1-dasar-dasar reaksi dan sifat kimia alam
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1-Dasar-dasar Reaksi Dan Sifat Kimia AlamTRANSCRIPT
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Dasar-dasar Reaksi dan Sifat
Kimia Alam
AF Assomadi
Kuliah Kimia Lingkungan I
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Hubungan
antar
sistem
lingkungan
dengan
manusia
dan
kehidupan
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Environmental
Chemistry
Is the study of the sources, reactions, transport, effects, and fates of chemical species in water, soil, air, and living environments, and the effects of technology thereon
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Pertukaran Zat/Materi antar sphere
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Siklus Karbon (C-Cycle)
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Siklus Nitrogen (N-cycle)
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Siklus
Sulfur
(S-cycle)
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Siklus Fosfat (P-cycle)
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Beberapa impact teknologi pada
lingkungan Agricultural perubahan lahan, drainase,
irigasi, pestisida Manufacturing polusi udara, polusi air, by-
produk limbah hazard dsb Extraksi and produksi mineral kerusakan
lingkungan dan polusi Produksi Energi dan penggunaannya
kerusakan lahan/tanah, polusi air (garam), emisi polutan udara (hujan asam) dsb
Transportasi Modern automobile, perubahan struktur tanah (jalan), emisi polusi udara, peningkatan penambangan minyak dsb
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technology can be applied to minimize
environmental impact
maximum energy efficiency, maximum utilization of raw materials, and minimum production of pollutant by-products
minimize pollution problems
maximum materials recycling and minimum waste product production
advanced biotechnologies
catalysts for efficient synthesis
minimize waste production
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Steady State Addition and Removal
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Kimia Air
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Siklus Air
(hydrolo
gic
cycle)
dalam triliun
liter/hari
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Sifat
Air
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Air Struktur terdiri atas 2 atom H
dan 1 atom O dalam setiap molekulnya
Struktur bersudut 105 o moment dipol tidak nol (polar)
Kemampuan sangat besar membentuk ikatan hidrogen (kelarutan molekul, logam, suspensi)
Pelarut yang universal Kapasitas panas tinggi Densitas terbesar pada 4 oC
(jaminan kelangsungan hidup)
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Ikatan Hidrogen
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Water Chemistry
The polarity of water causes it to be cohesive and adhesive.
Polarity unequal charge distribution in a molecule resulting in a region and a + region
cohesion: water molecules stick to other water molecules by hydrogen bonding
adhesion: water molecules stick to other polar molecules by hydrogen bonding
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Water Chemistry
cohesion
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Water Chemistry
adhesion
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Stratifikasi Air danau
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Major Aquatic Chemical Process
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Kesetimbangan CO2-CaCO3 di air
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Oksidasi-Reduksi di Air
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Oksigen di Air
O2 dibutuhkan terlarut di air untuk menjaga reaksi oksidasi-reduksi, respirasi, degradasi dst
Kelarutan O2 di air tergantung temperatur, pd 25 oC sekitar 8,5 mg/L; pada 0oC 14,74 mg/L
Dihasilkan dari proses fotosintesis alga/tumbuhan hijau di air dan proses aerasi
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CO2 di Air
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Kesetimbangan CO2 di Air
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Acids and Bases
Hydrogen ion (H+1) is the basis of the pH scale.
Greater H+1 concentration --- lower pH (acidic)
Lower H+1 concentration --- higher pH (basic)
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Acids and Bases
Acid: a chemical that releases H+1 ions.
pH below 7
Base: a chemical that accepts H+1 ions.
pH above 7
Buffer: a chemical that accepts/releases H+1 as necessary to keep pH constant
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Acids and Bases
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Acids and Bases
Most biological buffers consist of a pair of molecules, one an acid and one a base.
BUFFER SYSTEM IN HUMAN BLOOD
BASE ACID
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Acids and Bases
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Properties of Water
1. Water has a high specific heat.
- A large amount of energy is required to change the temperature of water.
2. Water has a high heat of vaporization.
- The evaporation of water from a surface causes cooling of that surface.
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Properties of Water 3. Solid water is less dense than liquid water.
- Bodies of water freeze from the top down.
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Properties of Water
4. Water is a good solvent.
- Water dissolves
polar molecules and
ions.
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Properties of Water
5. Water organizes nonpolar molecules. - hydrophilic: water-loving -hydrophobic: water-fearing - Water causes hydrophobic molecules to
aggregate or assume specific shapes.
6. Water can form ions. H2O OH
-1 + H+1
hydroxide ion hydrogen ion
Ionization; happens spontaneously
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Concentrations of main ions (Ca2+, Mg2+, K+, Na+, HCO3-, SO4
2-, Cl-, NO3-
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Monitoring surface waters chemistry
1954-1955, 1990-1991, 2000-
2001 Tebo fishpond basin
1964 - 2007 Stropnice river
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Water Quality Parameters
Temperature - Dissolved Oxygen (DO) - pH
Alkalinity - Hardness
Nitrates and Phosphates - Turbidity
Conductivity
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Temperature
Affects:
Water density
Gas solubility
Chemical reaction rates
Organism growth rates
Conductivity
pH
Dissolved Oxygen
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Q10 rule cold-blooded aquatic organisms
Predicts that growth rate will double
if temperature increases by 10C (18F) within their "preferred" range.
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Gases Dissolve in Water
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Dissolved Oxygen (DO)
DO is the measurement of oxygen
dissolved in water and available for
fish and other aquatic life.
Indicates health of an aquatic system.
Can range from 0-18 ppm.
Most natural water systems require 5-
6 ppm to support a diverse population.
Varies with time of day, weather, temperature.
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Dissolved Oxygen (DO)
Increase in organic waste
Increase in algae/plant vegetation
Decrease in DO available to organisms
Leads to changes in ecosystem as
organisms needing lots of DO are
replaced by organisms needing little.
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pH - p(otential of) H(ydrogen)
Determines the solubility of nutrients (PO4-3, NO3
-, C)
and heavy metals (Fe, Cu, etc)
Determines availability of these chemicals for use by aquatic life.
In natural water systems, determined largely by geology and soils.
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pH of natural waters
due to humic acid
Limestone, marble, CO3 rich
Pure rain, snow
Sea water
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Factors that affect pH
Algal blooms Bacterial activity Water turbulence Chemicals flowing into the water body Sewage overflows Pollution
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How pH affects aquatic life
Decreasing pH (e.g.: via acid rain)
Liberation of Al, metals
Toxic conditions
Chronic stress
Smaller, weaker fish
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Alkalinity
Alkalinity refers to the capability of water to neutralize acid.
Buffering capacity resistance to pH changes.
Common natural buffer: CO3
(carbonates like limestone).
Protects aquatic life.
Commonly linked to water
hardness.
In natural systems:
50 150 mg/L as CaCO3.
Limestone outcrop
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Hardness
Reflects dissolved
carbonate minerals.
Mostly of concern for
drinking water
standards.
Metals precipitate out
of solution.
Create scale/hard
water deposits
High alkalinity Hard water
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and Nitrate (NO3
-)
naturally-occurring
form of nitrogen
found in soil.
Forms by microbial
decomposition of
fertilizers, plants,
manures or other
organic residues
Plants uptake
nitrates (Spinach a
good source).
Phosphate (PO4-3)
naturally occurs in
rocks and minerals.
Plants uptake
weathered-out
elements and
compounds.
Animals ingest plants.
Water soluble.
Redfield Ratio: 106:16:1
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Nitrates
The U.S. EPA has set a maximum
contaminant level for NO3- in drinking
water of 10 parts per million (ppm)
Artificial sources: Livestock manure/urine
Failing septic systems
Synthetic fertilizers
Can lead to: eutrophication of natural
water systems
(overproduction of
vegetation)
Blue baby syndromne
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Artificial sources:
Sewage Laundry, cleaning fluids
Synthetic fertilizers
Can also lead to
eutrophication of
natural water
systems
(overproduction of
vegetation)
Phosphates
Blue green algae
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1990 and 1999 comparison
of Nitrates in Great Lakes
From US EPA
http://www.epa.gov/glnpo/monitoring/limnology/SprNOx.html
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Solutions??
Wetland restoration Reduce fertilizers
Reduce emissions WWTP/industry Reduce soil erosion
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Turbidity
Measures how
murky the water is
Estimates:
Mineral fraction
Organics
Inorganics
Soluble organic compounds
Plankton
Microscopic organisms
MODIS Image from NASA
http://rapidfire.sci.gsfc.nasa.gov/
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Causes of highly waters
In open waters, phytoplankton Closer to shore, particulates Resuspended bottom sediments
(wind)
Organic from stream and/or wastewater discharges.
Channelization Increased flow rates Too many bottom-feeding fish (such as carp)
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Effects of highly waters
Modify light penetration Increase sedimentation rate Smother benthic habitats Settling clay particles Fine particulate material also can damage sensitive structures
Decrease organism resistance to disease Prevent proper egg and larval development Macrophyte growth may be decreased Reduced photosynthesis can lead to lower daytime release of oxygen
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Conductivity Ability of a substance to conduct an electrical current.
In water, conductivity determined by types and quantities of dissolved
solids. (Commonly called Total Dissolved Solids = TDS)
Current carried by ions (negatively or
positively charged particles).
Eg: NaCl(aq) = Na + + Cl
Cl- Na+ Na+
Na+
Na+
Na+ Cl-
Cl-
Cl-
Cl-
Na+ Cl- Cl- Cl- Cl-
Na+ Na+ Na+ Na+ Na+ Na+ Na+ Na+
Cl- Cl- Cl- Cl-
Na+ Na+ Na+ Na+
Cl- Cl- Cl- Cl-
Na+ Na+ Na+ Na+
Cl- Cl- Cl- Cl-
Na+ Na+ Na+ Na+ Na+
Na+ Na+
Na+ Na+
Na+ Na+
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Conductivity
Conductivity of natural waters depends upon:
Ion characteristics (mobility, valence, concentration)
Water temperature
Geology
Size of watershed
Evaporation
Some artificial factors that can affect conductivity:
Wastewater
Urban runoff (especially road salt)
Agricultural runoff
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The most abundant components of a
kilogram of seawater.
The Components of Salinity