Spatial distribution of potentially toxic elements contaminations and risk indices of water and sediments in the Darband and Samana streams, Pakistan.

This study examined potentially toxic elements (PTE) of water and sediments in the Darband and Samana streams of Hangu District. Darband and Samana streams are the main fluvial ecosystems of Hangu District, Pakistan, directly or indirectly affecting more than 0.52 Million people. Water and sediment samples were collected and analyzed for PTE utilizing inductively coupled plasma mass spectrometry (ICP-MS). Water characteristics of Darband and Samana streams were noted within the WHO drinking water guidelines, except for Turbidity and sulfate. Most water characteristics showed higher values in the Samana stream than in the Darband stream. Similarly, most of PTE showed higher concentrations in sediments collected from the Samana stream than the Darband stream. For ecological risk evaluation, several pollution indices were employed to assess the eco-toxicological consequences. The highest contamination factor (CF) value of 15 and 20 were exhibited by molybdenum (Mo) in the Samana and Darband streams showing very high contamination. Similarly, the pollution load index (PLI) showed that 24% of the sediment samples were polluted (PLI > 1). Furthermore, a high ecological risk in a range of 160 < ERI < 320 was observed for Mo, while a low ecological risk ERI < 40 was by As for the Darband and Samana streams sediments. Statistical techniques revealed that various anthropogenic sources primarily contaminated in water and sediment. Therefore, this study recommends regular monitoring PTE contaminations in the area to avoid any health hazards in the future.

Heavy metal(loid)s contaminations in soils of Pakistan: a review for the evaluation of human and ecological risks assessment and spatial distribution.

Heavy metal(loid)s (HM) contaminations in the soil poses threats to the human and ecological community due to their bioaccumulation, toxicity, and persistent nature in the ecosystem. This review was designed to know about the HM contamination in soils, ecological risk, distribution, and potential health risks. Soil HM concentrations published in the last 30 years were collected from Springer, Science Direct, Willey, Mendeley, ResearchGate, Google Scholar, etc. HM concentrations were used for the geo-accumulation index (Igeo), contamination factor, as well as integrated indices such as spatial distribution of ecological risk index. Similarly, the Igeo pattern was observed in Sindh > Baluchistan > Punjab > Khyber Pakhtunkhwa > Gilgit-Baltistan > Islamabad. Moreover, the high ecological risk mean values ranged (160 < ERI < 320) due to cadmium (Cd) was exhibited in the Punjab and Khyber Pakhtunkhwa provinces and Islamabad. Non-carcinogenic risk like hazard quotient was found higher for children (1.59) of Punjab due to arsenic (As) ingestion, whereas the lower risk was observed due to Zn (2.5E-08) for adults of Punjab province via inhalation pathway. Similarly, the health index (HI) from exposure to As (1.61) in soil was higher than the rest of the HM. Moreover, cancerous risk was determined and found in the tolerable range (10-4-10-6). This study recommended that HM contaminants in the soil need to be monitored on regular basis, especially in Baluchistan, Gilgit-Baltistan, and Sindh provinces.

Heavy metal(loid)s contamination and potential risk assessment via groundwater consumption in the district of Hangu, Pakistan.

This study examined the concentration of heavy metal(loid)s (HM) in groundwater and associated health risks in the Hangu District, Pakistan. Seventy-one groundwater samples were selected from various sources to determine the concentration of twelve HM using the ICP-MS. The average concentrations of HM in groundwater were observed within acceptable guidelines proposed by the World Health Organization (WHO). Similarly, the groundwater of the study area based on the HM contamination index results was noted as an excellent group. Generally, the chronic daily intake (CDI) values for both adults and children were observed in the sequence of Fe > Zn > Ni > Mn > Cu > Sb > Cr > Mo > As > Pb > Co > Cd. The highest hazard quotient was computed for children through groundwater from the tube well. Moreover, both carcinogenic and non-carcinogenic hazards of groundwater were observed in the order of tube well > dug well > spring > bore well. The present study suggests that children were more susceptible to health risks than adults.

Potentially toxic elements' occurrence and risk assessment through water and soil of Chitral urban environment, Pakistan: a case study.

This study investigated the concentrations of potentially toxic elements (PTE) including copper (Cu), chromium (Cr), cobalt (Co), cadmium (Cd), nickel (Ni), iron (Fe), zinc (Zn), lead (Pb), molybdenum (Mo) and manganese (Mn) in water and soil of the Chitral city, Pakistan. For this purpose, water (n = 66) and soil (n = 48) samples were collected from various locations of the Chitral city and analyzed for the PTE concentrations. Determined PTE concentrations were evaluated for the human and ecological potential risk. Results revealed that hazard quotient through water consumption was less than the threshold limit (1). However, for soil, the Fe mean hazard index (HI > 1) value for children only surpassed the threshold limits. The mean cancer risk index values via soil exposure were higher (RI > 1 × 10-4) through consumption of Co, Ni and Cd for children and only Co for adults. Contamination factor (CF) values for Mo, Cd and Fe were found very high, considerable and moderate for 79%, 8% and 77% of sampling sites, respectively. Geoaccumulation index (Igeo) showed that soils were moderately-heavily polluted due to Mo. Potential ecological risk index (PERI) values exhibited considerable risk with an average risk index value in the range 190 < RI < 380. Higher values of CF, Igeo and PERI revealed the presence of pollution and pose risk to ecological environment.

Enrichment, spatial distribution of potential ecological and human health risk assessment via toxic metals in soil and surface water ingestion in the vicinity of Sewakht mines, district Chitral, Northern Pakistan.

This study focuses on enrichment, spatial distribution, potential ecological risk index (PERI) and human health risk of various toxic metals taken via soil and surface water in the vicinity of Sewakht mines, Pakistan. The samples of soils (n = 54) of different fields and surface water (n = 38) were analyzed for toxic metals including cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), nickel (Ni), zinc (Zn) and molybdenum (Mo). Soil pollution level was evaluated using pollution indices including geo-accumulation index (Igeo), contamination factor (CF), degree of contamination (CD), enrichment factor (EF) and PERI. CF showed moderate contamination of soil with Cd, Co, Fe and Mo, while Igeo values indicated moderate accumulation of Cu. For Cd, EF> 1.5 was found in agricultural soils of the study area. PERI findings presented a very high ecological risk (PERI > 380) at two sites (4%), considerable ecological risk at four sites (7.4%). Non-carcinogenic risk from exposure to Fe in soil was higher than limit (HI > 1) for both children and adults. Moreover, carcinogenic risk postured by soil contaminants i.e. Cd, Cr, Co and Ni in children was higher than their limits (except Pb), while in adults only Co posed higher risk of cancer than the limit (10-4) through soil exposure. Non-carcinogenic risks in children due to Cd, Co, Mo via surface water intake were higher than their safe limits (HQ > 1), while in adults the risk order was Cr > Cd > Cu > Pb > Co > Mo. Moreover, carcinogenic risk exposure due to Co > Cd > Cr > Ni from surface water (except Pb) was higher than the tolerable limit (1 × 10-4) both for children and adults. However, Pb concentrations in both soil and surface water exposure were not likely to cause cancer risk in the local population.