中空纤维膜超滤聚丙烯酸钠溶液

研究聚丙烯酸钠（PAAS）溶液的超滤行为,考察各操作参数对膜通量（J）和截留系数（R）的影响,结果表明,J随运行时间延长衰减不明显,随压差增大呈线性递增,随温度升高而增大,pH高于5时J基本不变;R随压差增大或温度升高均下降,随pH增大而增大。建立膜阻力（rf）模型,研究影响rf的主要因素,发现,rf随压差增大而增大,随温度升高而减少,pH低于5时rf随pH增大而迅速下降。研究PAAS溶液浓缩过程,当体积浓缩因子为16时,J衰减明显,截留液PAAS浓度（Cr）呈线性递增,渗透液PAAS浓度（Cp）在较长时期内基本不变,至浓缩后期,Cp轻微下降。以去离子水对浓缩液予以洗涤,随着洗涤液体积增大,Cr轻微下降,Cp逐渐趋于零。     

不同组合垂直潜流式人工湿地对高碳或氮污水的净化效果

4种组合的垂直潜流式人工湿地在高C和高N污染物负荷条件下都可以得到很好的污染物降解效果.VDFVUF湿地组合被确定为最优的组合,它在夏末(7月和8月)和初秋(9月)可以得到较高的污染物去除率,且在8月份可以达到最大值.VDF-VUF湿地组合对于COD、TN和TP去除率的平均值在高C污染物负荷条件下分别为(96.97 ±6.32)％、(89.45 ±5.29)％和(83.12±6.03)％;在高N污染物负荷条件下分别为(93.21±7.84)％、(94.27±4.36)％和(82.36±5.52)％.各种人工湿地组合的COD和TN的去除率都受到了季节变化、湿地组合类型以及这两者的综合效应的显著影响;但是TP的去除率则不受任何因素的显著影响.     

阳离子表面活性剂改性四氧化三铁-沸石复合材料对水中刚果红的去除作用

制备了四氧化三铁-沸石复合材料(磁性沸石)和阳离子表面活性剂改性磁性沸石(有机改性磁性沸石),采用X射线衍射分析对有机改性磁性沸石进行了表征,通过批量实验考察了有机改性磁性沸石对水中刚果红的吸附性能,并对相关的吸附机制进行了讨论。实验表明,有机改性磁性沸石对水中的刚果红具备良好的吸附能力,且有机改性磁性沸石对刚果红的吸附能力远远高于磁性沸石。有机改性磁性沸石对水中刚果红的吸附动力学符合准二级动力学模型,吸附平衡数据可以采用Langmuir、Freundlich和Dubinin-Radushkevich(D-R)等温吸附模型加以描述。根据Langmuir等温吸附模型计算得到的有机改性磁性沸石对刚果红的最大吸附容量为146 mg/g(pH 7和30℃)。有机改性磁性沸石对水中刚果红的吸附属于自发和放热的过程。有机改性磁性沸石吸附水中刚果红的作用机制包括静电吸引、有机相分配、氢键和表面配位。X射线衍射分析结果表明,有机改性磁性沸石含四氧化三铁,吸附刚果红后的有机改性磁性沸石可以很容易地通过外加磁场的作用快速地从水中分离出来。上述结果表明,有机改性磁性沸石适合作为一种吸附剂去除废水中的刚果红。     

Water–gas exchange of organochlorine pesticides at Lake Chaohu, a large Chinese lake

Organochlorine pesticides (OCPs), a potential threat to ecosystems and human health, are still widely residual in the environment. The residual levels of OCPs in the water and gas phase were monitored in Lake Chaohu, a large Chinese lake, from March 2010 to February 2011. Nineteen types of OCPs were detected in the water with a total concentration of 7.27?±?3.32 ng/l. Aldrin, DDTs and HCHs were the major OCPs in the water, accounting for 38.3 %, 28.9 % and 23.6 % of the total, respectively. The highest mean concentration (12.32 ng/l) in the water was found in September, while the lowest (1.74 ng/l) was found in November. Twenty types of gaseous OCPs were detected in the atmosphere with a total concentration of 542.0?±?636.5 pg/m³. Endosulfan, DDTs and chlordane were the major gaseous OCPs in the atmosphere, accounting for 48.9 %, 22.5 % and 14.4 % of the total, respectively. The mean concentration of gaseous OCPs was significantly higher in summer than in winter. o,p′-DDE was the main metabolite of DDT in both the water and gas phase. Of the HCHs, 52.3 % existed as β-HCH in the water, while α-HCH (37.9 %) and γ-HCH (30.9 %) were dominant isomers in the gas phase. The average fluxes were ?21.11, ?3.30, ?152.41, ?35.50 and ?1314.15 ng/(m²?day) for α-HCH, γ-HCH, HCB, DDT and DDE, respectively. The water–gas exchanges of the five types of OCPs indicate that water was the main potential source of gaseous OCPs in the atmosphere. A sensitivity analysis indicated that the water-gas flux of α-HCH, γ-HCH and DDT is more vulnerable than that of HCB and DDE to the variation of the parameters. The possible source of the HCHs in the water was from the historical usage of lindane; however, that in the air was mainly from the recent usage of lindane. The technical DDT and dicofol might be the source of DDTs in the water and air.     

The residual levels and health risks of hexachlorocyclohexanes (HCHs) and dichloro-diphenyl-trichloroethanes (DDTs) in the fish from Lake Baiyangdian, North China

The tissue and organs (muscle, brain, liver, and gill) of four species of freshwater fish from Lake Baiyangdian were analyzed for hexachlorocyclohexanes (HCHs) and dichloro-diphenyl-trichloroethanes (DDTs). The distribution characteristics were analyzed for HCHs and DDTs in various tissue and organs, which determined the health risks for humans. The research results showed that the wet weight content of all HCHs (∑HCHs) ranged from 0.05?～?14.53 ng?g^?1, with a mean of 3.47 ng?g^?1. The wet weight content of all DDTs (∑DDTs) ranged from ND to 8.51 ng?g^?1, with a mean of 2.41 ng?g^?1. For the various species of fish, the residual level of ∑HCHs was relatively higher in chub and grass carp and lowest in snakehead. The residual level of ∑DDTs was the highest in snakehead and did not exhibit a significant variance in the other three species. For the various tissues and organs, the contents of HCHs and DDTs were both highest in the fish liver, second highest in the fish gill, and lowest in the fish brain and muscle. Among the four types of isomers, the residual level of γ-HCH was relatively higher, while the residual level of α-HCH was the lowest. The content of p,p′-DDE was significantly greater to other forms of DDT and its isomer. The residual levels of HCHs and DDTs in fish were both below the national standard. However, the carcinogenic risk from the HCHs in parts of the tissue and organs of four fish species in Lake Baiyangdian exceeded the screen value threshold set by USEPA.     

Assessing the Relationship Between Landscape Patterns and Nonpoint‐Source Pollution in the Danjiangkou Reservoir Basin in China1

Abstract: The constrained ordination method from quantitative ecology was utilized to assess the relationship between landscape patterns and nonpoint‐source (NPS) pollution for the purpose of identifying effective water‐quality improvement practices in Danjiangkou Reservoir (DJKR) basin, China. The soil and water assessment tool (SWAT) was applied to simulate NPS pollution and the Fragstats model was applied to calculate the landscape metrics. The study concluded that organic nutrients formed the main NPS pollutant in the DJKR basin and that most of the NPS pollution occurred along with soil loss. Based on partial redundancy analysis, the conclusion that landscape metrics were significantly correlated to NPS pollution indices was obtained. Specifically, the composition of LULC (land use/land cover) was the most effective factor to estimate NPS pollution. Dry cultivated land was identified as the main source of NPS pollution, and paddy fields were characterized with the most intensive soluble nutrients loss. In addition, the reason that fragmented and complex landscape patterns exacerbate NPS pollution was that natural landscape composed most of this area. Moreover, the fragmented natural landscape indicated intensive agricultural activities that were the crucial trigger for NPS pollution. Combined with the economic condition in China, Conversion of Cropland to Forests Program (CCFP) should be conducted selectively and gradually in the DJKR basin.     

Impacts of simulated acid rain on cation leaching from the Latosol in south China

Acid rain is a problem of increasing agricultural, environmental, and ecological concerns worldwide. This study investigated impacts of simulated acid rain (SAR) on cation leaching from the Latosol in south China. Latosol is an acidic red soil and occurs in the tropical rainforest biome. Laboratory experiments were performed by leaching the soil columns with the SAR at a pH range from 2.5 to 7.0 over a 21-day period. A linear increase in effluent K⁺ concentration was found at the SAR pH 3.0, whereas an exponential decrease in effluent Na⁺ concentration was observed at all levels of the SAR pH. In general, leaching of Ca²⁺ and Mg²⁺ from the Latosol increased as the SAR pH decreased. There was a very good nonlinear correlation between the removal of soil K⁺ and the SAR pH (R² = 0.91), a good nonlinear correlation between the removal of soil Mg⁺² and the SAR pH (R² = 0.83), a fairly good nonlinear correlation between the removal of soil Ca⁺² and the SAR pH (R² = 0.56), and no correlation between the removal of soil Na⁺ and the SAR pH (R² = 0.06). Our study further revealed that the removal of soil cations such as K⁺, Ca⁺², and Mg⁺² can be quantified by the quadratic polynomial equations. In addition, impacts of the SAR on cation leaching depended not only on the SAR pH but also on the original soil pH.     

煤灰中部分重金属元素含量与燃料工况的关系模型

本文研究了燃烧温度、燃烧气氛、煤粉细度和灰粒细度等因素与煤燃烧产生的细微粒子中部分重金属元素含量的关系,建立了灰粒中元素含量与备因素关系的模型,发现燃烧工况和灰粒细度与灰粒中元素的含量具有一定的相关关系.用模型对不同灰粒中的元素含量进行了预报,可用控制燃烧条件来减少重金属元素向大气的释放.     

Study on the distribution characteristics and ecological risk of heavy metal elements in coal gangue taken from 25 mining areas of China

Environmental Science and Pollution Research - The long-term, high-yield production of coal has resulted in the large-scale accumulation of coal gangue on the ground surface, which causes serious...