Human activities could negatively affect the environmental quality in recent decades. In this regard, burning of agricultural wastes after harvesting emits gases such as carbon monoxide, carbon dioxide, nitrogen dioxide and other greenhouse gases into the atmosphere, which is a major factor of damaging the ozone layer, global warming and climate change. There are new approaches to reduce atmospheric carbon dioxide which one of them is stabilization of carbon of organic materials by biochar production. Biochar is a carbon rich material which is generated by pyrolysis process (heating in the absence or lack of oxygen environment). Regarding to the problems of burning agricultural residue and the importance of providing an appropriate alternative approach, this study was carried out to convert different types of agricultural waste to biochar and investigate the potential of them as heavy metal sorbents in aquatic environments. Agricultural wastes were used in this study included wheat straw, barley straw, rice husk and sawdust which were initially converted to biochar via pyrolysis furnace having the atmosphere of N 2 at temperatures of 300, 400 and 500 °C, thereafter the parameters such as percent biochar yields, moisture, ash, volatile matter, fixed carbon as well as pH values of biochars and raw materials were measured. Then considering the results of lead (Pb 10 mg/L) and cadmium (Cd 2 mg/L) adsorption, barley straw biochar which was produced at 500 °C (BS500) was selected for assessment of changing the biochar quality in various temperatures. Biochar quality was investigated through the elemental analysis, determination of specific surface area and pore size (BET) and surface imaging by scanning electron microscopy (SEM). Finally, different factors affecting the absorption process including pH (4,5,6,7,8), the amount of sorbent (0.1, 0.5, 1, 2 g/L), the initial concentration of Pb (2, 5, 10, 20, 50 mg/L) and cadmium concentration (0.1, 0.5, 1, 5, 10 mg/L) in the solution and the contact time (5, 10, 15, 30, 45, 60 120 minutes) were investigated and consequently the optimum values were used in Pb and Cd adsorption and desorption column test. The results showed that biochar yields, moisture and volatile matter of biochar samples were reduced, whereas ash content, fixed carbon and pH of the samples increased with increasing pyrolysis temperature. The results of BET and SEM imaging analyses of barley straw biochar showed that specific surface area increased with increasing temperature to 400° C and then decreased until 500° C. Besides, the pore size of BS500 was in the range of mesopores. By increasing the temperature from 300 to 500° C, the pores were emerged on the surface of biochar samples. Investigation of effective factors in Pb and Cd adsorption by BS500 revealed the optimum conditions of adsorption which were pH=6, the amount of sorbent 1 g/L and Cd concentration of 1 mg/L, Pb concentration of 10 mg/L and the contact time of 45 min. The results of the column experiments in optimum conditions showed that the amount of Pb and Cd adsorption by BS500 was 33 and 29 %, respectively. Furthermore, the desorption amounts of Pb and Cd using distilled water were, 6.5 and 9.8 %, respectively. Therefore, it can be concluded that the biochar samples derived from agricultural wastes have a considerable potential for removal of Pb and Cd from aquatic environments. Key words: Biochar, Climate change, Agricultural residue, Adsorption, Heavy metals