紫外光-超声波协同降解苯酚水溶液的研究

有机酚类化合物造成的水体的污染,直接危害着人类的健康和生态环境,如何有效地处理环境水样中有机酚类化合物,是当今人们普遍关注的一个问题。以苯酚水溶液为研究对象,在紫外光和功率为150 W、40 kHz超声波的协同作用下,对苯酚的降解效率和降解规律进行了初步的研究,讨论了溶液的酸度、光辐射的时间、H2O2及Fe2 (FeSO4)等因素对苯酚溶液降解的影响,结果表明,单一超声波对苯酚的降解率很低,不超过6.5%。在紫外光一超声波协同辐射60 min,溶液的pH值为3-4,加入6%H2O2 4 mL,加入0.1 nmol·L-1Fe2 (FeSO4)1.6 mL,可达到91.8%的降解率。试验证明,利用紫外光-超声波协同照射是降解苯酚的一种有效方法。     

超声粉碎-TOC/TN仪法直接测定污水处理厂废水中的总氮

污水处理厂废水经超声粉碎后,使用TOC/TN仪直接测定总氮.对仪器条件、进样方式、微波粉碎时间及加标回收率进行了探讨.相对标准偏差＜2.35％,测定结果与国标法一致,相对误差＜±1.3％,回收率为95.3％ ～97.8％.方法简便、快速、准确.     

超声强化技术在水处理中的应用研究进展

作为高级氧化技术,超声空化产生元选择性的强氧化性自由基,具有较大优势,但由于超声空化机理的特点使得有机物的完全矿化受到限制,而提高超声效率的常见方法有：优化频率、声强,与其他技术组合等。文章主要从超声波参数,添加剂,超声-高级氧化技术、超声-活性炭、超声-微生物处理、超声-石墨、超声-气浮、超声-膜处理、超声-混凝、超声-消毒技术等方面综述了超声强化技术原理及其在水处理中的应用研究进展。其中研究较少的方法有间歇超声、多频超声、充入多种气体以及超声与各工艺组合,如超声与活性炭、等离子体技术等组合,这些强化技术都-定程度的强化了超声效果。有些组合暂时未用于水处理,但经过完善也将大大催进水处理事业的发展。虽然超声波具有较大优势,但是由于其成本高,反应器生产技术限制。超声波大规模用于实际生产还需要较长-段时间。     

Limitations of Gravity Models in Predicting the Spread of Eurasian Watermilfoil

Abstract: The effects of non‐native invasive species are costly and environmentally damaging, and resources to slow their spread and reduce their effects are scarce. Models that accurately predict where new invasions will occur could guide the efficient allocation of resources to slow colonization. We assessed the accuracy of a model that predicts the probability of colonization of lakes in Wisconsin by Eurasian watermilfoil (Myriophyllum spicatum). We based this predictive model on 9 years (1990–1999) of sequence data of milfoil colonization of lakes larger than 25 ha (n =1803). We used milfoil colonization sequence data from 2000 to 2006 to test whether the model accurately predicted the number of lakes that actually were colonized from among the 200 lakes identified as being most likely to be colonized. We found that a lake's predicted probability of colonization was not correlated with whether a lake actually was colonized. Given the low predictability of colonization of specific lakes, we compared the efficacy of preventing milfoil from leaving occupied sites, which does not require predicting colonization probability, with protecting vacant sites from being colonized, which does require predicting colonization probability. Preventing organisms from leaving colonized sites reduced the likelihood of spread more than protecting vacant sites. Although we focused on the spread of a single species in a particular region, our results show the shortcomings of gravity models in predicting the spread of numerous non‐native species to a variety of locations via a wide range of vectors.     

Use of Fatty Acid Analysis to Determine Dispersal of Caspian Terns in the Columbia River Basin,U.S.A.

Abstract: Lethal control, which has been used to reduce local abundances of animals in conflict with humans or with endangered species, may not achieve management goals if animal movement is not considered. In populations with emigration and immigration, lethal control may induce compensatory immigration, if the source of attraction remains unchanged. Within the Columbia River Basin (Washington, U.S.A.), avian predators forage at dams because dams tend to reduce rates of emigration of juvenile salmonids (Oncorhynchus spp.), artificially concentrating these prey. We used differences in fatty acid profiles between Caspian Terns (Hydroprogne caspia) at coastal and inland breeding colonies and terns culled by a lethal control program at a mid‐Columbia River dam to infer dispersal patterns. We modeled the rate of loss of fatty acid biomarkers, which are fatty acids that can be traced to a single prey species or groups of species, to infer whether and when terns foraging at dams had emigrated from the coast. Nonmetric multidimensional scaling showed that coastal terns had high levels of C₂₀ and C₂₂ monounsaturated fatty acids, whereas fatty acids of inland breeders were high in C18:3n3, C20:4n6, and C22:5n3. Models of the rate of loss of fatty acid showed that approximately 60% of the terns collected at Rock Island Dam were unlikely to have bred successfully at local (inland) sites, suggesting that terns foraging at dams come from an extensive area. Fatty acid biomarkers may provide accurate information about patterns of dispersal in animal populations and may be extremely valuable in cases where populations differ demonstrably in prey base.     

超声波对剩余污泥化学调理的影响

以污泥脱水性能与沉降性能为指标,研究了超声波预处理对剩余污泥经阳离子聚丙烯酰胺（CPAM）进行化学调理时污泥减量效果的影响。试验结果表明,单独采用CPAM对剩余污泥进行化学调理时的ρ（最佳添加量）为120 mg.L-1,污泥滤饼含水率为81.2%;单独采用超声波处理剩余污泥时的最佳声能密度为0.04 W.mL-1,此时的滤饼含水率为80.4%。而当在采用CPAM对剩余污泥进行化学调理前先进行超声波预处理后,污泥滤饼含水率降至72.2%。试验结果表明这种联合处理方式不仅使剩余污泥的脱水性能大为改善,并且最佳CPAM投加量降低至60 mg.L-1,最佳超声声能密度降至0.03 W.mL-1,这表明联合处理方法降低了污泥处理成本。     

Epiphyte Biodiversity in the Coffee Agricultural Matrix: Canopy Stratification and Distance from Forest Fragments

Abstract: Quality of the agricultural matrix profoundly affects biodiversity and dispersal in agricultural areas. Vegetatively complex coffee agroecosystems maintain species richness at larger distances from the forest. Epiphytes colonize canopy trees and provide resources for birds and insects and thus effects of agricultural production on epiphytes may affect other species. We compared diversity, composition, and vertical stratification of epiphytes in a forest fragment and in two coffee farms differing in management intensity in southern Mexico. We also examined spatial distribution of epiphytes with respect to the forest fragment to examine quality of the two agricultural matrix types for epiphyte conservation. We sampled vascular epiphytes in a forest fragment, a shade polyculture farm, and a shade monoculture farm at 100 m, 200 m, and 400 m from the forest. Epiphyte and orchid richness was greater in the forest than in the monoculture but richness was similar in the forest and polyculture farm. Epiphyte species composition differed with habitat type, but not with distance from the forest. In the forest, epiphytes were distributed throughout tree canopies, but in the farms, epiphytes were primarily found on trunks and larger branches. Epiphyte richness and species similarity to forest species declined with distance from the forest fragment in the monoculture, but richness and similarity to forest species did not decline with distance from forest in the polyculture. This suggests polyculture coffee has greater conservation value. In contrast, monoculture coffee is likely a sink habitat for epiphytes dispersing from forests into coffee. Coffee farms differ from forests in terms of the habitat they provide and species composition, thus protecting forest fragments is essential for epiphyte conservation. Nonetheless, in agricultural landscapes, vegetatively complex coffee farms may contribute to conservation of epiphytes more than other agricultural land uses.     

Ecological Trap for Desert Lizards Caused by Anthropogenic Changes in Habitat Structure that Favor Predator Activity

Abstract: Anthropogenic habitat perturbation is a major cause of population decline. A standard practice managers use to protect populations is to leave portions of natural habitat intact. We describe a case study in which, despite the use of this practice, the critically endangered lizard Acanthodactylus beershebensis was locally extirpated from both manipulated and natural patches within a mosaic landscape of an afforestation project. We hypothesized that increased structural complexity in planted patches favors avian predator activity and makes these patches less suitable for lizards due to a heightened risk of predation. Spatial rarity of natural perches (e.g., trees) in arid scrublands may hinder the ability of desert lizards to associate perches with low‐quality habitat, turning planted patches into ecological traps for such species. We erected artificial trees in a structurally simple arid habitat (similar to the way trees were planted in the afforestation project) and compared lizard population dynamics in plots with these structures and without. Survival of lizards in the plots with artificial trees was lower than survival in plots without artificial trees. Hatchlings dispersed into plots with artificial trees in a manner that indicated they perceived the quality of these plots as similar to the surrounding, unmanipulated landscape. Our results showed that local anthropogenic changes in habitat structure that seem relatively harmless may have a considerable negative effect beyond the immediate area of the perturbation because the disturbed habitat may become an ecological trap.     

超声激发碘自由基降解水中磺胺嘧啶

以H2O2和KI作为分子碘(I2)的来源,研究超声/H2O2/KI体系对磺胺嘧啶(SD)的降解效果.考察超声/H2O2/KI体系中溶液初始pH值、H2O2和KI添加浓度等因素的影响.采用碘自由基抑制剂甲硫咪唑对体系中的活性物质进行分析.结果表明,超声/H2O2/KI体系显著提高了磺胺嘧啶的降解效果,磺胺嘧啶的去除率随溶液初始pH值(2.6~5.2)的升高而降低; H2O2和KI的添加浓度对磺胺嘧啶的去除率影响较大,磺胺嘧啶的去除率随其初始浓度的增大而降低.碘自由基(I·和I2-·)是超声/H2O2/KI体系降解磺胺嘧啶的主要活性物质.HPLC图谱表明,磺胺嘧啶降解的同时生成4种产物,磺胺为降解产物之一.     

管道补口热收缩带粘接质量超声检测试验研究

为解决管道补口热收缩带剥离强度人工抽检效率低、人为因素影响大的问题,采用水浸法开展基于超声检测的补口热收缩带粘接性能的试验研究,根据回波信号、时域等效强度It和频域等效强度If,分析了2.25 MHz、5 MHz时接收信号与粘接质量的关系。结果表明:当检测频率为2.25 MHz时,随着粘接质量的下降,回波信号R1-2呈增强趋势;当检测频率为5 MHz时,随着粘接质量的下降,有R1减弱、R2增强的趋势,发生脱粘时,R1异常增强,R2几乎减弱到零;同时,两种频率检测结果均表明时域等效强度It和频域等效强度If与粘接质量呈反比:粘接质量下降,It、If增强,可作为管道补口粘接质量定量评价的两项指标。此外,与2.25 MHz相比,5 MHz对于粘接质量的判别能力更强,更有利于实际检测。