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21.
Wendy L. Berelson Paul A. Caffrey Jeffrey D. Hamerlinck 《Journal of the American Water Resources Association》2004,40(5):1231-1246
ABSTRACT: In 2002, Wyoming became the first state to complete development of a statewide 1:24,000‐scale Watershed Boundary Dataset (WBD) under the new Federal Standards for Delineation of Hydrologic Unit Boundaries. The product was developed through the coordinated efforts of numerous state, federal, and local entities both within Wyoming and in neighboring states. Development of a comprehensive, standardized hydrologic unit boundary dataset in a “headwaters” state such as Wyoming poses a number of unique challenges. This paper details the WBD's development in Wyoming, highlighting technical methodology development and interagency coordination strategies. Evolution of the WBD standard is reviewed, addressing inconsistencies between definitions for hydro‐logic units and “true” watershed delineations. While automated methods are improving, manual and semi‐automated techniques continue to serve as valuable approaches to hydrologic unit boundary delineation given the quality of digital terrain models and the multijurisdictional nature of watershed based management. This case study provides insight on future development and maintenance of the WBD within and across other states and regions of the country and on opportunities for linking the WBD to related water resource geospatial data products like the National Hydrography Dataset. 相似文献
22.
调研区位于冈瓦纳大陆北缘。中生代以来班公湖—怒江洋及雅鲁藏布江洋相向俯冲、消亡,形成多岛弧—盆系洋陆的转化和陆内汇聚—高原隆升,构成了极复杂的构造格局。根据藏北1:25万邦多幅、措麦幅地质调查成果及区域前人资料综合分析,以多岛弧盆造山模式为理论,认为在Ⅰ级大地构造单元班公湖—怒江结合带及拉达克—冈底斯—拉萨—腾冲陆块上,由北至南可进一步划分晚侏罗世前陆盆地、白垩纪残余海盆、阿索构造混杂岩、燕山期岩浆弧、中生代复合弧后盆地、断隆带、晚燕山—喜马拉雅期岩浆弧带及新近纪—第四纪南北向地堑等Ⅱ级大地构造单元,将复杂的造山活动遗迹进行了有序的时空配置。 相似文献
23.
元宝山发电有限责任公司2号600 MW机组配套电除尘器由于设计效率低、燃烧煤种变化、设备老化等多方面原因,除尘效率下降,除尘器出口烟尘排放浓度超标严重。为了满足新的《火电厂大气污染物排放标准》的要求,对元宝山发电有限责任公司2号机组配套电除尘器进行升级改造,将原有的4台四电场静电除尘器增效改造为4台电袋复合式除尘器。通过电除尘器的改造,降低了除尘器出口粉尘排放浓度,提高了除尘效率,保证了2号机组电除尘器的安全稳定运行。 相似文献
24.
25.
火电机组湿法石灰石-石膏烟气脱硫成本与综合效益分析 总被引:3,自引:0,他引:3
选择单机为300、600、1000MW的火电机组,分别分析了含硫量在0.5%~3.00%范围内,火电机组脱硫成本的变化情况;并以单机300MW火电机组为例分析了给火电机组脱硫后产生的经济效益,最后简单探讨了电力行业烟气脱硫带来的环境效益。结果表明:对于同一火电机组,随着煤炭含硫量的增加,其脱硫成本呈下降趋势;当煤炭合硫量相同时,火电装机容量越大,其脱硫成本越小;而且火电机组脱硫后每年获得净利润远大于其脱硫成本,同时能够产生较大的环境效益。 相似文献
26.
Coal-fired utility boilers are now identified as the largest source of mercury in the United States. There is speculation that the installation of selective catalytic reduction (SCR) system for reduction of NOx can also prompt the oxidation and removal of mercury. In this paper, tests at six full-scale power plants with similar type of the SCR systems are conducted to investigate the effect of the SCR on the transformation of mercury speciation. The results show that the SCR system can achieve more than 70%-80% oxidation of elemental mercury and enhance the mercury removal ability in these units. The oxidation of elemental mercury in the SCR system strongly depends on the coal properties and the operation conditions of the SCR systems. The content of chloride in the coal is the key factor for the oxidization process and the maximum oxidation of elemental mercury is found when chloride content changes from 400 to 600 ppm. The sulfur content is no significant impact on oxidation of elemental mercury. 相似文献
27.
Ashutosh Bahugun Madhuri K. Lily Ashok Munjal Ravindra N. Singh Koushalya Dangwal 《环境科学学报(英文版)》2011,23(6):975-982
A new bacterial strain DMT-7 capable of selectively desulfurizing dibenzothiophene (DBT) was isolated from diesel contaminated
soil. The DMT-7 was characterized and identified as Lysinibacillus sphaericus DMT-7 (NCBI GenBank Accession No. GQ496620)
using 16S rDNA gene sequence analysis. The desulfurized product of DBT, 2-hydroxybiphenyl (2HBP), was identified and
confirmed by high performance liquid chromatography analysis and gas chromatography-mass spectroscopy analysis respectively.
The desulfurization kinetics revealed that DMT-7 started desulfurization of DBT into 2HBP after the lag phase of 24 hr, exponentially
increasing the accumulation of 2HBP up to 15 days leading to approximately 60% desulfurization of the DBT. However, further growth
resulted into DBT degradation. The induced culture of DMT-7 showed shorter lag phase of 6 hr and early onset of stationary phase
within 10 days for desulfurization as compared to that of non-induced culture clearly indicating the inducibility of the desulfurization
pathway of DMT-7. In addition, Lysinibacillus sphaericus DMT-7 also possess the ability to utilize broad range of substrates as sole
source of sulfur such as benzothiophene, 3,4-benzo DBT, 4,6-dimethyl DBT, and 4,6-dibutyl DBT. Therefore, Lysinibacillus sphaericus
DMT-7 could serve as model system for efficient biodesulfurization of diesel and petrol. 相似文献
28.
太湖及辽河流域表层沉积物中拟除虫菊酯的浓度水平及毒性评估 总被引:1,自引:0,他引:1
对辽河和太湖流域表层沉积物中8种常见的拟除虫菊酯:联苯菊酯、高效氯氟氰菊酯、氯菊酯、甲氰菊酯、氟氯氰菊酯、氯氰菊酯、氰戊菊酯、溴氰菊酯进行分析测定.结果显示,太湖流域中拟除虫菊酯含量范围为0.02~2.91ng·g-1(干重,下同),平均含量为0.63ng.g-1,处于相对较低的水平;辽河流域中的含量相对较高,其范围是0.14~19.6ng·g-1,平均含量为6.20ng·g-1.采用毒性单元TU(选用钩虾Hyallela Azteca的LC50)对拟除虫菊酯毒性风险进行估算,太湖流域∑TU值范围是0~0.40,相比之下,辽河流域的∑TU值高出很多,范围在0.10~1.73之间,其中有3个点位的∑TU值大于1,表明其具有一定的生态风险,其毒性主要来源于氯氰菊酯和氰戊菊酯. 相似文献
29.
A study was conducted to investigate the effects of metal mixtures on the Chironomus plumosus. Two methods of preparing the mixtures were used, the Toxic Unit (TU) method and the parts per million (PPM) + PPM method. A comparison was undertaken between the two methods to observe the ease with which (1) experiment could be conducted and (2) whether LC50 values could be obtained. In this study, it was noted that the PPM + PPM method was an easier method to conduct metal mixture experiments as the LC50 values could be easily calculated for individual metals and compared with the LC50 values of metals obtained from single metal experiments. The findings showed that the LC50 value for zinc (Zn) was more toxic for chromium (Cr) when it was reduced from 9.6 to 0.3 mg L?1, with silver the LC50 value became 3.6 mg L?1, 4.5 mg L?1 with nickel (Ni). In the PPM + PPM method, the LC50 value for Zn was observed to be 10.2 mg L?1 when in mixture with chromium, 23.8 mg L?1 with silver, and 13.4 mg L?1 with Ni. Changes in the 96 h LC50 value were found to be significant for all metals. 相似文献
30.
制氧机组均有各种类型的空压机、氧压机、氮压机以及透平膨胀机、气体输送管道等高噪声设备,声源多、声级高、分布面广,屏蔽效应复杂,对噪声源强的全面、准确分析以及针对性的隔声、消声、吸声等降噪措施,是治理制氧机组噪声的成功经验。 相似文献