Haider A. Khwaja

Mixing ratios of volatile organic compounds (VOCs) in the atmosphere of Karachi, Pakistan

Mixing ratios of carbon monoxide (CO), methane (CH4), non-methane hydrocarbons, halocarbons and alkyl nitrates (a total of 72 species) were determined for 78 whole air samples collected during the winter of 1998–1999 in Karachi, Pakistan. This is the first time that volatile organic compound (VOC) levels in Karachi have been extensively characterized. The overall air quality of the urban environment was determined using air samples collected at six locations throughout Karachi. Methane (6.3 ppmv) and ethane (93 ppbv) levels in Karachi were found to be much higher than in other cities that have been studied. The very high CH4 levels highlight the importance of natural gas leakage in Karachi. The leakage of liquefied petroleum gas contributes to elevated propane and butane levels in Karachi, although the propane and butane burdens were lower than in other cities (e.g., Mexico City, Santiago). High levels of benzene (0.3–19 ppbv) also appear to be of concern in the Karachi urban area. Vehicular emissions were characterized using air samples collected along the busiest thoroughfare of the city (M.A. Jinnah Road). Emissions from vehicular exhaust were found to be the main source of many of the hydrocarbons reported here. Significant levels of isoprene (1.2 ppbv) were detected at the roadside, and vehicular exhaust is estimated to account for about 20% of the isoprene observed in Karachi. 1,2-Dichloroethane, a lead scavenger added to leaded fuel, was also emitted by cars. The photochemical production of ozone (O3) was calculated for CO and the various VOCs using the Maximum Incremental Reactivity (MIR) scale. Based on the MIR scale, the leading contributors to O3 production in Karachi are ethene, CO, propene, m-xylene and toluene. r 2002 Elsevier Science Ltd. All rights reserved.

Heavy metal toxicity levels in the coastal sediments of the Arabian Sea along the urban Karachi (Pakistan) region

Heavy metals are stable and persistent environmental contam-inants since they cannot be degraded or destroyed. Therefore, theytend to accumulate in the soils and sediments. Excessive levels ofmetals in sediments affect marine biota and pose a risk to humanhealth through the consumption of seafood (Adams et al., 1992;Rowlatt and Lovell, 1994; Mucha et al., 2003; Feng et al., 2004;Zhang et al., 2007). The main anthropogenic sources of heavy met-als are various industrial point sources, including present and for-mer mining activities, foundries and smelters, and diffuse sourcessuch as piping, combustion by-products, traffic, etc. (NRC, 1989;Bryan and Langston, 1992; Long, 2000; Pekey, 2006; Hyun et al.,2007). Relatively volatile heavy metals and those that become at-tached to air-borne particles can be widely dispersed on very largescales. Heavy metals in aqueous and sedimentary transport (e.g.,river run-off) enter the normal coastal biogeochemical cycle andare largely retained within near-shore and shelf regions in propor-tion to geochemical controls (McAlister et al., 2005; Chaparro et al.,2005). Sediment analyses play a crucial role in assessing the degreeof heavy metal pollution and the resulting health risk associatedwith the food chain.Karachi is situated at the southern most part of Pakistan alongthe Arabian Sea and it is the largest business hub and the mostheavily populated urban centre in the vicinity. The coastal zoneof Karachi is about 167 km long. The estimated population of Kar-achiis morethan15 million.The rapidindustrializationandurban-ization of the city has altered the quality of the environment andcreated ecological disturbances and associated problems for the lo-cal community. Pollution in the Karachi coastal region is mainlyattributed to the Lyari and Malir rivers, which are served by vari-ous channels of untreated domestic and industrial waste, carryingmore than 300 million gallons per day (MGD) (1,125,000 m

Ion Chromatographic Determination of Anions in Environmental Samples

Abstract The use of ion-exchange chromatography with an IonPac AS 14 column, 3.5 mM Na2CO3/1.0 mM NaHCO3 eluent and suppressed conductivity detection provides a simple, cost-effective, fast, accurate, and highly sensitive method for the determination of F−, Cl−, NO2 −, Br−, NO3 −, PO4 2−, SO4 2−, and C2O4 2− at low μ/L levels in environmental samples. Data on sensitivity, selectivity, accuracy, and % relative standard deviation are described. The method is suitable for many environmental applications including atmospheric aerosols (exposed on cellulose, glass fiber, and quartz filters), rainwater, cloud water, potable- and non-potable waters, and carbonated waters. Dominant components of the aerosol were SO4 2−, NO3 −, and Cl−. Rainwater, on the other hand, has relatively very low concentrations of these three species. The wide-spread concentration range for Cl− in variety of water samples and the high concentrations for SO4 2− in drinking water are striking. Determination of the anionic composition of ca...

Obesity and public health in the Kingdom of Saudi Arabia

Abstract Overweight and obesity are now a global epidemic, with more than one in five people qualifying as obese worldwide. These conditions are accompanied by excessive rates of non-communicable diseases (NCDs) related to overweight, like type 2 diabetes mellitus, hypertension, and cardiovascular diseases. Saudi Arabia, which has become increasingly westernized over the past few decades now has one of the highest prevalence rates of overweight and obesity, even in children. This puts the population at great risk for increased rates of NCD mortality. Competing cultures is partly to blame, as the combination of persisting traditional Saudi cultural practices, modern cultural changes, and economic prosperity has created an obesogenic environment that promotes unhealthy eating, sedentary lifestyles, and weight gain. Overweight and obesity are more prevalent in Saudi women than in Saudi men. Interventions targeting the environment are needed in order to promote greater health through healthy eating decisions and increased physical activity or exercise (especially for women).

Air Quality in Mecca and Surrounding Holy Places in Saudi Arabia During Hajj: Initial Survey

The Arabian Peninsula experiences severe air pollution, the extent and sources of which are poorly documented. Each year in Saudi Arabia this situation is intensified during Hajj, the Holy Pilgrimage of Islam that draws millions of pilgrims to Mecca. An initial study of air quality in Mecca and surrounding holy sites during the 2012 Hajj (October 24-27) revealed strongly elevated levels of the combustion tracer carbon monoxide (CO, up to 57 ppmv) and volatile organic compounds (VOCs) along the pilgrimage route-especially in the tunnels of Mecca-that are a concern for human health. The most abundant VOC was the gasoline evaporation tracer i-pentane, which exceeded 1200 ppbv in the tunnels. Even though VOC concentrations were generally lower during a follow-up non-Hajj sampling period (April 2013), many were still comparable to other large cities suffering from poor air quality. Major VOC sources during the 2012 Hajj study included vehicular exhaust, gasoline evaporation, liquefied petroleum gas, and air conditioners. Of the measured compounds, reactive alkenes and CO showed the strongest potential to form ground-level ozone. Because the number of pilgrims is expected to increase in the future, we present emission reduction strategies to target both combustive and evaporative fossil fuel sources.

An assessment of air quality in the surrounding holy places of Mecca, Saudi Arabia during Hajj

B is a clean, renewable and abundant resource that can be converted to bio-char, bio-oil and fuel gas through various thermochemical processes. Conversion of biomass for high value products is an important development direction for biomass utilization, which has attracted more attention. In this study, a new method of biomass pyrolysis with exogenous nitrogen introduced was proposed. The influence of NH3 on the property of bamboo pyrolysis process and products characteristics was investigated with variant approaches (e.g. elemental analysis, automatic adsorption equipment, X-ray photoelectron spectroscopy and CHI760 electrochemical workstation) and as well as the influence of KOH (as activator). The results showed that, the specific surface area, the content of nitrogen and nitrogen-containing functional groups of bio-char increased significantly with NH3 introduced in. On the other hand, with the addition of KOH, the yield of bio-char increased obviously and it increased gradually with increasing KOH amount, and the specific surface area increased dramatically to 1873.17 m2 g-1. The content of nitrogen in bio-char increased greatly with KOH introduced in, especially the content of pyridinic-N and pyrrolic/pyridone-N, while it decreased slightly with increasing KOH amount, but nitrogen content was still relative high (9.1-10.4 wt.%). The formation mechanism of nitrogen-containing functional groups was proposed. Besides, electrochemical analysis showed that the specific capacitance of bio-char electrodes increased with increasing KOH content, and the largest specific capacitance could reach to 187 F g-1 at 1 A g-1 with good cycling stability. Therefore, it could be concluded that biomass nitrogen-enriched pyrolysis was a promising method for more efficient utilization of biomass resources.A insoluble palladium catalyst (Pd-pol) was obtained by copolymerization of the metal containing monomer Pd(AAEMA)2 [AAEMA− = deprotonated form of 2-(acetoacetoxy)ethyl methacrylate] with ethyl methacrylate (co-monomer) and ethylene glycol dimethacrylate (cross-linker), followed by in situ reduction of Pd(II) to Pd(0), to give polymer stabilized metal nanoparticles. The good swellability in water exhibited by Pd-pol rendered it an ideal potential catalyst for reactions carried out in a green solvent, such as water, since the migration of the reagents to the active sites would not be hampered by the solid support. With the aim to develop innovative catalytic processes that enable chemical transformations to be performed under mild and sustainable conditions with high efficiency, we decided to evaluate the catalytic activity of Pd-pol for several important organic reactions using water as solvent. Pd-pol resulted highly active and selective in catalyzing (figure 1): the Suzuki-Miyaura coupling between aryl bromides or activated aryl chlorides and phenylboronic acid; the oxidation of benzyl alcohols to aldehydes; the reduction of quinolines and nitroarenes by H2 or NaBH4. Pd-pol was recyclable for several consecutive runs (for example, at least 12 times in the nitroarene reduction). TEM analyses carried out on the catalyst showed that the active species were supported palladium nanoparticles having a mean size of 4 nm, which did not aggregate with the recycles. Recently, due to their low cost, Ni catalysts have been employed in several organic reactions (mainly hydrogenations). In this context, we synthetized a Ni catalyst similar to Pd-pol, starting from Ni(AAEMA)2 and we employed it as active and recyclable, insoluble catalyst for the reduction of different nitroarenes to give the corresponding anilines, under sustainable conditions. All these results proved that the proposed Pd or Ni based composite materials are excellent hybrid structures as efficient and reusable catalysts.A amino acids are versatile structures readily available by a number of methods and are accessible using very few transformations from economical starting materials. They can be functionalized by many chemical functions and offer a wide range of possible transformations. Particularly, unsaturated α-amino acids give access to many synthetic applications in all fields of chemistry. Among them, metal catalyzed cross-coupling reactions and cross metathesis are commonly used to generate peptide modifications and cyclization. They are very interesting and useful tools for “Click” Chemistry in peptidomimetic drug design or covalent modification of proteins. They can also be incorporated in compounds as beta-turn inducer to promote secondary structures. Finally they can be used for the preparation of stapled peptides. Some such amino acids are commercially attainable in enantiomerically pure form. Here, we present a stereoselective approach to synthesize unsaturated α-amino acids in optically active form. As a starting amino acid synthon for the asymmetric synthesis of amino acids NiII square-planar complexes of Schiff ’s bases of propargylglycine with chiral auxiliary (S)-2-N-(N`-benzyl-prolyl)aminobenzophenone (BPB) (1) was taken. As a result effective methods of asymmetric synthesis for novel enantiomerically enriched derivatives of (S)-propargylglycine (S)-propargylglycine (ee > 80%) was developed.