Topic: Soil pollution

Target group

High school / technical school student

Core curriculum

New core curriculum:

High school and technical high school. Chemistry – basic level:

XXII. Elements of environmental protection. Pupil:

2) lists the basic types of air, water and soil pollution (e.g. heavy metals, hydrocarbons, combustion products, freons, dusts, nitrates (V), phosphates (V) (orthophosphates (V)), their sources and impact on the state of the environment; describes the types of smog and its mechanisms formation;
3) suggests ways to protect the environment against pollution and degradation in accordance with the principles of sustainable development;
5) indicates the widespread use of plant protection products and risks to human health and environments resulting from careless use.

High school and technical high school. Chemistry – extended level:

XXII. Elements of environmental protection. Pupil:

2) lists the basic types of air, water and soil pollution (e.g. heavy metals, hydrocarbons, combustion products, freons, dusts, nitrates (V), phosphates (V) (orthophosphates (V)), their sources and impact on the state of the environment; lists activities (individual / comprehensive) that should be introduced to limit these phenomena; describes the types of smog and its mechanisms;
3) suggests ways to protect the environment against pollution and degradation in accordance with the principles of sustainable development;
5) indicates the widespread use of plant protection products and risks to human health and environments resulting from careless use.

Old core curriculum:

High school and technical high school. Chemistry – basic level:

XXII. Elements of environmental protection. Pupil:

2) lists the basic types of air, water and soil pollution (eg heavy metals, hydrocarbons, fuel combustion products, freons, pesticides, nitrates, phosphates (orthophosphates) and their sources, describes types of smog and the mechanisms of its formation.

General aim of education

The student discusses soil pollution.

Key competences

• communication in the mother tongue;

• communication in foreign languages;

• mathematical competence and basic competences in science and technology;

• digital competence;

• learning to learn.

Criteria for success
The student will learn:

• to define the concepts of soil degradation and devastation;

• to exchange and discuss sources and types of soil pollution;

• to discuss examples of the harmful effects of selected soil chemical pollutants (heavy metals, hydrocarbons, pesticides, nitrites and nitrates);

• to justify the relationship between the development of civilization and the existing soil pollution.

Methods/techniques

• expository

  • talk.

• activating

  • discussion;

  • mind map.

• programmed

  • with computer;

  • with e‑textbook.

• practical

  • exercices concerned;

  • experiment.

Forms of work

• individual activity;

• activity in pairs;

• activity in groups;

• collective activity.

Teaching aids

• e‑textbook;

• interactive whiteboard, tablets/computers;

• sheets of gray paper;

• colored markers.

Lesson plan overview

Introduction

1. The teacher hands out Methodology Guide or green, yellow and red sheets of paper to the students to be used during the work based on a traffic light technique. He presents the aims of the lesson in the student's language on a multimedia presentation and discusses the criteria of success (aims of the lesson and success criteria can be send to students via e‑mail or posted on Facebook, so that students will be able to manage their portfolio).

2. The teacher together with the students determines the topic – based on the previously presented lesson aims – and then writes it on the interactive whiteboard/blackboard. Students write the topic in the notebook.

3. Health and safety – before starting the experiments, students familiarise themselves with the safety data sheets of the substances that will be used during the lesson. The teacher points out the need to be careful when working with them.

Realization

1. Students will get acquainted with the fragment titled „Soil pollution” and analyze the table showing the types of pollutants.

2. The teacher divides the class into groups. Each receives a sheet of gray paper and colored markers. The students' task is to develop the issue of „Sources and types of soil pollution” based on available sources and presentation of collected information in any graphical form (in the form of a diagram, maps of concepts, infographics, etc.). After finishing work, group leaders present and discuss the effects of the team's activities.

3. The teacher informs the students that they will carry out the experiment „Testing the presence of nitrites in vegetables”. Students write down the research question and hypothesis in the form, and after the experiment they note their observations and conclusions. The teacher encourages young people to discuss, referring to the presented conclusions.

4. The teacher instructs students to familiarize themselves with the instruction of the experiment „Testing the effect of soil salinity on plant growth”. As before, students formulate a research question and hypothesis. After the experiment, the teacher asks the pupils what they have noticed - after discussing the observations, they note them in the indicated place. They also write the applications discussed on the forum.

5. The students, when working in pairs, carry out eksperiment „Detection of lead(II) ions in soil”, while completing simultaneously the observation form in the abstract. The participants share the insights made during the observation/experiment, and then formulate conclusions together. The teacher corrects possible mistakes.

6. The teacher presents the map „Soil pollution with heavy metals in Poland”. Pupils subject it to detailed analysis.

7. The students carry out an interactive exercise. The teacher makes sure that the task have been correctly completed and gives feedback.

Summary

1. The students consolidate the acquired information, discussing it with their nearest neighbors („tell your neighbor” method.

2. The teacher asks the students to finish the following sentences:

   • Today I learned ...

   • I understood that …

   • It surprised me …

   • I found out ...

   The teacher can use the interactive whiteboard in the abstract or instruct students to work with it

Homework

1. Prepare 5 questions about the area that could be found on the test of the lesson.

The following terms and recordings will be used during this lesson

Terms

Texts and recordings

Soil pollution

Soils, like the entire natural environment, may become polluted. Due to their sorptive properties, soils absorb a lot of chemical substances that penetrate into them in the form of:

• solids – ashes, plastics;

• liquids – wastewater discharged into water reservoirs and entering soil together with water;

• gases – harmful gases absorbed by the soil or first dissolved by water, and then entering soil together with water;

We talk about soil pollution when chemical substances occur in it in quantities exceeding their typical content and cause changes in soil properties that do not allow for its normal use.

The main sources of soil pollution caused by human activity:

• industrial – mining, energy, metallurgical, steel, chemical, construction industry;

• agricultural – too intensive fertilization, excessive use of pesticides;

• municipal – sewage and solid waste;

• communication – toxic substances and heavy metals contained in the vehicle exhaust, salt, which is sprinkled on ice‑covered road surfaces.

Pesticides are chemical compounds used, among others, for:

• plant protection against pests (insecticides) and fungi (fungicides),

• plant disease control (bactericides),

• weed removal (herbicides).

Pesticides spread in the environment through air and water, but they also remain in the soil. Due to the their exceptionally long shelf‑life, toxicity and high biological activity, pesticides pose a serious threat to the natural environment.

When the significant amounts of hydrocarbons which originate, among others, from petroleum and the products of its processing, i.e. gasoline, diesel oil, get into the soil, they can cause its exclusion from biological activity for the period of 10 -15 years. Soil supersaturation with these products destroys soil and plant microorganisms and causes oxygen deficiency.

An excess of nitrates in the soil reduces the resistance of plants to diseases and pests. Overfertilization of plants may be the cause of their physiological diseases. High‑grade mineral fertilizers used in excessive amounts may in many cases be more harmful than a shortage of nutrients in the soil. The plants grown in the soil contaminated with nitrates may also be harmful to consumers. In certain conditions, nitrates accumulated in the tissues of plants may undergo conversion to nitrites, which have carcinogenic properties (they promote cancer development).

Nitrogen needed for plant growth is taken up by plants in the nitrate $\text{N}{\text{O}}_{\text{3}}^{-}$ or ammonium form ${\text{NH}}_{\text{4}}^{\text{+}}$. However, it may also occur in the soil in the form of nitrites which are toxic to many plants. Not all vegetables accumulate nitrates and nitrites equally. These compounds are accumulated to a high extent by, for example: radish, beets, parsley, to a lesser extent – carrot, celery, potato and onion.

This pollution may lead to a significant reduction in plant resistance to diseases and pests. Plants grown in soils polluted with nitrates and nitrites contain an excess of these substances and have a negative impact on the health of consumers. Excess nitrates can be converted to nitrites, which contribute to the formation of very toxic compounds exerting carcinogenic activity. Processes of this type may occur, for example, when storing vegetables containing excessive amounts of nitrates.

Excessive concentration of salt in the soil solution makes it difficult or impossible for the plants to take up water. The degree of salinity depends on the amount of water in the soil. The negative reaction of plants to excess salt is their wilting, and at higher concentrations – dieback (halophytes are an exception). Salinity is caused by: chlorides, sulfates, sodium and potassium carbonates.
The effects of excessive salinity in Poland may be observed on the leaves of roadside trees in June and July.

Heavy metals – lead $\text{Pb}$, copper $\text{Cu}$, mercury $\text{Hg}$, cadmium $\text{Cd}$ – are another group of the chemical pollutants of soil. Over 90% of the total content of cadmium, copper, zinc and lead in soils comes from anthropogenic sources. A particularly high content of heavy metals in the soil was found in the areas adjacent to steel mills, galvanizing plants and mines.
Heavy metals polluting the soil accumulate in the tissues of plants and cause irreversible changes in their organisms. They are also toxic to consumers (they can cause many diseases, including cancer).

• The chemical sources of soil pollution include, among others, hydrocarbons and their derivatives, chemical fertilizers, pesticides, heavy metals.

• Contaminated soil is unsuitable for cultivation as harmful substances enter the consumer's organisms along with the plants grown.