Environmental Contamination and Water Quality: NZ Case Studies and Solutions

What is the definition of contamination?

The presence of unwanted or dangerous substances.

How is contamination often used interchangeably with pollution?

Pollution refers to damage caused to water, air, etc. by harmful substances or waste, while contamination is the presence of unwanted substances.

What role does concentration play in determining harm from chemicals?

Concentration is important as non-essential elements have no biological effects at low concentrations but can have negative effects at higher concentrations.

What is the optimal concentration for essential chemicals?

There is an optimal concentration where lower levels cause deficiency symptoms and higher levels result in toxic effects.

What are threshold values in environmental science?

Threshold values are normal ranges expected for chemicals in soil, plants, or organisms, with trigger values indicating concentrations that warrant investigation.

What is the significance of mg/kg in soil concentration?

mg/kg is equivalent to µg/g and is approximately equal to Parts Per Million (ppm).

What is the equivalent of 1% in mg/kg?

1% = 10,000 mg/kg.

What is background concentration?

The natural concentration of an element or compound that would exist without anthropogenic input.

What are organic contaminants in agricultural soils?

Organic contaminants include pesticides and dioxins, which are carbon-based and can often be broken down.

What are heavy metals and give examples?

Heavy metals are elements with a density greater than 5, such as lead, arsenic, and mercury, and they cannot be broken down.

What are radionuclides?

Radionuclides are heavy metals that emit radiation, such as thorium, radium, and uranium.

What are biological contaminants?

Biological contaminants include organisms like giardia and faecal coliforms that can lead to severe illness.

What is point source contamination?

Contamination arising from a single source or point, such as a metal smelter releasing heavy metals.

What happened in Orby, France regarding contamination?

A metal smelter released heavy metals into the surrounding land, leading to increased soil contamination.

What is the impact of heavy metal contamination on vegetation?

Heavy metals can lead to unusual soil conditions that support different types of vegetation, while organic matter may not decompose due to killed fungi and bacteria.

What are exposure pathways for contaminants?

Exposure pathways include food, dust, and water.

What is the issue with arsenic in agricultural soils in New Zealand?

Arsenic from sheep dips has contaminated soils, and urban sprawl is uncovering these sites in backyards.

What is dieldrin and its relevance to sheep dips?

Dieldrin is another chemical used in sheep dips that is becoming an issue as urban areas expand onto former agricultural lands.

What is CCA treatment for wood?

CCA (copper chromium arsenic) is used to treat wood to prevent decay, especially in fast-growing species like pinus radiata.

What is the relationship between heavy metals and soil contamination?

Heavy metals accumulate in soil and can lead to contamination that is difficult to remediate.

What is the significance of intervention values?

Intervention values are the maximum allowable concentrations of contaminants set by law.

How are mass and volume concentrations typically expressed in environmental science?

Mass is expressed in ng, µg, mg, g, kg, and t; volume is expressed in ml, l, dm³, and m³.

What does mg/l represent in water concentration?

mg/l is equivalent to µg/ml and is approximately equal to Parts Per Million (ppm).

What are trigger values in environmental monitoring?

Trigger values indicate concentrations that require further investigation due to potential contamination.

What is the consequence of not implementing technology to reduce emissions from contamination sources?

Failure to implement technology can lead to long-term environmental contamination and health risks.

What is the impact of contamination on human health?

Contaminants like lead and cadmium can cause severe health issues, including brain damage and kidney failure.

What is the importance of developing a contamination profile?

A contamination profile helps identify the extent and distribution of contaminants in an area.

What solution is used to treat wood in New Zealand to prevent decay?

CCA (copper chromium arsenic) solution

What are the components of CCA and their functions?

Copper is a fungicide, arsenic is an insecticide, and chromium immobilizes arsenic.

What is the average number of CCA-treated posts per hectare in Marlborough?

580 posts per hectare

What happens to arsenic concentration in CCA-treated posts over time?

Arsenic concentration increases in the aboveground part and decreases below ground.

What is a significant environmental concern regarding arsenic from CCA-treated wood?

Arsenic is leaching into the soil.

What is the impact of land use change in Marlborough vineyards?

Vineyards are being taken out of production due to contamination risks.

Why should posts for horse paddocks be untreated?

Horses may nibble on the posts and consume arsenic.

What is the difference between point source and non-point source contamination?

Point source contamination comes from a single source, while non-point source contamination is diffuse and affects a larger area.

What are heavy metals, and why are they a concern in agriculture?

Heavy metals do not break down over time and can accumulate in soils, leading to contamination.

What is the role of copper in vineyard management?

Copper is used as a fungicide to protect grape production from pathogens.

What was the consequence of copper fungicide use in Ōpōtiki?

High copper levels in soil led to weed death and poor tree health.

What are some remediation options for copper-contaminated soil?

Change land use, add chemicals to reduce bioavailability, plow soil, or remove topsoil.

What is cadmium, and why is it a concern in agriculture?

Cadmium is not essential for life, toxic to humans, and accumulates in the food chain.

How does cadmium accumulate in New Zealand soils?

Cadmium binds strongly to negatively charged topsoil and accumulates over time.

What is the estimated area of farmland in New Zealand exceeding cadmium guideline values?

Approximately 70,000 hectares.

What is 'decadmiation' in the context of fertilizers?

A process to remove cadmium from fertilizers, though it is expensive.

How does the application of superphosphate affect cadmium levels in soil?

It leads to cadmium accumulation, as superphosphate contains cadmium.

What is the threshold concentration of cadmium in soil before it becomes problematic?

1 mg/kg.

How long will it take for cadmium concentration to exceed 1 mg/kg with annual superphosphate application?

42 years.

What vegetables are commonly found to exceed safety limits for cadmium?

Spinach and lettuce.

What is the impact of cadmium contamination on human health?

It poses a risk of kidney failure in the elderly and other health issues.

What is the significance of copper being labeled as a 'certified organic' fungicide?

Despite being an inorganic compound, it is approved for organic farming.

What is the effect of copper contamination on soil productivity?

It can lead to permanent loss of productivity.

What is a common agricultural practice that leads to heavy metal contamination?

Use of copper fungicides and certain fertilizers containing heavy metals.

What is the relationship between copper concentration and soil pH?

Copper's safe level in soil depends on the pH level.

What is the environmental concern with cadmium in phosphate rock?

Cadmium accumulates in soils and can enter the food chain.

What is the consequence of high cadmium levels in agricultural produce?

Loss of export earnings and damage to New Zealand's 'clean green' image.

What is Cadmium (Cd)?

Cadmium is an element that cannot be created or destroyed.

Why is Cadmium a concern in New Zealand?

It is a human carcinogen and high concentrations can cause kidney failure and bone softening.

Where are the highest levels of Cadmium found in New Zealand?

In traditional dairy areas.

What is the safe limit of Cadmium in wheat and potatoes?

The safe limit is regularly exceeded.

What is the Tiered Fertiliser Management Strategy?

A strategy developed by the fertiliser industry to manage Cadmium levels in soil.

What does Tier 1 of the Tiered Fertiliser Management Strategy specify?

Cadmium levels less than 0.6 mg/kg, with no restrictions on superphosphate addition.

What is required in Tier 2 of the Tiered Fertiliser Management Strategy?

Cadmium levels between 0.6 - 1 mg/kg must not exceed 1.8 mg/kg within 100 years.

What happens in Tier 3 of the Tiered Fertiliser Management Strategy?

Cadmium levels between 1 - 1.4 mg/kg require a model to ensure levels remain below 1.8 mg/kg within 100 years.

What is the restriction in Tier 4 of the Tiered Fertiliser Management Strategy?

No increase in Cadmium levels is allowed if they exceed 1.8 mg/kg.

What is one proposed method to manage Cadmium in soil?

Soil removal by excavating the top 10 cm of contaminated soil.

What are the costs associated with soil removal for Cadmium management?

Costs can exceed land value, making it economically unfeasible.

What is a potential benefit of using plants to extract Cadmium?

It has been shown to work in principle but has not been commercially deployed.

What is the cost of production for using plants to extract Cadmium?

Approximately $1000 per hectare per year.

What is a disadvantage of using plants to extract Cadmium?

It also removes phosphorus, necessitating re-fertilization.

What is the cost of applying compost as an alternative to superphosphate?

Costs about NZ $1000 per hectare.

What is a drawback of using compost for soil management?

Compost can include contaminants and is not a permanent solution.

What is the effect of organic matter on Cadmium availability?

It binds Cadmium and makes it less available to plants.

What is the impact of rising agricultural production on soil contamination?

Increased agrichemicals lead to more soil contamination.

What are the three pathways for future agricultural practices regarding Cadmium?

Status quo, new rules, and taking charge with new solutions.

What is one suggested solution for Cadmium management in agriculture?

Using diammonium phosphate as a low-cadmium phosphate source.

What is a potential method for measuring Cadmium levels in soil?

Using sensors to measure water, fertiliser, and Cadmium levels.

What is a proposed innovative solution involving drones?

Subterranean drones that remove Cadmium from soil.

What is a genetic approach to managing Cadmium in agriculture?

Selectively breeding or genetically modifying plants to uptake more Cadmium.

What is the environmental concern regarding DDT?

It is ecologically toxic and bio-accumulates, despite being less toxic to humans.

What is the relationship between food production and Cadmium exposure?

Food from contaminated land increases human exposure to Cadmium.

What is the challenge with compost as a long-term solution?

It is a temporary fix, and Cadmium will still remain in the soil.

What is the significance of phosphorus in relation to Cadmium?

Phosphorus cannot be synthesized and is essential for plant growth.

Why is water quality important for New Zealand?

It is crucial for the '100% Pure NZ' brand, tourism, agriculture, and recreational activities like swimming and fishing.

What does water clarity indicate?

Water clarity is an indicator of water quality.

What is an oligotrophic lake?

A lake with few nutrients, considered healthy, such as Lake Coleridge.

What characterizes a eutrophic lake?

A eutrophic lake has high concentrations of nutrients, leading to turbid water and abundant bird life.

What is eutrophication?

The process of a water body being enriched with nutrients, transitioning from oligotrophic to eutrophic.

What are the Secchi depth measurements for different lake nutrient levels?

Oligotrophic: >10 m, Mesotrophic: 2-10 m, Eutrophic: 1-4 m, Hypereutrophic:

What can cause excessive algal growth in water bodies?

Run-off or leaching of fertilizers, particularly nitrogen (N) and phosphorus (P).

What are the consequences of algal blooms?

They can reduce oxygen levels, release toxins, and kill aquatic life due to anaerobic conditions.

What is the ecological standard for nitrate concentration in drinking water?

About 1 mg/L.

What is blue baby syndrome?

A condition in babies caused by high nitrate levels in drinking water.

What are the big four water contaminants in New Zealand?

Nitrate, phosphate, pathogens, and sediment.

How does sediment affect water quality?

It carries phosphates, reduces Secchi depth, and accumulates on the bottom, altering the water chemistry.

What is the major source of nitrates in NZ waterways?

Cows, particularly dairy cows, with 70% of nitrate leaching coming from their urine.

What happens to ammonia in the soil over time?

Ammonia transforms into nitrate, which can leach into waterways.

What is DCD, and why was it significant?

A compound developed to keep urea in the ground and prevent its transformation into nitrate, but it was banned due to export demands.

What is the impact of soil compaction on water quality?

It increases runoff susceptibility, allowing sediments and contaminants to enter waterways.

What is the effect of exotic fish like Koi carp on water quality?

They exacerbate sediment and reactive phosphate levels by consuming and excreting large amounts of sediment.

What is the condition of Lake Waikare?

It is a hyper-eutrophic lake that is dangerous to come into contact with due to high nutrient levels.

What are the consequences of reduced river flow?

Lower flow leads to less dilution of nutrients, worsening eutrophication.