基于颗粒物光量子雷达的颗粒物排放实时溯源及应用

在大气污染治理中,传统探测方式在局地大气颗粒物排放源的精准定位和实时溯源方面还有所不足。自主研发的1 550 nm波长颗粒物光量子雷达,具备探测效率高、人眼安全等特点,360°水平扫描一周仅需8.5 min。基于该雷达水平扫描监测,结合迭代拼接法和新发展的颗粒物示踪系数及污染源定位方法,可准确识别并定位出当地的污染排放源位置。对于部分污染排放定位溯源案例,结合多图展现并分析了颗粒物排放、扩散、传输、消散过程中的烟羽变化,并结合卫星图像确认了相应工业生产和建筑扬尘等典型颗粒物排放源。地面监测数据分析了部分污染源对监测站点颗粒物浓度的影响。该雷达通过低仰角、可重复性的快速扫描,结合符合颗粒物扩散规律的分析过程,在颗粒物污染实时溯源定位方面展现了极高的准确性。     

Interactive effects of cadmium and hypoxia on metabolic responses and bacterial loads of eastern oysters Crassostrea virginica Gmelin

Pollution by toxic metals including cadmium (Cd) and hypoxia are important stressors in estuaries and coastal waters which may interactively affect sessile benthic organisms, such as oysters. We studied metabolic responses to prolonged hypoxic acclimation (2 weeks at 5% O₂) in control and Cd-exposed (30 d at 50 μg L⁻¹ Cd) oysters Crassostrea virginica, and analyzed the effects of these stressors on abundance of Vibrio spp. in oysters. Hypoxia-acclimated oysters retained normal standard metabolic rates (SMR) at 5% O₂, in contrast to a decline of SMR observed during acute hypoxia. However, oysters spent more time actively ventilating in hypoxia than normoxia resulting in enhanced Cd uptake and 2.7-fold higher tissue Cd burdens in hypoxia. Cd exposure led to a significant decrease in tissue glycogen stores, increase in free glucose levels and elevated activity of glycolytic enzymes (hexokinase and aldolase) indicating a greater dependence on carbohydrate catabolism. A compensatory increase in activities of two key mitochondrial enzymes (citrate synthase and cytochrome c oxidase) was found during prolonged hypoxia in control oysters but suppressed in Cd-exposed ones. Cd exposure also resulted in a significant increase in abundance of Vibrio parahaemolyticus and Vibrio vulnificus levels during normoxia and hypoxia, respectively. Overall, Cd- and hypoxia-induced changes in metabolic profile, Cd accumulation and bacterial flora of oysters indicate that these stressors can synergistically impact energy homeostasis, performance and survival of oysters in polluted estuaries and have significant consequences for transfer of Cd and bacterial pathogens to the higher levels of the food chain.     

Screening of Cd tolerant genotypes and isolation of metallothionein genes in alfalfa (Medicago sativa L.)

In order to evaluate Cd tolerance in wide-ranging sources of alfalfa (Medicago sativa) and to identify Cd tolerant genotypes which may potentially be useful for restoring Cd-contaminated environments, thirty-six accessions of alfalfa were screened under hydroponic culture. Our results showed that the relative root growth rate varied from 0.48 to 1.0, which indicated that different alfalfa accessions had various responses to Cd stress. The candidate fragments derived from differentially expressed metallothionein (MT) genes were cloned from leaves of two Cd tolerant genotypes, YE and LZ. DNA sequence and the deduced protein sequence showed that MsMT2a and MsMT2b had high similarity to those in leguminous plants. DDRT-PCR analysis showed that MsMT2a expressed in both YE and LZ plants under control and Cd stress treatment, but MsMT2b only expressed under Cd stress treatment. This suggested that MsMT2a was universally expressed in leaves of alfalfa but expression of MsMT2b was Cadmium (Cd) inducible.     

Influence of the nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) on ammonia-oxidizing bacteria and archaea in rhizosphere and bulk soil

In agricultural plant production nitrification inhibitors like 3,4-dimethylpyrazole phosphate (DMPP) are used to retard the microbial nitrification process of fertilized ammonium to enhance the nitrogen supply for cultivated crops and to reduce nitrogen losses from the production system. Besides the well-known ammonia-oxidizing bacteria (AOB) it is known for a few years that also ammonia-oxidizing archaea (AOA) are able to perform the first step in nitrification, hence being also a target for a nitrification inhibitor. However, so far no information are available concerning the effectiveness of DMPP and its extent towards AOB and AOA, neither in bulk soil nor in the root-rhizosphere complex. We investigated in a field experiment performed according to agricultural practice the effect of DMPP on the abundance of AOB and AOA two, four and eight weeks after fertilization. We observed impaired abundances of AOB but not of AOA in both soil compartments that were still visible eight weeks after application, possibly indicating a reduced effectiveness of the nitrification inhibitor in our study.     

浊度传感器应用于连续监测污水厂进水悬浮颗粒浓度的研究

为使城市污水处理厂更合理高效的运营,可对进水悬浮颗粒浓度的实时监测来实现。通过对进水水样的悬浮颗粒浓度测量值与相应浊度值建立的关系曲线,达到对污水处理厂进水悬浮颗粒浓度（mg／L）的连续实时监测。文中给出了浊度传感器的校准方法,并建立浊度-悬浮颗粒浓度关系曲线,将其应用于某城市污水处理厂,得到单位时间进水悬浮颗粒总量的实时连续图。     

活性污泥总DNA提取方法的比较

从处理某制药废水的MBR反应器中采集活性污泥,评价不同DNA提取方法对其总DNA提取效率的影响。DNA提取分细胞裂解和DNA纯化2步,对细胞裂解比较了珠磨匀浆法、反复冻融法、十二烷基磺酸钠（sodium dodecyl sulfate,SDS）裂解法等7种方法;对DNA纯化比较了酚/氯仿纯化法和胶回收纯化法。结果表明,SDS裂解法、酚氯仿纯化法最优。通过条件优化实验,确定SDS裂解酚/氯仿纯化法在污泥量1.1 g,10 000 r/min离心5 min的操作条件下,获得的DNA产量（10 774 μg/g泥重）和纯度（OD₂₆₀∶OD₂₈₀=1.84）等综合指标最好。     

Characterization of bacterial diversity in an atrazine degrading enrichment culture and degradation of atrazine,cyanuric acid and biuret in industrial wastewater

An enrichment culture was used to study atrazine degradation in mineral salt medium (MSM) (T1), MSM+soil extract (1:1, v/v) (T2) and soil extract (T3). Results suggested that enrichment culture required soil extract to degrade atrazine, as after second sequential transfer only partial atrazine degradation was observed in T1 treatment while atrazine was completely degraded in T2 and T3 treatments even after fourth transfer. Culture independent polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) technique confirmed selective enrichment of genus Bacillus along with Pseudomonas and Burkholderia. Degradation of atrazine/metabolites in the industrial wastewater was studied at different initial concentrations of the contaminants [wastewater-water (v/v) ratio: T1, 1:9; T2, 2:8; T3, 3:7; T4, 5:5 and T5, undiluted effluent]. The initial concentrations of atrazine, cyanuric acid and biuret ranged between 5.32 and 53.92 µg mL^?1, 265.6 and 1805.2 µg mL^?1 and 1.85 and 16.12 µg mL^?1, respectively. The enrichment culture was able to completely degrade atrazine, cyanuric acid and biuret up to T4 treatment, while no appreciable degradation of contaminants was observed in the undiluted effluent (T5). Inability of enrichment culture to degrade atrazine/metabolites might be due to high concentrations of cyanuric acid. Therefore, a separate study on cyanuric acid degradation suggested: (i) no appreciable cyanuric acid degradation with accumulation of an unidentified metabolite in the medium where cyanuric acid was supplemented as the sole source of carbon and nitrogen; (ii) partial cyanuric acid degradation with accumulation of unidentified metabolite in the medium containing additional nitrogen source; and (iii) complete cyanuric acid degradation in the medium supplemented with an additional carbon source. This unidentified metabolite observed during cyanuric acid degradation and also detected in the enrichment culture inoculated wastewater samples, however, was degraded up to T4 treatments and was persistent in the T5 treatment. Probably, accumulation of this metabolite inhibited atrazine/cyanuric acid degradation by the enrichment culture in undiluted wastewater.     

Improving Anammox start-up with bamboo charcoal

Three Upflow Anaerobic Sludge Blanket (UASB) reactors were compared for Anammox enrichment using synthetic wastewater with Spherical Plastic (SP) and Bamboo Charcoal (BC) addition, and without carrier (CK). After four months of operation, the Anammox activity occurred in all reactors allowing continuous removal of ammonium and nitrite. Ammonium and nitrite removal efficiencies were all higher than 98% in steady phase with the effluent concentrations below 1 mg L⁻¹. The start-up time could be shortened from 117 to 97 d in CK and SP reactor to 85 d in BC amendment reactor. Quantitative PCR (q-PCR) analyses indicated a significant increase in the number of Anammox bacteria in BC amended reactor as compared with CK and SP during the entire start-up periods. The copy numbers of Anammox of 16S rRNA gene in the reactor with BC amendment could reach up to 6 × 10⁹ copies g⁻¹ Volatile Suspended Solids, around 22.5 times and 12.3 times greater than that in CK and SP reactor, respectively. BC addition could accelerate the start-up of Anammox and significantly increase the Anammox bacteria number.     

水中抑制物对定量PCR与膜过滤法检测E.coli的影响

针对水中病原微生物的污染,选择大肠埃希氏菌E.coli作为病原示踪剂,以E.coli染色体上β-葡萄糖醛酸酶uid A目的基因建立了SYBR Green实时荧光定量PCR的检测方法。该定量PCR方法灵敏度高,检测限可达104CFU/L,线性关系良好,相关系数为R2=0.999。研究表明,定量PCR与菌液浓度呈显著正相关R2=0.935。通过人工投加腐殖酸、COD,研究了水中抑制物对定量PCR和膜过滤MF培养法的影响。结果显示,腐殖酸可使E.coli在培养皿上的菌落变小聚集,且显色不明显,当腐殖酸量为20 mg/L时,浓度为50 CFU/100 m L的E.coli完全受到抑制,没有菌落出现。腐殖酸对PCR扩增的抑制作用明显,当腐殖酸浓度增加到10 mg/L,定量PCR检测结果基因拷贝数减少约1 log,增加到20 mg/L定性PCR检测结果为阴性。     

Detection of Listeria monocytogenes in ready-to-eat food by Step One real-time polymerase chain reaction

The aim of this study was to follow contamination of ready-to-eat food with Listeria monocytogenes by using the Step One real time polymerase chain reaction (PCR). We used the PrepSEQ Rapid Spin Sample Preparation Kit for isolation of DNA and MicroSEQ® Listeria monocytogenes Detection Kit for the real-time PCR performance. In 30 samples of ready-to-eat milk and meat products without incubation we detected strains of Listeria monocytogenes in five samples (swabs). Internal positive control (IPC) was positive in all samples. Our results indicated that the real-time PCR assay developed in this study could sensitively detect Listeria monocytogenes in ready-to-eat food without incubation.