苦草（Vallisneria natans）根系对沉积物中各形态磷的影响

采用磷分级提取的方法研究苦草(Vallisneria natans)生长过程中根系分布与沉积物不同形态磷和总磷的变化过程.在实验开始后20、50、80 d,分别测定苦草根系在沉积物的分布及沉积物中各形态磷的垂直变化.结果表明,苦草根系在实验装置中垂直分布在0~14 cm区域内.平均每株苦草根系根数为58条,平均根长为5.86 cm.苦草根系生物量在沉积物深度0~3、4~6、7~10、11~14 cm分配的质量分数分别为45.99%、32.75%、16.03%、5.23%.沉积物中总磷(TP),NaOH提取磷(NaOH-P)和有机磷(OP)含量在苦草根系分布集中区域内显著降低(P<0.05).HCl提取磷(HCl-P)和无机磷(IP)的含量无显著差异(P>0.05).     

Escherichia coli inactivation by pressurized CO2 treatment methods at room temperature: Critical issues

This study aims to increase the inactivation efficiency of CO_2 against Escherichia coli under mild conditions to facilitate the application of pressurized CO_2 technology in water disinfection. Based on an aerating-cycling apparatus, three different treatment methods(continuous aeration, continuous reflux, and simultaneous aeration and reflux) were compared for the same temperature, pressure(0.3–0.7 MPa), initial concentration, and exposure time(25 min). The simultaneous aeration and reflux treatment(combined method) was shown to be the best method under optimum conditions, which were determined to be 0.7 MPa, room temperature, and an exposure time of 10 min. This treatment achieved 5.1-log reduction after 25 min of treatment at the pressure of 0.3 MPa and 5.73-log reduction after 10 min at 0.7 MPa. Log reductions of 4.4 and 5.0 occurred at the end of continuous aeration and continuous reflux treatments at 0.7 MPa, respectively.Scanning electron microscopy(SEM) images suggested that cells were ruptured after the simultaneous aeration and reflux treatment and the continuous reflux treatment. The increase of the solubilization rate of CO_2 due to intense hydraulic conditions led to a rapid inactivation effect. It was found that the reduction of intracellular p H caused by CO_2 led to a more lethal bactericidal effect.     

成都市冬季大气消光系数及其组成的特征研究

由于气溶胶吸湿增长的复杂性和不确定性,大气消光的演化机理至今尚不十分清晰.为此,利用成都市2017年12月浊度仪和黑碳仪的逐时观测资料,结合同时次的环境气象监测数据,系统研究了该区域冬季对应550 nm大气消光系数及其组成的特征.结果表明:①观测期间大气消光系数为(1173.42±641.21) Mm~(-1),其中"干"气溶胶散射系数、"干"气溶胶吸收系数、干洁大气散射系数、气态污染物吸收系数和气溶胶吸湿性消光系数对其平均贡献率分别是53.02%、6.54%、1.50%、1.65%和37.29%.②大气消光系数、"干"气溶胶散射系数和气溶胶吸湿性消光系数的日变化为"单峰单谷型",而"干"气溶胶吸收系数和气态污染物吸收系数的日变化则分别表现为"单谷型"和"双峰双谷型".③明确了单位质量大气消光系数及其组成随相对湿度的变化特征,并就其各自成因进行了分析.     

三亚河红树林表层沉积物中好氧氨氧化微生物的分布特征及潜在硝化速率

氨氧化过程是硝化作用的限速步骤,氨氧化细菌(ammonia-oxidizing bacteria, AOB)和氨氧化古菌(ammonia-oxidizing archaea, AOA)是氨氧化作用的主要驱动者,其分布特征及其对硝化作用的相对贡献是氮素循环的研究热点.采用实时荧光定量PCR技术研究了三亚河红树林表层沉积物中好氧氨氧化微生物的分布特征,并通过测定潜在硝化速率分析了AOB和AOA对硝化作用的相对贡献率.结果表明,多数采样点中,AOA amoA基因丰度高于AOB amoA基因丰度; AOB丰度冬季较高,AOA丰度夏季较高,且冬季AOA和AOB丰度的比值较低;溶解氧、pH、总有机碳和硝态氮对AOB和AOA丰度影响较大; AOB和AOA在夏季的潜在硝化速率均高于冬季,冬季AOA对硝化作用的相对贡献率较高而夏季则是AOB在硝化作用中占主导地位,AOB和AOA的潜在硝化速率与amoA基因丰度均不存在显著相关性.     

扎赉诺尔煤业公司灵东矿采煤沉陷区环境治理分析

灵东矿煤炭开采造成地表大面积沉陷,根据矿井所在地的自然、气候条件和土地的适宜性,合理安排各类用地,对不同类型的沉陷地采取不同的治理方法,制定科学、合理的沉陷区治理措施,使治理区域最大限度的恢复原有生态系统。     

放射性核素大气扩散数值模拟研究综述

放射性核素大气扩散模式可以模拟放射性核素在不同尺度下的大气输送与扩散,为核电站选址、核事故应急提供科学依据.本文总结了目前广泛用于模拟核素扩散的多种模式,详细比较了各模式对放射性核素的衰变、输送和扩散、干/湿沉降和重力沉降以及辐射剂量等处理方法,总结归纳各个模式模拟的差异性.最后,对放射性核素大气扩散模式发展前景做了展望.对有针对性地提高模式模拟能力以及明确模式的发展方向具有重要的意义.     

我国植物VOCs排放速率的研究

1992～2000年,使用流动式、封闭式采样法,气相色谱-火焰离子化检测器,测定了我国4 种气候类型(温带-寒温带,温带,温带-亚热带,热带-亚热带),7 个地区(黑龙江,北京,福建,广东,四川,湖南,云南),共 58 种当地优势树种、庄稼和草地异戊二烯和单萜烯的排放速率.使用G93 算法,换算出相应异戊二烯和单萜烯的标准排放因子,并划分了这些排放因子的等级.同种树种在不同的气候带和季节的排放有明显的差异,通常,VOCs 排放速率南方高于北方,夏季高于冬季;阔叶树主要排放异戊二烯,针叶树主要排放单萜烯,但是我国南方相当数量的阔叶林的排放特征不符合上述规律.     

Synthesis and characterization of agricultural controllable humic acid superabsorbent

Humic acid superabsorbent polymer (P(AA/AM-HA)) and superabsorbent polymer (P(AA/AM)) were synthesized by aqueous solution polymerization method using acrylic acid (AA), acrylamide (AM) and humic acid (HA) as raw material. The effects of N,N'-methylenebisacrylamide (MBA) crosslinking agent, potassium peroxydisulfate (KPS) initiator, reaction temperature, HA content, ratio of AA to AM, concentration of monomer and neutralization of AA on water absorption were investigated. Absorption and desorption ratios of nitrogen fertilizer and phosphate fertilizer were also investigated by determination of absorption and desorption ratio of NH₄⁺, PO₄^3- on P(AA/AM-HA) and P(AA/AM). The P(AA/AM-HA) and P(AA/AM) were characterized by Fourier translation infrared spectroscopy, biological photomicroscope and scanning electron microscopy (SEM). The optimal conditions obtained were as follows: the weight ratio of MBA to AA and AM was 0.003; the weight ratio of KPS to AA and AM was 0.008; the weight ratio of HA to AA was 0.1; the mole ratio of AM to AA is 0.1; the mole ratio of NaOH to AA is 0.9; the reaction temperature was 60℃. P(AA/AMHA) synthesized under optimal conditions, has a good saline tolerance, its water absorbency in distilled water and 0.9 wt.% saline solution is 1180 g/g and 110 g/g, respectively. P(AA/AM-HA) achieves half saturation in 6.5 min. P(AA/AM-HA) is superior to P(AA/AM) on absorption of NH₄⁺, PO₄^3-. The SEM micrograph of P(AA/AM-HA) shows a fine alveolate structure. The biological optical microscope micrograph of P(AA/AM-HA) shows a network structure. Graft polymerization between P(AA/AM) and HA was demonstrated by infrared spectrum. The P(AA/AM-HA) superabsorbent has better absorbing ability of water and fertilizer, electrolytic tolerance and fewer cost than P(AA/AM) superabsorbent.     

两段式进水两级矿化垃圾反应器处理中晚期垃圾渗滤液

针对矿化垃圾反应器处理中晚期垃圾渗滤液时由于反硝化区缺少碳源而导致总氮去除率不佳的问题,开展以优先利用原水中的有机物充当碳源为目的的两段式进水两级矿化垃圾反应器处理工艺的研究。通过控制反应器的曝气量、好氧区和反硝化区,研究了两段式进水两级矿化垃圾反应器处理垃圾渗滤液的效果。结果表明,当进水渗滤液水力负荷为46.0 L/(m~3·d)时,在第一级反应器底部曝气量为1.86 m~3/(m~3·d),第二级反应器中上部曝气量为0.37 m~3/(m~3·d)的条件下,COD、NH_4~+-N、TP的平均去除率分别为84.1%、92.6%、85.6%,运行稳定后TN平均去除率达76.0%,处理效果较好。     

黄河口新生湿地土壤Fe和Mn元素的空间分布特征

2009年5月,在今黄河入海口北部的新生湿地区域,依据植被类型设置9个采样区,研究了不同植物群落下湿地土壤Fe和Mn含量的空间分布特征.结果表明,不同类型湿地土壤的Fe、Mn含量在水平分布上由三棱蔗草-朝天委陵菜湿地到光滩呈波动上升趋势,在垂直分布上则表现为不同的波动变化特征.成土母质决定湿地土壤Fe、Mn含量的空间分布,而海水、植被和土壤细颗粒对其也有重要影响.相关分析表明,Fe、Mn之间以及二者与粉粒、TN、NO-3-N和有机质呈极显著正相关(P<0.01),与黏粒呈显著正相关(P<0.05),说明Fe、Mn与N具有较好的共存性,土壤细颗粒和有机质是影响土壤Fe、Mn分布的主导因素.黄河口新生湿地的Fe含量范围为16.49~33.11 g·kg-1,均值为22.54 g·kg-1,与苏北潮滩湿地,中国黄土高原黄土和中国土壤的背景值相近,但略低于长江口湿地,红树林湿地和内陆湖泊湿地.Mn含量范围为305.87~711.39mg·kg-1,均值为451.09 mg·kg-1,低于中国黄土高原黄土和中国土壤的Mn含量背景值.