Seismic risk assessment for developing countries : Pakistan as a case study

Modern Earthquake Risk Assessment (ERA) methods usually require seismo-tectonic information for Probabilistic Seismic Hazard Assessment (PSHA) that may not be readily available in developing countries. To bypass this drawback, this paper presents a practical event-based PSHA method that uses instrumental seismicity, available historical seismicity, as well as limited information on geology and tectonic setting. Historical seismicity is integrated with instrumental seismicity to determine the long-term hazard. The tectonic setting is included by assigning seismic source zones associated with known major faults. Monte Carlo simulations are used to generate earthquake catalogues with randomized key hazard parameters. A case study region in Pakistan is selected to demonstrate the effectiveness of the method. The results indicate that the proposed method produces seismic hazard maps consistent with previous studies, thus being suitable for generating such maps in regions where limited data are available. The PSHA procedure is developed as an integral part of an ERA framework named EQRAM. The framework is also used to determine seismic risk in terms of annual losses for the study region

Organochlorine pesticides (OCPs) contaminants in sediments from Karachi harbour, Pakistan

Mangrove swamps, intertidal mudflats and creeks of backwaters represent main feature of Karachi harbour area. Karachi harbour sediment is under continuous influence of untreated industrial effluents and domestic waste discharged into the Harbour area vra Lyari River Sediment samples from sixteen locations were collected to evaluate the levels of contamination of organochlorine pesticides (OCPs) in Karachi harbour and adjoining areas. It has been observed that residual concentrations of various organochlorine pesticides were considerably higher in the semienclosed area of the upper Harbour in the vicinity of the discharge point of Lyari River. The residue of DDT mainly its metabolites (DDE and DDD) were widely distributed and have been detected in most of the sediment samples in relatively higher concentrations as compared to other OCPs. The higher levels of the DDTs would attribute to low tidal flushing of the area The high proportion of pp'-DDE in the most sediment sampled (41-95%) suggested old inputs of DDTs in the environment. Ratio of SDDT and DDT was in the range of 0,04 -0 24 at all locations which also reflects that the discharges of DDT were negligible in the Harbour area. This may be due to the restrictions being implemented on the use of DDTs and Pakistan has also switched over to natural pest control or using safer formulas. The data obtained during the study showed that concentration levels of other pesticides such as HCHs, HCB and Cyclodienes in the sediment were generally lower than the threshold levels known to harm wildlife by OCPs. The results clearly indicate that elevated concentration of organochlorine pesticides (OCPs) in the marine sediment of Karachi harbour and adjoining area was localized and much lower than the concentrations reported from neighbouring and regional countries which suggests/confirms that the present use of pesticide in Pakistan is environmentally safe

Wastewater driven trace element transfer up the food chain in peri-urban agricultural lands of Lahore, Pakistan

In peri-urban agricultural lands of Lahore city, untreated wastewater from trans-boundary Hudiara drain is widely used for agriculture. The irrigated water may pose a hazard of trace element (TE) contamination in agricultural produce and consequently threat to human health. This study was designed to investigate the quality and transferability of TE contamination in water, soil, fodder and buffalo milk. Samples from the 4 assets and products were collected at upstream, midstream and downstream sites along Hudiara drain. Potentially toxic elements (Cd, Cu, Ni and Zn) were analyzed using standard methods. Physicochemical analysis of water, bioaccumulation factor (BAF) from soil to fodder and Pearson correlation of metal contamination in water, soil, fodder and milk were determined. TE contamination increased from upstream to downstream site. Highest Cd concentration in water, soil, fodder and milk was 0.29 mg/L (downstream), 1.10 mg/kg (midstream), 2.12 mg/kg (downstream) and 0.29 mg/L (downstream), respectively, which surpassed permissible limits for all the 4 mediums. Similar results were found with Cu, Ni and Zn which increased downstream and the concentrations higher than permissible limits in all mediums except soil. Significantly high Hazard Index (HI) values were recorded for irrigation wastewater (23.25–31.75), fodder (7.41–11.13), and milk (11.12–17.85), which were increasing down the stream of drain. All 4 metals have shown strong positive correlation among water, soil, fodder and milk, showing transferability risk up to food chain. Transfer of TE from soil to fodder was highest for Ni (BAF 8.44) and lowest for Zn (BAF 0.41) with the following ascending trend: Zn < Cd < Cu < Ni. The physicochemical parameters of drain water also did not meet the permissible limits for wastewater irrigation. Use of untreated water of Hudiara drain for agriculture in peri-urban areas of Lahore needs to be stopped until appropriate treatment and reuse