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Algae propagation and movement control strategies _OBAO13_

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					Algae propagation and movement control strategies (OBAO13)
A movement of cyanobacteria
1.1 vertical
  ?Most of the freshwater algal species Microcystis (Microcys-tis), Anabaena
(Anabaena), beam filament algae (Aphanizomenon), plastic barbed algae
(Gloeotrichia), Lyngbya (Lyngbya) and Oscillatoria sp (Oscil -latoria), although these
lakes cyanobacteria may occur throughout the year, but generally only in the autumn
of China reached the water level. Many water bloom of cyanobacteria has airbags,
you can move vertically in the water.
Figure 1 shows the algae cells and the air bag in the water pressure in the diagram.
Figure 2 is a bouquet of silk water, algae and salt Navicula airbag electron microscope
(150 000 ×).
   The location of algae in the water by two mechanisms control. The first is the
growth rate compared with the algae, the airbag production stability. When the algae
sink and reduced light intensity and the sinking depth, the algae production rate of
greater than balloon cyanobacteria growth rate; each algae cell increase in the number
balloon to make it float. On the contrary, when the algae floating light intensity
increased, biomass growth rate of algae cells is greater than the rate of airbag
production, air bags reduce the algae cells to sink. The second mechanism is that with
the increase of photosynthesis, excitation of photosynthetic products (photosynthate)
penetration of active molecules, leading to cell turgor (t) (turgor pressure) increase,
the weaker the balloon burst, floating algae cells lose capacity. Algal photosynthesis
and sink until the infiltration activity decreased, the osmotic pressure decreased,
increased production of algae balloon, floating upward. Cyanobacteria can increase
under low light intensity characteristics of balloon cells, so that communities can take
algae-rich lake light areas (eg water); in high light decreased cell bag to avoid water
accumulation in the algae itself and the anti-ultraviolet radiation. In the calm wind,
due to increased water flow (upwelling currents) or over-floating algae in the water
sometimes accumulate. In fact, very close to the water environment is not conducive
to the survival of algae; bloom formation, the algae quickly die photo-oxidation
(undergo photooxidative death).
1.2 horizontal movement
   Horizontal movement of algae caused by water and wind movement. About 3 m / s
wind speed can make a small lake surface level of the water layer of drift, drive to the
lake algae accumulate downwind regions. In large shallow lake, the wind caused the
lake level cycle, the highest concentration of algae may appear in the level of the
central loop. Eutrophic or polluted lake water level can quickly accumulate wind drift
algae or dead fish floating garbage, causing water pollution.
jiulia - 2009-9-7 11:15:00
Northern Lake algal bloom in a summer promotion Sector Moral, floating sheet of
water to enter China from the large shift in the Taihu Lake Meiliang north to the Bay
of algal blooms increased. Xiao-Hua Bai, and others on the northern part of the
summer of 2004 I like the water of Taihu Lake of China's 6 days were
calculated bloom amount of wind drift into the Bay, 5 from the big lake Tianshui
China Meiliang drift to the area of the total area Meiliang 3.7% to 13.3%, up to 4.8 ~
17.4 km2. ZHU Yong-chun, who studied the Meiliang Bay under different wind algae
in the lake in the migration process. Simulation results show that the wind field for
different algae in the lake in the horizontal and vertical distribution of great influence,
and there is a critical wind speed, the range of 2 ~ 3 m / s between; when the wind
speed is less than critical velocity, the surface can water dynamics to be smooth as
there is no wave generation, surface algae in the water along the wind shift rapidly to
the windward shore, forming algal accumulation.
1.3 Summary
   Cyanobacteria can exercise. Cyanobacteria have a considerable part of the airbag,
the special structure so that it can be active for vertical movement; also some increase
in the vertical distribution of water related. Horizontal distribution of algae mainly
with water flow, wind speed and direction, the surface water layer of drift.
Suppose lake area 100 km2, the average water concentration of algae 10ug / L (a). In
the calm wind conditions, the distribution of algae in water depth of 4 m to the surface
movement, gathered in the surface 0.04 m thick, to form water blooms drift layer (b).
In windy conditions, 100 km2 resulting accumulation of cyanobacteria to 10km2 (C, d,
e), the formation of the algal blooms in disaster. At this point, the accumulation of
cyanobacteria in the 10km2 concentration was increased 1,000 times, the content of
microcystins may also increase a hundredfold.
This example tells us that once the outbreak of large-scale lake-wide lake of algal
blooms, accumulation of the next wind will occur somewhere in the water hazard
algal blooms in the region of billions or even tens of billions of investment but since
the algae can not.
2 algae growth
2.1 The growth in laboratory conditions
   In general, growth of algae under laboratory conditions in five stages:
(1) slow growth (1ag)
Under laboratory conditions, when water is moved cultured human test container, will
appear at this stage;
(2) exponential growth (exponentia1)
If the experimental environment, nutrients and space scales are unrestricted, the algae
into the exponential growth phase. The highest growth rate of algae at this stage, is
almost a straight line. We pay special attention to this phase (line) of the two extreme
points: N1 and N2, and its growth rate is:
K '= Ln (N2/N1) / (t2 1 t1)
Where N1 and N2 is the time t1 and t2 in the biomass.
When the growth rate of algae are known, can calculate the number of daily
separation of algae (Div) and doubling time (Gen't):
Div / day = K '/ Ln2
Gen "t = 1 | (Div / day)
(3) the decline in growth (declining growth rate)
As the algal growth, nutrients and carbon dioxide as limiting factors to algae growth
down. As excessive growth of algae, algal cells each covering (self.shading), light
intensity will also become a limiting factor.
(4) stagnation of growth (stationary)
Algae growth rate is zero at this stage, within hours of algae dramatic biochemical
changes occur.
(5) death (death)
When the metabolism of algae can not maintain the community enters the death phase;
stage very quickly due to death, often referred to as "collapse."
Dead algae lose pigment deposition (pigmentation), or being washed away, or cover
the surface of the water accumulation, causing water hypoxia and death of more
algae.
2.2 in the growth of cyanobacteria under natural conditions
   Beam filament algae (Aphanizomenon) in the 4 early May into late exponential
growth phase, cell number within a month's time peak; and of Anabaena
(Anabaena) and microcystins (Microcystis) in the September entry exponentially.
Clear Lake algae growth and succession of such a large extent changed the
lake's nutritional status; because beam filament algae (Apha-nizomenon)
and Anabaena (Anabaena), both with nitrogen fixation of cyanobacteria in summer as
lake Hypoxia causes the release of ammonia, inhibits nitrogen fixation of
cyanobacteria.
2.3 The control of algal bloom time
  ?Understand the growth of algae in the water laws to control algal blooms of great
significance; developed algae growth in the use of the law, to develop security alarm
value algal bloom has a lot of experience. Australia's urban water research
results show that at 20 ℃ under ideal conditions (laboratory culture), algae density
in the 14 ~ 46 d can be achieved within the "outbreak" level (27
000 / mL). For security purposes, algae "bloom" security
warning value (N1) is generally not more than 15 000 / mL. Water for recreation,
when Microcystis (Microcystis aeruginosa)> 50 000 cells / mL (NHMRc,
2005) or all of the cyanobacteria> 30 000 cells / mL, the first class action
should be taken (Action Level 1).
Figure 9 shows the growth rate of algae in two different (u = 0.1 / d, and u = 0.3 / d)
and two different initial cell numbers (1O0 / ml, and 1 000 / m1) when , cyanobacteria
community growth forecast and the corresponding alert level. In natural water bodies,
especially in hot weather, the algae communities are often in less than two days
doubled (u = 0.35 / d time); monitoring frequency and preventive measures need to be
such a rapid growth of algae characteristics into account. Figure 9 also told us that in
the algae is not high when the initial concentration of early prevention, even if the
algae growth rate is high, we still have a lot of time to exercise control.
jiulia - 2009-9-7 11:28:00
2.4 Summary
   Theoretically, algae, aquatic ecosystems, primary productivity, growth in its first
phase of the process is normal, is also an essential ecosystem component. Suppose N2
points to an outbreak of algae growth in water bloom, then the N1 point is prevention
of algal bloom early warning point, the algae growth in the early control measures
should be implemented in the near N1. N2 point is the algal bloom warning point,
should start contingency measures to reduce algal blooms caused by adverse effects.
In fact, the algae growth process gives us the implementation of early prevention and
control of time and concentration; as long as the time to seize the N1 to N2, is likely
to control the excessive growth of algae. Now mostly taken after the formation of
algal bloom technical measures, such as fishing algae. Some people would rather
spend 10 million yuan to buy a salvage boat, but do not want to spend 1 million yuan
to study the algae early prevention methods, this is undesirable.
3 early prevention and control of algal blooms in a number of technical
   ?Large-scale control of algal blooms in many technologies. Due to space
constraints, here to introduce and algal blooms in early prevention and control of the
two types of technology can not cover all, but they can gain enlightenment.
3.1 for the algal blooms in early prevention and control of hydraulic control
technology
  ?(1) diverting water dilution (Flushing) technology
  ?Transfer dilution is a familiar technology. In the early 20th century, 60 years Seattle,
Washington, Green Lake (Green Lake) on the use of diverting water dilution method,
the 14-month HRT reduced to 3 months, so that surface water nitrate nitrogen and
chlorophyll a substantial decline in increase the transparency of nearly 3m, remove
the algae (Aphanizomenon) bloom phenomenon. Marten Scheffe and Hosper other
people think, (a) Transfer dilution of the controlling algal blooms are particularly
effective (Figure 11 on); (b) even with high nutrient content of runoff, as long as
sufficient strength, China can effectively control the water ; (c) winter algae
concentration is low, the role of water transfer greater dilution.
In recent years, research results show that the control of water hydraulic retention
time is still effectively control the excessive growth of algae and effective way.
General water daily to replace 10% to 15% of the total volume of water,
medium-sized reservoirs once every 3O-day replacement of water, water can
effectively control algae bloom.
  ?(2) reservoir layer control technology
  ?Reservoirs are generally temperature stratification (thermocline) phenomenon, the
high concentration of nutrients in the bottom of hypoxia (anoxic layer) accumulation.
Summer B discharge from the reservoir to reduce nutrient load, effectively prevent the
exchange of upper and lower layer of water due to algal blooms. A discharge is
similar to the water transfer from the dilution water to reduce the number of algae in
the unit. Hierarchical control method of reservoir is very easy to change the
nutritional status of reservoir and heat conditions, may also adversely affect
downstream water bodies (for example, emissions from the reservoir bottom water
with high nutrients, often containing toxic hydrogen sulfide), used to go through a
more accurate calculation and simulation.
Most of the country's eastern plains is a river lake moraine lake moraine
lake and the sea, mostly connected with the river shallow lakes; the new medium and
large reservoirs are generally different height sluice gate. Successful overseas
experience tells us that the hydrodynamic conditions of use of its lakes and reservoirs
change the nutritional status and bio-geochemical processes, which control large areas
of lake and reservoir eutrophication and algal blooms is entirely feasible. Be noted
that for the algae bloom early prevention and control of water diversion or scheduling
technology and with the water running is different, the key to success lies in its
control algae growth and nutrient changes in the law. Water only in accordance with
the requirements of hydraulic control, it is often difficult work; but in many cases the
two can very well together.
  ?3.2 for the algal blooms in early prevention and control of chemical technology
  ?(1) Copper Algaecide complex ecological safety
Compared with other algaecide, copper algicidal effect efficient, stable, inexpensive,
and toxic effects on human health is low, these characteristics make copper
compounds into the United States control of the preferred algaecide algal growth.
Particularly as a source of drinking water in those reservoirs or water storage areas,
may not consider the toxicity of copper on fish and copper compounds has become
almost the only algaecide. However, copper sulfate on aquatic organisms as well as
the impact on aquatic ecology, can not be ignored; This makes the complex copper
algicide Study has made substantial progress. Murray-Gulde and others on the
effectiveness of three copper algaecide and safety testing of the system to do. Table 1
and Table 2 shows the results of their experiments. To Clearigate, for example, its
green algae (Raphido-celis subcapitata) is the critical burden of 7.9 ugCu / mg; If the
cast concentration of 1 mgCu / L, can effectively control algae growth in the
maximum cell density was estimated at 3.7 × 10 cells / ml. In their study, the shortest
copper algicide half-life of 2.6 d, show that the copper algicide on non-target species,
the long-term cumulative effects can not be considered, but the first 24 h exposure to
the toxic effects of the attention should be paid.
Mastin and Rodgers has confirmed that, compared with copper sulfate, copper
algicide complex on non-target species with high security, which the Cu-trine-Plus is
the highest. The results also showed that Daphnia magna (D.magna) are the four most
sensitive test animal species. No matter what kind of animal, its margin of safety is
adequate.
  ?(2) the complex effect of copper algaecide
  ?Greene County, Missouri McDaniel Lake in 2000 and 2002 outbreaks algal blooms,
with 2003 complex copper Cutrine-Plus control algae growth, algae density box
(box.plot) data (P = 25% ~ 75% of the data) for three consecutive years (2003 ~ 2005)
is less than 10 000 / l (Figure 13 above), the basic elimination of algal blooms;
complaints telephone also declined substantially.
In fact, since 2000 the United States in the use of complex copper control algal
blooms in drinking water, library research and application of many. In particular,
Clemson University, John Rodgers, Professor Ali sauna in the State of Water Ranch
Lake and Lake Whitney, Texas study shows that low concentration of complex copper
can control algae growth.
  ?(3) The fate of copper in the environment
  ?The fate of copper in the environment is particularly ecologists concern. Produced
algaecide copper sulfate into the water to form the copper ions will quickly translate
into a very low solubility of copper carbonate or copper hydroxide and precipitation,
reducing the efficiency of algaecide. Liu and others of that into a raised fish pond, 2
Cu, 90% or more in about two minutes to keep ponds with suspended particles
together, almost all of the copper will be transferred within two days mud which in
the end. In contrast, the copper complexes in water environment relatively stable, not
easily combine with other particles in the water, into the role of water after the time
can be extended five times more than copper sulfate. June 18, 2006 in McDaniel Lake,
Missouri, residual copper water measurement results show that after a week in the
cast copper complex, copper concentration in the water reached Missouri, the
requirements of natural resource management; 10 ~ 12 d after below the detection
limit of copper in water.
U.S. to use copper compounds as algaecide has been for decades, and many lakes,
especially the perennial drinking water database put copper preparations. A variety of
data indicate that the copper algaecide basically into the mud at the bottom of the
water body will not go back to the water, do not continue to fish or algae toxicity.
Wisconsin Man pocket ripple lake (Mendota Lake) in the 26-year period, to control
algae growth to bear the 771 t of copper. Washington State's Williams Lake
late Emperor Lou grams (Steilacoom Lake) in 1990, sediment copper test value of 1
025 mg / kg, but not very high concentrations of copper in water, and still need to use
algaecide algal growth suppression . The United States is currently no comprehensive
baseline sediment contaminants, sediment copper Washington State its benchmark
value of 390 mg / kg, and copper in our soil three standard (400 mg / kg) significant.
   In fact, the complex of copper algaecide very limited impact on the sediment.
According to some experts, a rough calculation, using the concentration of 50 ppb in
the copper complex solution control algae, per square kilometer of the water capacity
of 100 kg of copper applied, the increase of copper in the sediment is about 0.2 ppm.
Shanghai Dianshan sediment in copper 1O. 89 ppm, and 24.39 ~ 26.33 ppm, 50 ppb,
if five consecutive years, according to the level of complex control algae growth in
copper, copper content in sediments increased up to 1 ppm. The five consecutive
years without an outbreak of algal blooms, not only greatly reduce the algal toxins
may impact on drinking water, but also for the lake's ecological recovery
and respite for their valuable time to ask.
3.3 Summary
  ?Used to control the excessive growth of algae technology is not really complex,
diverting water dilution and chemical technologies are algal blooms in the early
effective means of prevention. In the past, withered diluted with water only as
emergency measures, we ignored it reduces the number of algae, changing the way of
algae and water sports state of the role of nutrients. Chemical technology is almost a
restricted area on tiger color, we deny the ppb level with the level of copper in
exchange for the great benefit the security of drinking water sources. Overseas
successful experience tells us that as long as we grasp the algae's growth
laws, the process of the Movement and disaster, to take early preventive technical
routes and large means of control, elimination of algal blooms on the drinking water
threat, lower algal Dai Hua to the other negative effects, it is entirely possible.
jiulia - 2009-9-7 11:28:00

				
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