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161.
Michael G. McManus Gregory J. Pond Lou Reynolds Michael B. Griffith 《Journal of the American Water Resources Association》2016,52(2):494-507
A challenge for statewide stream monitoring is visualizing the spatial and statistical characteristics of such data to compare the biotic condition of watersheds and relate that condition to watershed‐level estimates of instream variables. We used linked micromaps on stream survey data of 25 subbasins (766‐5,982 km2) for biotic condition, nine water quality, and two habitat variables. Subbasin biotic condition was negatively correlated with conductivity, magnesium and sulfate concentrations, and weakly positively correlated with habitat scores of sedimentation and embeddedness, with higher scores indicating better habitat. Positive spatial autocorrelation was detected among the subbasins in both habitat variables, iron concentration, pH, and exceedances of fecal coliform criteria as shown in linked micromaps. A spatial principal components analysis reduced the 11 environmental variables to two principal axes. The first axis synthesized a gradient of water quality and habitat scores among the subbasins. Subbasin biotic condition regressed on first axis subbasin scores had a significant, negative slope and accounted for 55% of the variation. Subbasins in degraded biotic condition had elevated conductivities and ion concentrations in northern and southern subbasins, and low habitat scores in western subbasins. Through linked micromaps, we compared the biotic condition among subbasins and identified stressors prevalent among subbasins that affected biotic condition. 相似文献
162.
Xiao-Yi Lou Yao-Guang Guo Dong-Xue Xiao Zhao-Hui Wang Shu-Yu Lu Jian-She Liu 《Environmental science and pollution research international》2013,20(9):6317-6323
Transition-metal is known to catalyze peroxymonosulfate (PMS) decomposition to produce sulfate radicals. Here we report reactions between PMS and chloride, without a need of transition metals, also can be used to degrade organic dye pollutant (Rhodamine B, (RhB)). Some important operating parameters, such as dosages of PMS and Cl?, pH of solution, temperature, ionic strength, and several common cations, were systematically investigated. Almost complete decoloration of RhB was achieved within 5 min ([PMS]?=?0.5 mM, [Cl?]?=?120 mM, and pH 3.0), and RhB bleaching rate increased with the increased dosages of both PMS and chloride ion, following the pseudo-first-order kinetic model. However, the total organic carbon (TOC) removal results demonstrated that the decoloration of RhB was due to the destruction of chromophore rather than complete degradation. RhB decoloration could be significantly accelerated due to the high ionic strength. Increasing of the reaction temperature from 273 K to 333 K was beneficial to the RhB degradation, and the activation energy was determined to be 32.996 kJ/mol. Bleaching rate of RhB with the examined cations increased with the order of NH4 +?<?Na+?<?K+?<?Al3+?<?Ca2+?<?Mg2+. Some major degradation products of RhB were identified by GC-MS. The present study may have active technical implications for the treatment of dyestuff wastewater in practice. 相似文献
163.
为了在低温13~14%下取得较好的硝化效果,分3个温度阶段25℃,16~17℃,13—14℃对活性污泥进行了驯化培养,研究了进水氨氮浓度和混合液COD对硝化污泥的影响。实验结果表明,硝化污泥经过驯化培养后,氨氮去除率可达80%以上,且在DO浓度为2ing/L,pH为6.7~7.5,进水氨氮为300mg/L,混合液COD为80mg/L条件下,硝化污泥能取得较快的增长,氨氮平均去除率可达89%。 相似文献
164.
Michael D. Lebowrtz James J. Quackenboss Mary Lou Soczek Mel Kollander Steve Colome 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1411-1415
Several investigators have developed indoor air quality questionnaires for use in field studies. The approach used in many of them have numerous features in common, but most of them are unique in their content (wording, format, item selection). It is thought that indoor air quality research could be greatly advanced if the primary or fundamental questions and instruments could be consolidated. The use of a basic set of "standard" questions would permit intercomparison of results from different research studies. It is generally agreed that environmental inventory questionnaires (EIQ) help to classify, at least in screening, relative concentration estimates, which precede exposure estimation. Thus, such instruments are not equivalent to monitoring for exposure assessment. However, data linkage and mega data bases are important for some comparative analyses of exposure assessment and exposure-response relationships. Standard instruments such as the EIQ are useful as a screening device to precede other tests to allow identification of potentially high exposure situations. They can also amplify information from other tests. General usage of standard questionnaires and protocols can lead to cumulative improvements in data collection, specificity and effectiveness. This has been the rationale for the present efforts by investigators to form a standardized environmental inventory questionnaire, under the auspices of the U.S. Environmental Protection Agency (EPA), Gas Research Institute (GRI), and Electric Power Research Institute (EPRI). 相似文献
165.
利用水泥的水化过程易受有机物影响的特点,采用硅酸盐水泥深度处理了垃圾渗滤液膜生物反应器(MBR)工艺出水,考察了不同因素,如投加量、初始pH、反应时间及振荡速率等对于渗滤液尾水中有机物的去除效果以及最佳工艺条件,并分析了渗滤液尾水中有机物的去除机理。结果表明,水化过程对渗滤液尾水中的有机物去除性能良好,且对不同有机物具有一定的选择性,尤其对具有近紫外区(200~400 nm)吸收峰特征的有机物去除效果更佳,同时发现,当投加量为50 g/L、pH=8.3(原渗滤液pH)、反应时间为24 h和振荡速度为200 r/min时,去除效果最佳,其COD、TOC和UV254的平均去除率分别达到55.6%、62.1%和68.8%。 相似文献
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170.
Kibet LC Allen AL Kleinman PJ Feyereisen GW Church C Saporito LS Way TR 《Journal of environmental quality》2011,40(2):412-420
The application of poultry litter to soils is a water quality concern on the Delmarva Peninsula, as runoff contributes P to the eutrophic Chesapeake Bay. This study compared a new subsurface applicator for poultry litter with conventional surface application and tillage incorporation of litter on a Coastal Plain soil under no-till management. Monolith lysimeters (61 cm by 61 cm by 61 cm) were collected immediately after litter application and subjected to rainfall simulation (61 mm h(-1) 1 h) 15 and 42 d later. In the first rainfall event, subsurface application of litter significantly lowered total P losses in runoff (1.90 kg ha(-1)) compared with surface application (4.78 kg ha(-1)). Losses of P with subsurface application were not significantly different from disked litter or an unamended control. By the second event, total P losses did not differ significantly between surface and subsurface litter treatments but were at least twofold greater than losses from the disked and control treatments. A rising water table in the second event likely mobilized dissolved forms of P in subsurface-applied litter to the soil surface, enriching runoff water with P. Across both events, subsurface application of litter did not significantly decrease cumulative losses of P relative to surface-applied litter, whereas disking the litter into the soil did. Results confirm the short-term reduction of runoff P losses with subsurface litter application observed elsewhere but highlight the modifying effect of soil hydrology on this technology's ability to minimize P loss in runoff. 相似文献