Environmental Science for Environmental Impact Analysis

1. Inspirasi dari kutipan ilmiah yang dituangkan ke dalam suatu kreasi, disusun
dan digunakan sebagai referensi pribadi untuk mendukung kegiatan kerja di kantor. Semoga bermanfaat
O L E H :
H E L M U T T O D O T U A S I M AM O R A
BADAN LINGKUNGAN HIDUP, PENELITIAN DAN PENGEMBANGAN
KABUPATEN SAMOSIR PROVINSI SUMATERA UTARA
BELAJAR TENTANG ANALISIS MENGENAI DAMPAK LINGKUNGAN HIDUP
(AMDAL) TENTANG BEBERAPA PARAMETER YANG MEMPENGARUHI
KUALITAS AIR DARI ASUPAN PAKAN KEGIATAN BUDIDAYA PERIKANAN AIR TAWAR
DAN ASUPAN KANDUNGAN ORGANIK DALAM AIR LIMBAH
PADA BADAN AIR

2. PENGUKURAN KANDUNGAN NITRAT
 How is Nitrate measured?
 A common method for nitrate measurement is Method 353.2.
Samples are run through a cadmium column to reduce nitrate
to nitrite. Nitrites react with an added reagent and generate a
red coloured solution whose absorbance is then measured
spectrophotometrically at 543 nm. The absorbance of the
solution is directly proportional to the concentration of nitrite
in the sample. Another method used for the detection of
nitrate in water is the nitrate electrode method. This method
operates in a similar fashion to a dissolved oxygen meter,
where an electric potential of a solution is correlated to the
concentration of nitrates in mg/L. Nitrate concentrations can
be reported as mg/L NO3 or as mg/L nitrate-nitrogen (NO3-
N).

3. PENGARUH NITRAT
 Why is Nitrate important?
 Nitrogen is a major nutrient for microbial life and is therefore very
important with regards to its effects on the environment. Among
nitrogen containing compounds, nitrate is the most common form
in water. All other dissolved forms of nitrogen (nitrite, ammonia
and organic nitrogen) get oxidized to nitrate over time. Nitrates are
found in both ground and surface water, originating from the
natural decaying process of biological matter. Many anthropogenic
sources also contribute to nitrate levels in the environment such as
industrial and municipal wastewater discharge and agricultural
runoff containing nitrogen based fertilizers and livestock manure.
Nitrate has a high solubility in water and will not be filtered out like
other contaminants as it seeps through the soil layers to
groundwater level. Measurement of nitrate is important for several
applications.

4. KANDUNGAN NITRAT DALAM LIMBAH
 In the drinking water industry, maximum contaminant levels
of 50 mg/L NO3 in the EU and 10 mg/L NO3-N in the USA
have been established for public safety. When nitrate enters
the bloodstream of humans they reduce the ability of red
blood cells to carry oxygen, which has serious health effects.
This is particularly important for infants under the age of 6
months where excessive levels of nitrates in their bloodstream
leads to a health condition known as methemoglobinemia or
“blue baby syndrome”. Thus, measuring and removing nitrate
from drinking water are important.
 Wastewater contains high amounts of nitrates from human
sewage and industrial process waste. Monitoring nitrate in
wastewater is important to ensure proper removal prior to
discharging into the environment.

5. PEMANTAUAN LEVEL KANDUNGAN NITRAT
 From an environmental perspective, monitoring nitrate levels in
surface water can indicate the potential for eutrophication or
“nutrient pollution”. The influx of nutrients to surface waters can
cause accelerated algal growth. When the large algae blooms die
out, bacterial action increases expending oxygen levels. Waters may
become hypoxic or anoxic, causing stress and possible death of
aquatic life. Monitoring nitrate input to surface waters not only
protects the health of the water body, but the safety of those who
rely on the source.
 Measuring Nitrate with UV-VIS technology
 Measuring nitrates and or/nitrites with UV-VIS technology is a
practical and reagentless solution for real-time monitoring. Nitrate
ions have natural absorbance peaks in the 200-220 nm wavelength
range in the UV spectrum. As the concentration of nitrates in water
or wastewater increases, the absorbance of light in this distinct
wavelength range will also increase.

6.  Common interferences with nitrate measurement at 220 nm, such as
organic compounds, nitrite, iron (II), hexavalent chromium and turbidity
or suspended solids are compensated for by measuring absorbance at
additional reference wavelengths in the UV-VIS spectrum where the
interfering compounds absorb, but nitrates do not. This multiple
wavelength approach ensures a high degree of precision and accuracy.
 Where is Nitrate measured?
 Influent of a drinking water plant from a ground or surface water source
 After blending of multiple sources to determine reduction
 Effluent drinking water for compliance assurance
 Pre and post ion exchange or reverse osmosis for removal efficiency
 In process for nitrogen removal from wastewater
 Environmental monitoring stations for contamination events or locating
source pollution

7.  Nitrate test strips are an affordable tool for quickly measuring nitrate (NO3) in
soil and water, and can help farmers and crop advisers adjust fertilizer inputs
to match the nitrogen (N) needs of various types of crops. There are now a
variety of brands of nitrate test strips available, many of which are
manufactured for testing the quality of aquarium water, but may also be
suitable for soil testing. All of the brands of test strips are used in a similar
fashion: the strip is briefly dipped into an extractant solution (for soil) or in
water, and allowed to develop color during a standard interval of time, usually
ranging between 30 and 60 seconds. After color develops on the strip, a color
chart, calibrated to either parts per million (ppm) of NO3 or expressed in ppm
equivalents of nitrogen (NO3-N), is used to determine the NO3 concentration of
the sample. Multiplying Nitrate-N concentration by a factor of 4.43 converts
the reading to NO3 concentration. Because the strips may continue to develop
color with time, it is important to always read the strips at a standard time
interval, or the measurements will not be accurate or repeatable. More detailed
information on using the nitrate test strips for monitoring soil nitrate levels was
presented in several of our past bulletins, newsletters, and blogs.

8. KANDUNGAN NUTRISI DALAM TANAH
 Depending on the soil type and crop nutrient requirements,
vegetable farmers need test strips that are accurate for soil NO3-N
concentrations ranging between from 5 to 30 ppm, which would
roughly correspond to a range of 10 to 60 ppm of NO3 in the nitrate
quick test extract solution. For strawberry production, and other
crops that have a slower N uptake rate than vegetables, growers
need test strips that are accurate over a narrower range of soil
NO3 concentrations (5 to 15 ppm NO3-N in soil). Past studies have
demonstrated that the Merckoquant test strip are accurate for
measuring soil NO3-N in the range of 10 to 40 ppm. Because more
brands of test strips have become commercially available in recent
years with varying ranges of sensitivity, and the need to identify test
strips that are accurate for measuring low concentrations of soil
NO3-N (0 to 15 ppm), we evaluated the accuracy and ease of using
six commercially available brands of test strips over a range of
nitrate concentrations found in commercial agricultural fields.

9. PROSEDUR
 Procedures:
 A stock solution of a known NO3 concentration was prepared by dissolving
a measured weight of sodium nitrate (NaNO3) into 1 liter of distilled
water. This stock solution was further dilluted with distilled water to
standard nitrate concentrations that matched the values of the color chips
of the various test strips evaluated in this study. The NO3 concentration of
each standard solution was confirmed by spectrophotometric analysis.
 Each brand of strip was evaluated at NO3 concentrations corresponding to
the color chips provided by the manufacturer. The Hach Aquacheck and
Lamotte Instatest NO3/NO2 strips differed from the other brands because
the color chips were calibrated in equivalents of NO3-N rather than
NO3. For convenience of displaying and comparing the data, results for
these two brands were converted to NO3 (by multiplying the NO3-N values
by 4.43). The Merckoquant NO3/NO2 test strip was the brand originally
tested by UC Cooperative Extension for use with the soil nitrate quick test,
and was considered the standard in this evaluation. This strip measures to
a maximum of 500 ppm NO3, but was only evaluated up to 250 ppm
NO3 (56 ppm NO3-N) for this test.

10.  Each brand of test strip was evaluated 4 times for each standard
NO3 solution corresponding to the manufacturer's chip color
chart. The procedure that we followed to determine
NO3 concentration was to dip the strip briefly in solution, and
hold it horizontally after removing it, allowing color to develop
for the interval specified by the manufacturer. Most strip
manufacturers recommended a 1-minute time interval between
wetting and reading the strip color.

11.  The manufacturer for API 5-in-1 and LaMotte Instatest 5-Way
recommended reading test strips after 30 seconds, but results
appeared to be more accurate after a 60 second interval,
therefore all results reported for these strips are from readings
taken 60 seconds after placing the strip in the test
solution. After waiting the specified interval, the color of the
test strip was compared to the color chips provided by the
manufacturer. If the test strip color matched one of the chips,
then the value of the chip was recorded. In many cases, the
color of the test strip was between 2 of the standard chips, and
in these cases an estimate was made based on comparing the
intensity of the color development with the 2 closest matching
chips. Because this method relies on visual observations, all
tests were made in a room with ample lighting and by one
observer.

12. HASIL
 Results:
 The mean NO3 values measured using different brands of test
strips were compared to the standard solution values in Table
1. Some brands of test strips appeared to be accurate at specific
ranges of NO3 concentration. The Merckoquant NO3/NO2 brand
was the most accurate for the full range of NO3 concentrations
(Table 1). The next most accurate brand over the entire range of
NO3concentrations evaluated was the LaMotte Instatest
NO3/NO2.

13.  The Hach Aquacheck was accurate for the range of 10 to 90 ppm
NO3 but measured NO3 lower than the standard solutions at
concentrations above 100 ppm NO3. The remaining brands of test
strips, LaMotte Instatest 5-way, API 5 in 1, Tetra 6 in 1 Easystrips,
all measured less NO3 than the standard solutions over the range of
20 to 200 ppm NO3. These strip brands should probably not be
used for the soil nitrate quick test and for assessing nitrate
concentration in irrigation water.
 Although the LaMotte Instatest NO3/NO2 also had good accuracy
across the range of 20 ppm to 220 ppm NO3, it did not have a
standard color chip for evaluating NO3 at low concentrations, and
therefore may not be suitable for strawberries and other crops
where soil nitrate is typically in the 5 to 15 ppm NO3-N range. Both
the Merckoquant and Hach brands were accurate for measuring
NO3at low concentrations (10 to 40 ppm). Although the Hach
Aquacheck strip had a color standard of 5 ppm NO3, the strip was
not able to measure NO3 at a concentration below 10 ppm (Table 1).

14. TABEL KLASIFIKASI KONSENTRASI NITRAT
Table 1. Comparison of nitrate-test strip and standard solution values.

15. TABEL PROPORSI TOKSIK

16. TABEL FLUKTUASI pH

17. AMONIA
 Ammonia is toxic to fish if allowed to accumulate in fish
production systems. When ammonia accumulates to
toxic levels, fish can not extract energy from feed
efficiently.
 If the ammonia concentration gets high enough, the fish
will become lethargic and eventually fall into a coma and
die. In properly managed fish ponds, ammonia seldom
accumulates to lethal concentrations. However, ammonia
can have so-called “sublethal” effects—such as reduced
growth, poor feed conversion, and reduced disease
resistance—at concentrations that are lower than lethal
concentrations.

18. PENGARUH pH
 Effects of pH and temperature on ammonia toxicity Ammonia
in water is either unionized ammonia (NH3) or the
ammonium ion (NH4+). The techniques used to measure
ammonia provide a value that is the sum of both forms. The
value is reported as “total ammonia” or simply “ammonia.”
(In this publication, “ammonia” refers to the sum of both
forms; the specific forms will be referred to as appropriate.)
 The relative proportion of the two forms present in water is
mainly affected by pH. Un-ionized ammonia is the toxic form
and predominates when pH is high.
 Ammonium ion is relatively nontoxic and predominates when
pH is low. In general, less than 10% of ammonia is in the toxic
form when pH is less than 8.0. However, this proportion
increases dramatically as pH increases.

19.  The proportion of toxic, un-ionized ammonia
increases as a function of pH and temperature. To
determine the proportion of un-ionized ammonia in
a water sample, draw a line from the pH of the water
straight up to the line that is closest to the water
temperature. From that point, draw a line to the
right until it intersects the graph’s vertical axis. That
point is an estimate of the percentage of un-ionized
ammonia in the water sample. Now, simply multiply
that number (divided by 100) by the total ammonia
concentration to estimate the un-ionized ammonia
concentration.

20.  In ponds, pH fluctuates with the photosynthesis (which increases pH) and
respiration (which reduces pH) of pond organisms.
 Therefore, the toxic form of ammonia predominates during the late
afternoon and early evening and ammonium predominates from before
sunrise through early morning. The equilibrium between NH3 and NH4+ is
also affected by temperature. At any given pH, more toxic ammonia is
present in warmer water than in cooler water.
 Ammonia dynamics in fish ponds The measurement of ammonia
concentration (and that of many other water quality variables) provides
only a snapshot of conditions at the time a water sample is collected. A
single measurement provides no insight into the processes that affect
ammonia concentrations; it is simply the net result of processes that
produce ammonia and processes that remove or transform ammonia.
 The relationships among these processes are complex, but the important
point is that the rates change differentially throughout the year and result
in the measured patterns.

21.  Ammonia sources The main source of ammonia in fish ponds
is fish excretion. The rate at which fish excrete ammonia is
directly related to the feeding rate and the protein level in
feed. As dietary protein is broken down in the body, some of
the nitrogen is used to form protein (including muscle), some
is used for energy, and some is excreted through the gills as
ammonia. Thus, protein in feed is the ultimate source of most
ammonia in ponds where fish are fed.
 Another main source of ammonia in fish ponds is diffusion
from the sediment. Large quantities of organic matter are
produced by algae or added to ponds as feed.
 Fecal solids excreted by fish and dead algae settle to the pond
bottom, where they decompose. The decomposition of this
organic matter produces ammonia, which diffuses from the
sediment into the water column.

22.  Ammonia sinks There are two main processes that result in the loss or
transformation of ammonia. The most important is the uptake of
ammonia by algae and other plants. Plants use the nitrogen as a
nutrient for growth, “packaging” the nitrogen in an organic form. Algal
photosynthesis acts like a “sponge” for ammonia, so anything that
increases overall algal growth will increase ammonia uptake. Such
factors include sufficient light, warm temperature, abundant nutrient
supply, and (to a point) algal density.

23.  The other important process of ammonia transformation
in fish ponds is “nitrification.” Bacteria oxidize ammonia
in a two-step process, first to nitrite (NO2-) and then to
nitrate (NO3 -). The main factors that affect nitrification
rate are ammonia concentration, temperature and
dissolved oxygen concentration. During summer,
ammonia concentration is very low and so nitrification
rates are also very low. During winter, low temperature
suppresses microbial activity. During spring and fall,
ammonia concentration and temperature are
intermediate, conditions that favor maximum
nitrification rates. Spring and fall peaks of nitrite
concentration are commonly seen in fish ponds.

24.  The effect of daily fluctuation in pH on un-ionized ammonia
concentration in fish ponds. The top horizontal line indicates a total
ammonia concentration of 2.5 mg N/L, which is assumed not to
change during the day. The two curved lines indicate daily changes
in un-ionized ammonia concentration where the maximum
afternoon pH is 9.0 or 9.5. These conditions indicate that fish may
be exposed to toxic, un-ionized ammonia concentrations for brief
periods during the late afternoon.
 Other processes, such as the volatilization of ammonia gas from the
pond surface into the air, are responsible for a relatively small and
variable amount of ammonia loss from fish ponds.
 When is ammonia most likely to be a problem? In fish ponds, it is
extremely unlikely that un-ionized ammonia would accumulate to a
concentration that would become toxic enough to kill fish. However,
unionized ammonia will occasionally accumulate to levels that
cause sub-lethal effects.

25.  The following analysis is based on water quality criteria
for ammonia developed by the U.S. Environmental
Protection Agency (EPA).
 The EPA has established three kinds of criteria (one
acute and two chronic) for ammonia (expressed as
nitrogen), based on the duration of exposure. The acute
criterion is a 1-hour average exposure concentration and
is a function of pH. One chronic criterion is the 30-day
average concentration and is a function of pH and
temperature. The other chronic criterion is the highest 4-
day average within the 30-day period and is calculated as
2.5 times the 30-day chronic criterion. The EPA criteria
help determine when ammonia might be a problem.

26.  During winter It is generally assumed that ammonia is not a problem in
the winter because feeding rates are very low. (Fish are fed on only the
warmest days of winter, usually when the water temperature is higher
than 50 °F.) However, ammonia concentration tends to be greater
during winter (2.5 to 4.0 mg/L, or even higher) than during summer
(less than 0.5 mg/L) (Fig. 3). The relatively low concentration during
summer can be attributed to intense photosynthesis by algae, which
removes ammonia. During winter, algae take up little ammonia but the
ammonia supply continues, primarily from the decomposition of
organic matter that accumulated on pond sediment during the growing
season. In general, the magnitude and duration of high ammonia
concentrations during the late fall and winter can be related to the total
amount of feed added to a pond during the preceding growing season.
PENGARUH MUSIM

27.  The 30-day chronic criterion for ammonia (as nitrogen)
in winter ranges from about 1.5 to 3.0 mg/L, depending
on pH. Ammonia concentrations during the winter
usually exceed this criterion. This may cause stress in fish
at a time of year when the fish immune system is
suppressed because of low temperature.
 After the crash of an algae bloom Some ponds have very
dense algae blooms dominated by one or two species. For
reasons that are not well understood, these blooms are
subject to spectacular collapse, often called a “crash,”
where all the algae suddenly die. When this occurs,
ammonia concentration increases rapidly because the
main mechanism for ammonia removal—algal uptake—
has been eliminated.

28.  Rapid decomposition of dead algae reduces the
dissolved oxygen concentration and pH and
increases ammonia and carbon dioxide
concentrations.After the crash of an algae bloom,
ammonia concentration can increase to 6 to 8 mg/L
and the pH can decline to 7.8 to 8.0. The 4-day
chronic criterion, the appropriate criterion to apply.
Approximate annual variation of total ammonia
concentration in fish ponds. Ammonia concentration
is generally lowest during summer and highest
during winter.

29.  following the crash of an algae bloom, ranges from about 2.0 mg/L
at pH 8.0 to about 3.0 mg/L at pH 7.8. Therefore, ammonia
concentration after the crash of an algae bloom may exceed the 4-
day chronic criterion.
 Occasionally during the late afternoons in late summer or early fall
Seasonal variation in ammonia concentration depends on algal
density and photosynthesis. When these are high, ammonia
concentration is low. Daily variation in the concentration of toxic,
un-ionized ammonia depends on changes in pH (from
photosynthesis) and, to a much lesser extent, temperature. In the
late summer or early fall, ammonia concentration begins to increase
but daily changes in pH remain large. In these situations, fish may
be exposed to ammonia concentrations that exceed the acute
criterion for a few hours each day. If late afternoon pH is about 9.0,
the acute criterion is about 1.5 to 2.0 mg/L total ammonia-nitrogen.

30.  Total ammonia-nitrogen concentrations during
summer are typically less than 0.5 mg/L, so fish are
unlikely to be stressed if the late afternoon pH is less
than 9.0. It is difficult to be more precise about the
risk of ammonia toxicity because of deficiencies in
the methodology used in research.
 Nearly all ammonia toxicity tests are conducted in
systems that maintain a constant ammonia
concentration. These conditions do not reflect the
fluctuating concentrations of NH3 in ponds.

31.  Accordingly, one must be careful when applying research results to
production situations. For example, in one study, growth of channel
catfish exposed to a constant ammonia concentration of 0.52 mg/L
NH3 was reduced by 50% relative to unexposed fish.
 However, brief (2- to 3-hour) daily exposure to 0.92 mg/L NH3
(such as might occur in ponds) did not affect growth and feed
conversion ratio. The fact that many fish can acclimate to repeated
exposure to high concentrations of un-ionized ammonia is a further
complicating factor.
 Ammonia management options On rare occasions ammonia
concentration becomes high enough to cause problems. What
practical steps can be taken if this occurs? The short answer is—not
much. Theoretically, there are several ways to reduce ammonia
concentration, but most approaches are impractical for the large
ponds used in commercial aquaculture.

32.  Following is a discussion of some options, their practicality and
their effectiveness. Stop feeding or reduce feeding rate The primary
source of nearly all the ammonia in fish ponds is the protein in feed.
When feed protein is completely broken down (metabolized),
ammonia is produced within the fish and excreted through the gills
into pond water. Therefore, it seems reasonable to conclude that
ammonia levels in ponds can be controlled by manipulating feeding
rate or feed protein level. This is true to some extent, but it depends
on whether you want to control it over the short-run (days) or the
long-run (weeks or months). In the short-run, sharp reductions in
feeding rate have little immediate effect on ammonia concentration.
 The ecological reason for this is based on the complex movement of
large amounts of nitrogen from one of the many components of the
pond ecosystem to another.
 In essence, trying to reduce ammonia levels by withholding feed can
be compared with trying to stop a fully loaded freight train running
at top speed—it can be done but it takes a long time.

33.  Producers can reduce the risk over the long-run by adjusting both
feeding rate and feed protein level. Limit feed to the amount that
will be consumed. In midsummer the maximum daily feeding rate
should be 100 to 125 pounds per acre. By feeding conservatively, the
potential for high ammonia in ponds and the risks associated with
sub-lethal exposure (disease, poor feed conversion, slow growth)
can be minimized.
 Increase aeration The toxic form of ammonia (NH3) is a dissolved
gas, so some producers believe pond aeration is one way to get rid of
ammonia because it accelerates the diffusion of ammonia gas from
pond water to the air. However, research has demonstrated that
aeration is ineffective at reducing ammonia concentration because
the volume of water affected by aerators is quite small in
comparison with the total pond volume and because the
concentration of ammonia gas in water is typically fairly low
(especially in the morning). Intensive aeration may actually increase
ammonia concentration because it suspends pond sediments.

34.  Add lime It has long been thought that liming ponds decreases
ammonia concentrations. In fact, using liming agents such as hydrated
lime or quick lime could actually make a potentially bad situation much
worse by causing an abrupt and large increase in pH. Increasing pH
shifts ammonia toward the form that is toxic to fish. In addition, the
calcium in lime can react with soluble phosphorus, removing it from
water and making it unavailable to algae.
 In ponds with similar algal density, daily fluctuations of pH in low
alkalinity pond waters are more extreme than those in waters of
sufficient alkalinity (greater than 20 mg/L as CaCO3; see SRAC
Publication No. 464). Therefore, liming can moderate extreme pH
values, particularly those that occur during late afternoon when the
fraction of total ammonia that is in the toxic form is highest.

35.  However, this technique is effective only in ponds with low
alkalinity. Most fish ponds have sufficient alkalinity. Increasing the
alkalinity above 20 mg/L as CaCO3 will not provide additional
benefit. Furthermore, liming does not address the root causes of
high ammonia concentration; it only shifts the distribution of
ammonia from the toxic to the non-toxic form by moderating high
pH in the afternoon. Fertilize with phosphorus Most of the
ammonia excreted by fish is taken up by algae, so anything that
increases algal growth will increase ammonia uptake. This fact is
the basis for the idea of fertilizing ponds with phosphorus fertilizer
to reduce ammonia levels. However, under “normal” pond
conditions, algae blooms in fish ponds are very dense and the rate of
algae growth is limited by the availability of light, not nutrients such
as phosphorus or nitrogen.
 Therefore, adding phosphorus does nothing to reduce ammonia
concentration because algae are already growing as fast as possible
under the prevailing conditions.

36.  The highest ammonia concentrations in fish ponds occur after the crash
of an algae bloom. Fertilization, particularly with phosphorus, may
accelerate the re-establishment of the bloom, but most ponds have
plenty of dissolved phosphorus (and other nutrients) to support a
bloom and do not need more.
 Reduce pond depth Algal growth (and therefore the rate of ammonia
uptake by algae) in fish ponds is limited by the availability of light.
Anything that increases light increases ammonia uptake. Theoretically,
dense algae blooms in shallow ponds will remove ammonia more
effectively than the same dense blooms in deeper ponds. On balance,
however, there are probably more benefits associated with deeper
ponds (e.g., ease of fish harvest, water conservation, more stable
temperatures, reduced effect of sedimentation on interval between
renovations).

37.  Increase pond depth Obviously, deeper ponds
contain more water than more shallow ponds.
Therefore, at a given feeding rate, deeper ponds
should have lower ammonia concentrations because
there is more water to dilute the ammonia excreted
by fish. In reality, deeper ponds do not usually have
enough water to significantly dilute ammonia when
compared to the large amounts of ammonia in
constant flux between various biotic and abiotic
compartments in ponds.

38.  Furthermore, deeper ponds are more likely to stratify and the
lower layer of pond water (the hypolimnion) can become
enriched with ammonia and depleted of dissolved oxygen.
 When this layer of water mixes with surface water in a
“turnover,” severe water quality problems may result. Flush
the pond with well water Ammonia can be flushed from
ponds, although pumping the huge volume of water required
to do so in large commercial ponds is costly, time-consuming
and unnecessarily wasteful. It is also deceptively ineffective as
an ammonia management tool. For
 example, assume the ammonia concentration in a full, 10-acre
pond is 1 mg/L. The ammonia concentration after pumping
500 gpm continuously for 3 days (equivalent to about 8 inches
of water) will be 0.90 mg/L, a drop of only 0.10 mg/L.

39.  Instead of simply running water through a pond as
in the example above, now assume that about 8
inches of water is discharged from the pond before
refilling with well water. In this case, the decline in
ammonia concentration will be slightly greater (to
0.83 mg/L), but even this decrease is not enough in
an emergency situation, particularly when the extra
time needed to drain the water before refilling is
considered. The difference in the two flushing
scenarios is related to the blending of pond water
with pumped water before discharge in the first case.

40.  Just as paddlewheel aeration creates a zone of sufficient dissolved oxygen
concentration, pumping groundwater creates a zone of relatively low
ammonia concentration adjacent to the water inflow.
 The effectiveness of this practice is questionable because it does not
address the root cause of the problem and wastes water. Flushing ponds is
not only ineffective, but highly undesirable because of concerns about
releasing pond
 effluents into the environment.
 Add bacterial amendments Common aquatic bacteria are an essential part
of the constant cycling of ammonia in a pond ecosystem. Some people
believe that ammonia accumulates in ponds because the wrong kind or
insufficient numbers of bacteria are present. If this were true, adding
concentrated formulations of bacteria would address the problem.
However, research with many brands of bacterial amendments has
consistently given the same result: Water quality is unaffected by the
addition of these supplements.

41.  Standard pond management creates very favorable conditions for
bacterial growth. Bacterial growth and activity is limited more by
the availability of oxygen and by temperature than by the number of
bacterial cells. Also, the most abundant type of bacteria in many
amendments (and in pond water and sediment) is responsible for
the decomposition of organic matter. Therefore, if bacterial
amendments accelerate the decomposition of organic matter,
ammonia concentration would actually increase, not decrease.
 Another kind of bacteria in amendments oxidizes ammonia to
nitrate. Adding them will not reduce the ammonia concentration
rapidly because the bacteria must grow for several weeks before
there is a large enough population to affect ammonia level.
 Add a source of organic carbon If the dissolved oxygen
concentration is adequate, adding a source of organic carbon, such
as chopped hay, to intensive fish ponds can reduce ammonia
concentration.

42.  Many bacteria in fish ponds are “starved” for organic carbon,
despite the addition of large amounts of feed. Organic matter in fish
ponds (dead algae cells, fish fecal solids, uneaten feed) does not
contain the optimum ratio of nutrients for bacterial growth. There is
more than enough nitrogen for bacterial growth so the excess is
released to the pond water.
 Adding organic matter with a high concentration of carbon relative
to nitrogen promotes the “fixation” or “immobilization” of the
ammonia dissolved in water. Incorporating ammonia into bacterial
cells packages the nitrogen into a particulate form that is not toxic
to fish. The down side of this approach is that it is hard to apply
large amounts of organic matter to large ponds and the effect on
ammonia concentration is not rapid. Furthermore, aeration will
have to be increased to address the demand for oxygen by large
quantities of decomposing organic matter.

43.  Add ion exchange materials
 Certain naturally occurring materials, called zeolites, can adsorb
ammonia from water. These are practical to use in aquaria or other
small-scale, intensive fish-holding systems, but impractical for
largevolume fish ponds.
 Some shrimp farmers in Southeast Asia have tried making monthly
applications of zeolite at 200 to 400 pounds per acre. However,
research has demonstrated that this practice is ineffective at reducing
ammonia concentration in ponds and it has now been abandoned.
 Add acid In theory, adding acid (such as hydrochloric acid) to water
will reduce pH. This can shift the ammonia equilibrium to favor the
non-toxic form. However, a large amount of acid is necessary to reduce
the pH in well-buffered ponds and it would have to be mixed rapidly
throughout the pond to prevent “hot spots” that could kill fish.
Furthermore, adding acid would destroy much of the buffering capacity
(alkalinity) of the pond before any change

44.  in pH could occur. Once the ammonia concentration is lowered, treated
ponds might require liming to restore the buffering capacity. Working
with strong mineral acids is a safety hazard for farm workers and for
fish.
 How often should ammonia be measured?
 From the foregoing discussion, you might assume that measuring
ammonia in ponds is unnecessary.
 After all, research has indicated that brief daily exposure to ammonia
concentrations far higher than those measured in commercial ponds
does not affect fish growth. And, on the rare occasions when ammonia
does become a problem, there is nothing you can do about it. However,
there are some special circumstances when it is worthwhile to monitor
ammonia levels.

45.  In the South, ammonia concentrations in most ponds usually start
increasing in September and peak about mid-October, about 5 to 6
weeks after the last stretch of high feeding rates. Then, about 2 to 4
weeks later, nitrite concentrations peak. This is a general pattern. It
does not apply to all ponds, and ammonia or nitrite problems can
occur with variable intensity at any time, especially between
September and March.
 Thus, the magnitude of the ammonia elevation in the early fall can
indicate the severity of the nitrite spike that will follow. Salt can
protect fish against nitrite toxicosis (see SRAC Publication No. 462).
If enough salt is added to ponds to achieve chloride levels of 100 to
150 mg/L, there is no reason to measure ammonia even as a
predictor of high nitrite concentrations.

46.  Ammonia should be measured every other day after the
crash of an algae bloom and weekly in the cooler months
of the year to identify ponds that may have a potential
problem with nitrite. Other than those times, it is
probably not necessary to measure ammonia in fish
ponds.
 To summarize, fish producers should not be alarmed if
ammonia concentration becomes elevated, although a
high ammonia level often indicates that nitrite
concentrations may soon rise. In this case, farmers
should focus on protecting fish from nitrite poisoning by
adding salt, rather than on trying to manage the
ammonia problem.

47.  Extra vigilance after an algae crash is also probably
warranted. Usually, the concentration of ammonia will
fall again once the bloom becomes re-established.
Because there is little that can be done to correct
problems with ammonia once they occur, the key to
ammonia management is to use fish culture practices
that minimize the likelihood of such problems.
 This means stocking fish at a reasonable density,
harvesting as often as practical to keep the standing crop
from being too large, and using good feeding practices
that maximize the proportion of the feed consumed by
fish.

48. NITRAT
 Nitrate in Ponds
 Nitrate, NO3-N,
 Nitrate is the final product from the breakdown of ammonia released
by the fish.
 Nitrate is not especially harmful to freshwater fish but is a potent plant
fertilizer and can contribute to the growth of unsightly and unwelcome
algae, such as green water or blanketweed. Ideally, the levels of nitrate
in the fish pond should be controlled to help reduce the likelihood of
these unwelcome algae blooms occurring. It is recommended that a
Nitrate Test Kit is used to determine the quantity present in the pond
and control the concentration through water changes.


49.  Nitrite in Ponds
 As the ammonia in the water begins to reduce, the secondary break
down product, nitrite will begin to increase and this is also very
poisonous to fish.
 Nitrite is a skin irritant and will cause the fish to display symptoms
of irritability such as rubbing themselves, jumping, or even
skimming across the surface of the pond. These symptoms are also
commonly associated with parasites and it is sensible to eliminate
nitrite as the cause before treating the pond.
 Nitrite also has a rather sinister effect on the pond fishes blood, as it
will bind very tightly with the red pigment and thereby preventing
the blood cells from absorbing vital oxygen from the water. Once the
nitrite has become associated with the red pigment, it turns the
blood a dull brown color and hence the popular name for nitrite
poisoning is "brown blood disease".

50.  A second group of micro-organisms, comprising mostly
species of Nitrobacter bacteria are responsible for breaking
down the nitrite into nitrate, which is the final breakdown
product but in the event of high nitrite levels occurring in the
pond, regular partial water changes need to be undertaken to
reduce the concentration of this pollutant.
 Nitrite is an odorless, colorless substance and its presence can
be detected using a Test Kit

51. Thank You
Dedicated to :
1. My loving wife , Hutapea Olga Y.V, dr;
2. My loving daughter :
a. Simamora Michelle Renata Robertina;
b. Simamora Helga Martha Davina;
Also :
1. Environment, Research and Development Agency of Samosir Regency Government
of North Sumatera Province;
2. People of Samosir Regency
3. All of You
Alumni :
PSMIL – Universitas Padjadjaran
at Bandung