Water Quality

Estimating The Amount Of Free Product In The Subsurface

Data Box Plot With Outliers

The first steps in the remediation of a site where an LNAPL spill has occurred is to try to limit the movement of contaminant plumes and to remove from the subsurface as much free product as possible. As long as free product is present, it continues to partition into the sorbed, dissolved, and vapor contaminant plumes, continually feeding their growth. Only after the mobile free product has been removed from above the water table can remediation of the contaminant plumes be effective. LNAPL...

Cyanide Cn Cas 57125 Hydrogen Cyanide Hcn Cas Background

Background Level Cyanide

Cyanide is a product of natural animal and vegetative decay processes and also is a component in many industrial waste streams. It is used extensively in mining to separate metals, particularly gold, from ores. In water, an equilibrium exists between the ionized (CN-) and unionized (HCN) forms, the fraction of each depending on pH (see Equation 7.1 and Figure 7.1). Below pH 9, the predominant form is HCN. HCN is more toxic than CN- and is the dominant form in most natural waters. HCN is...

Soil Groundwater and Subsurface Contamination

Fulvic Acid Fractions

Steps in the Typical Development of a Soil and Its Profile (Pedogenesis) 4.5 Contaminants Become Distributed in Water, Soil, and Air Air-Water Partition Coefficient Soil-Water Partition Coefficient Determining Kd Experimentally The Role of Soil Organic Matter The Octanol Water Partition Coefficient, Kow Estimating Kd Using Solubility or Kow 4.7 Mobility of Contaminants in the Subsurface Effect of Biodegradation on Effective Retardation Factor A Model for Sorption and Retardation Soil Properties...

Acidity And Alkalinity

Diagram Alkalinity

The alkalinity of water is its acid-neutralizing capacity. The acidity of water is its base-neutralizing capacity. Both parameters are related to the buffering capacity of water the ability to resist changes in pH when an acid or base is added . Water with high alkalinity can neutralize a large quantity of acid without large changes in pH on the other hand, water with high acidity can neutralize a large quantity of base without large changes in pH. Acidity is determined by measuring how much...

Predicting Bond Type From Electronegativities

60898 Curve

Intermolecular forces are electrostatic in nature. Molecules are composed of electrically charged particles (electrons and protons), and it is common for them to have regions that are predominantly charged positive or negative. Attractive forces between molecules arise when electrostatic forces attract positive regions on one molecule to negative regions on another. The strength of the attractions between molecules depends on the polarities of chemical bonds within the molecules and the...

Breakpoint Chlorination For Removing Ammonia

Chlorine Breakpoint Drinking Water

Chlorination can be used to remove dissolved ammonia and ammonium ion from wastewater by the chemical reactions NH3 + Cl2 NH2Cl + Cl- + H+. (6.6a) NH4+ + Cl2 NH2Cl + Cl- + 2 H+. (6.6b) Ammonia is converted stoichiometrically to monochloramine (NH2Cl) at a 1 to 1 molar ratio or a 5 to 1 ratio by weight of Cl2 to NH3-N. NHCl2 (dichloramine), and NCl3 (nitrogen trichloride or Suggested Maximum Parameter Levels in Water Used for Crop Irrigation total dissolved solids (TDS) mg L specific...

Chemical Fingerprinting

Chemical Fingerprint

Environmental professionals often need to do more than locate and clean up pollutants. They may need to help identify the sources of the contamination. Someone always has to pay for a remediation effort. The high costs that are often involved mean that any prudent potentially responsible party (PRP) will want convincing proof that he or she must accept responsibility for the pollution. Polluted sites often have a history of having different owners and uses, any or all of which may have...

Nitrogen Ammonia Nh3 Nitrite No2 And Nitrate No3

Solubility Curve

Nitrogen compounds of greatest interest to water quality are those that are biologically available as nutrients to plants or exhibit toxicity to humans or aquatic life. Atmospheric nitrogen (N2) is the primary source of all nitrogen species, but it is not directly available to plants because the N N triple bond is too strong to be broken by photosynthesis. Atmospheric nitrogen must be converted to other nitrogen compounds before it can become available as a plant nutrient. The conversion of...

Drinking Water Standards

Potential Health Effects from Ingestion of Water Increase in blood cholesterol, decrease in blood glucose. system problems, increased risk of cancer. Increased risk of developing benign intestinal polyps. Some people who use water containing chromium well in excess of the MCL for many years could experience allergic dermatitis. Short-term exposure gastrointestinal distress. Long-term exposure liver or kidney damage. Those with Wilson's disease should consult their doctor if their water systems...

National Recommended Water Quality Criteria

Adapted from EPA 822-Z-99-001, April 1999. Section 304 a 1 of the Clean Water Act requires the EPA to develop, publish, and revise water quality criteria so that they accurately reflect the latest scientific knowledge. These criteria are based solely on a scientific interpretation of data concerning the relation between pollutant concentrations and environmental and human health effects. Considerations of technological feasibility or economic impacts of attaining the recommended criteria are...

Processes That Remove Pollutants From Water

Contaminants that are dissolved or suspended in water can move to other phases by the following processes Volatilization Dissolved contaminants move from water or soil into air, in the form of gases or vapors. Sorption Dissolved contaminants become bound to solids by attractive chemical and electrostatic forces. Precipitation Dissolved contaminants are caused to precipitate as solids by changes in pH or oxidation-reduction potential, or they react with other species in water to form compounds...

Dnapl Free Product Plume

Movement Lnapl

Dense nonaqueous phase liquids, DNAPL, are nonaqueous phase liquids that are denser than water. If sufficient DNAPL is present, the free product sinks downward through the water table to the bottom of an aquifer. Only an impermeable obstruction, such as bedrock, stops the downward movement of DNAPL mobile free product. Some examples of DNAPL are Halogenated solvents (mostly chlorinated or brominated), either pure compounds or mixtures of solvents * Because of its greater viscosity, diesel fuel...

Drinking Water Treatment

Clean drinking water is the most important public health factor. But well over 2 billion people worldwide do not have adequate supplies of safe drinking water. Worldwide, between 15 to 20 million babies die every year from water-borne diarrheal diseases such as typhoid fever, dysentery, and cholera. Contaminated water supplies and poor sanitation cause 80 of the diseases that afflict people in the poorest countries. The development of municipal water purification in the last century has allowed...

Ph And Water Quality

Scale Common Substances

Pure water always contains a small number of molecules that have dissociated into hydrogen ions H and hydroxyl ions OH , as illustrated by Equation 3.1. The water dissociation constant, Kw is defined as the product of the concentrations of H and OH- ions, expressed in moles per liter where enclosing a species in square brackets is chemical symbolism that represents the species concentration in moles per liter. Because the degree of dissociation increases with temperature, Kw is temperature...

Measuring impurities

There are four characteristics of water impurities that are important for an initial assessment of water quality 1. What impurities are present Are they regulated compounds 2. How much of each impurity is present Are any standards exceeded for the water body being sampled 3. How do the impurities influence water quality Are they hazardous Beneficial Unaes-thetic Corrosive 4. What is the fate of the impurities How will their location, quantity, and chemical form change with time The chemical...

Odors Of Biological Origin In Water

Paper Basket Template

Odors from anaerobic surface waters, groundwater, and domestic wastewater are usually from inorganic and organic gases generated by biological activity. Anaerobic decomposition of nitrogenous or sulfurous organic matter often produces gases that contain sulfur and or nitrogen. Such gases are frequent causes of odors in water. The most common inorganic gases in water are carbon dioxide (CO2), methane (CH4), hydrogen (H2), hydrogen sulfide (H2S), ammonia (NH3), carbon disulfide (CS2), sulfur...

Selenium Se CAS 7782492 Background

Selenium is widely distributed in the earth's crust at concentrations averaging 0.09 mg kg. It occurs in igneous rocks, with sul des in v olcanic sulfur deposits, in hydrothermal deposits, and in porphyry copper deposits. The major source of selenium in the environment is the weathering of rocks and soils. In addition, volcanic activity contributes to its natural occurrence in waters in trace amounts. Volcanic activity is an important source of selenium in regions with high soil concentrations....

Rules of Thumb for pH Dependent Surface Charge

Kaolinite Surface Charge

At high pH, a negatively charged surface prevails. 2. At low pH, a positively charged surface prevails. 3. At some intermediate pH, the pH dependent surface charge is zero. This pH is called the point of zero charge (pzc). Cation and Anion Exchange Capacity (CEC and AEC) Cations are attracted to negative sites on a solid surface. Cation exchange capacity (CEC) is defined as the total number of negatively charged sites in a material at which reversible cation adsorption and desorption can occur....

Beryllium Be CAS 7440417 Background

Beryllium is a metal found in natural deposits as ores containing other elements and in some precious stones such as emeralds and aquamarine. Beryllium is not likely to be found in natural waters above trace levels due to the insolubility of oxides and hydroxides at normal environmental pHs. It has been reported to occur in U.S. drinking water at 0.01 to 0.7 J.g L. A major use of beryllium is as an alloy hardener. Its greatest use is in making metal alloys for nuclear reactors and the aerospace...

Cadmium Cd CAS 7440439 Background

Cadmium is usually present in all soils and rocks. It occurs naturally in zinc, lead, and copper ores, in coal, and other fossil fuels and shales. It often is released during volcanic action. These deposits can serve as sources to groundwaters and surface waters, especially when they are in contact with soft, acidic waters. The adsorption of cadmium onto soils and silicon or aluminum oxides is strongly pH-dependent, increasing as conditions become more alkaline. When the pH is below 6-7,...

Manganese Mn CAS 7439965 Background

Manganese is an abundant, widely distributed metal. It does not occur in nature as the elemental metal but is found in various salts and minerals frequently along with iron compounds. Soils, sediments, and metamorphic and sedimentary rocks are signi cant natural sources of manganese. The most important manganese mineral is pyrolusite (MnO2). Other manganese minerals are manganese carbonate (MnCO3, rhodocrosite) and manganese silicate (MnSiO3, rhodonite). Ferro-manganese minerals, such as...

Mercury Hg CAS 7439976 Background

Mercury is a liquid metal found in natural deposits of ores containing other elements. Mercury deposits occur in all types of rocks igneous, sedimentary, and metamorphic. Although cinnabar (HgS) is the most common mercury ore, mercury is present in more than 30 common ore and gangue minerals. Mercury exists in the environment as the elemental metal, as monovalent and divalent salts, and as organic mercury compounds, the most important of which are methyl mercury (HgCH3+) and dimethyl mercury...

Lead Pb CAS 7439921 Background

Lead minerals are found mostly in igneous, metamorphic and sedimentary rocks. The most abundant lead mineral is galena (PbS). Oxide, carbonate, and sulfate minerals are lanarkite (PbO), cerrusite (PbCO3), and anglesite (Pb(SO4), respectively. Commercial ores have concentrations of lead in the range 30-80 g kg. Metallic lead and the common lead minerals have very low solubility. Most environmental lead (perhaps 85 ) is associated with sediments the rest is in dissolved form. Although some lead...

Behavior Of Petroleum Hydrocarbons In The Subsurface

Clay Porosity

Because of their low water solubilities, most of the compounds classified as petroleum hydrocarbons are generally considered as nonaqueous phase liquids (NAPL). If mixed into water, NAPLs separate into a distinct liquid phase with a well-defined boundary between the NAPL and the water, like oil and water or milk and cream. NAPLs are further subdivided into light nonaqueous phase liquids (LNAPL) and dense nonaqueous phase liquids (DNAPL). LNAPLs are liquid hydrocarbon compounds or mixtures that...

Indicators Of Fecal Contamination Coliform And Streptococci Bacteria

Detecting and preventing fecal contamination is of prime importance for all drinking water systems and recreation water managers. Fecal wastes may contain enteric pathogens (disease-causing organisms from the intestines of warm-blooded animals) such as viruses, bacteria, and protozoans (which include Cryptosporidium and Giardia). Fecal contaminated water is a common cause of gastrointestinal illness, including diarrhea, dysentery, ulcers, fatigue, and cramps. It also may carry pathogens that...

Carbon Dioxide Bicarbonate And Carbonate

Carbonate Speciation Table

The reactive inorganic forms of environmental carbon are carbon dioxide (CO2), bicarbonate (HCO3), and carbonate (CO32). Organic carbon, such as cellulose and starch, is made by plants from CO2 and water during photosynthesis. Carbon dioxide is present in the atmosphere and in soil pore space as a gas, and in surface waters and groundwaters as a dissolved gas. The carbon cycle is based on the mobility of carbon dioxide, which is distributed readily through the environment as a gas in the...

Estimating The Amount Of Residual Lnapl Immobilized In The subsurface

Sorbed Residual Lnapl

Residual LNAPL in the subsurface is the portion that will not flow into a well. It is the part of an LNAPL spill that cannot be removed by pumping to the surface. Residual LNAPL must be remediated by biodegradation, soil flushing, or excavation. Residual LNAPL is retained in the unsaturated zone by adsorption and capillary forces. Therefore, small soil particles and large surface area both increase the amount of residual LNAPL retained. The soil retention factor (volume of LNAPL per volume of...

The Behavior Of Contaminants In Natural Waters

Every part of our world is continually changing, the unwelcomed contaminants as well as the essential ecosystems. Some changes occur imperceptibly on a geological time scale others are rapid occurring within days, minutes, or less. Oil and coal are formed from animal and vegetable matter over millions of years. When oil and coal are burned, they can release their stored energy in fractions of a second. Control of environmental contamination depends on understanding how pollutants are affected...

Nitrate NO3 CAS 14797558 Nitrite NO2 CAS 14797650 Background see Chapter 3 for a more detailed discussion

Nitrate and nitrite are highly soluble in water. Due to their high solubility and weak retention by soil, nitrate and nitrite are very mobile, moving through soil at approximately the same rate as water. Thus, nitrate and nitrite have a high potential to migrate to groundwater. Because they are not volatile, nitrate and nitrite are likely to remain in water until consumed by plants or other organisms. Nitrate is the oxidized form and nitrite is the reduced form. Aerated surface waters will...

Formation Of Petroleum Contamination Plumes

In the subsurface soil environment, petroleum compounds are present in four phases and four plumes. The four phases are 1. Liquid petroleum free product 2. Petroleum compounds adsorbed to soil particles 3. Dissolved petroleum components 4. Vaporized petroleum components Solubility Variability of Gasoline Components from Different Mixtures Concentration Dissolved in Water (mg L) Solubility Variability of Gasoline Components from Different Mixtures Concentration Dissolved in Water (mg L) Each...