Water Quality, Aquatic Biology, Soil Erosion, and Watershed Management

Comprehensive practice flashcards covering aquatic biology, water chemistry, drinking water treatment, soil erosion mechanics, criteria air pollutants, and watershed hydrology.

What chemical treatments are used to prepare sediment samples for microfossil and pollen analysis, and what is the specific function of each?

$48\%$ $\text{HF}$ removes silicates, $10\%$ $\text{HCl}$ removes colloids, $10\%$ $\text{KOH}$ removes humic acids and breaks up the sample, and acetolysis (sulfuric acid with acetic acid or acetic anhydride) removes organic materials.

What are the four major taxonomic groups of phytoplankton discussed in water quality analysis?

Green algae (Chlorophyta), Blue-green algae (Cyanobacteria), Diatoms (Bacillariophyceae), and Dinoflagellates (Pyrrophyta).

Which distinctive genus of freshwater and marine dinoflagellates is shown here, recognized by its prominent horns and flagellum?

Ceratium (Pyrrophyta).

What counting slide apparatus is shown in this diagram, and what precise liquid volume does its chamber hold for microscopic phytoplankton enumeration?

The Sedgewick-Rafter cell; it holds exactly $1\,\text{mL}$ of water.

What artificial substrate sampling device is pictured here, commonly deployed in both still and running waters to monitor macroinvertebrate colonization?

A Hester-Dendy sampler (constructed of multi-plate circular discs separated by spacers).

What type of bottom-water sampling device is shown in this photograph, and what is its main quantitative advantage?

An Ekman dredge (or Peterson/Ponar grab sampler), which provides quantitative benthic data by enclosing a known, fixed surface area of substrate.

How is Beck's Biotic Index ($BI$) calculated, and what do its constituent organism classes represent?

$BI = 2(nI) + nII$, where $nI$ is the number of Class I species (sensitive or intolerant forms tolerating no appreciable organic pollution) and $nII$ is the number of Class II species (facultative forms tolerating moderate pollution, but not anaerobic conditions).

What protocol and incubation parameters are standardly used to isolate and count coliform bacteria such as Escherichia coli in water samples?

Water is filtered through a membrane, placed onto an agar nutrient medium, incubated for $24\,\text{hours}$ at $44.5\,^\circ\text{C}$, and enumerated by counting the resulting red or magenta colonies.

In municipal drinking water treatment, what specific roles do alum and phosphoric acid play?

Alum is added as a coagulant to cause fine suspended particles to clump together and settle out; phosphoric acid (orthophosphate) is added to establish a protective mineral coating inside distribution pipes to prevent lead and copper from leaching into the water.

What chemical equilibrium phenomenon is illustrated in this diagram across varying water pH levels?

The percentage distribution of carbonate species in water: carbonic acid ($\text{H}_2\text{CO}_{3(aq)}$) predominates below $\text{pH}\;6.3$, bicarbonate ($\text{HCO}_3^-$) predominates between $\text{pH}\;6.3$ and $10.3$, and carbonate ($\text{CO}_3^{2-}$) dominates above $\text{pH}\;10.3$.

What stream pollution model is represented by this oxygen-sag curve, and what equation determines the critical downstream time ($t_c$) to the point of minimum dissolved oxygen?

The Streeter-Phelps oxygen-sag model; critical time is calculated as: $t_c = \frac{1}{k_r - k_d} \ln\left( \frac{k_r}{k_d} \left[ 1 - \frac{D_0(k_r - k_d)}{k_d L_0} \right] \right)$

What are the EPA Maximum Contaminant Levels (MCLs) for Fluoride, Nitrate, and Barium in public drinking water supplies?

Fluoride: $4\,\text{ppm}$ (or $4\,\text{mg/L}$); Nitrate: $10\,\text{ppm}$ (or $10\,\text{mg/L}$); Barium: $2\,\text{ppm}$ (or $2\,\text{mg/L}$).

Under EPA drinking water regulations, what are the Action Levels (AL) for Lead and Copper, and how are test results evaluated?

Lead action level is $15.0\,\text{ppb}$ ($0.015\,\text{mg/L}$) and Copper action level is $1300\,\text{ppb}$ ($1.3\,\text{mg/L}$); compliance is determined if the $90\text{th}$ percentile concentration of tested residential taps remains below the Action Level.

What are the three primary biological transformation processes in the aquatic nitrogen cycle, and what chemical conversions occur in each?

1. Nitrogen fixation (conversion of atmospheric $\text{N}_2$ to $\text{NH}_3$);
2. Nitrification (aerobic bacterial oxidation of $\text{NH}_3$ to $\text{NO}_2^-$ and then $\text{NO}_3^-$);
3. Denitrification (anaerobic reduction of $\text{NO}_3^-$ back to $\text{N}_2$ gas).

According to global assessments of soil degradation, what percentage of degraded soil is caused by water erosion versus wind erosion?

Out of $2\,\text{billion hectares}$ of degraded soil globally, water erosion accounts for $56\%$ and wind erosion accounts for $28\%$ (with chemical deterioration causing $12\%$ and physical deterioration causing $4\%$).

What are the three sequential physical steps that comprise the water erosion process?

1. Detachment of soil particles from the soil mass;
2. Transportation of detached particles downhill by floating, rolling, dragging, and splashing;
3. Deposition of transported particles at a location lower in elevation.

Which three types of water-induced soil erosion are illustrated here in order of increasing visual scale?

(a) Sheet erosion (thin uniform layer removed by raindrops); (b) Rill erosion (tiny flow channels forming); (c) Gully erosion (larger, deep flow channels and ravines).

What are the three physical transport mechanisms of wind erosion, and what particle size and movement proportion characterize each?

1. Saltation: short bounces along the ground ($0.1-0.5\,\text{mm}$ particles), accounting for $50-90\%$ of total soil movement;
2. Soil Creep: rolling or sliding of larger particles along the surface;
3. Suspension: fine dust ($< 0.1\,\text{mm}$) carried aloft into the atmosphere.

What are the six EPA 'criteria pollutants' regulated under the Clean Air Act?

Particulate matter (PM), ozone ($\text{O}_3$), sulfur dioxide ($\text{SO}_2$), nitrogen dioxide ($\text{NO}_2$), carbon monoxide ($\text{CO}$), and lead ($\text{Pb}$).

What are the EPA 24-hour average National Ambient Air Quality Standards for $PM_{10}$ and $PM_{2.5}$?

$PM_{10} < 150\,\mu\text{g/m}^3$ and $PM_{2.5} < 35\,\mu\text{g/m}^3$.

Which two major environmental disasters in 1969 helped mobilize public support for creating the U.S. Environmental Protection Agency (EPA)?

The Santa Barbara oil spill (January 28, 1969), which released $3\,\text{million gallons}$ of crude oil onto California beaches, and the Cuyahoga River fire near Cleveland, Ohio (June 22, 1969), caused by an oil slick.

In water quality management, what is the exact difference between a 'criterion' and a 'standard'?

A criterion is a definite scientific quantity upon which a judgment or recommendation can be based, whereas a standard is an official principle or threshold established and enforced by governmental agencies.

According to the 1986 ASIWPCA assessment, what was the primary source of nonpoint source impairment for U.S. rivers and lakes?

Agriculture, which accounted for $64\%$ of nonpoint source impairments in rivers and $57\%$ in lakes.

According to the 1986 ASIWPCA data, what is the single largest category of nonpoint source pollutant in rivers compared to lakes?

Sediment is the leading pollutant in rivers ($47\%$ of river impairments), whereas plant nutrients are the leading pollutant in lakes ($59\%$ of lake impairments).

What proportion of the United States population relies on groundwater as their freshwater drinking source, and what is its most common chemical contaminant?

$53\%$ of the U.S. population relies on groundwater; nitrate is the most frequently detected contaminant, exceeding $10\,\text{mg/L}$ in $1.2\%$ of community wells and $2.4\%$ of rural domestic wells.

What is the basic hydrological water yield equation for a watershed over long time horizons?

Water yield equals precipitation minus evapotranspiration ($P - ET$).

Why does timber harvesting of conifer stands result in a greater water yield increase than harvesting hardwood stands?

Conifers maintain year-round foliage with denser canopies, leading to higher annual interception and evapotranspiration; harvesting conifers removes a larger interception loss compared to deciduous hardwoods.

How does topographic slope aspect influence the water yield response following forest harvesting in the Northern Hemisphere?

North-facing slopes produce greater water yield increases than south-facing slopes because lower solar radiation reduces baseline evapotranspiration on north-facing aspects, maintaining higher soil moisture and higher water tables.

Which forest management technique is illustrated in this diagram, and what is its primary hydrological and environmental downside?

Clear-cutting (the removal of every tree from a stand), which significantly increases flooding, peak runoff discharge, and soil erosion that washes away seedlings.

Which timber harvesting method is shown here, and what ecological advantage does it provide over clear-cutting?

Strip cutting (harvesting timber in narrow, alternating strips along slopes), which lessens overall land damage, slows runoff, and allows adjacent uncut forest strips to naturally regenerate the cleared land.

What management techniques are used in western U.S. watersheds to manipulate snowpack accumulation, sublimation, and melting rates?

Patch cuts to accumulate snow in openings, snow fences to cause snow drifts and reduce sublimation, and coloring snow with sawdust, carbon black, or coke to alter albedo and control melting timing.