240
Keywords Strumica river basin · Nitrate · Arsenic · ANOVA · Factor analysis
8.1 Introduction
Most of the water found on earth (97.3%) is saline distributed mostly in oceans and
seas. The remaining water is freshwater that exists as ice in the polar caps and glaciers from which only 0.61% is freshwater found in lakes, rivers, streams, and
groundwater. Groundwater presents the most valuable natural resource of freshwater in the world. Around 95% of the total freshwater available for man on the earth
comes from the aquifers. According to a European Commission survey (2008),
almost 75% of the world population depends on groundwater as a primary source
for drinking water. About 60% of the total amount of groundwater is used for irrigation of agricultural land, and the remaining 40% of the exploitation is almost equally
distributed to domestic and industrial sectors (Vrba and van der Gun 2004).
Increasing population, industrialization, and agriculture practices are the main reasons for the uncontrollable exploitation of groundwater in many areas in the world,
especially in undeveloped countries. After a certain period, this may lead to a
decrease in groundwater quality and quantity. Restoring groundwater quality is a
very difficult, expensive, and time-consuming process. Considering this and the
small amount of freshwater available on the earth, it is of prime importance to assess
groundwater quality in each region as well as to identify possible sources of pollution threatening to decrease its quality to implement on time measures and practices
for protection and preservation of its quality.
The quality of groundwater situated under agriculture land is a function of hydrogeological factors such as the depth of the type of the aquifer, hydrological properties of soil, and the amount, timing, and location of aquifer recharge as well as a
function of contaminant factors. Groundwater contaminants are categorized as
pointed and nonpointed sources of pollution. Point sources are usually industrial
and manufacturing facilities, oil production and refining facilities, wastewater
plants, landfills, leaking underground storage tanks, septic tanks, spills, accidents,
etc. Аgricultural activities, seawater intrusion, urban runoff, pipeline networks,
acid-mine drainage, oilfield brine injection, dairies, and feedlots are usually recognized as a nonpoint source of pollution (AWWA 2003).
Natural processes like water-rock interaction and topographic composition are
the main contributors to the hydrogeochemical characteristics of groundwater. The
most common constituents in groundwater regarding its chemical quality are cations like calcium, magnesium, iron, potassium, manganese, and sodium and anions
like bicarbonate (HCO 3
−
), chloride (Cl
−
), fluoride (F
−
), nitrate (NO 3
−
), silica (SiO 2 ),
and sulfate (SO 4
2−
). Other constituents present which are less common but still very
important when accessing the chemical quality of groundwater are boron, arsenic,
lead, selenium, copper, zinc, barium, nitrite (NO 2
−
), and the gases oxygen, carbon
dioxide, methane, and hydrogen sulfide (Table 8.1) (Hem 1985). Groundwater
B. Kovacevik et al.
Keywords Strumica river basin · Nitrate · Arsenic · ANOVA · Factor analysis
8.1 Introduction
Most of the water found on earth (97.3%) is saline distributed mostly in oceans and
seas. The remaining water is freshwater that exists as ice in the polar caps and glaciers from which only 0.61% is freshwater found in lakes, rivers, streams, and
groundwater. Groundwater presents the most valuable natural resource of freshwater in the world. Around 95% of the total freshwater available for man on the earth
comes from the aquifers. According to a European Commission survey (2008),
almost 75% of the world population depends on groundwater as a primary source
for drinking water. About 60% of the total amount of groundwater is used for irrigation of agricultural land, and the remaining 40% of the exploitation is almost equally
distributed to domestic and industrial sectors (Vrba and van der Gun 2004).
Increasing population, industrialization, and agriculture practices are the main reasons for the uncontrollable exploitation of groundwater in many areas in the world,
especially in undeveloped countries. After a certain period, this may lead to a
decrease in groundwater quality and quantity. Restoring groundwater quality is a
very difficult, expensive, and time-consuming process. Considering this and the
small amount of freshwater available on the earth, it is of prime importance to assess
groundwater quality in each region as well as to identify possible sources of pollution threatening to decrease its quality to implement on time measures and practices
for protection and preservation of its quality.
The quality of groundwater situated under agriculture land is a function of hydrogeological factors such as the depth of the type of the aquifer, hydrological properties of soil, and the amount, timing, and location of aquifer recharge as well as a
function of contaminant factors. Groundwater contaminants are categorized as
pointed and nonpointed sources of pollution. Point sources are usually industrial
and manufacturing facilities, oil production and refining facilities, wastewater
plants, landfills, leaking underground storage tanks, septic tanks, spills, accidents,
etc. Аgricultural activities, seawater intrusion, urban runoff, pipeline networks,
acid-mine drainage, oilfield brine injection, dairies, and feedlots are usually recognized as a nonpoint source of pollution (AWWA 2003).
Natural processes like water-rock interaction and topographic composition are
the main contributors to the hydrogeochemical characteristics of groundwater. The
most common constituents in groundwater regarding its chemical quality are cations like calcium, magnesium, iron, potassium, manganese, and sodium and anions
like bicarbonate (HCO 3
−
), chloride (Cl
−
), fluoride (F
−
), nitrate (NO 3
−
), silica (SiO 2 ),
and sulfate (SO 4
2−
). Other constituents present which are less common but still very
important when accessing the chemical quality of groundwater are boron, arsenic,
lead, selenium, copper, zinc, barium, nitrite (NO 2
−
), and the gases oxygen, carbon
dioxide, methane, and hydrogen sulfide (Table 8.1) (Hem 1985). Groundwater
B. Kovacevik et al.