Trace metals as markers for historical anthropogenic contamination: Evidence from the Peshawar Basin, Pakistan.

Trace element concentrations in the youngest Holocene sedimentary archives, historical mining, and archaeological sites are reliable indicators for historical anthropogenic contamination. The Pleistocene-Holocene strata and the overlying archaeological sites of the Peshawar Basin, NW Pakistan provide sedimentary archives to explore historical anthropogenic controls on the distributions of trace elements. The basin with 2500 y of human civilization was sampled using archaeological trenches at Gor Khuttree and Hund, and six sections of youngest Pleistocene-Holocene strata along river banks. Geochemical analysis of high-resolution samples were conducted for both the lacustrine-floodplain sediments and archaeological sites. Results from various horizons of the archaeological sites provide signals for anthropogenic control on the distribution of As, Zn, Cu, Mo, Pb, Hg, Ag, and Au during the Meghalayan Stage of Holocene that gain progressive strength since the 18th century. The geochemical proxies negate direct mining of Cu-Pb and Zn in the area. The consistent, anthropogenic Ag and Au contribution to the system throughout the basin's archaeological history is a significant finding. When correlated against the anthropogenic mercury contamination, it appears that Hund was a major silver-gold panning site throughout its known history whereas Gor Khuttree was the major silver-gold processing center. The Peshawar Basin anthropogenic signals contribute to widespread European early Anthropocene signals at around 2000 BP related to the Greek and Roman mining. Signals during the Hindu Shahi period correlate well with the Medieval period mining and smelting peak signals observed in Europe and China. Hg, Ag, and Au concentrations in the area since the start of the 19th century CE correlates to the start of industrialisation. During the mid-20th century, these geochemical signals from the Gor Khuttree reflect anthropogenic contributions to the local system and correlate to the suggested base of a formalised Anthropocene.

Human exposure to arsenic in groundwater from Lahore district, Pakistan.

In the present study we determined As concentrations in healthy volunteers from three different age groups (children, adults and old age) residing in Lahore, Pakistan to gain insight into arsenic exposure to humans via drinking water. The results revealed that the concentrations of As were significantly (p<0.05) different among different sites, while non significant trends were observed among different age classes. As concentrations in blood and nails samples showed a significant (p<0.05) positive correlation. The mean concentrations of As were higher in nails samples (1.43µg/g) followed by blood samples (1.15µg/L); urine samples (0.82µg/l) and hair samples (0.74µg/g) based on all sites. The antioxidants enzyme activities in blood samples showed a significant (p<0.01) decrease with the increase in As concentrations. The result suggests that urgent action is needed to prevent further human exposure to As.