混凝前处理对猪场沼液MAP回收时抗生素残留的影响

养猪废水磷酸铵镁（MgNH₄PO₄·6H₂O,MAP）回收时会有大量抗生素转移至回收MAP固体中,采用混凝前处理去除沼液中抗生素减少后续回收MAP中抗生素残留.首先对比聚合硫酸铁（PFS）、壳聚糖（CTS）、阳离子型聚丙烯酰胺（CPAM）和非离子型聚丙烯酰胺（PAM）四种典型无机和有机混凝剂对抗生素去除效果.实验结果显示CPAM去除抗生素效果最好,四环素类抗生素（TCs）去除率为22.8%-44.8%,喹诺酮类抗生素（FQs）去除率为32.2%~70.3%,回收MAP固体中抗生素含量为TCs 8.6mg/kg~19.6mg/kg,FQs 0.8~12.33mg/kg.在此基础上,考察了pH值和CPAM投加量对CPAM去除抗生素的影响.当pH7.5-8.0、CPAM投加量为17.5mg/L时,TCs去除42.5%~50.6%,FQs去除率42.9%~66.3%;与没有混凝处理的沼液MAP回收相比,产物中TCs含量下降43.2%~54.1%,FQs含量下降50.1%~69.5%.     

Selection of cost-effective magnesium sources for fluidized struvite crystallization

Struvite crystallization has been considered a promising approach to recover phosphorus from wastewater. However, its practical application is limited, probably because of the high cost of magnesium(Mg). In this study, a comprehensive economic analysis was conducted using five Mg sources(MgCl_2, MgSO_4, MgO, Mg(OH)_2, and bittern) during the operation of a pilot-scale fluidized bed reactor(FBR), using swine wastewater as the case matrix. First, the economic operating conditions were investigated, and subsequently, the performance and the costs of the five Mg sources were compared. The results indicated that the FBR could be operated most economically at pH of 8.5 and Mg to phosphorus(Mg/P) molar ratio of 1.5. Under these conditions, no significant differences in phosphorus removal and product quality could be found between the five Mg sources. Selecting the most economical Mg source was thus highly dependent on the prices of the reagents and Mg sources. Low-solubility Mg sources were preferable when NaOH was priced higher, while high-solubility Mg sources proved more economical when HNO_3 was expensive. The bittern was the most economical choice only when the distances for total inorganic orthophosphate removal and struvite recovery were shorter than 40 and 270 km, respectively. The current study provides an overview of the economic selection of an Mg source, which can help reduce the cost of struvite crystallization.     

镁盐改性生物质炭的合成及其在废水氮磷资源化中的应用研究

通过直接沉淀-热改性法将纳米氢氧化镁晶体(Mg(OH)_2)负载在生物质炭(BC)上,系统研究了该改性材料(Mg(OH)_2-BC)对模拟废水中氮、磷的固定特性,并探讨了投加量、反应溶液pH、接触时间对吸附过程的影响.结果表明,Mg(OH)_2-BC在投加量为0.3 g·L~(-1),反应溶液初始pH为7,反应时间≥40 min时对氮、磷的固定效果最佳,最大吸附量分别达到58.8、130.0 mg·g~(-1).Mg(OH)_2-BC对氮、磷的吸附过程均符合准二级动力学模型,吸附过程受化学吸附机理的控制.通过SEM、XRD、FTIR等对反应产物进行表征分析,结果表明,Mg(OH)_2-BC对氮、磷的固定机制主要为鸟粪石结晶沉淀,也即化学沉淀.     

关于推广城市生活垃圾资源化的建议

本文以可持续发展和保护生态环境的观点,针对中国城市垃圾年产１．２亿吨及历年积存６０亿吨的处理问题,简要介绍和比较了四种基本的垃圾处理方法,着重推荐无害化综合处理方法,并从技术、经济、政府政策和企业运营等方面分析了无害化综合处理方法在全国普遍推广的可行性,预测了普遍推广后的环境效益、社会效益和经济效益。     

环境实验室分析数据质量控制技术

文章所论述的实验室分析数据的质量控制措施主要是通过对分析方法“适用性”的验证、质控考核以及± 2S单值连续控制图相结合的方法进行的。该方法可提高测试数据的精度和稳定性 ,也可提供全过程监测数据的误差范围。既适用于小批量单一水质指标的测试分析 ,也适用于大批量且水质浓度变化幅度较大的情况。避免了因环境因素变化而采用其它控制图带来的不便和困难。使用该质控技术可获得准确、稳定的分析数据     

Habitat selection models to account for seasonal persistence in radio telemetry data

Models for the analysis of habitat selection data incorporate covariates in an independent multinomial selections model (McCracken et al. 1998) Ramsey and Usner 2003 and an extension of that model to include a persistence parameter (2003). In both cases, all parameters are assumed to be fixed through time. Radio telemetry data collected for habitat selection studies typically consist of animal relocations through time, suggesting the need for an extension to these models. We use a Bayesian approach that allows for the habitat selection probabilities, persistence parameter, or both, to change with season. These extensions are particularly important when movement patterns are expected to differ seasonally and/or when availabilities of habitats change throughout the study period due to weather or migration. We implement and compare the models using radio telemetry data for westslope cutthroat trout in two streams in eastern Oregon.     

无磷洗衣粉并非控制水体富营养化的灵丹妙药

很多人认为，使用无磷洗衣粉便能有效解决令人烦恼的“水华”或“赤潮”问题。然而，无论是西方国家长达20年的实践经验，还是我国目前面临的现状显示，无磷洗衣粉对遏制水体富营养化现象作用并不十分明显!究其原因，面源污染和生活污水中的其它磷来源才是构成水体磷负荷的主要来源。因此，在国内外普遍兴建污水处理厂的前提下，是否有必要以洗涤效果不佳、可能会产生新的环境问题的无磷洗衣粉替代传统洗衣粉目前正遭到国外一些有识之士质疑。文章介绍了国外这方面的情况，并总结性地提出了我国在此方面应注意的问题。     

Fighting behavior in hermit crabs: the combined effect of resource-holding potential and resource value in Pagurus longicarpus

A study was conducted to determine whether asymmetries in both resource-holding potential (RHP) and resource value (RV) influence dominance and fighting behavior in the hermit crab Pagurus longicarpus. A total of 120 groups of three crabs were observed for 10 min in four experiments that tested all diverse combinations of equal/different RHP (i.e. ‘body size’) and equal/different RV (i.e. ‘shell size’ and ‘shell quality’). In a fifth experiment, dominant and subordinate individuals of the same size category (26 groups) were forced to enter shells of opposite quality than those previously occupied, and then the behavior of the reconstituted original groups was observed for additional 10 min. As expected, crabs in lower quality shells were more willing to initiate and to escalate fights. However, their attacks were directed to any crab of the group, independently of the defender's shell quality, and the fight duration did not vary with the different value of the resources at stake. This may indicate that P. longicarpus is unable to assess the quality of the shells available in its social environment but bases its tactical decisions during fights solely on its own resource. This suggestion was confirmed by the change in the fighting behavior of crabs whose shell quality was experimentally altered. This manipulation induced an overall increase in the intensity of aggression, drastic modification of crab behavior, and inversion of the hierarchy even though these crabs have had previous experiences of wins/losses and were familiar to the other members of the group. In this species, large crab size and/or the occupancy of adequate (and oversized) shells appeared to be the most likely determinant of contest resolution. Individuals seemed to retain a memory of the previously held resource and behaved accordingly.     

Remarkable Amphibian Biomass and Abundance in an Isolated Wetland: Implications for Wetland Conservation

Abstract:  Despite the continuing loss of wetland habitats and associated declines in amphibian populations, attempts to translate wetland losses into measurable losses to ecosystems have been lacking. We estimated the potential productivity from the amphibian community that would be compromised by the loss of a single isolated wetland that has been protected from most industrial, agricultural, and urban impacts for the past 54 years. We used a continuous drift fence at Ellenton Bay, a 10-ha freshwater wetland on the Savannah River Site, near Aiken, South Carolina (U.S.A.), to sample all amphibians for 1 year following a prolonged drought. Despite intensive agricultural use of the land surrounding Ellenton Bay prior to 1951, we documented 24 species and remarkably high numbers and biomass of juvenile amphibians (>360,000 individuals; >1,400 kg) produced during one breeding season. Anurans (17 species) were more abundant than salamanders (7 species), comprising 96.4% of individual captures. Most (95.9%) of the amphibian biomass came from 232095 individuals of a single species of anuran (southern leopard frog [Rana sphenocephala ]). Our results revealed the resilience of an amphibian community to natural stressors and historical habitat alteration and the potential magnitude of biomass and energy transfer from isolated wetlands to surrounding terrestrial habitat. We attributed the postdrought success of amphibians to a combination of adult longevity (often >5 years), a reduction in predator abundance, and an abundance of larval food resources. Likewise, the increase of forest cover around Ellenton Bay from <20% in 1951 to >60% in 2001 probably contributed to the long-term persistence of amphibians at this site. Our findings provide an optimistic counterpoint to the issue of the global decline of biological diversity by demonstrating that conservation efforts can mitigate historical habitat degradation.