ABSTRACT:A study was conducted to determine the effect of different concentrations of lead and cadmium on seed germination and seedling growth of Leucaena leucocephala. Seed were grown under laboratory conditions at 25, 50, 75 and 100 ppm of metal ions of lead and cadmium. Both lead and cadmium treatments showed toxic effects on various growth indices of L. leucocephala. Increasing the concentration of lead to 75 ppm, significantly (p<0.05) decreased seed germination as compared to control. Seedling and root growth was significantly (p<0.05) reduced at 50 ppm treatment of lead. Seed germination and root length significantly (p<0.05) decreased at 50 ppm treatment of cadmium as compared to control. The seedling dry weight also significantly (p<0.05) reduced at 25 ppm treatment of lead and cadmium. Cadmium treatment at 100 ppm showed comparatively pronounced effects in L. leucocephala seedlings as compared to lead. The results of the study suggest that due to better metal tolerance indices there is a possibility of growing L. leucocephala in areas contaminated with lead and cadmium. @ JASEM
This study presents the use of geographical information system (GIS) datasets and methods to investigate landslide susceptibility in the rugged mountainous terrain of Shigar and Shyok Basins in northern areas of Pakistan. Study area is situated in Karakorum mountainous region where catastrophic landslides occur frequently and pose a serious threat to local living conditions. Landslide susceptibility index maps were prepared by combining four main indicators groups: (1) human induced parameters, which contain Landsat 8 imagery and distance from roads; (2) topographical parameters, which include slope, aspect and plan curvature; (3) hydrological parameters, which contain stream power index, topographic wetness index and distance from drainage and (4) geological parameters, which consist of lithology and distance from major thrusts and faults. These layers were prepared in GIS environment, and analytical hierarchy process (AHP) based heuristic approach was adopted to generate final landslide susceptibility map for this preliminary regional level landslide hazard study. Three different susceptibility zones have been identified in the region. AHP weights with 0.04 consistency ratio were used in the preparation of final map. The final landslide susceptibility map of the study area indicates that the low, moderate, and high landslide susceptibility classes are respectively covering 23.2% (4745 km 2), 45% (6737 km 2), 23.2% (3444 km 2) when distance from roads, distance from drainage and distance from major thrusts and faults parameters were not incorporated in the analysis. Including distance from roads, distance from drainage and distance from major thrusts and faults parameters layers to the final landslide susceptibility analysis shows that moderate susceptibility class is the predominant landslide susceptibility category covering 88% (13,412 km 2) of the study area characterized by steep slopes (30 À45), low positive plan curvature (0À1) and weak lithology.
The effects of lead on root, shoot and seedling length, leaf area, number of leaves, plant circumference, seedling dry weight, root/shoot and leaf area ratios of Thespesia populnea L. were determined in greenhouse under natural environmental conditions with and without phytotoxic metal ions at 5, 10, 15, 20, and 25 µmol/l. Lead treatments have a strong influence on the growth and development of T. populnea by reducing significantly (P < 0.05) all the above parameters. Lead treatment at 5-25 µmol/l produced significant (P < 0.05) effects on seedling and root length, plant circumference and seedling dry weight of T. populnea, while lead treatment at 10-25 µmol/l produced significant (P < 0.05) effects on shoot length, number of leaves and leaf area as compared to control. Tolerance in T. populnea seedling at 25 µmol/l of lead treatment was lowest as compared to all other treatments.
Nitrogen oxide (NO x ) abatement has become the focus of air quality management strategies. In this study, we examined NO x sources and the atmospheric conversion of NO x in Karachi, Pakistan, a megacity in South Asia with serious particulate pollution problems. Oceanic contributions to NO x were quantified for the first time based on a novel approach using nitrogen/oxygen isotopic analysis in nitrate (δ 15 N−NO 3 − ; δ 18 O−NO 3 − ) and a Bayesian model. Our results showed that δ 15 N−NO 3 − in Karachi varied between −10.2‰ and +12.4‰. As indicated by the δ 18 O−NO 3 − findings (+66.2 ± 7.8‰), the •OH pathway dominated NO x conversion throughout the nearly two-year observation, but high NO 3 − events were attributed to the O 3 pathway. Coal combustion was the most significant source (32.0 ± 9.8%) of NO x in Karachi, with higher contributions in the autumn and winter; a similar situation occurred for biomass burning + lightning (30.3 ± 6.5%). However, mobile sources (25.2 ± 6.4%) and microbial processes (12.5 ± 7.5%) exhibited opposite seasonal trends. The oceanic contributions to NO x in Karachi were estimated to be 16.8%, of which lightning, shipping emissions, and microbial processes accounted for 20.3%, 46.3%, and 33.4%, respectively, emphasizing the dominance of shipping emissions as an oceanic NO x source.
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