The authors would like to thank the Sandtown Landfill in Felton, DE for sharing their knowledge and leachate.

1. System Setup
Note: A &#39;paired system&#39; refers to one aquarium tank and one raceway pond, run in parallel.
<ol>
	<li>For one paired system, use one 100 L aquaria tanks (AT), with an overhead mixer for the small-scale vessel, and one 1,000 L raceway pond (RWP), with a paddle wheel mixer for the large-scale vessel. Vessels used in this system are pictured in Figure 1.</li>
	<li>Inoculate all vessels with the same algae culture. Use a high density of the inoculation, resulting in a final density of no less than 0.1 g/L once diluted to the full volume in the tank or pond 10. It may take a considerable amount of time (weeks to months) to grow enough algae for this step.</li>
	<li>Use untreated landfill leachate as the nutrient source. Use leachate taken from a landfill that accepts mostly domestic waste and has low levels of toxins. Composition analysis for the leachate should be available from the landfill. The amount of leachate used in each tank or pond can vary depending on the strength of the wastewater, but final ammonia concentrations should measure 5-75 mg NH3-N/L.</li>
	<li>Start the 100 L aquaria tank with a 60 L working volume, and the raceway pond with a 600 L working volume. This study started with approximately 1 L leachate in 59 L of water in the aquaria tank, and 10 L leachate in 590 L of water in the raceway pond. Increase the concentration of leachate used over the course of this study.</li>
</ol>
<img alt="Figure 1" src="/files/ftp_upload/55256/55256fig1.jpg" /> 
Figure 1. Examples of an aquarium tank and raceway pond. An example of an aquarium tank (A) and raceway pond (B) are shown. <a href="http://cloudfront.jove.com/files/ftp_upload/55256/55256fig1large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
2. Weekly Operation and Sampling
<ol>
	<li>Operate the aquaria tank and raceway pond as semi-batch reactors with hydraulic retention times of three weeks. Each sampling period spans one week.</li>
	<li>Take a 125 mL sample from each vessel. This is the beginning of the week sample. Test samples according to the Sample Analysis protocol in sections 3.1-3.3.</li>
	<li>At the end of the week, take 125 mL samples from each vessel for analysis. After the end-of-week samples have been taken, empty the entire volume of the aquarium tank into the raceway pond.
	<ol>
		<li>Once per week, pump the entire volume of the aquarium tank into the raceway pond.</li>
	</ol>
	</li>
	<li>Remove one-third of the volume (for an average hydraulic retention time of 3 weeks) from the raceway pond. Replace volume removed with water and untreated leachate.</li>
	<li>Transfer approximately 60 L from the raceway pond back into the aquarium tank. This ensures that the aquarium tank and the raceway pond are starting with the same nutrient and biological conditions each week.</li>
	<li>Take 125 mL samples from all vessels for the analysis of the starting conditions for the next week.</li>
</ol>
3. Sample Analysis
<ol>
	<li>Test all beginning-of-the-week and end-of-the-week samples for ammonia-N, nitrate-N, nitrite-N, and biomass density.</li>
	<li>Measure biomass by standard total suspended solids (TSS) protocol, ASTM-D5907, using 0.45 &#181;m filters.
	<ol>
		<li>First weigh a filter paper and then filter 20-40 mL of sample using a vacuum filtration system. Dry the biomass/filter paper in an oven at 105 &#176;C for one hour, or until the weight of the biomass/filter paper no longer changes.</li>
		<li>Weigh biomass/filter paper, and subtract the initial mass of the filter paper. Divide this mass by the volume filtered to calculate the biomass density. Run in duplicate 11.</li>
	</ol>
	</li>
	<li>Measure ammonia, nitrate, and nitrite spectrophotometrically using a spectrophotometer.
	<ol>
		<li>Use 100 &#181;L of sample in the commercial method kit to determine ammonia concentration. Refer to the manufacturer&#39;s protocol.</li>
		<li>Use 1 mL of sample in the commercial method kit to determine nitrate concentration. Refer to the manufacturer&#39;s protocol.</li>
		<li>Use 10 mL of sample in the commercial method kit to determine nitrite concentration. Refer to the manufacturer&#39;s protocol.</li>
	</ol>
	</li>
	<li>Monitor environmental conditions (air temperature, solar radiation, wind speed) using a commercial weather station as well as tank/pond conditions (water temperature, pH, dissolved oxygen) using commercial probes and data logger. Refer to the manufacturer&#39;s protocol.</li>
</ol>
4. Statistical Analysis of Results
<ol>
	<li>Determine if the data collected is statistically normal. Determine normality of the data set using a Q-Q plot12.</li>
	<li>Determine correlations among parameters using Pearson&#39;s r or Spearman&#39;s p for normal and non-normal data, respectively13. Correlation parameters should include at least the following parameters: initial ammonia concentration, initial total nitrogen concentration, initial biomass density, ammonia removal rate, total nitrogen removal rate, biomass growth rate, and all environmental conditions.</li>
</ol>

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The authors have nothing to disclose.

System performance:
Over the course of an 8-week study, the productivity of the small- and large-scale vessels in a system were compared. In this study nitrogen and ammonia removal rates and biomass growth rates were used as measures of productivity of the treatment system. The system was operated as a semi-batch reactor, where each week was operated under discrete conditions. Representative results account for the first 8 weeks of system operation, however a full study would extend for much long...

Translation of bench-scale data to larger scale applications is a key step in the commercialization of bioprocesses. Production efficiencies in small-scale reactor systems, particularly those focusing on the use of microorganisms, have been shown to consistently over predict efficiencies occurring in commercial-scale systems 1,2,3,4. Challenges also exist in scaling up photosynthetic cultivation of algae and cyanobacteria from the laboratory scale to larger systems for the purpose of manufacturing high-value products, such as cosmetics and pharmaceuticals, for production of biofuels, and for the treatment of wastewater. The demand for large-scale algal biomass production is growing with the emerging industry for algae in biofuel, pharmaceuticals/nutraceuticals, and livestock feed 5. The methodology described in this manuscript aims to evaluate the influence of increasing scale of a photosynthetic reactor system on biomass growth rate and nutrient removal. The system presented here uses algae to remediate landfill leachate wastewater but can be adapted for a variety of applications.
Production efficiencies of large scale systems are often predicted using smaller scale experiments; however, several factors must be considered to determine the accuracy of these predictions, as scale has been shown to affect the performance of bioprocesses. For example, Junker (2004) presented results from a comparison of eight different-sized fermentation reactors, ranging from 30 L to 19,000 L, which showed that actual productivity at pilot- or commercial-scales was almost always lower than the values predicted using small-scale studies 4. Inequalities in vessel dimension, mixing power, agitation type, nutrient quality, and gas transfer were predicted to be the major causes for the decreased productivity 4. Similarly, it has been shown in algae growth reactors that biomass growth and biomass related products are nearly always reduced when scale is increased 6.
Biological, physical, and chemical factors change with the size of a reactor, with many of these factors influencing microbial activity at small scales differently than at larger scales 2,7. Since most full-scale systems for algae, such as raceway ponds, exist outdoors, one biological factor to consider is that microbial species and bacteriophages can be introduced from the surrounding environment, which may alter the microbial species present and thus the microbial function of the system. The activity of the microbial community will also be sensitive to environmental factors, such as light and temperature. Mass transfers of gasses and fluid motion are examples of physical factors that are influenced in the scale up of microbial processes. Achieving ideal mixing in small reactors is easy; however, with increasing scale, it becomes a challenge to engineer ideal-mixing conditions. At larger scales, reactors are more likely to have dead zones, non-ideal mixing, and reduced efficiencies in mass transfer 2. Since algae are photosynthetic organisms, commercial growth must account for changes in light exposure due to changes in water depth and surface area when increasing volume. High biomass density and/or low mass transfer rates can cause decreased CO2 concentrations and increased O2 concentrations, both of which may result in inhibition of biomass growth 8. Chemical factors in an algae growth system are driven by pH dynamics of the aquatic environment 2, which is consequently affected by changes in pH buffering compounds such as dissolved CO2 and carbonate species. These factors are compounded by complex interactions among the biological, physical, and chemical factors, often in unpredictable ways 9.
This study presents a paired reactor system designed to regulate and compare growth conditions in vessels of two different scales. The experimental protocol focuses on quantifying leachate treatment and algae growth; however, it could be adapted to monitor other metrics such as changes in the microbial community over time or the CO2 sequestration potential of algae. The protocol presented here is designed to evaluate the effect of scale on algal growth and nitrogen removal in a leachate treatment system.

<table border="0" cellpadding="0" cellspacing="0" width="1148">
	<colgroup>
		<col />
		<col />
		<col />
		<col />
	</colgroup>
	<tbody>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Aquarium Tank</td>
			<td style="width:135px;"></td>
			<td style="width:119px;"></td>
			<td style="width:612px;">Any 100+L aquarium tank with optically clear glass can be used</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:283px;">RW 3.5</td>
			<td style="width:135px;">MicroBio Engineering</td>
			<td style="width:119px;"></td>
			<td>Raceway Pond</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Eurostar 100 digital</td>
			<td style="width:135px;">IKA</td>
			<td style="width:119px;">4238101</td>
			<td style="width:612px;">Overhead mixers</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Leachate</td>
			<td style="width:135px;">Sandtown Landfill</td>
			<td style="width:119px;"></td>
			<td></td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Sampling Bottles</td>
			<td style="width:135px;">Nalgene</td>
			<td style="width:119px;"></td>
			<td>Plastic or glass, lab grade, 125-200mL&#160;</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Transfer Pumps</td>
			<td style="width:135px;"></td>
			<td style="width:119px;"></td>
			<td>Garden type pump with drinking water quality hoses will be suitable</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">AmVer Salicylate Test &#39;N Tube</td>
			<td style="width:135px;">Hach</td>
			<td style="width:119px;">2606945</td>
			<td>High Range Ammonia Tests</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">NitraVer X Nitrogen - Nitrate Reagent Set&#160;</td>
			<td style="width:135px;">Hach</td>
			<td style="width:119px;">2605345</td>
			<td>High Range Nitrate Tests</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">NitriVer 2 Nitrite Reagent Powder Pillows</td>
			<td style="width:135px;">Hach</td>
			<td style="width:119px;">2107569</td>
			<td>High Range Nitrite Tests</td>
		</tr>
		<tr height="21">
			<td height="21" style="height:21px;width:283px;">Hach DR2400 Spectrophotmeter</td>
			<td style="width:135px;">Hach</td>
			<td style="width:119px;"></td>
			<td>The DR2400 was discontinued, but any DR series Hach spectrophotometer can be used in this application.&#160;</td>
		</tr>
		<tr height="42">
			<td height="42" style="height:42px;width:283px;">EMD Microbiological Analysis Membrane Filters</td>
			<td style="width:135px;">Millipore</td>
			<td style="width:119px;">HAWG047S6</td>
			<td style="width:612px;">0.45&#181;m filters&#160;</td>
		</tr>
	</tbody>
</table>

comparison of scale in a photosynthetic reactor system for algal remediation of wastewater

An experimental methodology is presented to compare the performance of two different sized reactors designed for wastewater treatment. In this study, ammonia removal, nitrogen removal and algal growth are compared over an 8-week period in paired sets of small (100 L) and large (1,000 L) reactors designed for algal remediation of landfill wastewater. Contents of the small and large scale reactors were mixed before the beginning of each weekly testing interval to maintain equivalent initial conditions across the two scales. System characteristics, including surface area to volume ratio, retention time, biomass density, and wastewater feed concentrations, can be adjusted to better equalize conditions occurring at both scales. During the short 8-week representative time period, starting ammonia and total nitrogen concentrations ranged from 3.1-14 mg NH3-N/L, and 8.1-20.1 mg N/L, respectively. The performance of the treatment system was evaluated based on its ability to remove ammonia and total nitrogen and to produce algal biomass. Mean &#177; standard deviation of ammonia removal, total nitrogen removal and biomass growth rates were 0.95&#177;0.3 mg NH3-N/L/day, 0.89&#177;0.3 mg N/L/day, and 0.02&#177;0.03 g biomass/L/day, respectively. All vessels showed a positive relationship between the initial ammonia concentration and ammonia removal rate (R2=0.76). Comparison of process efficiencies and production values measured in reactors of different scale may be useful in determining if lab-scale experimental data is appropriate for prediction of commercial-scale production values.

The aim of this study is to compare the biomass growth and nutrient removal capabilities of algal cultures grown in small- and large-scale reactors. This study uses two paired systems, referred to as System 1 and System 2, to duplicate its findings. These representative results are from an 8-week period, February through April, 2016. The first raceway pond was inoculated with algae originally sourced from an outdoor pond in Philadelphia, PA 14. This culture was gro...

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Comparison of Scale in a Photosynthetic Reactor System for Algal Remediation of Wastewater

An experimental methodology is presented to compare the performance of small (100 L) and large (1,000 L) scale reactors designed for algae remediation of landfill wastewater. System characteristics, including surface area to volume ratio, retention time, biomass density, and wastewater feed concentrations, can be adjusted based on application.

An experimental methodology is presented to compare the performance of two different sized reactors designed for wastewater treatment. In this study, ...

comparison-scale-photosynthetic-reactor-system-for-algal-remediation

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8.9K Views.  Drexel University. An experimental methodology is presented to compare the performance of small (100 L) and large (1,000 L) scale reactors designed for algae remediation of landfill wastewater. System characteristics, including surface area to volume ratio, retention time, biomass density, and wastewater feed concentrations, can be adjusted based on application.

Video: Comparison of Scale in a Photosynthetic Reactor System for Algal Remediation of Wastewater

Physical, Chemical and Biological Characterization of Six Biochars Produced for the Remediation of Contaminated Sites

The physical and chemical properties of biochar vary based on feedstock sources and production conditions, making it possible to engineer biochars with specific functions (e.g. carbon sequestration, soil quality improvements, or contaminant sorption). In 2013, the International Biochar Initiative (IBI) made publically available their Standardized Product Definition and Product Testing Guidelines (Version 1.1) which set standards for physical and chemical characteristics for biochar. Six biochars made from three different feedstocks and at two temperatures were analyzed for characteristics related to their use as a soil amendment. The protocol describes analyses of the feedstocks and biochars and includes: cation exchange capacity (CEC), specific surface area (SSA), organic carbon (OC) and moisture percentage, pH, particle size distribution, and proximate and ultimate analysis. Also described in the protocol are the analyses of the feedstocks and biochars for contaminants including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), metals and mercury as well as nutrients (phosphorous, nitrite and nitrate and ammonium as nitrogen). The protocol also includes the biological testing procedures, earthworm avoidance and germination assays. Based on the quality assurance / quality control (QA/QC) results of blanks, duplicates, standards and reference materials, all methods were determined adequate for use with biochar and feedstock materials. All biochars and feedstocks were well within the criterion set by the IBI and there were little differences among biochars, except in the case of the biochar produced from construction waste materials. This biochar (referred to as Old biochar) was determined to have elevated levels of arsenic, chromium, copper, and lead, and failed the earthworm avoidance and germination assays. Based on these results, Old biochar would not be appropriate for use as a soil amendment for carbon sequestration, substrate quality improvements or remediation.

Biochar is a carbon-rich material used as a soil amendment with the ability to sustainably sequester carbon, improve substrate quality and sorb contaminants. This protocol describes the 17 analytical methods used for the characterization of biochar, which is required prior to large scale implementation of these amendments in the environment.

The physical and chemical properties of biochar vary based on feedstock sources and production conditions, making it possible to engineer biochars with ...

Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial Isochrysis Algal Biomass

The need to replace petroleum fuels with alternatives from renewable and more environmentally sustainable sources is of growing importance. Biomass-derived biofuels have gained considerable attention in this regard, however first generation biofuels from edible crops like corn ethanol or soybean biodiesel have generally fallen out of favor. There is thus great interest in the development of methods for the production of liquid fuels from domestic and superior non-edible sources. Here we describe a detailed procedure for the production of a purified biodiesel from the marine microalgae Isochrysis. Additionally, a unique suite of lipids known as polyunsaturated long-chain alkenones are isolated in parallel as potentially valuable coproducts to offset the cost of biodiesel production. Multi-kilogram quantities of Isochrysis are purchased from two commercial sources, one as a wet paste (80% water) that is first dried prior to processing, and the other a dry milled powder (95% dry). Lipids are extracted with hexanes in a Soxhlet apparatus to produce an algal oil (&#34;hexane algal oil&#34;) containing both traditional fats (i.e., triglycerides, 46-60% w/w) and alkenones (16-25% w/w). Saponification of the triglycerides in the algal oil allows for separation of the resulting free fatty acids (FFAs) from alkenone-containing neutral lipids. FFAs are then converted to biodiesel (i.e., fatty acid methyl esters, FAMEs) by acid-catalyzed esterification while alkenones are isolated and purified from the neutral lipids by crystallization. We demonstrate that biodiesel from both commercial Isochrysis biomasses have similar but not identical FAME profiles, characterized by elevated polyunsaturated fatty acid contents (approximately 40% w/w). Yields of biodiesel were consistently higher when starting from the Isochrysis wet paste (12% w/w vs. 7% w/w), which can be traced to lower amounts of hexane algal oil obtained from the powdered Isochrysis product.

Experimental Protocol for Biodiesel Production with Isolation of Alkenones as Coproducts from Commercial Isochrysis Algal Biomass

Detailed methods are presented for the production of biodiesel along with the co-isolation of alkenones as valuable coproducts from commercial Isochrysis microalgae.

The need to replace petroleum fuels with alternatives from renewable and more environmentally sustainable sources is of growing importance. ...

Use of a Battery of Chemical and Ecotoxicological Methods for the Assessment of the Efficacy of Wastewater Treatment Processes to Remove Estrogenic Potency

Endocrine Disrupting Compounds pose a substantial risk to the aquatic environment. Ethinylestradiol (EE2) and estrone (E1) have recently been included in a watch list of environmental pollutants under the European Water Framework Directive. Municipal wastewater treatment plants are major contributors to the estrogenic potency of surface waters. Much of the estrogenic potency of wastewater treatment plant (WWTP) effluents can be attributed to the discharge of steroid estrogens including estradiol (E2), EE2 and E1 due to incomplete removal of these substances at the treatment plant. An evaluation of the efficacy of wastewater treatment processes requires the quantitative determination of individual substances most often undertaken using chemical analysis methods. Most frequently used methods include Gas Chromatography-Mass Spectrometry (GCMS/MS) or Liquid Chromatography-Mass Spectrometry (LCMS/MS) using multiple reaction monitoring (MRM). Although very useful for regulatory purposes, targeted chemical analysis can only provide data on the compounds (and specific metabolites) monitored. Ecotoxicology methods additionally ensure that any by-products produced or unknown estrogenic compounds present are also assessed via measurement of their biological activity. A number of in vitro bioassays including the Yeast Estrogen Screen (YES) are available to measure the estrogenic activity of wastewater samples. Chemical analysis in conjunction with in vivo and in vitro bioassays provides a useful toolbox for assessment of the efficacy and suitability of wastewater treatment processes with respect to estrogenic endocrine disrupting compounds. This paper utilizes a battery of chemical and ecotoxicology tests to assess conventional, advanced and emerging wastewater treatment processes in laboratory and field studies.

Endocrine Disrupting Compounds (EDC) pose a substantial risk to the aquatic environment. Municipal wastewater treatment plants are major contributors to the estrogenic potency of surface waters. The methodology provided in this paper allows for an assessment of the efficacy and suitability of wastewater treatment processes with respect to EDC removal.

Endocrine Disrupting Compounds pose a substantial risk to the aquatic environment. Ethinylestradiol (EE2) and estrone (E1) have recently been included in ...

Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling from hydrothermal sources in the Precambrian ocean was oxidized by molecular oxygen [O2] produced by cyanobacteria. The oldest BIFs, deposited prior to the Great Oxidation Event (GOE) at about 2.4 billion years (Gy) ago, could have formed by direct oxidation of Fe(II) by anoxygenic photoferrotrophs under anoxic conditions. As a method for testing the geochemical and mineralogical patterns that develop under different biological scenarios, we designed a 40 cm long vertical flow-through column to simulate an anoxic Fe(II)-rich marine upwelling system representative of an ancient ocean on a lab scale. The cylinder was packed with a porous glass bead matrix to stabilize the geochemical gradients, and liquid samples for iron quantification could be taken throughout the water column. Dissolved oxygen was detected non-invasively via optodes from the outside. Results from biotic experiments that involved upwelling fluxes of Fe(II) from the bottom, a distinct light gradient from top, and cyanobacteria present in the water column, show clear evidence for the formation of Fe(III) mineral precipitates and development of a chemocline between Fe(II) and O2. This column allows us to test hypotheses for the formation of the BIFs by culturing cyanobacteria (and in the future photoferrotrophs) under simulated marine Precambrian conditions. Furthermore we hypothesize that our column concept allows for the simulation of various chemical and physical environments &#8212; including shallow marine or lacustrine sediments.

Laboratory Simulation of an IronII-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria

We simulated a Precambrian ferruginous marine upwelling system in a lab-scale vertical flow-through column. The goal was to understand how geochemical profiles of O2 and Fe(II) evolve as cyanobacteria produce O2. The results show the establishment of a chemocline due to Fe(II) oxidation by photosynthetically produced O2.

A conventional concept for the deposition of some Precambrian Banded Iron Formations (BIF) proceeds on the assumption that ferrous iron [Fe(II)] upwelling ...

Production and Measurement of Organic Particulate Matter in a Flow Tube Reactor

Organic particulate matter (PM) is increasingly recognized as important to the Earth's climate system as well as public health in urban regions, and the production of synthetic PM for laboratory studies have become a widespread necessity. Herein, experimental protocols demonstrate approaches to produce aerosolized organic PM by &#945;-pinene ozonolysis in a flow tube reactor. Methods are described for measuring the size distributions and morphology of the aerosol particles. The video demonstrates basic operations of the flow tube reactor and related instrumentation. The first part of the video shows the procedure for preparing gas-phase reactants, ozonolysis, and production of organic PM. The second part of the video shows the procedures for determining the properties of the produced particle population. The particle number-diameter distributions show different stages of particle growth, namely condensation, coagulation, or a combination of both, depending on reaction conditions. The particle morphology is characterized by an aerosol particle mass analyzer (APM) and a scanning electron microscope (SEM). The results confirm the existence of non-spherical particles that have grown from coagulation for specific reaction conditions. The experimental results also indicate that the flow tube reactor can be used to study the physical and chemical properties of organic PM for relatively high concentrations and short time frames.

This paper describes the operation procedure for the flow tube reactor and related data collection. It shows the protocols for setting the experiments, recording data and generating the number-diameter distribution as well as the particle mass information, which gives useful information about chemical and physical properties of the organic aerosols.

Organic particulate matter (PM) is increasingly recognized as important to the Earth's climate system as well as public health in urban regions, and the ...

Measuring and Mapping Patterns of Soil Erosion and Deposition Related to Soil Carbonate Concentrations Under Agricultural Management

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes in elevation are related to changes in near-surface soil carbonate (CaCO3) profiles. The objective is to describe a simple conceptual model and detailed protocol for repeatable field and laboratory measurements of these quantities. Here, accurate elevation is measured using a ground-based differential global positioning system (GPS); other data acquisition methods could be applied to the same basic method. Soil samples are collected from prescribed depth intervals and analyzed in the lab using an efficient and precise modified pressure-calcimeter method for quantitative analysis of inorganic carbon concentration. Standard statistical methods are applied to point data, and representative results show significant correlations between changes in soil surface layer CaCO3 and changes in elevation consistent with the conceptual model; CaCO3 generally decreased in depositional areas and increased in erosional areas. Maps are derived from point measurements of elevation and soil CaCO3 to aid analyses. A map of erosional and depositional patterns at the study site, a rain-fed winter wheat field cropped in alternating wheat-fallow strips, shows the interacting effects of water and wind erosion affected by management and topography. Alternative sampling methods and depth intervals are discussed and recommended for future work relating soil erosion and deposition to soil CaCO3.

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes in elevation are related to changes in near-surface soil carbonates. Repeatable methods for field and laboratory measurements of these quantities and data analysis methods are described here.

Spatial patterns of soil erosion and deposition can be inferred from differences in ground elevation mapped at appropriate time increments. Such changes ...

Techniques for Investigating the Anatomy of the Ant Visual System

This article outlines a suite of techniques in light microscopy (LM) and electron microscopy (EM) which can be used to study the internal and external eye anatomy of insects. These include traditional histological techniques optimized for work on ant eyes and adapted to work in concert with other techniques such as transmission electron microscopy (TEM) and scanning electron microscopy (SEM). These techniques, although vastly useful, can be difficult for the novice microscopist, so great emphasis has been placed in this article on troubleshooting and optimization for different specimens. We provide information on imaging techniques for the entire specimen (photo-microscopy and SEM) and discuss their advantages and disadvantages. We highlight the technique used in determining lens diameters for the entire eye and discuss new techniques for improvement. Lastly, we discuss techniques involved in preparing samples for LM and TEM, sectioning, staining, and imaging these samples. We discuss the hurdles that one might come across when preparing samples and how best to navigate around them.

This article outlines a suite of techniques in light and electron microscopy to study the internal and external eye anatomy of insects. These include several traditional techniques optimized for work on ant eyes, detailed troubleshooting, and suggestions for optimization for different specimens and regions of interest.

This article outlines a suite of techniques in light microscopy (LM) and electron microscopy (EM) which can be used to study the internal and external eye ...

A Flexible Low Cost Hydroponic System for Assessing Plant Responses to Small Molecules in Sterile Conditions

A wide range of studies in plant biology are performed using hydroponic cultures. In this work, an in vitro hydroponic growth system designed for assessing plant responses to chemicals and other substances of interest is presented. This system is highly efficient in obtaining homogeneous and healthy seedlings of the C3 and C4 model species Arabidopsis thaliana and Setaria viridis, respectively. The sterile cultivation avoids algae and microorganism contamination, which are known limiting factors for plant normal growth and development in hydroponics. In addition, this system is scalable, enabling the harvest of plant material on a large scale with minor mechanical damage, as well as the harvest of individual parts of a plant if desired. A detailed protocol demonstrating that this system has an easy and low-cost assembly, as it uses pipette racks as the main platform for growing plants, is provided. The feasibility of this system was validated using Arabidopsis seedlings to assess the effect of the drug AZD-8055, a chemical inhibitor of the target of rapamycin (TOR) kinase. TOR inhibition was efficiently detected as early as 30 min after an AZD-8055 treatment in roots and shoots. Furthermore, AZD-8055-treated plants displayed the expected starch-excess phenotype. We proposed this hydroponic system as an ideal method for plant researchers aiming to monitor the action of plant inducers or inhibitors, as well as to assess metabolic fluxes using isotope-labeling compounds which, in general, requires the use of expensive reagents.

A simple, versatile, and low-cost in vitro hydroponic system was successfully optimized, enabling large-scale experiments under sterile conditions. This system facilitates the application of chemicals in a solution and their efficient absorption by roots for molecular, biochemical, and physiological studies.

A wide range of studies in plant biology are performed using hydroponic cultures. In this work, an in vitro hydroponic growth system designed for ...

Potato Virus X-Based microRNA Silencing (VbMS) In Potato.

Virus-based microRNA silencing (VbMS) is a rapid and efficient tool for functional characterization of microRNAs (miRNAs) in plants. The VbMS system has been developed and applied for various plant species including Nicotiana benthamiana, tomato, Arabidopsis, cotton, and monocot plants such as wheat and maize. Here, we describe a detailed protocol using PVX-based VbMS vectors to silence endogenous miRNAs in potato. To knock down the expression of a specific miRNA, target mimic (TM) molecules of miRNA of interest are designed, integrated into plant virus vectors, and expressed in potato by Agrobacterium infiltration to bind directly to the endogenous miRNA of interest and block its function.

Potato Virus X-Based microRNA Silencing VbMS In Potato.

We present a detailed protocol for potato virus X (PVX)-based microRNA silencing (VbMS) system to functionally characterize endogenous microRNAs (miRNAs) in potato. Target mimic (TM) molecules of miRNA of interest are integrated into the PVX vector and transiently expressed in potato to silence the target miRNA or miRNA family.

Virus-based microRNA silencing (VbMS) is a rapid and efficient tool for functional characterization of microRNAs (miRNAs) in plants. The VbMS system has ...

A Small-Scale Setup for Algal Toxicity Testing of Nanomaterials and Other Difficult Substances

Ecotoxicity data is a requirement for pre- and post-market registration of chemicals by European and international regulations (e.g., REACH). The algal toxicity test is frequently used in regulatory risk assessment of chemicals. In order to achieve high reliability and reproducibility the development of standardized guidelines is vital. For algal toxicity testing, the guidelines require stable and uniform conditions of parameters such as pH, temperature, carbon dioxide levels and light intensity. Nanomaterials and other so-called difficult substances can interfere with light causing a large variation in results obtained hampering their regulatory acceptance. To address these challenges, we have developed LEVITATT (LED Vertical Illumination Table for Algal Toxicity Tests). The setup utilizes LED illumination from below allowing for a homogenous light distribution and temperature control while also minimizing intra-sample shading. The setup optimizes the sample volume for biomass quantification and does at the same time ensure a sufficient influx of CO2 to support exponential growth of the algae. Additionally, the material of the test containers can be tailored to minimize adsorption and volatilization. When testing colored substances or particle suspensions, the use of LED lights also allows for increasing the light intensity without additional heat generation. The compact design and minimal equipment requirements increase the possibilities for implementation of the LEVITATT in a wide range of laboratories. While compliant with standardized ISO and OECD guidelines for algal toxicity testing, LEVITATT also showed a lower inter-sample variability for two reference substances (3,5-Dicholorophenol and K2Cr2O7) and three nanomaterials (ZnO, CeO2, and BaSO4) compared to Erlenmeyer flasks and microtiter plates.

We demonstrate algal toxicity testing for difficult substances (e.g., colored substances or nanomaterials) using a setup illuminated vertically with an LED.

Ecotoxicity data is a requirement for pre- and post-market registration of chemicals by European and international regulations (e.g., REACH). The algal ...