Introduction
Lead (Pb) contamination is a pervasive issue in many low-income neighborhoods throughout the United States. The toxicity of lead poses significant risks to human health, and proves to be especially harmful for children in terms of cognitive and physical development. Lead in the environment is primarily related to a legacy of anthropogenic sources including leaded gasoline, leaded paint, and various industrial applications. Although the presence of heavy metals is ubiquitous in the environment, heavy metal contamination in soils is generally the result of anthropogenic sources. These sources have been mostly phased out in North America during the past several decades. However, Pb contamination is a persistent problem especially …show more content…
This process of accumulation occurs gradually over time and can often become hazardous to human health and the environment. Characterizing the adsorption of Pb is an important aspect of understanding the mobility of the compound in soils. The ability of soils to retain heavy metals by adsorption may determine the availability of biological uptake and if the contamination will affect resources such as surface or groundwater. Variable soil types have differing capacities to adsorb metals, and the two primary factors that influence this mechanism are pH and presence of organic material (Baird, …show more content…
Adsorption increased with higher pH and more than 90% total Pb was adsorbed with pH >6.0. This also correlated higher SOC which indicates that soil organic matter (SOM) is an important component for the sequester of Pb. Models tended to under-predict Pb adsorption at low pH (probably due to overestimation of iron(III) competition) and over-predict at higher pH (possibly due to the presence of dissolved organic matter). It was found that SOM was the dominant adsorbent of Pb at pH between 3.0 to 5.0. Increased pH resulted in more adsorption to Fe (hydr)oxides. Pb adsorbed by clay decreased with higher pH and adsorption to Al hydroxides was comparatively minor. Pb binding to Fe hydroxides is a critical characterization factor to consider when modeling Pb behavior in
Lead (Pb) contamination is a pervasive issue in many low-income neighborhoods throughout the United States. The toxicity of lead poses significant risks to human health, and proves to be especially harmful for children in terms of cognitive and physical development. Lead in the environment is primarily related to a legacy of anthropogenic sources including leaded gasoline, leaded paint, and various industrial applications. Although the presence of heavy metals is ubiquitous in the environment, heavy metal contamination in soils is generally the result of anthropogenic sources. These sources have been mostly phased out in North America during the past several decades. However, Pb contamination is a persistent problem especially …show more content…
This process of accumulation occurs gradually over time and can often become hazardous to human health and the environment. Characterizing the adsorption of Pb is an important aspect of understanding the mobility of the compound in soils. The ability of soils to retain heavy metals by adsorption may determine the availability of biological uptake and if the contamination will affect resources such as surface or groundwater. Variable soil types have differing capacities to adsorb metals, and the two primary factors that influence this mechanism are pH and presence of organic material (Baird, …show more content…
Adsorption increased with higher pH and more than 90% total Pb was adsorbed with pH >6.0. This also correlated higher SOC which indicates that soil organic matter (SOM) is an important component for the sequester of Pb. Models tended to under-predict Pb adsorption at low pH (probably due to overestimation of iron(III) competition) and over-predict at higher pH (possibly due to the presence of dissolved organic matter). It was found that SOM was the dominant adsorbent of Pb at pH between 3.0 to 5.0. Increased pH resulted in more adsorption to Fe (hydr)oxides. Pb adsorbed by clay decreased with higher pH and adsorption to Al hydroxides was comparatively minor. Pb binding to Fe hydroxides is a critical characterization factor to consider when modeling Pb behavior in