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The present study was conducted to investigate the concentrations of potential toxic metals (PTMs) in agricultural soil (n = 25) and their bioaccumulation in wheat crop (n = 25) collected from alongside the Kurram River, Pakistan. The highest concentrations of Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn in soil samples were 0.16, 19.5, 14.7, 46.5, 13.5, 14.5, 14.0, and 19.7 mg kg−1, respectively. In the edible tissues of cultivated wheat crop, the highest concentrations of Cd, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were 0.15, 10.00, 8.75, 22.25, 11.00, 11.25, 10.50, and 7.50 mg kg−1, respectively. The selected PTM concentrations in soil samples were observed within their respective permissible limits set by the Food and Agriculture Organization (FAO) and State Environmental Protection Administration (SEPA) China, while in wheat crops, the Cr and Pb concentrations were above the permissible limits of both FAO and SEPA China. The results showed that the orders of PTMs were Fe > Zn > Cr > Cu > Ni > Pb > Mn in soil and Fe > Ni > Mn > Pb > Cr > Cu > Zn in wheat. The highest PTM concentrations were reported in the sample collected near dumping sites. The results of different soil pollution indices including geo-accumulation index (Igeo), contamination factor (CF), and enrichment factor (EF) indicated that the soil of the study area was moderately to severely contaminated. The ADI values of wheat crops were less than 1, while the HQ varied among different PTMs with the highest value of 2.118 for Pb, and the lowest for Zn (0.007). The results indicated that anthropogenic intervention has made a substantial contribution to soil contamination with PTMs and subsequent uptake by wheat, which may exert potential human health risk. [ABSTRACT FROM AUTHOR]

• UV irradiation induced obvious aggregation of GO in NaCl solutions. • HA/FA from different climate zones promoted GO aggregation under UV irradiation. • HA/FA physicochemical properties affected GO aggregation under UV light. • DOM and UV light promoted GO aggregation due to rGO generation and DOM degradation. • GO aggregation was controlled by the content of C-C/C=C groups and C-O group. Aggregation of graphene oxide (GO) is significantly affected by dissolved organic matter (DOM) in natural waters, while DOM's climate zone and light irradiation is seldom considered. This study investigated the effect of humic/fulvic acid (HA/FA) from various climate zones of China on aggregation of small (200 nm) and large (500 nm) GO under 120-h UV irradiation. GO aggregation was promoted by HA/FA because UV irradiation decreased hydrophilicity of GO and steric forces among particles. GO generated electron and hole pair under UV irradiation, which reduce GO with more hydrophilic oxygen-containing functional group (C-O) to rGO with high hydrophobicity and oxidize DOM into organic matter with smaller molecular weight. Most severe GO aggregation was observed with Makou HA from Subtropical Monsoon climate zone and Maqin FA from Plateau and Mountain climate zone, which was primarily because HA/FA's high molecular weight and aromaticity dispersed GO initially that facilitated UV penetration. GO aggregation ratio was positively correlated with graphitic fraction content (R 2 = 0.82-0.99) and negatively correlated with C-O group content (R 2 = 0.61-0.98) in the presence of DOM under UV irradiation. This work highlights different dispersity of GO during photochemical reactions in various climate zones, providing new insight into the environmental implications of nanomaterial release. [Display omitted] [ABSTRACT FROM AUTHOR]