Potentially harmful metals,and health risk evaluation in groundwater of Mardan,Pakistan:Application of geostatistical approach and geographic information system

This study investigates the values of pH,total dissolved solids(TDS),elevation,oxidative reduction potential(ORP),temperature,and depth,while the concentrations of Br,and potentially harmful metals(PHMs)such as Cr,Ni,Cd,Mn,Cu,Pb,Co,Zn,and Fe in the groundwater samples.Moreover,geographic information system(GIS),XLSTAT,and IBM SPSS Statistics 20 software were used for spatial distribution modeling,principal component analysis(PCA),cluster analysis(CA),and Quantile-Quantile(Q-Q)plotting to determine groundwater pollution sources,similarity index,and normal distribution reference line for the selected parameters.The mean values of pH,TDS,elevation,ORP,temperature,depth,and Br were 7.2,322 mg/L,364 m,188 mV,29.6℃,70 m,0.20 mg/L,and PHMs like Cr,Ni,Cd,Mn,Cu,Pb,Co,Zn,and Fe were 0.38,0.26,0.08,0.27,0.36,0.22,0.04,0.43 and 0.86 mg/L,respectively.PHMs including Cr(89%),Cd(43%),Mn(23%),Pb(79%),Co(20%),and Fe(91%)exceeded the guideline values set by the world health organization(WHO).The significant R^(2)values of PCA for selected parameters were also determined(0.62,0.67,0.78,0.73,0.60,0.87,-0.50,0.69,0.70,0.74,-0.50,0.70,0.67,0.79,0.59,and-0.55,respectively).PCA revealed three geochemical processes such as geogenic,anthropogenic,and reducing conditions.The mineral phases of Cd(OH)_(2),Fe(OH)_(3),FeOOH,Mn_(3)O_(4),Fe_(2)O_(3),MnOOH,Pb(OH)_(2),Mn(OH)_(2),MnO_(2),and Zn(OH)_(2)(-3.7,3.75,9.7,-5.8,8.9,-3.6,2.2,-4.6,-7.7,-0.9,and 0.003,respectively)showed super-saturation and under-saturation conditions.Health risk assessment(HRA)values for PHMs were also calculated and the values of hazard quotient(HQ),and hazard indices(HI)for the entire study area were increased in the following order:Cd>Ni>Cu>Pb>Mn>Zn>Cr.Relatively higher HQ and HI values of Ni,Cd,Pb,and Cu were greater than one showing unsuitability of groundwater for domestic,agriculture,and drinking purposes.The long-term ingestion of groundwater could also cause severe health concerns such as kidney,brain dysfunction,liver,stomach problems,and even cancer.

Utilization of Bayer Red Mud Derived from Bauxite for Belite-Ferroaluminate Cement Production

Bayer red mud(BRM)is a kind of industrial solid waste characterized by huge volume and high alkalinity.Its disposal generates serious environmental pollution and occupies a large number of farmland.The utilization and recycling of BRM is currently a crucial issue and needs to be addressed as soon as possible.The chemical composition of BRM is similar to cement clinker.In this study,the feasibility of preparing Belite-ferroaluminate clinker(BFAC)with different BRM was explored.The physical properties,mechanics performance,radioactivity levels and trace harmful metals leaching were measured.XRD,BEI and EDS were used to characterize the mineral formation,and SEM is used to reveal the solidified mechanism of trace harmful metal.The results show that the preparation of BFAC using a certain amount of BRM was feasible.The formed phases in clinkers mainly included C_(4)A_(3)Š,C_(2)S and C_(4)AF.The flexural strength and compressive strength of BFAC at 3 days increased whereas 28 and 90 days decreased with the increase of BRM due to the formation of higher C_(4)AF and lower C_(2)S.The formation of large amounts of Al_(2)O_(3)·3H_(2)O gel and Fe_(2)O_(3)·3H_(2)O gel in hydration products enhanced the adsorption capability to heavy metals and other ions.The trace harmful metal concentration in the leaching solution was much less than the upper limits.The radioactivity level of leaching solution was close to natural radioactive background.BRM is safe as raw material of BFAC.