四溴双酚-A和五溴酚对红鲫甲状腺组织结构的影响

将红鲫(Carassius auratus)分别暴露于0.25 mg·l-1四溴双酚A(TBBPA)和0.05 mg·l-1五溴酚(PBP)中6周,采用组织切片的方法,观测红鲫甲状腺滤泡形态结构的变化,并以100 mg·l-1高氯酸钠(NaClO4)和0.25 mg·l-1氯化镉(CdCl2)作为参照,探讨TBBPA和PBP在体时(in vivo)对鱼类甲状腺可能的致毒机理.结果显示,经TBBPA和PBP暴露后,红鲫甲状腺发生了滤泡上皮增厚、细胞肥大和增生等现象,表明这两种溴化阻燃剂均能造成甲状腺结构的损伤.这与NaClO4所引起的甲状腺滤泡的变化非常相似,而与CdCl2所引起的滤泡上皮变薄刚好相反.由此推测,TBBPA和PBP在鱼体内可能引起甲状腺素水平的降低,进而导致甲状腺滤泡细胞的代偿性增生和肥大.     

一体化A/O工艺中溶解氧对脱氮除碳的影响

根据好氧-缺氧生物脱氮的工艺原理,设计了一体化A/O反应器,并就DO对其脱碳、脱氮处理效果的影响进行研究。结果表明,在水力停留时间HRT=12h,进水COD为300mg/L左右时,COD的平均去除率为93%。当好氧区DO在5mg/L左右时,脱氮效率最高,TN去除率达到70%。当好氧区DO为3￣4mg/L时,氨氮和总氮的去除可达到动态一致,它们的去除率均在50%～60%之间。     

同步脱氮除磷工艺中好氧池最适氧浓度研究

AB工艺无厌氧、缺氧段,氮、磷的去除率低,不具备深度脱氮除磷功能。而A2/O工艺具有同步脱氮除磷功能,可以作为AB工艺改造方案之一。试验以实际生活污水为对象,研究好氧池中不同的溶解氧浓度范围内系统对COD、氮、磷的去除效果。试验结果表明,好氧池DO对COD的去除影响较小,出水平均值达到21.9mg/L;对氨氮的去除则起着关键作用,在DO为3.0mg/L以下时,氨氮的去除率随着DO的增大而升高;DO为1.5～2.5mg/L时总氮去除效果最佳,过低、过高对总氮的去除都不利;总磷的去除效果几乎不受好氧池DO的影响,但厌氧池和缺氧池的释磷、吸磷过程却受DO的影响变化较大。系统中厌氧池和缺氧池同时出现了反硝化和吸磷作用,但尚不能判断是否存在反硝化除磷现象。     

基于ASM1的A/O系统工艺参数对出水水质影响研究

在ASM1模型基础上,结合A/O工艺,建立了A/O工艺污水处理厂模型.通过Matlab软件平台进行数值模拟,探讨了不同污泥龄和内回流比条件下,COD、氨氮和硝酸盐氮出水浓度的变化规律.最后将模拟值与污水排放标准进行比对,得出污泥龄为11 d,内回流比为200%时为最优工况参数.     

分段进水A/O工艺流量分配方法与策略研究

分段进水缺氧/好氧(A/O)工艺是一种高效的污水生物脱氮工艺。但原水多点投配给该工艺带来诸多好处的同时, 也为其优化运行带来一定困难。其中,可行的流量分配方法的建立是分段进水工艺发挥其优势并高效运行的瓶颈问题。提出3种不同的流量分配方法并进行相应的理论分析: (1) 采用等负荷流量分配法,其遵循的原则是保证各段硝化菌负荷相同, 以利于硝化菌生长,优先满足系统硝化, 最大程度地降低出水氨氮浓度; (2)采用流量分配系数, 原则是各缺氧段进水有机物质恰好可以为上段好氧区产生的硝酸盐氮反硝化提供充足的电子供体。 利用该方法可以充分利用原水中碳源,发挥缺氧区反硝化潜力,并保证最后一段进水量最少, 降低出水硝酸盐氮含量; (3)末端集中进水,用于暴雨等产生洪峰流量时, 将进水点向系统末端移动, 并加大末端进水量, 以减小二沉池固体负荷, 避免污泥冲刷流失。3种流量分配方法的提出,可以应对水厂不同的进水水质和出水要求,增强分段进水A/O生物脱氮工艺的实际可操作性,提高处理效率,为目前采用分段进水A/O工艺的污水厂的优化运行管理提供可靠的理论借鉴。     

Impact of global warming on agricultural product markets: stochastic world food model analysis

Climatic change through global warming and drought is a major issue for agricultural production. Most researchers who discuss the effects of such changes on agriculture report estimated yield changes based on crop process models. However, studies focusing on the impact of climatic change on agricultural product markets are very rare. This paper examines the relationship between climatic change and world food markets, i.e., the supply and demand of crops, by using a stochastic version of a world food model, the International Food and Agricultural Policy Simulation Model. The results suggest that variations in the production of maize and soybeans in some major producing countries will be large, and variations in the producer prices of all crops will increase. Countries that suffer higher price risk because of high sensitivity to temperature fluctuations may need to consider changes in cropping patterns.     

Stability of the conjugated species of environmental phenols and parabens in human serum

In humans, the metabolism of environmental phenols may include the formation of conjugated species (e.g., glucuronides and sulfates), but the free species—not the conjugated forms—are considered biologically active. Therefore, information on the concentration of these free species in blood or urine could be helpful for risk assessment. Because conjugates could hydrolyze to their corresponding free forms during collection, handling, and storage of biological specimens, information on the temporal stability of the conjugates is of interest. Previously, we reported the temporal stability of urinary conjugates of several environmental phenols, but data on the stability of phenols' conjugated species in serum, albeit critical if concentrations of free and conjugated species are compared, are largely unknown. In the present study, we investigate the stability of the conjugates of four phenols—bisphenol A, benzophenone-3, triclosan, and 2,5-dichlorophenol—and two parabens—methyl paraben and propyl paraben—in 16 human serum samples for 30 days at above-freezing temperature storage conditions (4 °C, room temperature, and 37 °C). These conditions reflect the worst-case scenarios that could occur during the short-term storage of biological samples before their long-term storage at controlled subfreezing temperatures. We found that the percentage of the conjugated species of the four detected compounds (2,5-dichlorophenol, triclosan, and methyl and propyl parabens) in these serum specimens even when stored at 37 °C for at least 30 days did not vary significantly. These preliminary data suggest that the phenols' serum conjugates appear to be more stable than their corresponding urinary conjugates, some of which started to hydrolyze within 24 h under similar storage conditions. The reported stability of these conjugated species in human serum also suggests that the free species are unlikely to have resulted from the hydrolysis of their corresponding conjugates. This information could be important for interpreting the low concentrations of free phenol species detected in serum samples of nonoccupationally exposed populations. To our knowledge, this is the first study to report on the stability of conjugated species in serum, and as such requires replication.     

Plutonium as a chronomarker in Australian and New Zealand sediments: a comparison with Cs

The construction of high resolution chronologies of sediment profiles corresponding to the last 50-100 years usually entails the measurement of fallout radionuclides ²¹⁰Pb and ¹³⁷Cs. The anthropogenic radionuclide, ¹³⁷Cs, originating from atmospheric nuclear weapons testing can provide an important “first appearance” horizon of known age (1954-1955), providing much-needed validation for the sometimes uncertain interpretations associated with ²¹⁰Pb geochronology. However, while ¹³⁷Cs usually provides a strong signal in sediment in the northern hemisphere, total fallout of ¹³⁷Cs in the southern hemisphere was only 25% that of the north and the low activities of ¹³⁷Cs seen in Australian and New Zealand sediments can make its horizon of first appearance somewhat arguable. Low ¹³⁷Cs fallout also limited the size of the 1963-1964 fallout peak, a peak that is usually seen in northern hemisphere sediment profiles but is often difficult to discern south of the equator.This paper shows examples of the use of nuclear weapons fallout Pu as a chronomarker in sediment cores from Australia (3 sites) and New Zealand (1 site). The Pu profiles of five cores are examined and compared with the corresponding ¹³⁷Cs profiles and ²¹⁰Pb geochronologies. We find that Pu has significant advantages over ¹³⁷Cs, including greater measurement sensitivity using alpha spectrometry and mass spectrometric techniques compared to ¹³⁷Cs measurements by gamma spectrometry. Moreover, Pu provides additional chronomarkers associated with changes in the Pu isotopic composition of fallout during the 1950s and 1960s. In particular, the ²³⁸Pu/^239+240Pu activity ratio shows distinct shifts in the early 1950s and the mid to late 1960s, providing important known-age horizons in southern hemisphere sediments. For estuarine and near-shore sediments Pu sometimes has another significant advantage over ¹³⁷Cs due to its enrichment in bottom sediment relative to ¹³⁷Cs resulting from the more efficient scavenging of dissolved Pu in seawater by sediment particles.     

Hemoglobin (Hb) immobilized on amino-modified magnetic nanoparticles for the catalytic removal of bisphenol A

Catalytic removal of bisphenol A from aqueous solution with hemoglobin immobilized on amino-modified magnetic nanoparticles as an enzyme catalyst was reported. The amino-modified magnetite nanoparticles were firstly prepared by the coprecipitation of Fe²⁺ and Fe³⁺ with NH₃·H₂O and then modified by 3-aminopropyltriethoxysilane. The immobilization process was optimized by examining enzyme concentration, glutaraldehyde concentration, cross-link time, and immobilization time. The optimum conditions for the removal of bisphenol A with immobilized hemoglobin were also investigated. Under the optimality conditions, the removal efficiency of bisphenol A was about 80.3%. The immobilization had a beneficial effect on the stability of hemoglobin and conversions of bisphenol A. According to the proposed breakdown pathway and the intermediates, the enzyme-catalytic removal of bisphenol A by the immobilized hemoglobin is considered to be an effective method.     

Assessment of typical pollutants in waterborne by combining active biomonitoring and integrated biomarkers response

Organic pollutants, heavy metals and pharmaceuticals are continuously dispersed into the environment and have become a relevant environmental emerging concern. In this study, a situ assay to assess ecotoxicity of mixed pollutants was carried out in three typical sites with different priority contaminations in Guangzhou, China. Chemical analysis of organic pollutants, metals and quinolones in three exposure sites were determined by GC-ECD/MS, ICP-AES and HPLC, as well as, a combination of biomarkers including: ethoxyresorufin O-deethylase (EROD); aminopyrine N-demethylase (APND); erythromycin N-demethylase (ERND); glutathione S-transferase (GST); malondialdehyde (MDA); CYP1A; and P-glycoprotein (P-gp) mRNA expressions were evaluated in Mugilogobius abei. Results of chemical analysis in sediment samples revealed that the dominant chemicals were organic pollutants and heavy metals in Huadi River while quinolones in the pond. Bioassays indicated that differences among sites were in relation to some specific biomarkers. EROD and GST activities significantly increased after 72 h in situ exposure, but no difference was observed among the exposure sites. APND, ERND and MDA exhibited dissimilar change patterns for different priority pollutants. CYP1A and P-gp mRNA expressions were significantly induced at all exposure sites, whilst P-gp activity was typical for S2 with the highest levels of quinolones. The molecular biomarkers seemed to be more susceptible than enzyme activities. These assays confirmed the usefulness of applying a large array of various combined biomarkers at different levels, in assessing the toxic effects of mixed pollutants in a natural aquatic environment.