高氨废水短程硝化特性简

采用SBR装置,针对高氨废水的特点,在高氨条件下,以高氨低氧为转化手段,实现高氨废水短程硝化过程中亚硝化菌的驯化与积累。控制温度为28~31℃,曝气量为15~60 L/h,pH控制在7.8~8.2的条件下连续运行78 d。实验结果表明,运行11 d后实现了短程硝化,从11 d至78 d属于系统氨氮负荷提高期。在运行过程中,氨氮污泥负荷从开始的0.023 kg/（kg·d）逐步上升为0.3 kg/（kg·d）,最高时达到0.34 kg/（kg·d）,此时氨氮去除率仍维持90%以上。为观察驯化后短程硝化菌的形态,取驯化好的污泥进行电镜扫描,结果表明,污泥中的细菌形态主要以球状菌为主。     

Alterations in neurobehaviors and inflammation in hippocampus of rats induced by oral administration of microcystin-LR

Microcystin-LR (MC-LR) is a widely studied toxic peptide secreted by certain water blooms of cyanobacteria that exhibit hepatotoxicity and neural toxicity. This study aimed to observe the neurotoxic effects of low-dose MC-LR exposure by oral administration. Male Sprague-Dawley (SD) rats were administered orally every 2 days for 8 weeks with pure water and 0.2, 1.0, and 5.0 μg/kg MC-LR. The Morris water maze test was used to assess the spatial learning and memory capability of rats. The activation of astrocytes and nitric oxide synthase (NOS) was evaluated by immunohistochemistry, and concentrations of nitric oxide (NO) in rat hippocampus were analyzed. Slight liver dysfunction was observed in the 5.0 μg/kg MC-LR-treated rats. Impairment of spatial learning and memory was also observed in the 5.0 μg/kg MC-LR-treated rats. Astrocytes in the hippocampus of the 5.0 μg/kg MC-LR-treated rats showed enhanced activation and cell density; the inflammatory indicators, NOS and NO, increased in accordance with astrocyte activation. This study showed that oral exposure of MC-LR had adverse affects on neurobehaviors, and induced inflammation in memory-related brain regions.     

Impact of irreversible sorption of phthalate acid esters on their sediment quality criteria

The equilibrium partitioning (EqP) method has been applied to establish sediment quality criteria (SQC); however, it does not consider the nonlinear irreversible sorption of many organic contaminants. In this research, the sorption and desorption of two phthalate esters (PAEs), dimethyl phthalate (DMP) and di(2-ethylhexyl) phthalate (DEHP), in four natural sediments collected from the Yangtze River and the Yellow River were studied; the impact of irreversible sorption of DMP and DEHP on SQC has been evaluated. Based on the reversible and irreversible biphasic sorption model, the values of maximum irreversible sorption capacity (q(max)(irr)) were 125.19 μg g(-1)-337.37 μg g(-1) for DMP and 515.87 μg g(-1)-591.40 μg g(-1) for DEHP. The q(max)(irr) value was positively related to the organic carbon and black carbon contents, cation exchange capacity, and surface area of the sediments. The values of the irreversible sorption coefficient K(oc)(irr) for both DEHP and DMP in the four sediments approximated to a constant of 10(6.46 ± 0.38), which was 1-2 orders of magnitude higher than their reversible sorption coefficient K(oc)(irr). The values of SQC for PAEs based on the EqP method were modified by involving the irreversible sorption. The modified SQC of DEHP could be 2 to 20 times higher than the value predicted by the EqP method, and the assessment results for DEHP contamination in the sediments with the modified SQC were more reasonable than those with the non-modified SQC. It indicated that the current SQC based on the EqP method may be unnecessarily strict for specific organic compounds and the irreversible sorption should be taken into account.     

茨榆山乡上窝铺泥石流灾害特征及防治对策

秦皇岛北部山区泥石流地质灾害隐患威胁着当地居民的生命财产安全,严重阻碍了乡村经济的快速发展。以青龙满族自治县茨榆山乡上窝铺泥石流为例,通过实地调查与数据分析,确定了泥石流成因、类型、活动状况、危害性、危险区范围;获取了泥石流流体重度规律、泥石流流速、泥石流流量、一次性固体冲出物主要力学参数特征;根据泥石流的特点及主要参数,提出监测预警方案及工程治理方案。     

Assessment of Traffic Noise Pollution from 1989 to 2003 in Lanzhou City

On the basis of the continuous traffic noise data observed at 142 sites distributed in 52 roads from 1989 to 2003, the characteristics of traffic noise and effect factors were analyzed through traffic noise indices, such as Lep, L10, L50, L90, TNI, and Pn. Our findings allow us to reach a number of conclusions as follows: Firstly, traffic noise pollution was serious, and its fluctuant characteristic was obvious, resulting in a great intrusion to public in Lanzhou City during last 15 years. Secondly, traffic noise made a distinction between trunk lines and secondary lines, west-east direction roads and north-south direction roads. Thirdly, spatial character and time rule of traffic noise were obvious. In addition, traffic volume, traffic composition, road condition, and traffic management were identified as the key factors influencing traffic noise in this city.     

The land ecological evolutional patterns in the source areas of the Yangtze and Yellow Rivers in the past 15 years, China

Based on land ecological classification of the source regions of the Yangtze and Yellow Rivers and field investigation, two phases of TM remote sensing data obtained in 1986 and 2000 were compared. From spatial variations and type transformation trends, the spatial changes and evolutional patterns of land ecosystem in the source regions of the two rivers were analyzed using the analytical method of landscape ecological spatial patterns. Results show that middle and high-cover high-cold steppe areas degraded considerably by 15.82%, high-cover high-cold meadow areas by 5.15%, while high-cold swamp meadow areas decreased by 24.36%. Lake water area was reduced by 7.5%, especially the lakes in the source region of the Yangtze River. Land desertification is developing rapidly and the average of desertified land area has increased by 17.11%. Desertified land in the source region of Yellow River is expanding at an annual rate of 1.83%. Analysis of the evolutional pattern of land ecotypes shows that the general tendencies of spatial evolution in the regions are coverage reduction and desertification of high-cold steppe, cover reduction and steppification of high-cold meadows, and desiccation of swamp meadows. As a result, land ecological spatial distribution pattern in the region is changing and the state of eco-environment declining.     

Screening of flocculant-producing microorganisms and flocculating activity

A strain saccharomycete STSM-I with high flocculanting activity was isolated from activated sludge with conventional methods.The high production rate and the low cost STSM-I medium was obtained by selecting different kinds of media, carbon source, nitrogen source and inorganic salt ion. The best flocculant-producing conditions were found by changing medium initial pH, culture temperature and ventilation flow. The best flocculating effect was obtained by changing positive ion types, density and concentration of flocculant.     

致突变的致癌剂和非致癌剂在引发DNA股间交联上的显著差别

借碱洗脱法证明：具有致突变能力的致癌剂1,2－二溴乙烷和肼在经过代谢活化后,均剂理相关地引起L1210细胞中DNA的股间交联。相反,动物致癌试验表现阴性的突变剂溴乙烷,以及通过各种致癌动物试验均显示阴性的传统常用致突变剂羟胺,在代谢活化以后的同样条件下均不能引起L1210细胞中DNA的股间交联。这证明了双区理论的致癌观点,即致癌剂必须是双官能烷化剂,其同时引起互补碱对的交联将引起癌变。相反,股内单一碱基的变异则可能引起致突变作用。并用APCI／SIM（大气压化学电离／选择离子质谱）证明：1,2－二溴乙烷与DNA碱基对的模型反应,与致突实验一致主要引起G－C对的交联和发生G－C→A－T突变。     

一些致突变剂与致癌剂分子流行病学的研究进展

分子流行病学是一种新兴的并迅速发展的研究领域。它结合了内剂量、生物有效剂量、生物效应和个体易感性效应等流行病方法学的实验检测方法,如接触性生物标记：尿中的代谢物、DNA加合物;蛋白质加合物和彗星实验参数检测的DNA损伤;效应性生物标记：染色体畸变、姊妹染色单体交换、策核、次黄嘌呤－鸟嘌呤磷酸核糖转移酶基因（HPRT）的突变,编码p53或p21蛋白的肿瘤基因的活化;易感性生物标记：CYP1A1、GSTM1、GSTT1、NAT2等基因的多态性。但无论什么实验都需要人类监测的可靠根据。直到现在仍不能解释基因型、接触性生物标记与效应性生物标记之间的关系。