B5203 - Management of Pollutants in the Soil-Water-Plant System

Learning outcomes

Learning outcomes

At the end of the course, the student will have acquired the knowledge to analyze, evaluate, and enhance the main self-purification processes implemented by the soil-plant system against pollutants through retention and degradation processes, as well as to plan restoration interventions to reduce the impact of pollutants in agro-forestry systems and water bodies. In particular, the student will have developed the ability to (1) correlate the behavior of pollutants in the soil-water-plant system to the physical-chemical characteristics of the pollutants themselves, the soil, and the water body in question; (2) critically read scientific publications and technical reports concerning the evaluation and prediction of soil and water pollution phenomena, and their subsequent translocation to the plant; (3) outline possible strategies to reduce pollution levels and/or mitigate their effect in the soil-water-plant system.

Course contents

1. Prerequisites

This course is a continuation of an educational path that began in Bachelor's Degree programs, at the end of which students should have acquired knowledge regarding the chemical, physical, and biological properties of the soil, as well as plant biology and biochemistry. The foundational courses are soil chemistry, agricultural biochemistry, agricultural microbiology, and plant biology. A recommended preparatory text to fill any potential gaps in this area is "Fondamenti di Chimica del suolo" (Patron Editore): Chapters 1, 3-9.

The course Management of Pollutants in the Soil-Water-Plant System aims to provide the necessary knowledge to evaluate the fate of pollutants in soil and water, and to implement possible interventions to reduce their concentration in environmental matrices using eco-friendly and sustainable techniques such as phytoremediation. The study of the effects of both organic and inorganic polluting chemical species—often of anthropogenic origin—in the soil and their management is integrated with the study of Soil Quality Indices (Module taught by Prof. Luciano Cavani). Together, the modules “Management of Pollutants in the Soil-Water-Plant System" and "Soil Quality Indices" constitute the tools for a correct assessment of the chemical and biochemical Quality of the soil (Integrated Course).

The course is divided into 2 teaching units: classroom lectures (36 hours) and supplementary teaching activities (24 hours).

Classroom lectures are aimed at understanding the chemical-physical and biological mechanisms that influence the persistence of organic and inorganic pollutants in the soil, water, and plants, and that allow for the prediction of their environmental fate. The knowledge acquired during classroom lectures is a prerequisite for the supplementary teaching activities. Supplementary teaching serves to consolidate the information learned during frontal teaching, foster interpersonal relationships among students, improve communication in technical and scientific fields, and raise awareness that the acquired knowledge can be put at the service of the community. Students are encouraged to address an environmental pollution issue, for which they are asked to organize and re-elaborate the concepts learned during frontal teaching to propose solutions (problem-solving approach), first within working groups and subsequently as a spokesperson for the group.

1. Classroom teaching (36 hours)

1.1. Adsorption of pollutants on soil components (10 hours)

1.1.1 Soil characteristics and pollutant adsorption. Introduction to the course and assessment methods. Definition of pollutant and main environmental pollutants. Partition equilibria of pollutants among the main environmental compartments. Texture: structure of expandable and non-expandable phyllosilicates and adsorption; nucleophilic characteristics of the siloxane cavity of expandable phyllosilicates; isomorphic substitutions and hydration state effects on the adsorption of organic and inorganic pollutants. Soil organic matter and adsorption. Adsorption on soil oxides and hydroxides. Phase diagrams of hematite and gibbsite. Pollutant adsorption as a function of soil pH.

1.1.2 Pollutant characteristics and soil adsorption. Chemical-physical properties: solubility, vapor pressure, Henry's law constant, n-octanol-water partition coefficient (\(K_{ow}\)), soil-water partition coefficient (\(K_{d}\)), acid or base dissociation constant, and the effect of pollutant charge on adsorption.

1.1.3. Macroscopic effects of pollutant adsorption in soil. Adsorption and desorption isotherms: batch and column techniques. Reversibility and irreversibility of adsorption. Thermodynamics of adsorption.

1.1.4. Adsorption at the molecular level. Adsorption mechanisms: van der Waals interactions, hydrophobic bonding. Adsorption as a cooperative process. Hydrogen bonding. Protonation. Cation exchange. Cation bridging, water bridging. Anion exchange. Ligand exchange.

1.2. Degradation of pollutants in soil and water (8 hours)

1.2.1. Abiotic degradation. Potential energy of reversible and irreversible adsorption: adsorption and abiotic degradation. Soil characteristics influencing degradation: outer-sphere and inner-sphere adsorption complexes. Isomorphic substitutions and degradation. pH-catalyzed hydrolytic degradation in heterogeneous and homogeneous phases. Photolytic processes: direct photolysis and the Jablonski diagram, indirect photolysis. Titanium dioxide-catalyzed degradation: water purification.

1.2.2. Biotic degradation. Definition and characteristics. Chemical-physical properties of the soil-root interface: rhizospheric gradients (pH, nutrients, redox potential, exudates, microbial activity, enzymatic activities). Influence of the rhizosphere on soil mineral structure. Soil characteristics influencing biotic degradation. Microbial degradation: direct and indirect types. Oxidation, hydrolysis, and reduction reactions. Biobeds (biological beds).

1.3. Heavy metals and Potentially Toxic Elements (8 hours)

1.3.1. Metals in the soil-water-plant system. Metals and heavy metals. Speciation of metals in soil. Metals in the soil solution (free ions, ion pairs, organometallic complexes). Metal availability as a function of pH. Effect of dissolved organic matter on long-distance metal transport and transport into water bodies. Metals and redox potential. Phytoextraction in the presence of chelating agents. Toxicity of heavy metals: copper, zinc, arsenic, cadmium, nickel, lead.

1.3.2. Acid rain. Formation, evolution, and effects on the soil-plant system. Acidification and soil buffering capacity (carbonate phases, organic matter, exchangeable bases). Mobile aluminum: formation conditions and effects on the apoplast.

1.4. Soil-water system pollution and plant contamination (10 hours)

1.4.1. General concepts of pollution. GUS (Groundwater Ubiquity Score) index. Mitigation measures for soil and water body pollution. Current regulations on soil and water pollution. Low-environmental-impact decontamination techniques: chemical-physical techniques, cation exchange, composting, phytoremediation.

1.4.2. Plant uptake of organic pollutants. Entry of contaminants into the plant: predictive uptake models. Phytostabilization: root concentration factor and pollutant \(K_{ow}\). Phytodegradation: transpiration stream concentration factor and pollutant \(K_{ow}\). Translocation of acidic contaminants in the plant: ion-trap theory. Enzymatic phytotransformation: Phase I (oxidations, hydrolysis, reductions), Phase II (conjugation with low-molecular-weight biomolecules), Phase III (conjugation with high-molecular-weight biomolecules). Phytovolatilization.

1.4.3. Plastics in the soil-water-plant system. Production. Environmental fate. Effect on soil characteristics (moisture, organic matter content, microbial load). Interaction between microplastics and other pollutants in soil and water. Plastics inside the plant.

1.4.4. PFAS in the soil-water-plant system. Production. Geographical distribution. Translocation to the plant. Bioaccumulation along the trophic chain (food web).

2. Case studies (24 hours)

The supplementary teaching activities will address the following case studies:

2.1. Land application of livestock manure on agricultural soils: antibiotics, antibiotic resistance, nitrates, ammonia, and other malodorous emissions. Possible interventions to minimize environmental and social issues associated with these soil amendment practices.

2.2. Wetlands for the collection and treatment of wastewater from agricultural farms. Functions and operations. Removal of pesticides, nitrogen, and phosphorus. Modeling the removal process with predictive validity.

2.3. Plastics, bioplastics, micro-, and nano-plastics in agricultural soils. Definitions, production processes, and methods for analysis and quantification. Possible interventions to minimize environmental issues and crop yield reductions resulting from the presence of plastics in soils. Effect of micro- (and nano-) plastics on the environmental dynamics of other contaminants.

2.4. PFAS in water bodies, soils, and food production. Characteristics, monitoring, and potential removal interventions.

Each case study consists of the following activities:

(1) Introductory seminar on the topic. The seminar may be held by the professor, her research collaborators, or industry experts and technicians.

(2) Group work. Students will be invited to form groups of 3–4 members, depending on the class size. Each group will review one scientific report (review article) related to the topic under consideration. A spokesperson for each group will then present the content of the report and the observations emerged within the group to the class.

(3) Presentation of potential solutions. Discussion of solutions provided by scientific literature and research results obtained by the professor within projects dedicated to the aforementioned case studies. This will be followed by a classroom discussion open to all students.

(4) Laboratory activities aimed at the extraction and quantification of pollutants of environmental interest from soil, water, and plants.

Readings/Bibliography

Periodic table of the elements.

Agrofarmaci - Conoscenze per un uso sostenibile, Gruppo Perdisa Editore, II Parte (pg. 151-377). The book will be freely given by the teacher.

Inquinamento e risanamento del suolo. Patron Editore Bologna 2026. Digital book at bSmart books.
Marschner H., Mineral Nutrition of Higher Plants. Academic Press, London, 1995. Chapter 15: The soil/root interface.

Teaching methods

Classroom Lectures:

Through classroom lectures, students acquire knowledge of the primary mechanisms of pollution and self-purification within the soil-water-plant system, the main measures for protecting soil and water quality, and potential pollution mitigation techniques. The acquisition of knowledge and understanding will be constantly monitored throughout the lectures through continuous interaction between the professor and students, engaging them in problem-solving activities related to the discipline. This professor-student interaction also aims to foster independent judgment and improve communication skills

Laboratory Practicals:

 The preparation for laboratory practicals involves several stages: rationalizing the purpose of the experiment; understanding the techniques used to conduct it; handling and processing the samples to be analyzed; collecting and processing the data obtained; and interpreting the final data in light of the knowledge acquired during lectures. During the practicals, various application scenarios will be presented. Within these scenarios, students (individually or in groups) must select a work program to follow throughout the duration of the practicals. At the end of these activities, they will be required to produce a technical report and deliver a short oral presentation on the work performed.

Those students who do not attend the laboratory practicals may write a report based on materials made available by the professor in the virtual learning spaces

"In consideration of the types of activities and teaching methods adopted, attendance at this training activity requires all students to complete Modules 1 and 2 in e-learning mode [https://www.unibo.it/it/servizi-e-opportunita/salute-e-assistenza/salute-e-sicurezza/sicurezza-e-salute-nei-luoghi-di-studio-e-tirocinio] and to participate in Module 3, which provides specific training on health and safety in study and internship areas. Information on the dates and attendance procedures for Module 3 can be found in the dedicated section of the degree programme website."

Assessment methods

Assessment of student learning is based on the evaluation of the report submitted at the end of the laboratory practicals, completed by an oral presentation of the work performed. During this session, students will also be asked questions (oral exam) aimed at assessing their level of preparation on the theoretical part of the course. The final grade will result from the integration of the marks earned in the two modules that make up the Integrated Course (C.I.) "Soil Chemical and Biochemical Quality". The assessment must be passed as a whole, and candidates must achieve a mark of at least 18/30 in each of the two modules. The final grade will be an average of the scores achieved in each of the 2 disciplinary areas.

Upon specific request by the student, it is possible to take the exam in English.

Teaching tools

For lectures, overhead projectors, PCs, video projectors, and whiteboards will be used.

Laboratory practicals will take place in the teaching laboratory of Chemistry, Agricultural Biochemistry, and Food Technologies (Lab CBA) of the Department of Agricultural and Food Sciences (University of Bologna).

Office Hours

Monday from 9:00 to 11:00 AM, by prior appointment with the professor via email.

For further information, please visit the website of Ilaria Braschi [https://www.unibo.it/sitoweb/ilaria.braschi].

Office hours

See the website of Ilaria Braschi