As the demand of energy increases, renewable technologies are dominating in the recent years. Solar energy is one of the leading technologies in all of the renewable energies, due to its simplicity. In Pakistan, solar PV stand-alone units are mostly used to meet the energy requirements. During production of solar PV panel, it emits out lot of waste heat and it is necessary to calculate these emissions. This study investigates the complete Life Cycle Analysis (LCA) of two different types of solar panels which are locally available in Hyderabad markets. Complete modeling of Monocrystalline and Polycrystalline PV panels has been done by using GaBi software. This study shows the complete waste heat emissions during each stage of PV panel production. Two different types (Monocrystalline and Polycrystalline) of solar panels are designed under the dimensions of 1 m2. It is calculated that Monocrystalline PV panels are more efficient than Polycrystalline PV panels and they generates more units of electricity under same temperature conditions during its complete life. To enhance the electrical efficiency of solar PV panel, cooling system must be provided across it. The comparative analysis shows that Polycrystalline PV panels requires less amount of electrical energy as compare to Monocrystalline PV panels resulting in the reduction of waste heat emission. At the end of life, this study highlights the significance of recycling of solar panels which consider the reuse of the raw material. In this study, the combination of mechanical, thermal, and chemical process of recycling is considered. Recycling rate of solar PV panel has been assumed to be 90%.  Recycling of raw material reduces the waste heat emission during purification process of raw material. Thus, cost is reduced and beneficial for environmental aspects. Result shows that recycling of solar PV panel is more beneficial than landfill for environmental and economic aspects.

Located in the lowest part of the Indus Basin, Pakistan's Sindh Province has been severely affected by extreme events due to climate change. This study analyzes the drought characteristics in Sindh Province from 1902 to 2015 using 3-month and 12-month timescales of the Standardized Precipitation Evapotranspiration Index (SPEI). The Spatial "K" luster Analysis using Tree Edge Removal (SKATER) method was used to divide the study area into four zones with similar climatic characteristics. Then, the run theory was applied to characterize droughts (drought duration, severity, intensity, and peak) in each zone. The non-parametric Mann-Kendall trend test was also applied to analyze statistically significant trends by zone and drought characteristic. It was found that all four zones experienced a decrease in SPEI throughout the analyzed period. The effects of climate change are more evident when we analyzed drought characteristics in two time slices, i.e., pre and post-1960. The results showed that in the post-1960 time slice, droughts increased in duration, severity, intensity, and peaks over the entire study area under both 3 and 12-month SPEI. The findings of this study can assist policymakers and water managers in devising policies for managing limited water resources under changing patterns of droughts in Sindh Province.

The global demand for food is growing with the population and urbanization, which puts pressure on water resources, which need assessing and quantifying water requirements. Adopting efficient irrigation methods to optimize water use is essential in this situation. In this study, crop water productivity (CWP) of major crops in the Rohri canal command area was estimated by the ratio of yield and actual evapotranspiration (ETa). Analyzing the CWP of major crops, water scarcity challenges can be tackled by selecting the most feasible irrigation methods. However, ETa was calculated and aggregated for all four stages of the crop growth period: initial, crop development, flowering stage, and maturity seasons. The crop yield data were obtained from the districts’ agricultural statistics. For this purpose, evapotranspiration products of Landsat 5 and 8 were downloaded from Earth Engine Evapotranspiration Flux (EEFlux). Landsat images were processed in a GIS environment to calculate ETa. The approach suggests developing a CWP database for major crops like wheat, cotton, and rice to improve irrigation water management. The objectives of this study are to estimate and analyze the difference in the CWP and evapotranspiration of major crops for the Rabi and Kharif seasons with high and moderate flows during 1998–2019. It comprises nine districts of Sindh that come under the Rohri Canal command area. To analyze the difference in CWP between the Rabi and Kharif seasons for all study crops of the seasons of Rabi (2014–2015 and 2016–2017) and Kharif (1998 and 2017). The growing periods for wheat, cotton, and rice in the Rohri Canal command area are 160, 195, and 180 days, respectively. The estimated ETa of the Rohri canal command area and CWP were in good agreement with the literature-reported values. Hence, enhanced agricultural productivity can be achieved by making considerable investments to improve agricultural research and extension systems.

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The present study focused on different brands of chewing food products which containing some toxic metals (TMs) and essential metals and these samples were analyzed to determine the levels of some toxic metals (Pb, Cd, Ni, Cr and Mn) and essential metals (Ca, Cu, Fe, K, Mg, Na and Zn). The samples of gutka (100), sweet supari (63), sweet paan (16) and paan masala (21) were randomly collected from different shops of Karachi, Pakistan. The validity of conventional wet acid digestion method (CAD) was assessed by analyzing two certified reference materials (CRM) Virgina tobacco leaf (CTA-VTL-2) and Bovine liver (1577b) and standard addition recovery test. The limit of detections (LODs, n=10) of the method were found to be 0.144, 14.4, 8.89, 2.76, 4.06, 15.3 and 2.99, 22.9, 9.97, 4.54, 1.89, 1.76 µg L -1 for Ca, Cu, Fe, K, Mg, Na, Zn, Cd, Cr, Mn, Ni and Pb, respectively. The CAD method was successfully applied to real samples for the determination of toxic and essential metals.