Water Science - Science topic

KC Denmark A/S is a global supplier of equipment. They have a range of Manta nets complete with accessories such as digital flow meters. I have just received a quotation from then.

You may consider visiting their website.

Regards

Dear E. F. Latif ,

They have journals without APC for authors independent on whether your university or institution has made a “subscribe open contribution” or not. They state “The following journals operate under a Subscribe to Open (S2O) model. Each year, institutions, organisations and individuals contribute to our annual Open Access goal by 'subscribing' to individual journals or to the entire journal package. These S2O subscriptions allow us to waive author fees (APCs) in these journals.

To help us sustain this model and ensure that our journals can remain Open Access, individual authors can choose to support the model by contributing the cost of what would have been the journal’s APC towards an individual S2O subscription. For more information on this, contact subscriptions@iwap.co.uk” (so they ask individual authors for a voluntary contribution, which you obviously can decline).

So, the journal “Water Science and Technology” is a journal without APC, see https://iwaponline.com/Open_Access/pages/publication_fees This is thanks to what they call “Open Access through Subscribe2Open”. Personally, I never heard of this, but if I understand it correctly it is possible thanks to institutions who “subscribe” to their journals. This way they can waive the APC for authors who publish in one of their journals under this construction.

We must wait and see if this is a sustainable way of publishing open access.

By the way, it looks like a pretty good and solid journal.

Best regards.

That is a good question.

There is no denying the fact that all micro organisms including viruses survive in an aquatic environment. COVID-19 is no exception. From there it can can be transmitted to humans by various means!!

Thank you so much Bayan Hussien

Dear Alexandra

1- The initial freezing point of food was estimated from the mole fractions of individual solutes in the aqueous phase such as ions, sugars, acids and alcohol.

2- Moreover, every kind of foodstuff had on your own component that is different with another varieties.

3- foods are full of Vitamins, minsrals, soluble and insoluble fiber withe diffrent vapor and freezing point temperature.

Every part of these component had specific freezing point.

First of all, It depends on the type of adsorbent material that you used.

In heavy metal removal processes, desorption/regeneration of adsorbents is one of the essential aspects as it controls the economy of water treatment technology.

For effective regeneration of adsorbents and metal recovery, acids (such as HCl, H₂SO₄, HNO₃, HCOOH and CH₃COOH), alkalis (such as NaOH, NaHCO₃, Na₂

CO₃, KOH and K₂CO₃), salts (such as NaCl, KCl, (NH₄)₂SO₄, CaCl₂2H₂O, NH₄NO₃, KNO₃ and C₆H₅Na₃O₇2H₂O), deionized water, chelating agents and buffer solutions (such as bicarbonate, phosphate and tris) were used in various studies.

From the previous answers, a lot has been said regarding the potentials usefulness of dams, which is really good. I would like to adress in this answer, for the sake of discussion, some key points regarding why dams can be problematic to us.

It appears that during the past decades, wild river streams (ones that run free from headwaters to confluence) have nearly been wiped and then replaced by river dams. Fact is, dams disrupt natural systems and subsequently thwart the work of rivers. They block fish runs, seasonal flood patterns, affecting redistribution of nutrients (like marine nitrogen delivered by salmon to feed the inlands).

Dams encourage unsustainable growth, displace people, often indigenous people

Very often, dams are built through grants of institutions and rarely benefit the local people. Most of the generated hydropower (if any) is delivered to big cities, not the rural villages displaced by the dams.

Even from a design perspective, it appears dams are made to fail. A huge reservoir surfaces mean terrible annual evaporation losses. Silting is unavoidable. Even the largest reservoirs silt up. When they collapse, it is nightmarish.

Some researchers point out dams are not the solution to our energy crisis. Solar and wind can provide far more reliable, long-term energy than hydropower with far fewer environmental costs.

Dr. Namayandeh, a paper from the 1990s called "Beyond BACI: the detection of environmental impacts on populations in the real, but variable, world" by Underwood started quite a conversation in the literature. Good place to start.

Do a targeted search within work by Iris Möller https://www.geog.cam.ac.uk/people/moeller because she has published a lot on this topic.

Decentralizing the food system will be unavoidable because the large scale agroindustry that supports monoculture will not be able to survive the losses of water, soil, yields. Already, food production and security on the global scale is insured by small, family farmers. These produce quality foods on very small land surfaces. Their garden/farms are biologically diverse and integrate also medicinal plants, herbs as they learned from their ancestors. Conserving this knowledge is very important because our centralized food system and agriculture have become very homogeneous. Consequently, preserving seed germplasm and breeds of domestic animals is now becoming more and more important to counteract the whims of unpredictable weather patterns. Therefore, agroecology, which is the science of sustainable food systems will gain more traction in the restoration/regenerative type of agriculture that all countries in the world need to insure food security despite global climate change.

There are studies like the below one that examine correlation between soil properties and GHG:

Hi Dear Mahin

Do you want to use GIS for calculating SPI due to input format of files?

I mean that Are your input files in nc4 or nc format?

Regards,

Nasrin

Good day

You can download the reference blow.

Sincerely

Please spell out the themes....

Dear N B Narasimha Prasad,  Thank you for clarification of your approach to water quality issues in agriculture. Organic as you realize is something that can or cannot help in water quality issues depending on how it is done.

In terms of organic agriculture, the use of composting can be highly beneficial to water quality issues and raw manures can be problematic to fugitive nutrient affecting water quality.

I imagine that much of the recommendation for Indian farmers is done on recommendations which are not always supported by soil and tissue analysis.

When an analysis is available there is also an issue that most farmers have little background in interpreting them and may not have the necessary equipment to optimize their implementation.

. Thank you for your much-needed efforts to guide and encourage farmers on the subcontinent of India. 

I agree with answer Biswas above:

Reverse Osmosis for reducing effluent quantity for evaporation, reuse of the

recovered RO permeate in tanneries’ process, evaporation of the RO concentrate

in evaporator, reuse of the recovered condensate in tanneries process, recovery of

crystallised salt, recycle of un-crystallised salt for evaporation with RO

concentrate, and storage of the recovered salt in safe impervious covered storage facility. For details you may visit http://www.iwma.in/Guidelines%20on%20ZLD.pdf

Thanks for your cooperation. By the way, Oxygen supply was normal and yes you are right ..there might be another factors regarding Tilapia mortality during LD 50 experiment against s. agalactiae.  .

Bioturbation is the reworking and mixing of soil/sediment at

the sediment–water interface by soil living macroinvertebrates mostly and benthic macroinvertebrates and fish, accomplished collectively by burrowing,

feeding, irrigation, resuspension, secretion, excretion and

transporting activities of organisms, which alter the structure and properties of the soil/sediment and thereby influence diffusive

and/or advective transport of both solutes and particulate matters

(Koretsky et al., 2002; De Haas et al., 2005; Janssen et al.,

2005;Meysmanet al., 2006).

To get an idea you may read our paper published in Ecological Engineering: 35 (2009) 1444–1453 (Bioturbation potential of chironomid larvae for the sediment–waterphosphorus exchange in simulated pond systems of varied nutrient enrichment).

Salinity and Electrical conductivity are interrelated. Temperature may be indirectly related. But Dissoved Oxygen is a different parameter may not much related to salinity/EC/Temperature of water.

salinity is measured by electrical conductivity (EC) using a conductivity bridge. The total salt content of a soil can be estimated from this measurement. A more precise method involves evaporation of the aqueous extract and weighing the residue (total dissolved solids, TDS).

EC(dS/m)*640=TDS(mg/l) (Accuracy -+10)

in water the TSS is a well-mixed sample is filtered through a weighed standard glass-fiber filteand the residue retained on the filter is dried to a constant weight at 103 to 105°C. The increase in weight of the filter represents the total suspended solids.  To obtain an estimate of total suspended solids, calculate the difference between total dissolved solids and total solids.

while ‘Dissolved solids’’ is the portion of solids that passes through a filter of 2.0 µm (or smaller) nominal pore size under specified conditions. ‘‘Suspended solids’’ is the portion retained on the filter.

Sum concentrations (in milligrams per liter) of constituents to calculate the total dissolved solids are as follows: Total dissolved solids = 0.6 (alkalinity*#(2)) + Na+ + K+ + Ca2+ + Mg2+ + Cl−+ SO42− + SiO32− + NO3− + F−

Both the anion and cation sums should be 1/100 of the measured EC value. If either of the two sums does not meet this criterion, that sum is suspect; reanalyze the sample. The acceptable criteria are as follows: 100 × anion (or cation) sum, meq/L = (0.9–1.1) EC

If the ratio of calculated TDS to conductivity falls below 0.55, the lower ion sum is suspect; reanalyze it. If the ratio is above 0.7, the higher ion sum is suspect; reanalyze it. If reanalysis causes no change in the lower ion sum, an unmeasured constituent, such as ammonia or nitrite, may be present at a significant concentration. If poorly dissociated calcium and sulfate ions are present, the TDS may be as high as 0.8 times the EC. The acceptable criterion is as follows: calculated TDS/conductivity = 0.55–0.7

The acceptable criteria for this ratio are from 0.55 to 0.7. If the ratio of TDS to EC is outside these limits, measured TDS or measured conductivity is suspect; reanalyze.

The most important factor that affects level of production of the solar still is the amount of solar radiation on the glass cover, called irradiance. Not all of the solar energy that contacts the glass will actually be used for evaporation of the water in the basin because it gets reflected and absorbed by anything it passes through. An energy flow diagram that shows that part of the sunlight is reflected and absorbed by the glass, the water, and the basin surface. If the still is not perfectly sealed and insulated there will be heat losses to the surroundings.

I made (in attachment) easy to use excel sheet. It calculates potential evapotranspiration (PET) and basic water balance components based on Thornthwaite 1948 version. Try it. 

Dear Mr. Omonova,

A quick way of estimating Salinity is to use a conductivity meter and read off the electrical conductivity (EC). The idea being that a salty solution, because it is full of charged particles will conduct electricity. Most conductivity meters give readings in micro Siemens per cm (µS/cm). Most fresh (drinking) water will have less than 100 µS/cm conductivity (EC). 

Relation between conductivity (EC) and TDS: TDS is more precisely measured in the laboratory by evaporating a measured sample gently to dryness then calculating how much solids are left. Conductivity is usually given as µS/cm which measures the ability of the sample to conduct an electric current.

There is no exact but an approximate relationship between conductivity as µS/cm and TDS as ppm. In water with a higher proportion of sodium chloride to get TDS in ppm just multiply the EC µS/cm reading by 0.5. For most other water (like in hydroponics solutions) use a factor of 0.67 or 0.7 instead.

Relation between EC and chloride concentration: The electrical conductivity [EC] and chloride ion concentration values of ground water samples (in Mexico) were found to be related by the linear equation: [Cl-] = 4.928 EC (R> 0.94). [Reference: Cien. Inv. Agr. 39(1):229-239. 2012].

Hope the information is interesting and useful to you.

 This study aimed to evaluate the behaviour of two horizontal subsurface flow constructed wetland units regarding solids build up and clogging of the filter medium. In order to analyse the causes of this process, which is considered the major operational problem of constructed wetlands, studies were carried out to characterize accumulated solids and hydraulic conductivity at specific points of the beds of two wetlands (planted with Typha latifolia and unplanted units) receiving effluent from an upflow anaerobic sludge blanket reactor treating sanitary sewage (population equivalent of 50 inhabitants each unit). 

Hi Javad

see to be sites

PowerPoint in this case. I hope helpful

easypaper.parsiblog.com/...

Dear Vahid, this is an idea that was proposed by Anders Worman in a paper in WRR. I translate it in a much simpler fashion that maybe can fit your case. Let us suppose that we are at steady state. If you have a digital elevation model of the watershed, and if you can estimate the permeability of the soil and its thickness on the hillslope, you can compute the soil gradient from the dem and assume that it is also the hydraulic gradient in the subsurface flow on the hillslope. Then using the Darcy's law you can sum the contribution from the different hillslope along each steepest gradient direction and obtain the overall subsurface contribution.  

Possibly this is not the simplest way but it captures a relevant feature that is the hydraulic gradient, whose proxy is here the slope gradient. I hope this can be of help

Marco 

It is actually pretty complicated to determine the carbon footprint of a crop because of all the energy inputs that go into the growing and harvesting process.  Everything from preparing the soil, fertilizer, herbicide and/or insecticide, or even release of insectivores to reducing spraying insecticides and then harvest.  The biggest contribution to the carbon footprint could be transportation, depending on how far the plant is shipped.  I would focus on a "cost per mile" calculation and assume most of the rest of the carbon footprint is about equal no matter where it is grown.

i hope there may be a chances of contamination while sterilization it may be because of spore forming bacteria

I would stick with standard methods.  If I were to vary or customize, I would have analytical chemist review.  Yes, normally a preservative (anesthetic) might be added to both sample and blank, but if it affects results, that is a potential source of error and I would check on alternative preservative methods if they exist, or perhaps rerun duplicate samples over a week or two to see how sample changes.  I assume you have seen the Standard Methods Manual for Water and Wastewater, but if not it may address your question.  If you purchase reagents from Hach Chemical Company, they may have a technical section to help you.

Please check the following link and PDF attachment also.

From water quality data , the water quality index can be evaluated and for this published work is available along with softwares.

That depends on your downstream analysis.  Are you wishing to preserve epigenetic marks?  prevent fragmentation?  

Why are you wanting to preserve the cells anyway?  Why not just do the extraction now and store the DNA instead?

4 degrees is no good.  you will need to drop to -20 at the minimum and possibly -80 for longer term, but that will begin begin to show fragmenting of the cell DNA if you store it there long enough.  Again, it depends on the application and if you care, the fragmentation is minor.

Prof. Saad Alasfoor,

Yes! it is now possible using Double Acting Hydraulic Ram Pump see the video of how it works. It uses minimal power to extract water from around 200ft deep water well. We have prepared a prototype of single acting ram pump as you see here and have started working on Double acting soon within 2 months from this post just looking for some funding.

ph must be less than 5.5

TDS must be less than 300

room temperature is prefferable

Thanks Murat Ay.

In fact, I tested all the methods included in FL Toolbox, and the better was LOM.

The Relationship between electrical conductivity and the concentration of dissolved ions is a function of the major ions. If you want to prepare a solution of Nacl, then you should use the specific relation of Ec versus TDS for chlorides, and you can find it in the figure 11, page 68 of the USGS Water Supply Paper 2254 at :

Based on this graph for a 2 dS/m (2000 micro S/Cm in the figure 11) you should have a solution of water and NaCl with Cl concentartion of around 410 mg/lit (the exact value of concentration should be computed on the curve for chloride) . It means that you need around 675 mg of NaCl solved in 1 liter of distilled water. 

by the way, how much water do you have used for solving the 1.17 Kg of salt?

Total suspended solids (TSS) can be accurately measured by filtration through  0.45 Mili micron membrane fibre.. Detail about analysis is well describable in published literatures. 

For the measurement of COD in sea water kindly refer :

Liu Li, and others 2005, Chemical oxygen demand of  seawater determined with a microwave heating method Journal of ocean university of China, volume 4, issue 2, page 152-156.

This is on line available.

Hi Javad,

Socio-economic drought occurs when the demand for an economic goods exceeds supply as a result of a weather related deficit in water supply. Here are some useful links and attachments on socio-economic drought.

Good Luck

Arsenic can also be released into groundwater through 'reductive release'... it just depends on what form the arsenic is within the groundwater.

Dear Sir 

Please use the following formula for converting watt ( energy ) in to depth in mm of water 

1 Watt /m2 = 0.0864 MJ /m2/day

1 MJ /m2/day  =0.408 mm /day .

So please  follow the above  calculation  procedure. Refer FAO Irrigation and Drainage 56 , page no.212.

Have you ever heard the phrase Time and Temperature in regards to chemical reactions? The warmer the temp the faster the reaction. Same applies to floor cleaning. Warmer water and cleaners will just work faster and arguably better in dissolving grease, oils, and caked on crud. 

I agree with Michael J Lynch and would also say that the same would apply to countries within the EU.This question can only be answered by reference to a particular jurisdiction.

In the UK the answer will also be dependent on the nature of the complaint. For food complaints either the trading standards department or environmental health departments will deal with it but which department depends on the nature of the complaint. Note that these departments will normally not be part of the same local authority as, except for cities and other "unitary authorities" , trading standards are based in county councils but environmental health are in district councils. It is very complex.

Even worse is the situation with respect to environmental complaints. There is a central Environment Agency in England and Wales but Scotland and Northern Ireland have their own central regulator and the Welsh EA is devolved to some extent.These bodies deal with permitting of major industrial processes and theoretically should deal with complaints about the processes they oversee. In practice many such complaints along with complaints about odor, noise etc from smaller processes and from domestic premises will be dealt with by the environmental health department in the district council, at least in the first instance.

Environmental health deal with statutory nuisances but for proceses holding any environmental permit they may not apply statutory nuisance laws without the permission of central government.

The local authority also issues permits for some industrial processes either for air pollution issues only (part B  proceses) and some for all aspects of environmental releases (part A2). Again it is very complex and cannot really be dealt with in a question such as this. If you are interested in following this up further you need to read a good basic environmental law textbook based on UK law. Try Ball and Bell.

Hello Mahin.  What about this set of list?  The first one uses SPI and GIS.

Regards!

You can get some idea from this document I prepared for Sri Lanka

Thank you

There are many regression algorithms that can be used in your case such as multiple linear regression, generalized linear modeling, generalized additive modeling, etc.

You can implement these methods easily in R. through stats, glm, gam packages.

The most accurate algorithm is generalized additive modeling that leads to more accurate prediction than other methods.

Thank you very much for all the suggestions, we will try out the best option for our samples.

Dear Dr. Sumanth

This book is about medicinal plants and may be useful for you. Author : Dr. Shafik Balba.

Dear Mario and Alastair,

Thank you for your time and consideration. 

C (12 g/mol) + O₂  (32 g/mol) --> CO₂

With a BOD of 30,000 mg/L, you must have a minimum TOC of 11,250 mg/L which is impossible with a TDS of 2,000 mg/L.

Hi Sudipta Kumar Hore

Please find the attachment. Hope it will be helpful for you,

Moreover, it is necessary  to have some basic knowledge about MODIS products, MODIS Processing Levels, MODIS Temporal Resolution, MODIS Spatial Resolution etc.

thanks FC Prinsloo.

I am researching about leak detection in urban water distribution system using calibration nodal pressure, for this reason I need manometric data in some node of water network.

Hi

Please see these papers:

See if Figure 5 may possibly help

file:///C:/Users/Subhash/Downloads/Impact%20of%20recharge%20from%20a%20check%20dam%20on%20groundwater%20quality.pdf

When one raise water quality as an issue, it should start by asking "water for what use", because the suitability on the basis of quality will depend on the use the water is intended for.  Obviously, for drinking purposes, WHO's guideline must be adhered to, and for irrigation purposes, FAO's guideline need to be adhered to.  In UAE, drinking water is supplied from desalination, and irrigation water comes from sewage plants after treating or from groundwater.  Still, a lot of treated water is discharged to the sea, which is perfectly suited for irrigation.  So, what is required in UAE is a management strategy to maximise the use of treated sewage for irrigation, and minimise groundwater pumping.  I am attaching a paper prepared for a conference, but not presented.  This may give you some ideas about what can be done to minimise discharge of good quality treated sewage water to the sea.

Hi Elias, are you generating Thiessen polygons from the 19 stations, and the ground data from the NCDC stations ? If the 19 stations are reliable, that might be adequate, or would you wish for greater spatial representation ?  If so, you could create another Thiessen polygon set from the NCDC stations for the same time period, and compare the two spatial rainfall layers. If you are interested,  I used a MATLAB function to generate Thiessen/Voronoi polygons for rainfall in the pub below:

Elias, I would suggest that the answer depends on the question you are trying to answer. For example, sampling at the Beauchamp location with the same methods Beauchamp used would allow you to make direct comparisons to determine if changes had occurred over time - regardless of whether or not that location is representative of the entire lake. But if you do not intend to make any comparisons to Beauchamp's study or results, you are free to see if there would be a more "representative" sampling location. Ideally you should sample more than one location to be able to capture the spatial variability in the lake. But if you're limited to one location, you should first sample a number of randomly placed locations and then find which of those is closest to the average of all of them in the measures you're interested in.

Dear Luis,

the composition of the best synthetic NOM stream simulating real surface waters is extremely dependent on (i) which water resource you are considering, (ii) which season you want to simulate (ii) what type of process should treat your NOM.

Usually, authors consider a mix of standard humic, fulvic and sometimes tannic acids originating from terrestrial or aquatic bodies (lake, rivers etc.). Generally, the organic matter originating from terrestrial sources makes up an important fraction of the NOM in small water bodies.

An example of practical application for nanotube adsorption:

More general references:

1. http://mounier.univ-tln.fr/rcmo/php_biblio/PDF/4884.pdf

2. vanLoon G. W. and Duffy S. J., (2005). Environmental Chemistry – A global Perspective, New York, Chapter 12, pp. 254-264, Oxford University Press, Second Edition.

Hope it helps,

Pierre

Check my home page or my website www.moelbermann.com under publications. I have three publications on CH4 and CO2 emissions from flooded reservoirs using soil with different C stocks. Note that these papers are based on soil incubations. My colleague Dr. Sherry Schiff at the University of Waterloo (Department of Earth and Environmental Sciences) and her research team evaluated CO2 and CH4 fluxes from reservoirs. I am not sure however, if these were from sediment or the water surface, or both. You would have to check her website for publications (her former PhD student J. Venkiteswaran was working on this) or contact her. Also, in the past there has not been much concern with N2O emissions from reservoirs (at least 10+ years ago when I was involved in this work in northern Ontario, Canada -- Boreal forest). However, I recently read that there are now some potential N2O concerns. Hope this helps.

I do not know the area you work. But if your area is analytical chemistry as mine, you should use the same solvent you use to inject to validate and inject your samples. Thus, the results will be more reliable.

For GCMS ACN and EtAc work perfectly, in my case, I prefer EtAc, but all depends on your compounds and the matrix you work with.

For surface irrigation you may take the help of SURDEV Software

The first question or assumption is that you are going to use gravimetric determination of water.

- Presence of colloidal material that can hold water until higher temperatures therefore, some problems can arrive from the uncertainties of equilibrium time

- Presence of organic material that can volatilize and oxidize (organic soils)

if you plan use microwaves that should keep attention in soils with mica,montmorillonite that are not reliable.

if you have a homogeneous soil not with the characteristics listed than a small sample (20 - 50  g) will give satisfactory results

Some discussion about it  was reviewed here

TEIXEIRA, G. W.; SINCLAIR, F. L.; HUWE, B.; SCHORTH, G. Soil water. In: SCHORTH, G. e SINCLAIR, F. L. (Ed.). Trees, crops and soil fertility: concepts and research methods. Oxon: CABI, 2003. cap. 234, p.209.

Wow, this is really a wide topic and not that simple. My remark to the first answer, see the following literature: WEIHERMÜLLER, L., et al. In situ soil water extraction: A review. Journal of environmental quality, 2007, 36. Jg., Nr. 6, S. 1735-1748.

This is a good question, and one that comes up often when using indicators based on optical properties.  High levels of protein-like fluorescence (perhaps from the manure/associated microbial activity?) can sometimes interfere with HIX because of a corresponding peak in the 'L' region.  Similar interferences can occur with SUVA.  It is a good idea to look at the full emission spectrum at Ex=254 nm to see whether this is the case.  Zsolnay (2003) "Dissolved organic matter: artefacts, definitions,

and functions" also outlies some other potential difficulties when using HIX.

Yes, in Australia there is very strict water allocation systems in place, significant surface water is allocated for food production (agricultural activities) in the Murray Darling Basin area (main food bowl region), however the water allocation follows a balance approach for beneficial water usages as follows (a) irrigation-major allocation (b) town supply (c) domestic use (d) environmental flows (environmental water for smooth functioning of ecosystems, in recent time government is buying water from irrigators to increase environmental flows) (f) others –Industry. Though there are annual (predetermined allocation based on the forecasted volume of water expected to be available) however, resources availability are monitored every fortnight and adjustments are made accordingly. There are major water savings programmes via improvement of irrigation infrastructure and modernization (improved metering, computer aided water supply, irrigation channel remediation (plastic and clay lining), pipelining, automatic regulator, upgrading dethridge wheel, reuse and recycle of water, rainwater harvesting.

Hi Qinghui,

Indeed when algae grow exponentially an exponential equation (or even better a logarithmic one) will evidently give a good prognosis of the number of algal cells in suspension, on the condition that you know the number of algal cells at the start of the growth phase.

When algae are not in exponential growth, but in stationary or decline (dying off) stage, growth rate actually cannot be calculated at all. By definition growth rate can only be calculated when there is growth. In stationary or declining algal populations, there is no growth, hence do not try to calculate growth rate,it won't work. You can however calculate the rate of decline.

But prime in this story is that you will have to determine the number of (in vivo) algal cells in suspension, whatever you want to calculate or model. A simple way to perform this is to use a spectrophotometer at the wavelengths of maximal chlorophyll absorption.The higher the absorption, the more algal cells, according to the Lambert-Beer relationship.

Hence,make a dilution series of algal suspensions, starting from a know cell number in suspension and establish a calibration curve which gives you suspended algal cell numbers in function of chlorophyll absorption (in vivo).

This will allow you to validate your models of growth and decay,with pretty good accuracy.

Without measuring the algal cell numbers, your model(s) will remain very approximate as well as your estimations of growth or decay rate.

Hope this helps a bit.

Cheers,

Frank

a density of liquid water is 0.997 g/mL at 25 C, and 0.958 g/mL at 100 C. Thus, if you start from 1000 mL (0.997 kg) , you will end up with 0.997 kg of water with volume about 1040 mL at 100 C.

300 C is close the supercritical state of water (374 C), you will need a pressure about 200 atm to keep water in liquid state. You can find yourself the density of water at this T

Hej. Lianna. The below mentioned article was successful with my friend who worked with anaerobic DNA extraction from hot springs. I hope this paper would be helpful for you. title. A procedure for the isolation of Deoxribonucleiacid from Microorganisms. J. Murmur.

Different soil-to-water dilutions would not yield a linear relationship (you're still working with 2 different phases). That is because different ions will be selectively retained by the soil surface differently depending on their concentrations in the solution phase. For a negatively charged surface, such as most soils, divalent cations are more strongly retained than mono-valent cations, upon dilution. You can find detailed info. about cation exchange reactions and selectivity in many soil chemistry textbooks.

By the way, if you are only interested in EC measurements, you can make a saturated soil paste and use a portable EC meter, which costs about $50, to read EC easily and quickly.

Hope this helps, NVH.

These include Persistent organic pollutants (POPs), they are toxic chemicals that adversely affect human health and the environment around the world. Because they can be transported by wind and water, most POPs generated in one country can and do affect people and wildlife far from where they are used and released. They persist for long periods of time in the environment and can accumulate and pass from one species to the next through the food chain.Many people are familiar with some of the most well-known POPs, such as PCBs, DDT, and dioxins. POPs include a range of substances that include:

Intentionally produced chemicals currently or once used in agriculture, disease control, manufacturing, or industrial processes. Examples include PCBs, which have been useful in a variety of industrial applications (e.g., in electrical transformers and large capacitors, as hydraulic and heat exchange fluids, and as additives to paints and lubricants) and DDT, which is still used to control mosquitoes that carry malaria in some parts of the world.

Unintentionally produced chemicals, such as dioxins, that result from some industrial processes and from combustion (for example, municipal and medical waste incineration and backyard burning of trash).

POPs work their way through the food chain by accumulating in the body fat of living organisms and becoming more concentrated as they move from one creature to another. This process is known as "biomagnification." When contaminants found in small amounts at the bottom of the food chain biomagnify, they can pose a significant hazard to predators that feed at the top of the food chain. This means that even small releases of POPs can have significant impacts.

Dear Ahmed.

Your question is usually asked by people more attentive and generally the response is inadequately informed. If you want to know the reason for the difference in boundaries should start studying concepts in hydrodynamic stability.

Not suggest beginning your study is made in classic books of stability theory, as Chandrasekhar or Drazin, these books are good for those who already know theory of stability and needs answer a question more complicated. The reason is that we do not advise to questions like yours is best to get the concept of stability from the point of view of Lyapounov (do not look directly read the book Lyapounov!).

The concept of stability from the point of view of Lyapounov is purely energetic, in which a stable flow is introduced a perturbation, with an energy E.

If the variation of this energy dE / dt <0 and it decreases monotonously to zero we say that the flow is stable globally monotonous.

If dE / dt <0 and decreases to zero, but no in a way monotonous, it is asymptotically stable on average.

If dE / dt> or <0, depending on the intensity of energy E, introduced in the system, it is conditionally stable.

If, for dE / dt <0, only for infinitesimal disturbances he presents linear instability, and finally,

if for any E, dE / dt> 0 it is unstable.

Now, for any of the intervals has two values of control, a control value R (which to some extent could be considered Reynolds), which defines, roughly, the transition boundary between different regions of instability. However, only for the first two conditions this value may be regarded as a unique value, as in the other two R is a function of E.

Now it has another problem Reynolds should not really be expressed by VD / nu, but the product of this ratio for a further two linear dimensions that are dropped in the dimensional analysis , ie the correct definition of the Reynolds be (VD / nu) * (D / L)² (read Schilichiting Chapter VI c).

From these considerations it can be said:

There are a number of critical control R where the flow is always stable, it would be in the case of circular cylindrical conduits (2100) or open channels (500) (do not forget the relationship dimensions that represent the shape of the flow), above these will continue in laminar flow as the energy of the disturbance inserted.

Conclusions:

1) The books are all right, except that the authors adopt simplifications, preventing better understanding of the topic.

2) Teachers and authors know this, but 99% of students and readers prefer two control numbers without further explanation. I.e. prefer the fast track!

Chloral hydrate is also known as trichloroacetaldehyde monohydrate and 2,2,2-trichloro-1,1-ethanediol. Chloral hydrate and its metabolites, trichloroacetic acid and dichloroacetic acid, are formed as by-products when water is disinfected with chlorine. Additional chloral hydrate can be formed if water containing chlorine is mixed with food containing humic and fulvic acids (Wu et al., 1998). Humic and fulvic acids are organic precursor molecules. The factors which influence Chloral hydrate formation include: Concentration of disinfectant used, concentrations of organic matter and other Disinfection by-products (DBP) precursors present in water presented for chemical disinfection, temperature, pH, contact time, length of the distribution network.

Thanks for ur answers.......

Is there any chemical method available for acetate estimation..... Because we don't have these instruments