Is urban development an urban river killer? A case study of Yongding Diversion Channel in Beijing, China

The high population and concrete environment alter urban areas by changing temperature, rainfall runoff, and water resource utilization activities. This study was conducted to investigate the water quality features of the Yongding Diversion Channel in Beijing, China, and its relationship with rainfall and urban development. Monthly water quality data were obtained from April to October of 2004 at monitoring sites of Sanjiadian, Gaojing, Luodaozhuang, and Yuyuangtan. The monthly water quality grades from 2007 to 2011 were also investigated and compared with those of other rivers. Dissolved oxygen and pH showed greater decreases after one or two moderate rainfall events than several light rainfall events. The potassium permanganate index （CODMn）, ammonia nitrogen （NH3-N） and total phosphorus （TP） increased more after several light rainfall events than after one or two moderate or heavy rainfall events. Pollutant concentrations （CODMn, NH3-N, TP） in downstream regions showed greater changes than those in upstream areas after heavy rainfall events. Intense human activities around the channel greatly influenced the water quality of the channel in rainy season because of runoff pollution; however, heavy rainfall had a strong dilution effect on the pollutant concentrations in rivers. Overall, urban development has obviously deteriorated the water quality of the Yongding Diversion Channel as indicated by an increase in the water quality index from 3.22 in 2008 to 4.55 in 2010. The Pearson correlation between monthly rainfall and water quality indices from 2007 to 2011 ranged from 0.1286 to 0.6968, generally becoming weaker as rainfall and rainfall runoff became more random and extreme.     

溢油模型理论及研究综述

油在水中的行为和归宿是一个复杂的过程,包括在重力、表面张力、惯性力和粘性力作用下的物理扩展,挥发、乳化、溶解、光氧化和生物降解等风化过程引起的化学变化,流场、风场等动力因素作用下的漂移运动以及随机部分。通过总结国内外的研究现状,概括了各个模型的理论依据、基本假设、应用范围,并对今后发展方向提出了几点展望。     

Emission reduction characteristics of a catalyzed continuously regenerating trap after-treatment system and its durability performance

The primary purpose of this study was to investigate the effect of a catalyzed continuously regenerating trap(CCRT)system composed of a diesel oxidation catalyst(DOC)and a catalyzed diesel particulate filter(CDPF)on the main gaseous and particulate emissions from an urban diesel bus,as well as the durability performance of the CCRT system.Experiments were conducted based on a heavy chassis dynamometer,and a laboratory activity test as well as X-ray photoelectron spectroscopy(XPS)test were applied to evaluate the changes of the aged CCRT catalyst.Results showed that the CCRT could reduce the CO by 71.5%and the total hydrocarbons(THC)by 88.9%,and meanwhile promote the oxidation of NO.However,the conversion rates for CO and THC dropped to 25.1%and 55.1%,respectively,after the CCRT was used for one year(～60,000 km),and the NO oxidation was also weakened.For particulate emissions,the CCRT could reduce 97.4%of the particle mass(PM)and almost 100%of the particle number(PN).The aging of the CCRT resulted in a reduced PM trapping efficiency but had no observable effect on the PN;however,it increased the proportion of nucleation mode particles.The activity test results indicated that the deterioration of the CCRT was directly relevant to the increase in the light-off temperatures of the catalyst for CO,C_3H_8 and NO_2.In addition,the decreased concentrations of the active components Pt~(2+) and Pt~(4+) in the catalyst are also important factors in the CCRT deterioration.     

Dovehicular emissions dominate the source of C6-C8aromatics in the megacity Shanghai of eastern China?

The characteristic ratios of volatile organic compounds (VOCs) to i-pentane, the indicator of vehicular emissions, were employed to apportion the vehicular and non-vehicular contributions to reactive species in urban Shanghai. Two kinds of tunnel experiments, one tunnelwith more than 90% light duty gasoline vehicles and the otherwithmore than 60% light duty diesel vehicles, were carried out to study the characteristic ratios of vehicle-related emissions from December 2009 to January 2010. Based on the experiments, the characteristic ratios of C6-C8 aromatics to i-pentane of vehicular emissions were 0.53 ± 0.08 (benzene), 0.70 ± 0.12 (toluene), 0.41 ± 0.09 (m,p-xylenes), 0.16 ± 0.04 (o-xylene), 0.023 ± 0.011 (styrene), and 0.15 ± 0.02 (ethylbenzene), respectively. The source apportionment results showed that around 23.3% of C6-C8 aromatics in urban Shanghai were from vehicular emissions, which meant that the non-vehicular emissions had more importance. These findings suggested that emission control of non-vehicular sources, i.e. industrial emissions, should also receive attention in addition to the control of vehicle-related emissions in Shanghai. The chemical removal of VOCs during the transport from emissions to the receptor site had a large impact on the apportionment results. Generally, the overestimation of vehicular contributions would occur when the VOC reaction rate constant with OH radicals (k_OH) was larger than that of the vehicular indicator, while for species with smaller kOH than the vehicular indicator, the vehicular contribution would be underestimated by the method of characteristic ratios.     

Occurrence of veterinary antibiotics in struvite recovery from swine wastewater by using a fluidized bed

Antibiotics in wastewater pose pharmacological threats to phosphorous recovery. Recovered struvite particles possessed significantly antibiotic residues. Smaller granules contained much more antibiotics than the larger ones. Organic matters and struvite granulation process exerted significant impacts. Recovering phosphorus from livestock wastewater has gained extensive attention. The residue of veterinary antibiotics in the wastewater may be present in the recovered products, thereby posing pharmacological threats to the agricultural planting and human health. This study investigated antibiotic occurrence in the struvite particles recovered from swine wastewater by using a fluidized bed. Results revealed that tetracyclines possessed significant residues in the struvite granules, with the values ranging from 195.2 mg·kg⁻¹ to 1995.0 mg·kg⁻¹. As for fluoroquinolones, their concentrations varied from 0.4 mg·kg⁻¹ to 1104.0 mg·kg⁻¹. Struvite particles were of various sizes and shapes and displayed different antibiotic adsorption capacities. The data also showed that the smaller granules contained much more antibiotics than the larger ones, indicating that the fluidized granulation process of struvite crystals plays an important role on the accumulation of antibiotics. For tetracyclines, organic matters and struvite adsorption exerted significant impacts on tetracyclines migration. The outcomes underscore the need to consider the residues of antibiotics in resource recovery from wastewater because they exert pharmacological impacts on the utilization of recovered products.     

The association between heavy metal soil pollution and stomach cancer: a case study in Hangzhou City,China

Stomach cancer (SC) is a severe health burden, with nearly half of the world’s cases found in China. Noticeably, the emissions of heavy metals into the environment have increased alongside rapid urbanization and industrialization in China. However, as regards carcinogenic associations, the relationship between heavy metals and SC is yet unclear. Based on 9378 newly diagnosed SC cases in Hangzhou City from 2009 to 2012, this work is concerned with the quantitative characterization of the spatial distribution pattern of SC incidence and its geographical association with soil heavy metals by means of a novel geographical model. The results show that (a) Cd is one of the severe soil pollutants in Hangzhou; (b) higher SC incidence clusters are in central Hangzhou, whereas lower clusters are found in the northeast and southwest with a male to female incidence ratio about 2.2:1; (c) although when considered separately, the heavy metals in this work do not have a considerable impact on the distribution of SC incidence in Hangzhou City, nevertheless, the joint effects of multiple heavy metals have significant impacts on SC risk. The present work calls for a rigorous quantitative assessment of the integrated heavy metal soil pollution and its effects on SC incidence.     

Preparation and Adsorption Performance of Nano-hydroxyapatite-Enhanced Acrylamide Hydrogel Adsorbent

Journal of Polymers and the Environment - In this study, a hydrogel adsorbent was successfully synthesized using hydroxyapatite/acrylamide/β-cyclodextrin to adsorb heavy metal ions and dyes in...