The potential of the flora from different regions of Pakistan in phytoremediation: a review

Soil and water quality is greatly affected by environmental pollution due to the increasing trend of urbanization and industrialization. In many developing countries, including Pakistan, the situation is more alarming as no preventive measures are still taken to tackle the problem. Although in developed countries, many techniques are used to remediate the environment including phytoremediation. It is the most eco-friendly technique in which plants are used to remove pollutants from the environment. Pakistan has also a great diversity of plants which could be used for the remediation of environmental pollutants. To our knowledge, few studies from Pakistan were reported about the use of flora for phytoremediation. According to recent literature, 50 plant species from Pakistan are studied for remediation purposes. In this review, the potential of different plant species for phytoremediation from Pakistan has been discussed along with their comparison to other countries to relate future perspectives.     

Relationship between THC concentration in blood and impairment in apprehended drivers

OBJECTIVE: The most important psychoactive ingredient in cannabis, Delta (9)-tetrahydrocannabinol (THC) is one of the most frequently detected substances in blood samples from suspected impaired drivers in Norway. There is growing concern over possible links between the use of cannabis and increased risk of motor-vehicle crashes. Experimental studies have provided useful information on the role of THC and dose-effect relations with respect to psychomotor performance. The main purpose of the present study was to investigate whether a physician's judgment on impairment in a real-life setting among suspected drugged drivers, was related to blood THC concentration. METHODS: In Norway a police physician performs a clinical test for impairment (CTI) shortly after apprehension. The Norwegian Institute of Public Health analyze blood samples from all drivers suspected of driving under the influence of non-alcoholic drugs. In the present study 589 samples from approximately 30,000 cases of suspected drug impaired driving from the period 1997-99, contained THC as the only drug. In 456 of these cases a conclusion of the CTI was available. RESULTS: 230 (54%) drivers were considered not impaired and 226 (46%) impaired. Impaired drivers had higher blood THC concentration than the drivers who were judged as not impaired (median; 2.5 ng/mL (range; 0.3-45.3 ng/mL) vs 1.9 ng/mL (range; 0.32-24.8 ng/mL), (p < 0.05). Furthermore, drivers with blood THC concentrations above 3 ng/mL had an increased risk for being judged impaired compared to drivers with lower concentration ranges. CONCLUSION: The relationship between the concentration of THC in blood and risk of being assessed impaired found in this cross-sectional study of suspected drugged drivers, supports findings from previous experimental studies of concentration related effects of THC on psychomotor performance and driving skills.     

Speciation of 210Po and 210Pb in air particulates determined by sequential extraction

Speciation of (210)Po and (210)Pb in air particulates of two Syrian phosphate sites with different climate conditions has been studied. The sites are the mines and Tartous port at the Mediterranean Sea. Air filters were collected during September 2000 until February 2002 and extracted chemically using different selective fluids in an attempt to identify the different forms of these two radionuclides. The results have shown that the inorganic and insoluble (210)Po and (210)Pb (attached to silica and soluble in mineral acids) portion was found to be high in both sites and reached a maximum value of 94% and 77% in the mine site and Tartous port site, respectively. In addition, only 24% of (210)Pb in air particulates was found to be associated with organic materials probably produced from the incomplete burning of fuel vehicle and similar activities. Moreover, the (210)Po/(210)Pb activity ratio in air particulates was higher than that in all samples at both sites and varied between 3.85 in November 2000 at Tartous port site and 20 in April 2001 at the mine area. These activity ratios were also higher than the natural levels. The (210)Po/(210)Pb activity ratio was also determined in each portion resulting from the selective extraction and found to be higher than that in most samples. The sources of (210)Po excess in these portions are discussed. Soil suspension, which is common in the dry climate dominant in the area, sea water spray and heating of phosphate ores were considered; polonium is more volatile than the lead compounds at even moderate temperature. Furthermore, variations in the chemical forms of (210)Po and (210)Pb during the year were also investigated. However, the results of this study can also be utilized for dose assessment to phosphate industry workers.     

New Biopolymer Nanocomposite of Starch-Graft Polystyrene/Montmorillonite Clay Prepared Through Emulsion Polymerization Method

Starch-g-polystyrene (Starch-g-PS)/Montmorillonite nanocomposites were prepared via free-radical graft copolymerization of styrene and starch in the presence of montmorillonite clay, by emulsion polymerization method using potassium persulfate (KPS) as an initiator/catalyst and sodium dodecylbenzensulfonate (SDBS) as an emulsifier. The nanocomposites with different clay content 0, 2.5, 5.0, 7.5 and 10 weight percent of starch were prepared and the changes in layer-stacked structures of the clay particles in the resulted nanocomposite compounds were examined by using of X-ray diffraction and FT-IR spectroscopy. Finally the thermal degradation behavior and morphology of nanocomposites were studied using thermal gravimetric analysis (TGA) and SEM, respectively.     

Rapid full‐scale bioremediation of perchlorate in soil at a large brownfields site

The former Bermite site north of Los Angeles, California, was used to manufacture various explosives and related products containing energetic compounds, including perchlorate. Remediation of perchlorate in site soil and groundwater is being conducted to meet regulatory requirements and allow planned redevelopment activities to proceed. The general approach to perchlorate remediation of shallow soil at the site includes excavation of affected soils followed by ex situ bioremediation. Glycerin was chosen for use as an electron donor because of its stability, safety, low cost, and regulatory acceptance. However, full‐scale bioremediation operation with glycerin initially resulted in inconsistent results despite consistent perchlorate biodegradation observed in treatability study microcosms. To eliminate the inconsistency and optimize the biotreatment process, additional studies were performed in the field on parallel tracks to determine crucial factor(s) that influenced inconsistent breakdown of perchlorate in site soils. Total Kjeldahl nitrogen (TKN) was determined to be a significant factor limiting perchlorate biodegradation. The addition of di‐ammonium phosphate (DAP) resulted in the consistent and complete perchlorate removal, generally within two weeks of incubation with a median destruction rate of about 200 μg/kg/day. Soil processing rates were gradually increased over the year, and, by the summer, approximately 2,000 to 2,500 tons of soil were being processed per day with a total of approximately 160,000 tons processed by the end of July. The total unit treatment cost for the process is about approximately $35/ton. The glycerin‐DAP process is playing a major role in the remediation of this 1,000‐acre former industrial site. © 2008 Wiley Periodicals, Inc.     

Effect of liming on the distribution of heavy metals in untreated industrial sewage sludge produced in Pakistan for the cultivation of <Emphasis Type="Italic">Sorghum bicolor</Emphasis> (L.)

The recycling of sewage sludge on agriculture land represents an alternative, advantageous, disposal of this waste material. The aim of the present study was to evaluate the feasibility of using industrial sewage sludge, produced in Pakistan, as a fertiliser. Agricultural soil amended with 25% (w/w) sewage sludge with or without lime treatment was used for growing a variety of sorghum (PARC-SS-1). The mobility of the heavy metals (HMs) (Cd, Cu, Cr, Ni, Pb and Zn) and metalloid (As) in the untreated industrial waste water sewage sludge (UIWS) samples were assessed by applying a modified BCR (Community Bureau of Reference) sequential extraction procedure. The single extraction procedure comprised of the application of mild extractant (CaCl₂) and water for the estimation of the proportion of easily soluble metal fractions. The precision and accuracy of BCR was evaluated by using a certified reference material of soil amended with sewage sludge BCR 483. The plant available metal contents, as extracted by the deionised water and 0.01 M CaCl₂ solution and exchangeable fraction of BCR sequential, decreased with lime application in the range of 10–44% for As, Cr, Ni, Pb and Zn, except in the cases of Cd and Cu, where their mobility was increased by 10% and 24%, respectively. Sludge amendment enhanced the dry weight yield of sorghum and the increase was more obvious after liming up to 25%. The uptake of HMs were lower in test samples (3.2–21.8%), except for Cu and Cd, which was higher (4%), while they were below the permissible limit of these metals. The present experiment demonstrates that liming was important in factors facilitating the growth of sorghum in sludge-amended soil.     

A new strategy for determination of hydroxylamine and phenol in water and waste water samples using modified nanosensor

A carbon paste electrode modified with p-chloranil and carbon nanotubes was used for the sensitive and selective voltammetric determination of hydroxylamine (HX) and phenol (PL). The oxidation of HX at the modified electrode was investigated by cyclic voltammetry (CV), chronoamperommetry, and electrochemical impedance spectroscopy. The values of the catalytic rate constant (k), and diffusion coefficient (D) for HX were calculated. Square wave voltammetric peaks current of HX and PL increased linearly with their concentrations at the ranges of 0.1–172.0 and 5.0–512.0 μmol L^?1, respectively. The detection limits for HX and PL were 0.08 and 2.0 μmol L^?1, respectively. The separation of the anodic peak potentials of HX and PL reached to 0.65 V, using square wave voltammetry. The proposed sensor was successfully applied for the determination of HX and PL in water and wastewater samples.     

Vulnerability of the South African farming sector to climate change and variability: An indicator approach

This paper analyses the vulnerability of South African agriculture to climate change and variability by developing a vulnerability index and comparing vulnerability indicators across the nine provinces of the country. Nineteen environmental and socio‐economic indicators are identified to reflect the three components of vulnerability: exposure, sensitivity, and adaptive capacity. The results of the study show that the regions most exposed to climate change and variability do not always overlap with those experiencing high sensitivity or low adaptive capacity. Furthermore, vulnerability to climate change and variability is intrinsically linked with social and economic development. The Western Cape and Gauteng provinces, which have high levels of infrastructure development, high literacy rates, and low shares of agriculture in total GDP, are relatively low on the vulnerability index. In contrast, the highly vulnerable regions of Limpopo, Kwazulu‐Natal and the Eastern Cape are characterised by densely populated rural areas, large numbers of small‐scale farmers, high dependency on rain‐fed agriculture and high land degradation. These large differences in the extent of vulnerability among provinces suggest that policymakers should develop region‐specific policies and address climate change at the local level.     

Impact of utilizing reflector,single-axis and two-axis sun trackers on the performance of an evacuated tube solar collector

ABSTRACT

In this paper, a novel evacuated tube solar collector (ETSC) is first designed and built. Then, the impact of adding reflector, reflector plus single-axis sun tracker and reflector plus two-axis sun tracker to the built ETSC on the thermal efficiency of the ETSC is evaluated both theoretically and experimentally. In this regard, four identical versions of the proposed ETSC have been built and utilized in four collectors built and presented in this research work. The first collector is the same proposed built ETSC, the second collector is a parabolic trough solar collector comprising one built ETSC and a reflector (ETSC+R), the third collector is composed of one built ETSC, a reflector and a single-axis sun tracker all built in this study (ETSC+R+ ST), and the fourth collector consists of one built ETSC, a reflector and a two-axis sun tracker all built in this study (ETSC+R+ DT). Theoretical basis and concepts of the four collectors are formulated and analyzed in separate subsections. Theoretical results are outlined and highlighted at the end of each subsection. Experimental measurements and data obtained from the operation of the four collectors in the four seasons are presented that point by point verify theoretical results obtained in this study. To provide a comprehensive view, a techno-economic numerical comparison is performed between the four collectors. The following points, which are also the novelty and contributions of this work, are deduced from theoretical concepts, experimental data, and comparison provided in this study:

?There is no technical and economic justification for adding a reflector to an ETSC that results in forming a parabolic trough solar collector (ETSC+R) without any sun tracker.

?There is no economic justification for adding a single-axis sun tracker to a parabolic trough solar collector (ETSC+R).

?There is no economic justification for adding a two-axis sun tracker to a parabolic trough solar collector (ETSC+R).

?Comparing between a two-axis sun tracker and a single-axis sun tracker, adding the single-axis type to a parabolic trough solar collector (ETSC+R) is more advantageous.