An intensive study on aerosol optical properties and affecting factors in Nanjing, China

The optical properties of aerosol as well as their impacting factors were investigated at a suburb site in Nanjing during autumn from 14 to 28 November 2012. More severe pollution was found together with lower visibility. The average scattering and absorption coefficients(B sca and B abs) were 375.7 ± 209.5 and 41.6 ± 18.7 Mm~(-1), respectively. Higher ?ngstr?m absorption and scattering exponents were attributed to the presence of more aged aerosol with smaller particles. Relative humidity(RH) was a key factor affecting aerosol extinction. High RH resulted in the impairment of visibility, with hygroscopic growth being independent of the dry extinction coefficient. The hygroscopic growth factor was 1.8 ± 1.2 with RH from 19% to 85%.Light absorption was enhanced by organic carbon(OC), elemental carbon(EC) and EC coatings,with contributions of 26%, 44% and 75%(532 nm), respectively. The B sca and B abs increased with increasing N_(100)(number concentration of PM_(2.5)with diameter above 100 nm), PM_1 surface concentration and PM_(2.5)mass concentration with good correlation.     

Phosphate adsorption performance of a novel filter substrate made from drinking water treatment residuals

Phosphate is one of the most predominant pollutants in natural waters. Laboratory experiments were conducted to investigate the phosphate adsorption performance of a(NFS) made from drinking water treatment residuals. The adsorption of phosphate on the NFS fitted well with the Freundlich isotherm and pseudo second-order kinetic models. At p H 7.0, the maximum adsorption capacity of 1.03 mg/g was achieved at 15°C corresponding to the wastewater temperature in cold months, and increased notably to 1.31 mg/g at 35°C.Under both acidic conditions(part of the adsorption sites was consumed) and basic conditions(negative charges formed on the surface of NFS, which led to a static repulsion of PO43-and HPO42-), the adsorption of phosphate was slightly inhibited. Further study showed that part of the adsorption sites could be recovered by 0.25 mol/L Na OH. The activation energy was calculated to be above 8.0 k J/mol, indicating that the adsorption of phosphate on NFS was probably a chemical process. Considering the strong phosphate adsorption capacity and recoverability, NFS showed great promise on enhancing phosphate removal from the secondary treated wastewater in the filtration process.     

Evaluation of drinking water treatment combined filter backwash water recycling technology based on comet and micronucleus assay

Based on the fact that recycling of combined filter backwash water（CFBW）directly to drinking water treatment plants（WTP）is considered to be a feasible method to enhance pollutant removal efficiency,we were motivated to evaluate the genotoxicity of water samples from two pilot-scale drinking water treatment systems,one with recycling of combined backwash water,the other one with a conventional process.An integrated approach of the comet and micronucleus（MN）assays was used with zebrafish（Danio rerio）to investigate the water genotoxicity in this study.The total organic carbon（TOC）,dissolved organic carbon（DOC）,and trihalomethane formation potential（THMFP）,of the recycling process were lower than that of the conventional process.All the results showed that there was no statistically significant difference（P>0.05）between the conventional and recycling processes,and indicated that the genotoxicity of water samples from the recycling process did not accumulate in 15 day continuous recycling trial.It was worth noting that there was correlation between the concentrations of TOC,DOC,UV₂₅₄,and THMFPs in water and the DNA damage score,with corresponding R² values of 0.68,0.63,0.28,and 0.64.Nevertheless,both DNA strand breaks and MN frequency of all water samples after disinfection were higher than that of water samples from the two treatment units,which meant that the disinfection by-products（DBPs）formed by disinfection could increase the DNA damage.Both the comet and MN tests suggest that the recycling process did not increase the genotoxicity risk,compared to the traditional process.     

粘土岩处置库陇东预选区社会经济条件调查研究

对陇东地区进行社会经济条件调查,得出陇东地区内有庆阳市和平凉市两大城市,以2013年统计数据为准,庆阳市和平凉市平均人口密度分别为97人/平方千米和219人/平方千米,均高于甘肃省平均人口密度(61人/平方千米);陇东地区生产总值达947．29亿元,占甘肃省生产总值的15．11%,属经济发达地区;且陇东地区含有丰富的煤炭和石油资源;可以得知陇东地区区域人口密度高,经济发达,资源丰富。从社会经济条件分析,陇东地区不适合作为中国高放废物粘土岩地质处置库预选区。     

Effects of pH,initial Pb2+ concentration,and polyculture on lead remediation by three duckweed species

Various geographical duckweed isolates have been developed for phytoremediation of lead. The Pb²⁺ removal efficiency of Lemna aequinoctialis, Landoltia punctata, and Spirodela polyrhiza was investigated in monoculture and polyculture at different levels of pH and initial Pb²⁺ concentrations. L. aequinoctialis was not sensitive to the tested pH but significantly affected by initial Pb²⁺ concentration, whereas synergistic effect of pH and initial Pb²⁺ concentration on removal efficiency of L. punctata and S. polyrhiza was found. Although the majority of polycultures showed median removal efficiency as compared to respective monocultures, some of the polycultures achieved higher Pb²⁺ removal efficiencies and can promote population to remove Pb²⁺. Besides, the three duckweed strains could be potential candidates for Pb²⁺ remediation as compared to previous reports. Conclusively, this study provides useful references for future large-scale duckweed phytoremediation.

     

A hybrid procedure for MSW generation forecasting at multiple time scales in Xiamen City,China

Accurate forecasting of municipal solid waste (MSW) generation is crucial and fundamental for the planning, operation and optimization of any MSW management system. Comprehensive information on waste generation for month-scale, medium-term and long-term time scales is especially needed, considering the necessity of MSW management upgrade facing many developing countries. Several existing models are available but of little use in forecasting MSW generation at multiple time scales. The goal of this study is to propose a hybrid model that combines the seasonal autoregressive integrated moving average (SARIMA) model and grey system theory to forecast MSW generation at multiple time scales without needing to consider other variables such as demographics and socioeconomic factors. To demonstrate its applicability, a case study of Xiamen City, China was performed. Results show that the model is robust enough to fit and forecast seasonal and annual dynamics of MSW generation at month-scale, medium- and long-term time scales with the desired accuracy. In the month-scale, MSW generation in Xiamen City will peak at 132.2 thousand tonnes in July 2015 – 1.5 times the volume in July 2010. In the medium term, annual MSW generation will increase to 1518.1 thousand tonnes by 2015 at an average growth rate of 10%. In the long term, a large volume of MSW will be output annually and will increase to 2486.3 thousand tonnes by 2020 – 2.5 times the value for 2010. The hybrid model proposed in this paper can enable decision makers to develop integrated policies and measures for waste management over the long term.     

Heuristics and biases in cyber security dilemmas

Cyber security often depends on decisions made by human operators, who are commonly considered a major cause of security failures. We conducted 2 behavioral experiments to explore whether and how cyber security decision-making responses depend on gain–loss framing and salience of a primed recall prior experience. In Experiment I, we employed a 2 × 2 factorial design, manipulating the frame (gain vs. loss) and the presence versus absence of a prior near-miss experience. Results suggest that the experience of a near-miss significantly increased respondents’ endorsement of safer response options under a gain frame. Overall, female respondents were more likely to select a risk averse (safe) response compared with males. Experiment II followed the same general paradigm, framing all consequences in a loss frame and manipulating recall to include one of three possible prior experiences: false alarm, near-miss, or a hit involving a loss of data. Results indicate that the manipulated prior hit experience significantly increased the likelihood of respondents’ endorsement of a safer response relative to the manipulated prior near-miss experience. Conversely, the manipulated prior false-alarm experience significantly decreased respondents’ likelihood of endorsing a safer response relative to the manipulated prior near-miss experience. These results also showed a main effect for age and were moderated by respondent’s income level.     

水体中卤乙酸(HAAs)的产生、测定方法与控制途径

对饮用水中普遍存在的消毒副产物形式HAAs的产生、测定方法以及控制途径进行了阐述.并对影响HAAs生成的主要因素投氯量、溴的影响以及卤乙酸副产物(HAAFP)含量等进行了分析.生物活性炭技术是一种非常有效的控制HAAs含量和减少HAAFP含量的方法,对于保障饮用水安全性具有重要意义.     

泰山顶与济南市大气臭氧浓度变化规律研究

利用2003年7月至9月在泰山顶和济南市3个月的臭氧（O3）自动连续监测数据,对两地O3浓度的频率分布、日变化和日际变化等特征进行对照分析。实验结果表明,泰山顶O3小时平均浓度频率分布比较集中,济南市O3小时平均浓度频率分布比较分散。泰山顶各月O3小时平均浓度的平均值和日均值均高于济南市;泰山顶O3小时平均浓度的最大值低于济南市,而O3小时平均浓度的最小值要高于济南市。泰山顶O3小时平均浓度日变化规律与济南市O3小时平均浓度日变化规律有很大差别,泰山顶O3小时平均浓度日变化很平缓,最大值与最小值相差不大,济南市O3小时平均浓度一般在中午和午后浓度较高,早晨和夜晚较低。