What is a source zone?

Following the definition given in Chapter 1, source zones are volumes that have been in contact with separate phase contaminants and that act as reservoirs that sustain a contaminant plume in groundwater, surface water, or air or that act as a source for direct exposure.

What is monitored natural attenuation?

Monitored natural attenuation (MNA) is an in situ remediation technology that relies on naturally occurring and demonstrable processes in soil and groundwater which reduce the mass and concentration of the contaminants.

What are the three sources of characterization?

An acronym, PAIRS, can help you recall the five methods of characterization: physical description, action, inner thoughts, reactions, and speech. Physical description – the character’s physical appearance is described.

What are the 3 zones of a river?

A simplified longitudinal model captures these observed changes by disaggregating the river into three zones: headwaters zone, transfer zone, and depositional zone (Figure 1.2). The headwaters zone generally has the steepest slope. As the water moves over these slopes, sediment erodes and is carried downstream.

What is natural attenuation?

Natural attenuation relies on natural processes to decrease or “attenuate” concentrations of contaminants in soil and groundwater. Scientists monitor these conditions to make sure natural attenuation is working.

What is MNA remediation?

Monitored Natural Attenuation (MNA) is an important, common groundwater remediation technology used for treating some dissolved groundwater contaminants. MNA relies on natural attenuation processes to achieve site-specific remediation objectives within a reasonable time frame compared to more active approaches.

What are the 5 methods of characterization?

The five methods are physical description, action, inner thoughts, reactions, and speech. We examined each method in a short example in order to have a good understanding of how authors use the various methods of characterization to develop the characters and create images for the audience.

What are the 8 methods of characterization?

Terms in this set (8)

• Physical Description. The first method of characterization, and the most common.
• Name Analysis.
• Attitude/appearance.
• Dialogue.
• Thoughts.
• Reactions of Others.
• Action or Incident.
• Physical/Emotional Setting.

What is Zone erosion?

An area where stream channel erosion is likely to result in damage to or loss of property, buildings, infrastructure, utilities or other valued resources. An Erosion Hazard Zone provides a boundary outside of which resources are not expected to be threatened as a result of future stream erosion.

Where is the littoral zone?

A littoral zone is the near shore area from the high water line to where the sunlight penetrates to the sediments in a waterbody. This zone may or may not contain plant life but it is the optimal region for aquatic plants to grow. Littoral zones are present in both fresh and saltwater environments.

Is natural attenuation economical?

Natural attenuation utilizes the natural soil environment to decontaminate a petroleum hydrocarbon-impacted soil. It is popular, because it is one of the most cost-efficient technologies available. However, it may not be the most time-effective approach available.

What is Bioslurping?

Bioslurping combines approaches of bioventing and vacuum-enhanced free-product recovery to address two separate contaminant media.

How does natural source zone depletion occur in the subsurface?

LNAPL Natural Source Zone Depletion (NSZD) occurs through the combined action of natural processes that reduce the mass of LNAPL in the subsurface. Key NSZD processes include volatilization, dissolution, and biodegradation; these processes reduce LNAPL mass, saturation, and mobility over time.

What is the net current density in the depletion region?

In the P-side of the depletion region, where holes drift by the electric field with the electrical conductivity σ and diffuse with the diffusion constant D, the net current density is given by {\\displaystyle {\\bf {E}}} is the electric field, e is the elementary charge (1.6×10 −19 coulomb), and p is the hole density (number per unit volume).

Which is the only element left in the depletion region?

The only elements left in the depletion region are ionized donor or acceptor impurities. The depletion region is so named because it is formed from a conducting region by removal of all free charge carriers, leaving none to carry a current.

Why is the depletion region called the conducting region?

The depletion region is so named because it is formed from a conducting region by removal of all free charge carriers, leaving none to carry a current. Understanding the depletion region is key to explaining modern semiconductor electronics: diodes, bipolar junction transistors, field-effect transistors,…