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Barbara?BarlettaEmail authorView author&#;s OrcID profile Isobel?J.?Simpson Nicola?J.?Blake Simone?Meinardi Louisa?K.?Emmons Omar?S.?Aburizaiza Azhar?Siddique Jahan?Zeb Liya?E.?Yu Haider?A.?Khwaja Muhammad?A.?Farrukh Donald?R.?Blake 《Journal of Atmospheric Chemistry》2017,74(1):87-113
We investigate the composition of 63 C2-C10 nonmethane hydrocarbons (NMHCs), methane (CH4) and carbon monoxide (CO), in Jeddah, Mecca, and Madina (Saudi Arabia), in Lahore, (Pakistan), and in Singapore. We established a database with which to compare and contrast NMHCs in regions where ambient levels and emissions are poorly characterized, but where conditions are favorable to the formation of tropospheric ozone, and where measurements are essential for improving emission inventories and modeling. This dataset will also serve as a base for further analysis of air pollution in Western Saudi Arabia including, but not limited to, the estimation of urban emissions and long range pollution transport from these regions. The measured species showed enhanced levels in all Saudi Arabian cities compared to the local background but were generally much lower than in Lahore. In Madina, vehicle exhaust was the dominant NMHC source, as indicated by enhanced levels of combustion products and by the good correlation between NMHCs and CO, while in Jeddah and Mecca a combination of sources needs to be considered. Very high NMHC levels were measured in Lahore, and elevated levels of CH4 in Lahore were attributed to natural gas. When we compared our results with 2010 emissions from the MACCity global inventory, we found discrepancies in the relative contribution of NMHCs between the measurements and the inventory. In all cities, alkenes (especially ethene and propene) dominated the hydroxyl radical (OH) reactivity (k OH) because of their great abundance and their relatively fast reaction rates with OH. 相似文献
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Thomas E. McHugh John A. Connor Farrukh Ahmad 《Ground Water Monitoring & Remediation》2004,24(2):139-140
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In unpolluted areas the log-normal distribution of individuals per species fits well data from many benthic communities. Using a simple plotting method, under slight pollution the data show a distinct break in the normally straight line log-normal plot and the plot covers more geometric classes than data from unpolluted areas. Under more severe pollution stress the data show a return to a log-normal distribution, but with a shallower slope, and span more geometric classes than data from less polluted areas. The above-mentioned patterns are consistent for spatial effects of pollution in Oslofjord and for temporal effects in data from a Scottish sea loch and also apply to other communities. An explanation of the reasons for such patterns is given and consideration given to the robustness of and application of the methods described. 相似文献
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The Wheeler diagram is a type of chronostratigraphic chart and is one of the fundamental instruments available in the geologists' toolkit that is used to understand spatiotemporal relationships of strata. Over the last four decades, these diagrams have continued to improve due to advances in seismic technology. This article examines the historical developments behind Wheeler diagrams, not only stressing their merits, but also their pitfalls and the role that sequence stratigraphic principles have played in interpreting these diagrams. It is emphasized that the diagrams are only complete if one utilizes the thicknesses of a sequence stratigraphic unit (sequence, systems tracts) – a missing dimension that turns a 3D Wheeler diagram into 4D. The article also argues that the latter 4D diagrams represent the future for Wheeler diagrams. 相似文献
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Like other Asian countries, Pakistan is facing the issue of air pollution due to rapid urbanization, enormous transportation increases, and other related human activities. Moreover, continuously increasing emission sources have not only raised pollutant concentrations but also their types, thus damaging both human health and the environment. Faisalabad is the third largest megacity of Pakistan and its state of air quality is getting worse due to factors such as industrialization, high traffic volumes, and extensive fossil‐fuel‐burning activities. This review article aims to highlight the present status of air pollution in this city with special reference to particulate matter, elemental profiles, gaseous pollutants, organic–inorganic particulate contents as well as their sources. The concentration levels of these entities were also compared with other national and international cities, and related environmental standards. It is found that current levels of these pollutants are beyond safety limits as specified by various environment protection agencies and organizations. Several weak aspects and gaps are also identified along with suggestions for improvements of the present situation and directions for future research. 相似文献
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The Punjab Platform is a gently dipping monocline that has been drilled since the 1960s with a low success ratio. Most of the drilling targets in the past were based on the structural interpretation. Furthermore, the exploration focus remained in Paleozoic sequences, and little attention has been paid to the Cretaceous systems. In this paper, a prograding Cretaceous (Sembar-Goru) mega-sequence is subdivided into three sequences using a semi-automated and integrated workflow. A data-driven chronostratigraphic chart is prepared, which revealed several regressive stages in the study area. The sands developed during these stages are laterally sealed by shales and claystones that form a stratigraphic play. The stratigraphic play area lies in a shoreface environment where shoreface sands are expected to be charged by underlying Lower Cretaceous black shales. A prominent gas cap above the proposed stratigraphic play further increases the confidence on the presence of a reservoir. This paper is the first attempt to study the Cretaceous deltaic sequences in the study area, which has remained unexplored for the last six decades. 相似文献
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