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Old 08-23-2013, 12:43 PM   #1 (permalink)
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Default Toxicity / Deficiency Literature Research

This thread was originally part of "trouble on the farm - help!" thread but since several of the following posts went out of the original question's scope I have moved them here. This thread contains values for nutrient toxicity and other related bits of information.

http://5e.plantphys.net/article.php?ch=t&id=289

Immobile nutrients are: Ca, Fe, B, Ni and Mn

Mobile nutrients are: N, P, K, and Mg.

Variably mobile nutrients: Cu, Zn, S, and Mo.

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Old 09-05-2013, 10:38 AM   #2 (permalink)
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Default Re: trouble on the farm - help!

I did a bit of reading and digging around and found this:

----------------------------
From a hydroponics site:
"Optimum concentrations for tomatoes are: Boron 0.44, Copper 0.05, Chlorine 0.85, Manganese 0.62, Molybdenum 0.06, Zinc 0.09, Iron 2.5 ppm (mg/L)."

"Macro nutrients:
N between 113-144 ppm, P of 62 ppm, K of 199, Mg of 50, Ca 122-165"

From:
http://ag.arizona.edu/hydroponictomatoes/nutritio.htm
----------------------------

Then I had a look in the database and found two relevant articles one says:
"Zinc toxicity depends on pH, which controls the concentration of zinc in solution. High concentrations of zinc can cause toxicity in plants. The general symptoms are stunting of shoot, curling and rolling of young leaves, death of leaf tips and chlorosis. ~80 uM zinc caused Typha latifolio to show chlorosis.

Zinc toxicity is also known to inhibit root growth in terrestrial plants."
From:
Effect of Metal Toxicity on Plant Growth and Metabolism: I. Zinc
Sustainable Agriculture
2009, pp 873-884
http://link.springer.com/content/pdf...-2666-8_53.pdf
http://link.springer.com/content/pdf..._53.pdf#page-1

----------------------------
In another article I found this
"Soluble Zn and the ratio of Zn2+ to organic Zn-ligand complexes increase at low pH, especially in soils of low soluble organic matter content.

Toxicity symptoms include reduced yields and stunted growth, Fe-deficiency-induced chlorosis through reductions in chlorophyll synthesis and chloroplast degradation, and interference with P (and Mg and Mn) uptake (Carroll & Loneragan, 1968; Boawn & Rasmussen, 1971; Foy et al., 1978; Chaney, 1993). Crops differ markedly in their susceptibility to Zn toxicity. In acid soils, graminaceous species are generally less sensitive to Zn toxicity than most dicots, although this is reversed in alkaline soils (Chaney, 1993). Among dicots, leafy vegetable crops are sensitive to Zn toxicity, especially spinach and beet, because of their inherent high Zn uptake capacity (Boawn & Rasmussen, 1971; Chaney, 1993). There is also genetic variation in sensitivity to Zn toxicity within species, including soybean, and rice."
From:
Zinc in plants Martin R. Broadley1, Philip J. White2, John P. Hammond3, Ivan Zelko4,5, Alexander Lux4,5 Article first published online: 7 FEB 2007 DOI: 10.1111/j.1469-8137.2007.01996.x
http://onlinelibrary.wiley.com.ezpro...996.x/abstract
----------------------------

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Old 09-05-2013, 12:17 PM   #3 (permalink)
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Default Re: trouble on the farm - help!

I looked at a hydroponics site and the suggested range at which food plants do well varies from 0.02 to 0.2 ppm zinc. I had a look at their suggested ranges for NO3 and PO4 to put it all in perspective and they suggest NO3 should be from 70 to 200 ppm and PO4 from 30-90 ppm. So I suspect that their Zn recommendations are also higher than what we'd want for our aquatic systems.
From:
http://www.tps.com.au/hydroponics/nutrient.htm
----------------------------

Here is a post from a few years ago from Kekon (I really miss that guy - he had some great insight into micros).
Quote:
Originally Posted by Kekon
But boron... is very mysterious element for me. I was always told the range between toxicity and deficiency is very narrow. Most fertilizers usually contains B:Zn in a ratio of 2:1. I use RO water and added typically 0.008..0.02 pmm of B weekly. I saw negative results when boron dose was higher than 0.015 ppm weekly. However, my Macradra began to grow exceptionally well when such dose was added to the tank (0.015 ppm weekly). But other plants seemed to grow slower.

I don't know how much boron is removed by my RO filter. I was told that reverse osmosis membrane removes only 50% boron from the tap water. I estimated that in my tank the best result are obtained when I add 0.008..0.015 ppm of boron (weekly) and 0.006..0.02 ppm of zinc (weekly). Of course this work in my tank when only RO water is used.
From:
http://www.aquaticplantcentral.com/f...tml#post491680
---------------------------

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Old 09-14-2013, 09:52 PM   #4 (permalink)
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Default Re: trouble on the farm - help!

Did some more research today. This time on sodium.

Sodium is not an essential element for plants (it is for animals but not plants - except for salt loving halophytes). This means you ideally want your sodium levels to be 0 in the aquarium.

Sodium interferes with potassium uptake in a competitive manner. This means you can help stop salt toxicity by having more potassium in the water. Calcium will also lessen sodium toxicity but you must be careful not to disrupt the Ca:Mg (4:1) ratio or else you'll get issues from that.

Salt stress affects all the major processes such as growth, photosynthesis, protein synthesis, and energy and lipid metabolism.
Pg 124 from Hydroponic Food Production by Howard M. Resh.
"Salinity may inhibit uptake of certain ions. High sulfate concentrations promote the uptake of sodium (leading to sodium toxicity), decrease the uptake of calcium (leading to calcium deficiency, especially in lettuce), and interfere with potassium uptake. High calcium concentrations in nutrient also affect potassium uptake. High total salt contents are thought to affect calcium uptake, leading to "blossom-end-rot" symptoms in tomatoes. Saline conditions reduce the availability of certain micro-elements, especially iron, so that additional iron must be added. In addition to chloride and sodium toxicity, boron toxicity is relatively common with some saline waters."
It is proving somewhat difficult to get an exact value for sodium that causes toxicity. Apparently for a lot of terrestrial plants a value of 100-200 mM NaCl will cause severe stunting and issues. This translates to 5,855 mg/L (ppm) which seems absurdly high for aquatic plants, so again, I think we are seeing the difference between soil and water media.

I did managed to dig up an old post about sodium started by kekon (I miss that guy and his questions), and it seems that levels of up to 35 ppm Na are apparently safe for aquatic plants (according to a member on APC). I'll have to verify this concentration, but it seems a reasonable value (for now) provided the K and Ca are dosed in larger amounts to compensate.

According to a lettuce study (hydroponics setup) Na of 50 ppm can be toxic, and the hydroponics site (below) considers 161ppm Na and 202 ppm Cl is "through the roof" high. This first stage of toxicity seems to be due to the terrestrial plants losing their ability to osmo-regulate, so they dry out and start dying. This obviously isn't an issue in aquatics, so perhaps aquatics have some slight resistance to the first effects of salt. Still it seems that 50 ppm should be the upper limit, and probably much less. Ideal is 0 ppm remember!
http://www.manicbotanix.com/hydropon...c-growing.html
Myriophyllum spicatum's 50% reduction in biomass limit is apparently 3,617-4,964 ppm for Cl- with no mention of Na's toxicity level.
http://www.rebuildingi93.com/documen...Evaluation.pdf
So it seems that if you keep it below 50 ppm you should be alright.

I'll try do a bit more digging to find a more well defined limit for Na.

Kekon's thread:
http://www.aquaticplantcentral.com/f...ul-plants.html
*Update*
Found a few more sites on sodium in hydroponics which are in the general area as the research above, so I feel pretty comfortable saying that you shouldn't have sodium levels over 50 ppm, so I'll say this is probably where toxicity starts.
http://www.maximumyield.com/inside-m...ation-you-have
*Update* 11/13/2013
I found a good review on Sodium toxicity in aquatic plants and algae. The review states that 1000-2000 ppm is where issues with growth started to show up in the most intolerant species studied. This means at concentrations of 1000-2000 ppm Na the plants started to die back. Interpreting this in terms of our tanks and dosing levels, this means you should see no signs of growth inhibition or die back if you have 10x less concentrated levels (why 10x less? this is the "uncertainty factor" I have chosen for plant data based on my readings - "uncertainty factors" are commonly used in science when you study results in one species and apply it to another but they are usually much more strict like 100 or 1000x). In other words 100-200 ppm Na should pose no problems at all.

The article goes on to say that the toxic effects of sodium are because:
Pg 115
"Toxic effects originate because the high external salt concentration induces greater diffusion of ions into root cells and results in elevated ionic concentrations in the cytoplasm. This can reduce plant performance by: (a) increasing membrane permeability, particularly by reducing the calcium to sodium ratio; (b) breaking down enzyme and active exclusion mechanisms; (c) increasing the transport of sodium chloride to shoots where high concentrations of chloride and/or sodium in expanded leaves can cause chlorosis and death; (d) interfering with the uptake of potassium; high sodium to potassium ratios are known to inhibit many enzyme activities and characterize non-halophytes in saline conditions."
From
Article:A review of the salt sensitivity of the Australian freshwater biota
Author:Hart, BT
Journal:Hydrobiologia
ISSN:0018-8158
Date:1991
Volume:210
Issue:1
Page: p105

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Old 09-15-2013, 10:45 AM   #5 (permalink)
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Default Re: trouble on the farm - help!

Very strange.

I found two articles that specifically talk about sodium chloride concentrations and aquatic plants. It seems that 50% reduction in dry weight after 32 days of exposure to NaCl for several aquatic plants was between 1,820 - 3,617 ppm. This was for Myrio. spicatum and Potamogeton pectinatus. And the other article talked about other aquatic plants like hydrilla verticillata, najas quadalupensis, vallisneria americana, azolla caroliniana, salvinia rotundifolia, lemna minora, eichornia crassipes, and pistia stratiotes that seemed to decline in salt concentrations around 2.5-6.6% salt (25,000 ppm - 66,000ppm). This study seemed to notice that the emersed larger floating plants were more susceptible to salt than any other plant, then the aquatic submersed group, and finally the small floating plants were the most tolerant.

Based on this info it seems that aquatic plants can tolerate fairly high levels before their dry biomass is reduced. But I wonder what exactly this means though. Dry bio mass? Does that mean that if they started with 100 grams of plant and at the end of the study they were left with 50 grams? If so wouldn't that mean that the plants weren't growing anymore and were already dying at much lower ppm salt? It didn't say 50% reduction in growth rate, it said 50% biomass reduction.

What do you make of this info?
Studies I read - both are accessible for free if you google them:
Ambient Aquatic Life Water Quality Criteria for Chloride.
Effects of Salinity on Growth of Several Aquatic Macrophytes.
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Old 09-15-2013, 07:39 PM   #6 (permalink)
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Default Re: trouble on the farm - help!

Chelated copper is safer for aquatic plants and fish (this is the form that micro fertilizers use like CSM+B), but will kill algae equally as well as non-chellated. Copper becomes much more toxic at low alkalinity - under 50 ppm and becomes much less toxic above 250 ppm. So in the soft water conditions we like to keep in our tank copper becomes more of an issue. Copper will precipitate out and accumulate in the sediments at the bottom of our tanks.
http://edis.ifas.ufl.edu/fa008
Copper toxicity is very fast acting and will start to kill plants and algae within about 48 hours. 1 ppm Copper is used for controlling algae and aquatic plants. 1-5 ppm copper is toxic to fish and livestock. Apparently some aquatic plants can handle more copper.
http://plants.ifas.ufl.edu/manage/co...florida#Copper
The 1 ppm limit is backed up by a number of studies:




1) The IC50 (toxicity level) was recorded at 1.1 ppm Cu.

This study is actually fascinating, because it tested Cu and Zn and then Cu and Zn concentrations together on duckweed's growth. They grew the controls using 0.03 ppm of Cu and 0.08 ppm of Zn.

What they found was that growth yields were reduced from 100% control to 86.5% when Cu was at 0.23 ppm, and for Zn it was reduced from 100% to 93.1% at 0.18 ppm Zn. At 2.03 ppm Cu growth was reduced to 31.2% and for zinc it was reduced to 80.6% at 2.08 ppm.

Based on this study I believe the appropriate copper levels are around 0.03 Cu for good long term growth. Anything over that and you should start to see general decrease in growth rate. For zinc 0.08 seems a safe baseline value to shoot for.
From:
Effects of zinc and copper on growth and metal accumulation in duckweed, Lemna minor, Bulletin of Environmental Contamination and Toxicology
September 1994, Volume 53, Issue 3, pp 442-449
2) This other study looked at the toxicity of copper and other metal ions to Elodea canadiensis (which was chosen because it is considered to be typical of submersed aquatic plants). They measured the concentration of metal that reduced photosynthetic oxygen evolution (photosynthesis) in Elodea. They saw that 0.15 ppm Cu showed a 50% reduction in photosynthesis for Elodea, and at 0.13 ppm Cu for Duckweed. At 0.5 ppm Cu 100% of photosynthesis was inhibited and causes death to the plants over time. Strangely they say that in their study the 50% inhibition of photosynthesis for zinc occurred at 8 ppm zinc.

From:
Toxicity of copper and other metal ions to Elodea canadiensis, B. T. BROWN & B. M. RATT1GAN
CSIRO, Division of Plant Industry, PO Box 1600, Canberra City, ACT, Australia
Judging by the other data on Zn that I've found it seems that high levels of Zn don't harm plants by inhibiting photosynthesis like copper does, but might do so by other means since the first study above shows zinc reduces growth yield (dry weight) at much lower concentrations.

3) Here are some results of copper at various concentrations and duckweed. The control copper level was 0.016 ppm Cu. And you can see a difference between control and 0.2 ppm already.
From:
To duckweeds (Landoltia punctata), nanoparticulate copper oxide is more inhibitory than the soluble copper in the bulk solution (2011)
Jiyan Shi, Aamir D. Abidc, Ian M. Kennedyc, Krassimira R. Hristovaa, Wendy K. Silka,*
4) This study discussed how Zn concentrations of between 0.1 ppm reduced the area of the mitotic cells in Festuca rubra plants, this caused serious root extension and a lower # of cells undergoing mitosis. At 0.2 ppm Zn mitosis was half that of control, and at 0.5 ppm Zn less than 10% of the cells were undergoing mitosis. At 1 ppm Zn no mitosis was observed, and the entire plant's growth rate was greatly slowed.

This study also mentions how Zn seems to interfere with Fe's assimilation into the photosynthetic mechanism at some point leading to iron deficiency symptoms (chlorosis in new growth). It also mentioned how adding extra Ca, chelating agents like EDTA and organics all help reduce Zn toxicity.

Phosphorous deficiency may also enhance the toxicity of Cu.
From: pg 293
Toxicity of heavy metals (Zn, Cu, Cd, Pb) to vascular plants: A literature reviewby P hlsson, Anna-Maj Balsberg Water, Air, and Soil Pollution, ISSN 0049-6979, 10/1989, Volume 47, Issue 3-4, pp. 287 - 319

Ultimately, I feel quite comfortable saying that copper toxicity is 0.10 - 0.15 ppm. Your copper levels should be far below this, 0.03 ppm or lower.

I'd argue that for zinc the toxicity level is somewhere between 0.12-0.40 ppm, so you should maintain a Zn level below 0.08 ppm to be on the safe side.

Just by reading through the journals I get the sense that there are a lot of factors at play that may make micros more or less toxic, so the values recommended in my post are meant to give you a ballpark idea of where your values should be. They are not hard and fast 100% guaranteed in every case. However, you should keep them at or below what I've stated to be on the safe side.

David Kessler heads research and development at Atlantis Hydroponics, he wrote values he believes are safe for aquatic systems. A lot of the values he mentions are similar to the values I've been finding so its nice to be in the general area (though keep in mind this is for hydroponics not aquatics):
http://www.maximumyield.com/inside-m...ation-you-have

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Old 09-15-2013, 11:01 PM   #7 (permalink)
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Default Re: trouble on the farm - help!

Some interesting info about clado and Cu and Zn. It won't grow above 0.08 ppm Zn and above 0.12 ppm Cu.

Cladophora glomerata grows well between 15-25C and its growth limits are 6-30C, at 33C and up the algae starts turning white and dying. Higher light promotes more prolific branching.


Studies on the Growth of Riverian Cladophora in Culture
Archiv fur Mikrobiologie 58, 21-29(1967)
B.A. Whitton

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Old 09-24-2013, 07:25 PM   #8 (permalink)
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Default Re: trouble on the farm - help!

Interesting info I just found:

Sodium, cobalt, silicon and selenium can be beneficial to some plant species but they are not essential or even necessary for growth.



From:
http://www.soils.wisc.edu/~barak/soi...6/listofel.htm
Did a bit more digging and found this info. The concentrations below are suggested concentrations for the substrate. The values are in mg/Kg, which are essentially the same units as mg/L which translates directly into ppm. It seems that this guy suggests about 1000x higher nutrients then we typically dose, so if you simply divide by 1000 you get the values on the right of the graph which I added. These seem to be very close to what we consider appropriate dosing for aquatic plants and furthermore, they are very close to my previous research on what levels of micros are needed and what levels are toxic. I think this is probably the best summary of appropriate concentrations so far.


Quote:
Please note that concentrations, whether in mg/kg (=ppm, parts per million) or Percent (%), are always based on the weight of dry matter, instead of the fresh weight. Fresh weight includes both the weight of the dry matter and the weight of the water in the tissue. Since the percentage of water can vary greatly, by convention, all concentrations of elements are based on dry matter weights.
From:
Typical concentrations sufficient for plant growth. After E. Epstein. 1965. "Mineral metabolism" pp. 438-466. in: Plant Biochemistry (J.Bonner and J.E. Varner, eds.) Academic Press, London.
http://www.soils.wisc.edu/~barak/soi...6/macronut.htm
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Old 10-25-2013, 10:25 AM   #9 (permalink)
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Default Re: trouble on the farm - help!

Two thoughts on how to tackle the CO2 deficiency symptom problem.

1) Probably the easiest thing I can think of to figure out if your tank is CO2 deficient is to add plants that can split the carbonate bond and deposit calcium on their leaves. If you raise the temperature of the water so it is fairly warm then less gas would dissolve in the tank. If you have no circulation in the tank then even less gas would dissolve, and finally plant the tank heavily so the plants use up whatever is in the water. In these conditions if you have a plant that can split the carbonate bond you should start seeing calcium deposited on the leaves as the CO2 is depleted and the plant is forced to switch to carbonate as a CO2 source. Once you see calcium on the leaves you know the tank is definitely CO2 limited and can observe plant deficiency symptoms.

2) The second is more technical and expensive, but I was browsing ebay when I found this Ohmeda 5250 RGM CO2 Monitor which can measure the CO2 with a fairly high degree of accuracy (0.3% variation).

I suppose someone could buy one of these medical devices and directly measure the CO2 coming out of the water and determine the concentration.

Which do you think is more convincing proof of low CO2 or are they both decent proof?

Technical specs:
http://www.dreveterinary.com/veterin...gm-co2-monitor

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Old 10-26-2013, 11:33 PM   #10 (permalink)
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Default Re: trouble on the farm - help!

I just found some interesting tests which might help us get more accurate nutrient readings. The phosphate and iron digital meters are within most people's price range while the nitrate meter is a little more pricey. If the tests are as accurate as they claim then they might be worth looking into. The reviews on them seem overwhelmingly positive, so perhaps they are worth it?

Phosphate (HI 713 Checker HC Handheld Photometer)
$45.99 from Amazon (it requires reagents which cost $7 for 25 tests)
http://www.amazon.com/Hanna-Instrume...d_sbs_indust_1



Quote:
The HI 713 Checker HC Handheld Photometer for Phosphate is a portable tester for measuring orthophosphates in natural, waste, and drinking waters.

The HI 713 bridges the gap between less accurate chemical test kits, and expensive professional test instrumentation. The HI 713 features a resolution of 0.01 ppm (250 points) and 4% + or - 0.04 accuracy of reading. To use, zero the instrument with your water sample, then add the reagent. Place the vial into the checker, press the button and read the results within seconds.

The HI 713 operates in temperatures from 0 to 50 degrees C (32 to 122 degrees F)/RH max 95% with a range of 0.00 to 2.50 ppm (mg/L) with precision + or - 0.04 ppm (mg/L) + or - 4% of reading at 25 degrees C. The device operates on one 1.5V AAA battery, with an auto-off function that shuts off the device after two minutes of non-use. Dimensions are 81.5 x 61 x 37.5 mm (3.2 x 2.4 x 1.5”) and weight is 64 g (2.25 oz.).

Orthophosphates are present in water from the natural weathering of mineral deposits, agricultural runoff, untreated sewage, fertilizers and, as an addition to drinking water, to inhibit corrosion. Phosphate photometers are used by researchers, manufacturers, and individuals to measure phosphate levels in the environment, and in the home.

Hanna Instruments manufactures a wide variety of analytical instrumentation, including pH meters, multi-parameter meters, electrodes, chemical reagents, and buffer solutions. Founded in 1978, Hanna is headquartered in Woonsocket, RI, with subsidiaries in 32 countries. Hanna Instruments holds many firsts in the field of analytical instrumentation, including a pH electrode with a built-in temperature sensor, an electronic pocket-sized pH tester, and a replaceable electrode pH pocket tester. To ensure the quality of its products, Hanna is a vertically integrated manufacturer and does not subcontract any part of its manufacturing.
Iron (Hanna Instruments HI 721 Checker HC Handheld Photometer)
$52.41 from amazon (also needs reagens which are about $7 for 25 tests)
http://www.amazon.com/Hanna-Instrume..._rhf_ee_s_cp_4



Quote:
The Hanna Instruments HI 721 Checker HC Handheld Photometer is a portable tester for monitoring iron levels .

The HI 721 bridges the gap between less accurate chemical test kits, and expensive professional test instrumentation. The HI 721 operates using a silicon photocell light detector, and has an accuracy of + or - 0.04 ppm or + or - 2% of reading at 25 degrees C, using an adaptation of Standard Method 3500-Fe B. To use, zero the instrument with your water sample, then add the reagent. Place the vial into the checker, press the button, and read the results within seconds. The reaction between the reagent and iron within the water causes an orange tint in the sample.

The HI 721 operates in temperatures from 0 to 50 degrees C (32 to 122 degrees F)/RH max 95% non-condensing with a range of 0.00 to 5.00 ppm (mg/L). The device operates on one 1.5 V AAA battery, with an auto-off function that shuts off the device after three minutes of non-use. Dimensions are 81.5 x 61 x 37.5 mm (3.2 x 2.4 x 1.5”) and weight is 64 g (2.25 oz.).

Colorimeters are used to determine the concentration of a substance in a solution by measuring the amount of light transmitted through the sample, often after adding a reagent. Iron colorimeters are used in water and soil analysis to monitor iron in ground water and industrial, agricultural, and mining run-off.

Hanna Instruments manufactures a wide variety of analytical instrumentation, including pH meters, multi-parameter meters, electrodes, chemical reagents and buffer solutions. Founded in 1978, Hanna is headquartered in Woonsocket, RI, with subsidiaries in 32 countries. Hanna Instruments holds many firsts in the field of analytical instrumentation, including a pH electrode with a built-in temperature sensor, an electronic pocket-sized pH tester, and a replaceable electrode pH pocket tester. To ensure the quality of their products, Hanna is a vertically integrated manufacturer and does not subcontract any part of its manufacturing.
Nitrates (Hanna Instruments HI 96728 LR Nitrate Portable Photometer)
$185.69 (needs reagents as well which are inexpensive)
http://www.amazon.com/Hanna-Instrume...ble+Photometer



Quote:
Nitrates are present in nature as a result of decomposition of organic microorganisms or due to their use as fertilizers. Nitrates reduce to nitrites, which in turn easily combine to form substances dangerous to man. A maximum level of 45 milligrams per liter (ppm) is established as a worldwide guideline for nitrate concentration in water. In Europe, the maximum consented level of nitrates in potable water is 50.0 milligrams per liter (ppm), while in the USA the EPA has established a guideline for the maximum level of nitrate (nitrogen) of 10 milligrams per liter (NO-3-N), which corresponds to 45.0 milligrams per liter of nitrates. The HI96728 meter measures the nitrate content in water and wastewater. This meter uses an exclusive positive-locking system to ensure that the cuvette is in the same place every time it is placed into the measurement cell. HI96728 is supplied with 2 sample cuvettes with caps, 9V battery and instruction manual. 0.0 - 30.0 milligrams per liter pH range. 0.1 milligrams per liter pH resolution. +/-0.5 milligrams per liter +/-10 percent of reading at 25 degree C accuracy. Tungsten lamp. Silicon photocell with narrow band interference filter at 525nm light detector. 0 - 50 degree C (32 - 122 degree F); RH maximum 95 percent non-condensing environment. Auto-off: after 10 minutes of non-use in measurement mode, after 1 hour of non-use in calibration mode with last reading reminder. Measures 7.6" length by 4.1" width by 2.7" height. Adaptation of the photometric method.
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