16.4.5 Oxidation-Reduction Potential
Oxidized and reduced soils have redox potential in the range of 400–700 and
250–300 mV, respectively (Pezeshki and DeLaune 2000). Redox potential plays a
significant role in the reactivity of some soil oxides (Fe and manganese (Mn)) with
organic and inorganic pollutants in soil (Alamgir 2016). It controls the predominant
chemical speciation and sorption of metal(loid)s (As, Cr and selenium (Se)) in soil
(Landner and Reuther 2004). Generally reducing condition favours decline in
mobility of positively charged ions in soil (Gonsior et al. 1997).
16.5 Effects on Environment and Socioeconomic Segment
16.5.1 Effects on Soil
Organic and inorganic pollutants may cause alteration in soil pH, CEC and salinity
and dispersion and/or flocculation of clays and adversely affect soil aggregation,
mechanical strength and stability of soil (Zong and Lu 2019; Salem et al. 2017).
Extremely high levels of nitrogen, phosphorous and potassium (NPK) in soil
significantly lower the total porosity, water retention capacity and macroaggregate
content and increase soil bulk density, plasticity index, coefficient of linear extensibility and tensile strength (Zong and Lu 2019). Soil pollution enables prodigious
quantity of nitrogen to escape into the atmosphere through volatilization and denitrification (Fungo et al. 2019). Moreover, organic matter decomposition in soil emits
sulphur dioxide and other associated compounds, instigating acid rain (Bricker and
Rice 1993). Toxic elements, i.e. Cr, Cd and As, exhibit antagonistic behaviour with
essential micronutrients in soil such as Zn, Cu, Mn, Mg and Fe for active binding
sites of roots (Gautam et al. 2017). Various organic and inorganic pollutants inhibit
the nitrification process and cause salinization of soil due to their highly saline
properties. Soil pollution also causes loss of nutrients present in it, hindering plants
ability to thrive therein, which consequently may result in soil erosion and
disturbances in the balance of soil flora and fauna.
Soil biological properties play pivotal roles in affecting soil fertility and primary
production through organic matter decomposition, nutrient cycling and aggregate
formation (Brevik and Sauer 2015). Soil microbial communities and enzymatic
activities are very sensitive to changes in soil properties accredited to pollution
and thus are considered as indicators of soil fertility (Xu et al. 2015). Pollutants in
soil interact with microorganisms and affect their normal metabolic functioning,
thereby affecting the soil fertility and production (Saxena et al. 2015; Behera and
Prasad 2020). Bastida et al. (2017) found that frequent use of agrochemicals
adversely affects the water storage capacity, structure and function of microbial
communities in soil.
462
M. Gautam et al.
Oxidized and reduced soils have redox potential in the range of 400–700 and
250–300 mV, respectively (Pezeshki and DeLaune 2000). Redox potential plays a
significant role in the reactivity of some soil oxides (Fe and manganese (Mn)) with
organic and inorganic pollutants in soil (Alamgir 2016). It controls the predominant
chemical speciation and sorption of metal(loid)s (As, Cr and selenium (Se)) in soil
(Landner and Reuther 2004). Generally reducing condition favours decline in
mobility of positively charged ions in soil (Gonsior et al. 1997).
16.5 Effects on Environment and Socioeconomic Segment
16.5.1 Effects on Soil
Organic and inorganic pollutants may cause alteration in soil pH, CEC and salinity
and dispersion and/or flocculation of clays and adversely affect soil aggregation,
mechanical strength and stability of soil (Zong and Lu 2019; Salem et al. 2017).
Extremely high levels of nitrogen, phosphorous and potassium (NPK) in soil
significantly lower the total porosity, water retention capacity and macroaggregate
content and increase soil bulk density, plasticity index, coefficient of linear extensibility and tensile strength (Zong and Lu 2019). Soil pollution enables prodigious
quantity of nitrogen to escape into the atmosphere through volatilization and denitrification (Fungo et al. 2019). Moreover, organic matter decomposition in soil emits
sulphur dioxide and other associated compounds, instigating acid rain (Bricker and
Rice 1993). Toxic elements, i.e. Cr, Cd and As, exhibit antagonistic behaviour with
essential micronutrients in soil such as Zn, Cu, Mn, Mg and Fe for active binding
sites of roots (Gautam et al. 2017). Various organic and inorganic pollutants inhibit
the nitrification process and cause salinization of soil due to their highly saline
properties. Soil pollution also causes loss of nutrients present in it, hindering plants
ability to thrive therein, which consequently may result in soil erosion and
disturbances in the balance of soil flora and fauna.
Soil biological properties play pivotal roles in affecting soil fertility and primary
production through organic matter decomposition, nutrient cycling and aggregate
formation (Brevik and Sauer 2015). Soil microbial communities and enzymatic
activities are very sensitive to changes in soil properties accredited to pollution
and thus are considered as indicators of soil fertility (Xu et al. 2015). Pollutants in
soil interact with microorganisms and affect their normal metabolic functioning,
thereby affecting the soil fertility and production (Saxena et al. 2015; Behera and
Prasad 2020). Bastida et al. (2017) found that frequent use of agrochemicals
adversely affects the water storage capacity, structure and function of microbial
communities in soil.
462
M. Gautam et al.