石墨烯薄膜原子氧剥蚀行为及电阻特性

目的研究石墨烯薄膜在原子氧空间环境的适应性,为其在航天器上应用提供参考。方法采用刮涂法制备石墨烯薄膜,将石墨烯薄膜材料及石墨烯电阻传感器置于微波源原子氧设备内开展原子氧试验,原子氧剂量分别为3.0×10^20 atoms/cm2和7.5×10^20 atoms/cm^2,研究薄膜表面形貌、结构、成分及电阻性能的变化。结果采用刮涂法可制备氧含量较低的石墨烯薄膜,原子氧剂量为7.5×10^20 atoms/cm^2情况下,石墨烯薄膜的厚度损失为5.3μm,原子氧反应率为7.14×10^-25 atoms/cm^3。原子氧作用后,石墨烯薄膜中碳原子无序程度增大,C—O、—COOH官能团含量降低,C=O官能团含量增加。石墨烯电阻传感器的R0/R比值随原子氧剂量增加线性降低,0.8μm厚度薄膜可探测最大原子氧剂量为5×10^19 atoms/cm^2,增加薄膜厚度有望提高传感器的使用寿命。结论得到了石墨烯薄膜厚度损失、原子氧反应率、微观结构及电阻特性的变化规律,可为石墨烯薄膜的空间应用提供技术支撑。     

Identification of rice cultivars with low brown rice mixed cadmium and lead contents and their interactions with the micronutrients iron, zinc, nickel and manganese

Paddy fields in mining areas are usually co-contaminated by a cocktail of mixed toxic heavy metals (e.g., Cd and Pb in Pb/Zn mines). However, previous studies on rice cultivars screened for effective metal exclusion have mostly focused on individual metals, and have been conducted under pot-trial or hydroponic solution conditions. This study identified rice cultivars with both low Cd and Pb accumulation under Cd-and Pb-contaminated field conditions, and the interactions of the toxic elements Cd and Pb with the micronutrient elements Fe, Zn, Mn and Ni were also studied. Among 32 rice cultivars tested, there were significant differences in Cd (0.06-0.59 mg/kg) and Pb (0.25-3.15 mg/kg) levels in their brown rice, and similar results were also found for the micronutrient elements. Significant decreases in concentrations of Fe and Mn were detected with increasing Cd concentrations and a significant elevation in Fe, Mn and Ni with increasing Pb concentrations. A similar result was also shown by Cd and Ni. Three cultivars were identified with a combination of low brown rice Cd and Pb, high micronutrient and grain yield (Wufengyou 2168, Tianyou 196 and Guinongzhan). Present results suggest that it is possible to breed rice cultivars with low mixed toxic element (Cd, Pb) and high micronutrient contents along with high grain yields, thus ensuring food safety and quality.     

基于区域产量法测算的福建省农业生态足迹

为了使生态足迹模型能更好地反映区域实际,文章对生态足迹模型中的计算项目做了较大改进。首次计算了肉类的耕地生态足迹和人畜排泄物污染生态足迹。新建了纳污土地、CO2吸收林地、水资源地三种生态足迹类型以强调农业污染的严重性和土地、林地的多重生态功能;将化石能源地并入CO2吸收林地;剔除牧草地类型,将肉类耗粮生态足迹并入耕地类型;将污染源从化石燃料扩展到人畜排泄物、化肥、农药领域,计算了CO2、N、P和农药等污染物的生态足迹。用福建省最近5 a的平均产量测算了2007年福建农业生态足迹,包括农业投入品生态足迹、农业劳动力消费生态足迹和农业污染物排放生态足迹三部分,然后与生态承载力分类比较以测度农业生产的生态占用情况。测算结果表明,2007年福建省农业生态足迹中,林地、水域、建成地、纳污土地占有实际生态承载力的比例较低,分别为1.4%、1.2%、13.4%和24.6%;而耕地占生态承载力的比例达到了94.2%;水资源地是实际生态承载力的2.2倍,出现了严重的生态赤字。最后提出相应的建议。     

萃取-反萃法综合回收磷矿浮选尾矿中磷和镁

针对某磷矿浮选尾矿的资源特点,将其作为高镁低品位磷矿进行处理,用萃取-反萃法分离酸浸液中的镁和磷。选择正丁醇作为萃取剂,在磷酸浓度为30%、萃取相比为1:1,温度为常温,萃取时间为5min的均衡搅拌条件下,五氧化二磷萃取率可达68%以上;用水作为反萃剂,在其加入量为反萃前有机相体积的30%,反萃时间为3min,常温条件下进行反萃,反萃率可达90%以上。该研究为综合回收磷矿浮选尾矿提供了基础性资料,     

煤矸石作无土栽培基质的可行性研究

煤矸石是我国煤炭工业主要的废弃物之一,一方面占用大量农田和土地,另一方面也成为固、液和气三害俱全的污染源,造成了一系列生态环境问题。为了加强对煤矸石利用以使其资源化,试验在分析煤矸石的理化性质的基础上,采用复合脱硫剂对煤矸石进行脱硫处理,探讨了脱硫煤矸石基质对小白菜的生长、产量和品质的影响。结果表明:煤矸石的容重小、孔隙度大、气水比适中,无重金属污染。当加入复合脱硫剂处理时,其对全硫和有效硫的脱除率分别为86.12%和89.16%。脱硫煤矸石基质栽培小白菜产量、维生素C和可溶性糖含量分别为4.51kg/m2、45.76mg/100g、60.2mg/kg,均高于土壤栽培,分别为土壤栽培的1.11、1.24、1.23倍,与炉渣栽培相接近,NO3-含量却低于土壤。     

我国主要蔬菜和粮油作物的砷含量与砷富集能力比较

根据国内外文献报道,对蔬菜和粮油作物中砷的累积特点和富集能力进行总结和分析.结果表明.清洁区和污染区蔬菜的砷含量变幅分别为0.001-1.07 mg·kg-1和0.001-8.51 mg·kg-1(鲜重),均值分别为0.035 mg·kg-1和0.068 mg·kg-1不同种类蔬菜的砷含量由大到小,依次为:叶菜类>根茎类>茄果类>鲜豆类;清洁区和污染区粮油作物的砷含量变幅分别为0.001-2.20 mg·kg-1和0.007-6.83 mg·kg-1(干重),均值分别为0.081 mg·kg-1和0.294 mg·kg-1,其中水稻的砷含量显著高于小麦和玉米.从富集系数来看,叶莱类蔬菜的砷富集系数最高,芹菜、蕹菜、茼蒿、芥菜等蔬菜的抗砷污染能力较弱.粮食作物玉米的抗砷污染能力较强.与蔬菜砷限量标准(GB4810-1994)相比,我国砷污染区的蔬菜中有32.2%的样本砷含量超标,其中叶菜类和根茎类的超标率分别为47.9%和12.8%.与粮食砷限量标准(GB4810-1994)比较,我国污染区粮油作物的样本砷超标率为34.8%,其中水稻的超标率高达42.9%.玉米和小麦的超标率均高于20%.     

紫外光降解反应器去除氯苯气体模型的建立与应用

从光化学反应过程出发,基于线性光源球面辐射能量分布（LSSE）,以反应器内部空间的辐射能吸收密度、空塔停留时间、进口浓度等为主要参数,建立了气相环境中紫外光化学反应器去除氯苯的数学模型.结果表明,建立的模型能很好地模拟和预测紫外光化学反应器对氯苯气体的去除性能.氯苯气体的紫外光化学反应表现出一级反应动力学的特征.该模型包含了紫外光降解反应器设计的主要参数,同时被用于预测了反应器在不同进口浓度和不同空塔停留时间条件下的出口氯苯浓度,进而获得不同进口浓度达标排放所需要的最小空塔停留时间,为气相污染物的紫外光降解反应器的设计与运行提供了重要的理论指导.     

Variation of grain Cd and Zn concentrations of 110 hybrid rice cultivars grown in a low-Cd paddy soil

Enhanced Cd uptake and Zn depletion in rice grains and high potential for food Cd exposure by the high-yielding hybrid cultivars of China had been addressed. A field experiment was conducted in 2006 to determine the di erence in grain Cd and Zn between cultivars. Total 110 cultivars including super rice and common hybrid rice cultivars were grown on a single paddy soil (Entic Haplaquept) with a neutral reaction and low total Cd content. Grain Cd and Zn concentrations were determined with graphite atomic adsorption spectrophotometer (GFAAS) and flame atomic adsorption spectrophotometer (AAS) respectively.Wide variation of Cd content in grain was found in a range of 0.004–0.057 mg/kg, while the Zn content in a range of 10.25–30.06 mg/kg among the cultivars. Higher Cd but lower Zn concentration in grains of super rice cultivars was observed compared to the common hybrid ones. A highly significant positive linear correlation of grain Cd/Zn with grain Cd was found for super rice and common hybrid cultivars, meanwhile much higher slope for these hybrid cultivars than the reported non-hybrid cultivars was also observed. Using the limit value of the Chinese chemical guidelines for foods (MOHC and SSC, 2005), calculated potential risk of food Cd exposure with “Zn hungry” through diet intake was prominent with all the studied 110 hybrid rice cultivars, possessing high potential health problems for rice production in South China using the super rice cultivars. Breeding of genotypes of rice cultivars with low grain Cd and low Cd/Zn ratio is needed for rice production in acidic red soils where Cd bioavailability is prevalently high.     

Fe2+浓度对生物产氢动力学的影响

研究了Fe²⁺在0～1 500 mg/L 范围内对混合细菌发酵产氢动力学的影响.结果表明,以葡萄糖为底物,在35℃ 和初始pH为7.0时,当Fe²⁺浓度为0～300 mg/L 时,混合细菌发酵葡萄糖的最大累积产氢量和平均产氢速率都随着Fe²⁺浓度的增加而增加;当Fe²⁺浓度为300 mg/L 时,最大累积产氢量和平均产氢速率最高,分别为302.3 mL和30.0 mL/h .当Fe²⁺浓度为0～350 mg/L 时,比产氢率随着Fe²⁺浓度的增加而增加,当Fe²⁺浓度为350 mg/L 时,最大比产氢率为311.2 mL/g .修正的Logistic模型能很好地描述累积产氢量随时间的变化规律.修正的Han-Levenspiel模型能很好地描述Fe²⁺浓度对平均产氢速率的影响.     

胶州湾沉积物氮的环境生物地球化学意义

利用氮的分级浸取技术,研究了胶州湾不同粒级沉积物中氮的赋存形态.研究表明,胶州湾沉积物中可转化态氮可分为离子交换态、弱酸浸取态、强碱浸取态和强氧化剂浸取态.不同粒级沉积物中各形态氮占可转化态氮的比例各不相同.在细、中和粗粒级沉积物中,强氧化剂浸取态氮是可交换态氮的优势形态,分别占可转化氮的35.38%、44.38%和58.69%.在中、粗粒级沉积物中,强碱浸取态氮是无机氮的主要赋存形态,分别占可转化态氮的26.31%和25.85%.在细粒级沉积物中,离子交换态氮是优势态的无机氮,占可转化态氮的27.67%.相关分析表明,对于胶州湾来说,沉积物的粒度越细,氮的含量就越高,各形态氮大致与细、中粒级沉积物含量呈正相关,而与粗粒级沉积物含量呈负相关.研究还表明,不同粒级沉积物中氮与浮游植物数量、叶绿素a以及上覆水体中硝酸盐的含量大致都在一定程度上呈正相关,这一方面说明了沉积物对上覆水体元素的含量有着不可忽视的影响,另一方面也说明了沉积物中的氮对海水的富营养化水平有着较好的指示和十分重要的环境意义.