APES Unit 5B - Sustainable land and water use

5.9 - Mining

Mining operations are increasingly forced to access lower grade ores due to the depletion of more accessible ores. This necessitates increased resource use, which consequently leads to greater waste and pollution (EIN-2.K.1). Mining involves extracting commercially valuable concentrated mineral deposits, known as Ore, which often contain Metals—elements capable of conducting electricity, heat, and providing structural properties. The known quantity of a resource available for mining is called the Reserve. To reach the ore, Overburden (soil, vegetation, and rocks) must be removed. Post-extraction, waste materials like Tailings & Slag are separated from the valuable mineral and typically stored in ponds at the mining site.

Surface Mining

Surface mining involves removing large portions of soil and rock (overburden) to access the ore underneath (EIN-2.K.2). Examples of surface mining include Open Pit Mining, Strip Mining (which removes vegetation and soil, increasing susceptibility to erosion and habitat loss), Mountaintop Removal (which is extremely damaging to landscapes and habitats and severely impacts nearby streams), and Placer Mining (which extracts minerals from deposits in river beds or surface gravels). Environmental effects of surface mining include increased stream turbidity (cloudiness), elevated particulate matter (PM) in the air, and habitat loss.

Subsurface Mining

Because easily accessible coal reserves are diminishing, subsurface mining is often necessary, although it is significantly more expensive (EIN-2.L.2). This method involves drilling a vertical “shaft” into the ground with an elevator to transport workers and resources. Risks associated with subsurface mining include: poor ventilation leading to toxic gas exposure, mine shaft collapse, injury from falling rocks, and long-term health risks such as lung cancer, exposure to asbestos, and potential for fires or explosions.

Environmental Impacts of Mining

Mining generates significant environmental impacts. Mining wastes comprise the soil and rock displaced, along with waste materials such as slag and tailings remaining post-extraction (EIN-2.L.1). While mining provides low-cost energy and raw materials, detrimental effects include habitat destruction, groundwater contamination, dust particle release, and methane emission from coal mining. Specifically, Acid Mine Drainage occurs when rainwater contaminates abandoned mine tunnels, mixing with pyrite to create sulfuric acid. Rainwater carrying this sulfuric acid then infiltrates local streams and groundwater, lowering the pH and increasing the solubility of toxic metals (e.g., mercury, aluminum) harmful to aquatic organisms. Additionally, coal mining releases Methane (CH_4) from surrounding rock, which contributes to greenhouse gas emissions and worsens climate change, even after mine closure. Mining, particularly coal mining, also generates soot and particulate matter detrimental to respiratory health.

Mine Reclamation

Mine Reclamation is the process of restoring the land to its original state after mining ceases. This process includes several steps: filling of empty mine shafts or holes, restoring the original contours of the land, returning topsoil, removing harmful acids, metals, and tailings, and replanting native vegetation to restore the ecological community.

5.10 Urbanization

Urbanization can lead to the depletion of resources and saltwater intrusion within the hydrologic cycle (EIN-2.M.1). It transforms natural landscapes into urban spaces by removing vegetation, leading to a rise in impervious surfaces, such as roads and buildings, which prevent water infiltration into the ground and result in flooding (EIN-2.M.3). This prevents groundwater recharge, causing precipitation to flow directly into local water bodies. Furthermore, urbanization increases atmospheric carbon dioxide levels, affecting the carbon cycle, through the burning of fossil fuels and waste in landfills (EIN-2.M.2). Cement production, construction machinery, deforestation, and increased landfill volumes all exacerbate CO_2 emissions and lead to the loss of future carbon sequestration potentials.

Urbanization in Coastal Cities and Population Trends

In coastal cities, the over-extraction of groundwater lowers the water table pressure, enabling saltwater intrusion into groundwater supplies. This contamination is further exacerbated by sea-level rise due which contaminates fresh groundwater with salt. There is a migration trend in the US and other nations toward urban areas from rural locales, often resulting in suburban population growth. Urban areas typically have higher population densities, potentially leading to reduced driving and minimized land-use impact per individual, though city centers often experience population decline.

Urban Sprawl

Urban Sprawl is characterized by the population shifting from densely populated areas to lower-density suburbs, posing various environmental challenges (EIN-2.M.4). Causes include lower property costs in suburbs, cars facilitating easy commuting thanks to the expansion of highway systems, and economic decline leading to reduced city services. The expansion of highway systems promotes easier travel, leading to increased driving and fuel tax revenues used for further infrastructure development. A major consequence is urban blight, where abandoned homes and businesses contribute to further population exodus.

Urban Solutions

Solutions to mitigate urban sprawl and runoff issues include implementing Urban Growth Boundaries (laws limiting development beyond defined urban lines), fostering enhanced public transport and walkable city designs, and utilizing Mixed Land-Use Planning to combine residential, commercial, and entertainment areas to foster walkability. Building Up, Not Out (vertical construction) minimizes impervious surfaces, lowering urban runoff potential, especially when green roofs or rooftop gardens are integrated for additional runoff reduction, CO_2 sequestration, and air pollution filtration.

5.11 Ecological Footprint

Ecological Footprints quantify resource demands and waste generation for individuals or societies, defined as the measure of consumption expressed in terms of land area required (EIN-2.N.1). Factors contributing to the ecological footprint include the needs for: land for agriculture (food production), raw materials (wood, metals, plastics), housing space, electricity sources (coal, natural gas, solar, and wind farms), and landfill space for generated waste.

Ecological Footprint vs. Carbon Footprint

The ecological footprint is measured in global hectares (gha), where one global hectare equates to 2.47 acres of biologically productive land. In contrast, the Carbon Footprint is calculated in tonnes of CO2 emitted per year, encompassing all CO2 generated from activities such as the consumption of material goods, food production processes, and energy utilization in transport and utilities.

Factors Impacting Footprint

Factors that increase the ecological footprint include increased affluence (resulting in larger homes, more travel, and greater consumption of goods), higher meat consumption (necessitating more land, water, and energy inputs), and reliance on fossil fuels for heating, electricity, and travel. Factors that decrease the ecological footprint include utilizing renewable energy sources (such as wind and solar), advocating for public transportation, adopting plant-based diets, and minimizing travel and overall consumption. Currently, the global average footprint stands at 1.85 Earths, meaning humanity consumes 1.85 times the resources the Earth can regenerate annually, while the average US footprint is equivalent to 5.1 Earths.

5.12 Sustainability

Sustainability involves living on Earth while utilizing resources without depleting them for future generations (STB-1.A.1). Sustainable yield refers to the quantity of renewable resources that can be harvested without compromising future availability (STB-1.A.2). The Maximum Sustainable Yield (MSY) is the highest amount of a renewable resource that can be harvested without impacting the resource's future supply; this typically equates to about half of the carrying capacity.

Environmental Indicators of Sustainability

Key environmental indicators that guide sustainability efforts include biological diversity, food production capacity, average global surface temperatures, CO2 concentration, human population dynamics, and resource depletion metrics (STB-1.A.1). Biodiversity (genetic, species, and ecosystems) is crucial, as its decline signals problems such as pollution, habitat destruction, and climate change. Food Production reflects the ability of soil, water, and climate conditions to support agriculture, with threats arising from climate change, soil degradation, groundwater depletion, and increased meat consumption. Maintaining a narrow temperature range is critical for life; therefore, increasing Atmospheric Temperature & CO2 Levels due to deforestation and fossil fuel combustion indicates unsustainable practices. Lastly, growth in the Human Population & Resource Depletion correlates with escalating resource depletion and environmental degradation, affecting air and water quality and habitat destruction.

5.13 Reducing Urban Runoff

Decreased infiltration in urban areas leads to inadequate groundwater recharge and the washing away of pollutants into storm drains and subsequently local water bodies. Polluting substances and their effects include: salt (leading to plant and insect mortality), sediment (increasing turbidity), fertilizer (causing eutrophication), pesticides (harming non-target species), and oil and gasoline (suffocating aquatic life and insects).

Solutions to Urban Runoff

Strategies to enhance water infiltration and mitigate urban runoff encompass replacing conventional pavement with Permeable Pavement, which permits stormwater infiltration, recharges groundwater, and minimizes runoff and pollutant transport (STB-1.B.1). Permeable pavement is more costly than conventional pavement but effectively decreases flooding during heavy rainfall events. Rain Gardens are strategically placed gardens designed to enhance runoff absorption into garden soil, encourage stormwater control, and create environments for pollinators while also sequestering CO2. Promoting Public Transit reduces the number of vehicles on the road, subsequently decreasing pollutants leaking into streets and storm drains. Finally, Building Up, Not Out minimizes impervious surfaces, lowering urban runoff potential, with integrated green roofs providing additional runoff reduction and CO2 sequestration benefits.

5.14 Integrated Pest Management (IPM)

Integrated Pest Management (IPM) combines several approaches to control pest species while reducing environmental disruption. Strategies include biological controls, physical methods, and limited chemical interventions such as biocontrol, intercropping, crop rotation, and using natural pest predators (STB-1.C.1). IPM reduces the risks pesticides pose to wildlife, water supplies, and human health, and limits pesticide residues on crops and lowers mortality rates for non-target species. It also helps in reducing the contamination of surface and groundwater by agricultural pesticide runoff.

IPM Techniques and Drawbacks

IPM methods utilize diverse management strategies. Crop Rotation involves changing the primary crop to impede pest establishment by disrupting preferred food sources. Intercropping involves planting a mix of crops to provide habitat for natural predators or attract beneficial insect species. Biocontrol introduces predators or parasites that naturally control the pest population, such as ladybugs for aphids or parasitic wasps for caterpillars. While effective, IPM practices may be complex and costly compared to conventional pesticide application methods, requiring substantial time investment and financial resources for research and management of diverse crop types.

5.15 Sustainable Agriculture

Soil conservation aims to prevent soil erosion (STB-1.E.1) as the US suffers topsoil loss ten times faster than it can regenerate. These strategies—including contour plowing, terracing, perennial crops, no-till agriculture, and strip cropping—are critical for retaining nutrients, moisture, decomposers, and organic matter.

Soil Conservation and Fertility Techniques

Contour Plowing reduces runoff and erosion by plowing along natural land contours. Terracing captures water runoff to prevent soil erosion on sloping lands. Perennial Crops preserve soil structure year-round while preventing soil exposure between harvests. Improving soil fertility can involve crop rotation and the addition of green manure and lime (STB-1.E.2). Crop Rotation alternates crops; for example, legumes like peas or beans have nitrogen-fixing bacteria that enhance soil nitrogen content. Green Manure refers to residual plant matter from cover crops that stabilize soil and enrich nutrients when incorporated back. Liming Soil neutralizes acidic soil through the application of calcium carbonate, which improves nutrient availability and reduces toxic metal solubility. Finally, Rotational Grazing practices involve regularly shifting livestock between different pastures to prevent overgrazing and promote robust pasture growth (STB-1.E.3).

5.16 Aquaculture

Aquaculture has grown due to its efficiency, requiring minimal water, space, and fuel (STB-1.F.1). The benefits include efficient fish production with minimal resource requirements compared to terrestrial livestock and lowering the likelihood of fishery collapses. However, aquaculture poses significant Drawbacks. High-density environments increase waste production associated with pollutants like E. coli. Aquaculture can lead to wastewater contamination and risks that encapsulated fish will escape, competing or breeding with wild populations. High fish density raises disease occurrences applicable to wild fish (STB-1.F.2), and fish reliance on antibiotics can lead to water contamination issues.

5.17 Sustainable Forestry

Sustainable forestry practices minimize ecological damage such as habitat loss and soil erosion through methods like selective cutting and strip cutting, where only specific trees are removed. This approach minimizes logging vehicle use to prevent soil compaction and ensures that logged areas are reforested with the same species.

Mitigation and Fire Management

Methods for addressing deforestation include Reforestation: planting trees in deforested locations to restore ecological balance and habitat (STB-1.G.1). Sustainable practices also involve using recycled materials and repurposing wood. Protecting forests from harmful organisms can be managed using Integrated Pest Management (IPM) and selectively removing afflicted trees, which helps prevent broader forest infections and encourages healthier growth by reducing density (STB-1.G.2).

Managing Fire Risks is critical. Fire suppression (preventing natural fires) can lead to the accumulation of dead biomass, elevating risks for future, larger fires. Therefore, Prescribed Burns (controlled burns) can be enacted to manage natural fires and reduce future wildfire risk effectively (STB-1.G.3). Controlled burns help in nutrient recycling post-fire, prevent larger future fires by consuming excess dry biomass, and maintain ecological balance.