Spatiotemporal evaluation of water quality incidents in Japan between 1996 and 2007

We present a spatiotemporal evaluation of water quality incidents in Japan considering incident numbers, incident causes, pollutant categories, and pollution effects. Water pollution incidents in first-class river systems almost tripled to about 1487 in the 12 years from 1996 to 2007. In addition, oil makes up the largest proportion of pollutants nationwide (76.61%) and the major source of pollution for each region in Japan. Moreover, every category shows a growth trend, especially since 2005. The main cause of incidents was “Unknown” (43%), followed by “Poor working practice” (24%), and then by “Accident” (10%) and “Other” (10%). In Hokuriku, however, the main cause of incidents was “Poor working practice” (36%), which is greater than “Unknown” (30%). Finally, waterworks (approximately 60%) was the largest of four kinds of water supply infrastructure affected by pollution incidents, followed by simplified waterworks. The population affected by offensive odors and tastes peaked in 1990 and has been decreasing. Overall, the results show the characteristics of incidents from 1996 to 2007, with significant implications for adaptation measures, strategies and policies to reduce water quality incidents.     

基于生物标志物法的珠江流域有机碳溯源及DIC施肥效应研究

内源有机碳由地表水体水生光合固定DIC产生,是岩石风化碳汇的重要组成部分。为准确区分河陆地流水体中的内源有机碳及计算其所占比例,本文选取珠江流域作为研究区,通过不同季节的野外采样调查,利用类脂生物标志物法,结合传统水化学特征,揭示河流中有机碳的来源差异;最终根据有机碳的时空分布规律与水-岩-土-气-生相互作用分析,明确流域岩性及气候变化对碳汇的影响。结果表明:(1)珠江流域水体中冬季和夏季内源有机碳占总有机碳比例的平均值分别为65%和54%,表明水生植物光合作用导致的初级生产力的重要性;(2)内源有机碳比例和水生藻类生物量与DIC浓度和呈现出显著的正相关关系,表明DIC对水生植物光合作用具有施肥效应;(3)雨季因降雨稀释DIC浓度和冲刷外源有机质,对水生植物的施肥效应减弱,生成的内源有机质减少,且携带的外源有机质增加,导致内源比例减少;(4)高悬浮质(TSS)可以遮挡水体表层太阳光,减弱水生光合作用强度,降低内源有机碳的形成;但在TSS浓度比较低的情况下,其对水生植物生长繁殖的影响则体现在为其提供空间和营养物,从而增加水生藻类生物量及内源有机碳比例。     

Comparison of different semi-empirical algorithms to estimate chlorophyll-a concentration in inland lake water

Based on in situ water sampling and field spectral measurement from June to September 2004 in Lake Chagan, a comparison of several existing semi-empirical algorithms to determine chlorophyll-a (Chl-a) content was made by applying them to the field spectra and in situ chlorophyll measurements. Results indicated that the first derivative of reflectance was well correlated with Chl-a. The highest correlation between the first derivative and Chl-a was at 680 nm. The two-band model, NIR/red ratio of R_710/670, was also an effective predictor of Chl-a concentration. Since the two-band ratios model is a special case of the three-band model developed recently, three-band model in Lake Chagan showed a higher resolution. The new algorithm named reverse continuum removal relies on the reflectance peak at 700 nm whose shape and position depend strongly upon chlorophyll concentration: The depth and area of the peak above a baseline showed a linear relationship to Chl-a concentration. All of the algorithms mentioned proved to be of value and can be used to predict Chl-a concentration. Best results were obtained by using the algorithms of the first derivative, which yielded R ² around 0.74 and RMSE around 6.39 μg/l. The two-band and three-band algorithms were further applied to MERIS when filed spectral were resampled with regard to their center wavelengths. Both algorithms showed an adequate precision, and the differences on the outcome were small with R ² = 0.70 and 0.71.     

Assessment of Chlorophyll-a Concentration and Trophic State for Lake Chagan Using Landsat TM and Field Spectral Data

In this study, we present the digital evaluation of Landsat TM data and field spectral measurements for retrieving chlorophyll-a (chl-a) concentration and trophic state index in Lake Chagan of Northeast China. Chl-a concentration of the lake can be estimated from the band ratio (TM4/TM3) and the field spectral data at 670 nm (absorption peak) and at 700 nm (reflectance peak). The results show that the best determination coefficient (R ²) is 0.67 from the TM data, by which chl-a distribution can be mapped. Based on chl-a determination from laboratory analysis, field spectral and TM data, the modified trophic state index (TSI_M) was applied to assess the lake’s trophic state. With the available data in Lake Chagan, each algorithm demonstrates the similar result for assessing the lake’s chl-a and trophic state. Our results indicate that Landsat TM and field spectral data could be used effectively to determine chl-a concentration and evaluate the trophic state of Lake Chagan in the study.     

Differences in the treatment efficiency of a cold-resistant floating bed plant receiving two types of low-pollution wastewater

A floating bed system vegetated with Oenanthe javanica was adopted in this study to treat two types of low-pollution wastewater (LPW): polluted river water (PRW) and treated domestic wastewater (DW). The water was treated for 111 days during the low-temperature season. The results indicated that the total nitrogen (TN) removal rates were higher in the DW groups than in the PRW groups during the initial 30 days. This difference may stem from the different C/N ratio of the influent. As the water temperature rose above 15.5 °C after March 12, the purification capability of nitrogen in the DW groups was enhanced, and the removal rates of TN were 89.8 and 76.8 % in DW and the control 2 at 111 days. Conversely, the performance of total phosphorus (TP) removal was robust during the initial stage of the experiment, despite receiving domestic wastewater with a relatively high N/P ratio (16:1). The TP removal rates in DW were as high as 91.5 % compared to 78.9 % in PRW at 30 days. At the same time, the N/P ratios of plant tissue were higher in the DW groups compared to that in the PRW groups. Plant uptake played a significant role in nutrient removal in the PRW groups (52.5 % for TN, 68.2 % for TP), followed by sedimentation. In contrast, plant uptake only accounted for 25.3 % of TN removal and 24.1 % of TP removal in DW. The results provide engineering parameters for the future design of an ecological remediation technology for LPW purification.     

Nonmethane Hydrocarbons in Ambient Air of Hazy and Normal Days in Foshan, South China

A first study of nonmethane hydrocarbons (NMHCs) on hazy and normal days was performed in Foshan for providing deep insight into the local deteriorating air quality. Ethane, propane, i-pentane, ethene, propene, ethyne, benzene, and toluene were eight most abundant compounds, accounting for 71%-85% of total NMHCs. Most hydrocarbons showed much higher levels on hazy days than normal days together with hydrocarbon/ethyne ratios and diurnal variations, indicating hazy days are more dominated by vehicular emission. Correlation coefficients (R(2)) of ethane, propane, ethane, propene, benzene, and total NMHCs with ethyne were 0.62-0.83, indicating these compounds are mainly related to vehicular emission. R(2) analysis indicated that solvent usage is responsible for toluene and other aromatic hydrocarbons (e.g., ethylbezene). Benzene/toluene (B/T) ratio was 0.44±0.23 during whole sampling periods, again indicating vehicular emission is the dominant source. Lower B/T ratio (0.30±0.14) on hazy days than that (0.58±0.21) on normal days suggested that solvent usage emitted toluene.     

基于GIS的陕西省滑坡灾害空间分异特征探讨

滑坡是陕西最主要的地质灾害形式。以陕西省县域滑坡密度为测度指标,运用ARCGIS9.2、Geoda095i软件提供的空间分析方法,对滑坡灾害空间分异特征及其原因进行了探讨分析,以期为陕西省滑坡灾害防治及经济与社会可持续发展提供决策参考。     

220kV变压器高压套管发热问题的分析与处理

结合金凤220 kV变电站1号主变C相中压套管发热问题的案例,介绍了该台主变高压套管发热问题的原因与处理过程。通过对高压套管的解体及红外热成像检测的综合分析,确定了造成高压套管发热及最初影响检修人员对发热部位误判的原因,对此类问题的分析与处理提出了具体的建议,可提高运行设备的可靠性。     

高效苯降解菌的筛选鉴定及其在生物过滤塔处理苯的填料选择

从污水处理厂曝气池的活性污泥筛选出1株苯的高效降解真菌HD-3,经形态特征、ITS基因序列系统学分析,确定HD-3为杂色曲霉Aspergillus versicolor,该菌株8 d内对初始浓度439.3 mg/L和4 393 mg/L的苯的降解率分别为78.56%和33.96%。当苯的初始浓度为439.3 mg/L,HD-3降解苯的最适温度为30℃,最适pH为4.5。在此基础上,提出了采用不同填料生物过滤塔处理苯废气的工艺,并进行了实验研究,实验结果表明:(1)随着苯的浓度提高,苯的降解率逐渐降低。当苯的浓度为200 mg/m3时,煤质柱状活性炭生物过滤塔、生物陶粒生物过滤塔、竹材生物过滤塔的苯平均去除率(REave)分别为93.63%、93.16%和82.38%;当苯的进口浓度增加到3 000 mg/m3时,3种生物过滤塔的苯平均去除率(REave)分别为78.89%、68.43%和51.87%。(2)不同填料对苯的去除能力不同,煤质柱状活性炭>生物陶粒>竹材。     

两种干旱指标在干旱致灾因子危险性中的对比分析——以宁夏为例

致灾因子是灾害风险分析理论体系中的重要组成部分,干旱致灾因子危险性指数由干旱强度和发生概率共同决定。基于致灾因子危险性指数计算模式,对比分析了宁夏中南部山区降水距平百分率和标准化降水指数两种常用干旱指标在致灾因子危险性中的应用。分析结果表明,基于两种干旱指标的宁夏中南部山区干旱致灾因子危险性分布趋势一致,且均与实际相符,考虑到计算的简单易行,可以选择降水距平百分率作为宁夏干旱致灾因子危险性指数分析的依据。从全区干旱灾害风险区划的分析表明,宁夏干旱致灾因子危险性大致呈由南到北逐步增加的趋势。