most abundant members of the PAE group were dimethyl phthalate (DMP) (10.1 ng m(-3), average), diethyl phthalate (DEP) (3.4 ng m(-3)), dibutyl phthalate (DBP) (58.8 ng m(-3)), butylbenzyl phthalate (BBP) (3.2 ng m(-3)), di-2-ethylhexyl phthalate (DEHP) (20.3 ng m(-3)) and di-n-octyl phthalate (DOP) (1.2 ng m(-3)). The average contribution of PAEs in the gas phase to the total PAE concentration (Sigma(6)PAE, sum of six PAE congeners) ranged from 75.0% to 89.2%. Both particulate- and gas-phase Sigma(6)PAE concentrations decreased with increasing temperature. Experimentally determined gas-particle partitioning (K(p)) of PAEs is well-correlated with their vapor pressure. The Sigma(6)PAE levels in the urban area are approximately 3.5 times as high as the levels found at the suburban station. The vertical profiles from 1.5 to 30.0m above the ground display slight height dependence.