Metals

Lead (source, exposure pathway, health impact, regulation)

source: mostly anthropogenic (pipes, cigarettes, paint)

exposure pathway: ingestion of drinking water; inhalation of smoke/paint

impact: calcium stress —> blocks energy production, damages myelin sheaths 

regulation: Clean Air Act; Bipartisan Infrastructure Bill

all metals impact

growth and development

what metals are non-toxic

minerals for nutrition and human health

Mercury (source, exposure pathway, health impact, regulation)

source: natural sources of organic mercury (volcanos); anthropogenic of inorganic (coal combustion, mining, personal care products, mother to baby

exposure pathway: fly ash —> oxidation produces methylmercury —> deposited on surface land/water —> contaminated fish 

impact: neurotoxin with cognitive and motor defects; bioaccumulates and biomagnifies in fish

regulation: Safe Drinking Water Act; Methylmercury Fish Criterion

Arsenic (source, exposure pathway, health impact, regulation)

source: natural (volcanos, weathering of rock) and anthropogenic (mining, smelting metals, insecticides/pesticides) 

exposure pathway: ingestion of drinking water/food 

impact: incorporated into biological processes —> short term and long term (growth and development) adverse outcomes

regulation: Resource Conservation and Recovery Act (disposal of solid and hazardous waste)

greatest source of metals in the environment

coal combusting power plants

fly ash: definition, how it is stored

fine, powdery residue from coal burning

stored in landfills or ponds and can leach into groundwater supply

critical mineral

non-fuel substance that has 

• high risk of supply chain disruption

• high importance to energy

what is the motivation for deep sea mining

US is majorly import dependent for minerals

anticipated impacts of deep sea mining

light pollution — impacts birds, other marine industries

noise pollution — impacts marine animal communication

sediment plumes — kick up dust and circulates toxic metals

Bioaccumulation

what cannot be excreted accumulates in fat tissue

Biomagnification & biomagnification factor

Larger predator consumes many smaller prey that contain the toxin —> concentration in bigger fish that are used for food supply 

biomagnification factor represents amount of toxin in organism over that in surrounding water

Safe Drinking Water Act (SDWA) and mercury

limited permissible levels of mercury in water systems

Clean Air Act and lead

outlawed lead gasoline for vehicles to address concern for dermal exposure

methods of toxic metal remediation

physical, chemical, biological

physical remediation and example

removal from the environment

coal washing: removing mercury from coal before burning

chemical remediation and example

transform into a less toxic or harmful form

additives to water supply (phosphate accumulates on lead pipes; lime solidifies metals and removed them)

biological remediation

use living organisms to transform, uptake, or otherwise reduce associated harm

phytoremediation

plants (hyperaccumulators) added to water or soil to uptake, accumulate, or transform metals

phytoextraction

plants absorb metals from soil & water → store in roots, stems, leaves

phytodegradation

plants break down metals with enzymes they naturally produce to transform it