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ICAR AICE-JRF/SRF Soil Contamination, Toxicology & Remediation: practice questions

ICAR AICE-JRF/SRF (PhD) — Environmental Sciences (subject 71) and Agricultural Meteorology (subject 60) · India · National Testing Agency for ICAR

Original practice questions written to the published syllabus · not past papers
10worked here, free
25written to this exam in this subject
12syllabus units

What this subject covers

Heavy metals, pesticides, plastics and emerging contaminants in soils: fate, toxicity to organisms and people, risk assessment, and remediation including phytoremediation and microbial methods.

In the exams: ICAR AICE subject 71 Unit 4 (soil pollution, remediation); GATE ES Sections 7 and 9 (soil contamination, health risk assessment); UGC NET Unit 6

What ICAR AICE-JRF/SRF asks from it

ICAR AICE-JRF/SRF Environmental Sciences (Unit 4)

Soil pollution sources, heavy metals and their mobility, pesticides and POPs, bioaccumulation and biomagnification, phytoremediation types and hyperaccumulators, bioremediation, itai-itai and Minamata cases.

Where the 25 questions fall

How our questions for ICAR AICE-JRF/SRF spread across the units of Soil Contamination, Toxicology & Remediation. Difficulty: 0 easy, 13 medium, 12 hard.

Heavy metals: forms, mobility and plant uptake3
Sources of soil contamination: industrial, agricultural, urban2
Organic contaminants and xenobiotics2
Microplastics and emerging contaminants in agricultural soils2
Bioaccumulation and biomagnification2
Principles of toxicology: dose-response, LD50, NOAEL2
Ecotoxicology and ecological risk assessment2
Human health risk assessment: hazard, exposure, dose, risk characterisation2
Permissible limits and soil screening values2
Physical and chemical remediation2
Bioremediation and phytoremediation2
Contaminant leaching to groundwater2

10 practice questions, worked

Choose an answer, then open the working. Each explanation says why the right answer is right and why the others are not.

1 · Sources of soil contamination: industrial, agricultural, urban · medium

Which sources contribute zinc, copper and antibiotics to farm soils?

  1. Manures from animals fed additives
  2. Rainfall over remote mountain areas
  3. Clean canal water from glaciers
  4. Sand used to level irrigated fields
Answer and working

A. Manures from animals fed additives

Feed additives and veterinary drugs are excreted in manure.

2 · Organic contaminants and xenobiotics · medium

A high log Kow indicates that a chemical:

  1. Evaporates instantly from the soil surface
  2. Is hydrophobic and sorbs to organic matter
  3. Dissolves readily in water in all soils
  4. Is always non-toxic
Answer and working

B. Is hydrophobic and sorbs to organic matter

Such chemicals also tend to bioaccumulate in fats. Hydrophobic chemicals do not dissolve readily and are not necessarily non-toxic.

3 · Organic contaminants and xenobiotics · hard

Why can 'aged' organic contaminants in soil be less bioavailable than fresh ones?

  1. They evaporate completely after one year in all soils and climates
  2. They become more water-soluble as they age
  3. They migrate into micropores and organic matter, slowing desorption
  4. They are converted into heavy metals over time
Answer and working

C. They migrate into micropores and organic matter, slowing desorption

Ageing reduces the fraction available to organisms and extractants.

4 · Microplastics and emerging contaminants in agricultural soils · medium

Why are PFAS called 'forever chemicals'?

  1. They are radioactive with long half-lives
  2. Their carbon-fluorine bonds resist degradation
  3. They are produced continuously by soil bacteria
  4. They are found only in deep space
Answer and working

B. Their carbon-fluorine bonds resist degradation

Extreme persistence leads to accumulation in water, soils and organisms.

5 · Microplastics and emerging contaminants in agricultural soils · hard

Which additive associated with plastics is a concern as it leaches into soils?

  1. Phthalate plasticisers
  2. Nitrogen gas
  3. Water vapour
  4. Calcium carbonate filler only
Answer and working

A. Phthalate plasticisers

Plasticisers and flame retardants can leach from plastics.

6 · Bioaccumulation and biomagnification · medium

Biomagnification refers to:

  1. Uptake from water alone
  2. Leaching to groundwater
  3. Breakdown of chemicals by soil microbes over time
  4. Rising concentration up trophic levels
Answer and working

D. Rising concentration up trophic levels

Bioconcentration is uptake from water; bioaccumulation includes all routes.

7 · Principles of toxicology: dose-response, LD50, NOAEL · hard

IARC Group 2A means an agent is:

  1. Probably carcinogenic to humans
  2. Possibly carcinogenic to humans
  3. Carcinogenic to humans
  4. Not classifiable
Answer and working

A. Probably carcinogenic to humans

Group 1 carcinogenic; 2B possibly; 3 not classifiable. Group 1 is the strongest evidence category, 2B weaker, 3 not classifiable.

8 · Ecotoxicology and ecological risk assessment · medium

What does HC5 from a species sensitivity distribution represent?

  1. The half-life of five compounds in a reference soil
  2. The highest concentration in 5% of samples
  3. The concentration hazardous to 5% of species
  4. The concentration killing 5% of one species
Answer and working

C. The concentration hazardous to 5% of species

It aims to protect 95% of species. It is a community-level value, not a single-species or sample statistic.

9 · Bioremediation and phytoremediation · hard

For nickel, a hyperaccumulator is commonly defined as a plant with shoot concentrations above:

  1. 10 mg/kg
  2. 100,000 mg/kg
  3. 100 mg/kg
  4. 1,000 mg/kg
Answer and working

D. 1,000 mg/kg

Thresholds differ by metal. Zinc and cadmium thresholds are set at different values.

10 · Contaminant leaching to groundwater · medium

DRASTIC is a method for mapping:

  1. Soil erosion rates
  2. Aquifer vulnerability to contamination
  3. Crop water requirements across seasons
  4. Air quality indices
Answer and working

B. Aquifer vulnerability to contamination

It weights depth to water, recharge, aquifer, soil, topography, vadose zone and conductivity.

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Read the subject

Soil Contamination, Toxicology & RemediationThe full study manual, free ICAR AICE-JRF/SRFFormat, sections and how it has changed

More ICAR AICE-JRF/SRF practice

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Soil Contamination, Toxicology & Remediation for other exams

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