Evaluation and use of a diffusion-controlled sampler for determining chemical and dissolved oxygen gradients at the sediment-water interface

Field and laboratory evaluations were made of a simple, inexpensive diffusion-controlled sampler with ports on two sides at each interval which incorporates 0.2-m polycarbonate membrane to filter samples in situ. Monovalent and divalent ions reached 90% of equilibrium between sampler contents and the external solution within 3 and 6 hours, respectively. Sediment interstitial water chemical gradients to depths of tens of centimeters were obtained within several days after placement. Gradients were consistent with those determined from interstitial water obtained by centrifugation of adjacent sediment. Ten milliliter sample volumes were collected at 1-cm intervals to determine chemical gradients and dissolved oxygen profiles at depth and at the interface between the sediment and water column. The flux of dissolved species, including oxygen, across the sediment-water interface can be assessed more accurately using this sampler than by using data collected from benthic cores.     

Effects of inorganic nitrogen application on the dynamics of the soil solution composition in the root zone of maize

The effect of inorganic nitrogen (N) fertilizer on the ionic composition of the soil solution under maize (Zea mays L.) was studied. A pot experiment was carried out with two treatments combined factorially, with or without N application (Ca(NO₃)₂; +N and –N treatments, respectively), and with or without plants. Three looped hollow fiber samplers were installed in each pot to sample soil solutions nondestructively from the root zone, seven times during the 50-day growth period. Plants were harvested on the 50th day, and their nutrient contents determined.Effects of N fertilizer on the soil solutions were observed by the first sampling, 2 days after sowing. The concentrations of Ca and NO₃ ^– and electrical conductivity (EC) increased significantly in the +N treatments as direct effects of fertilizer application. In addition, the concentrations of Mg, K, Na and H⁺ also increased and that of P decreased significantly as indirect effects caused by the re-establishment of chemical equilibria. This suggested the greater supply as well as the greater possibility of leaching loss not only of NO₃ ^– but also of Ca, Mg and K. In the treatments with plants, the concentrations of NO₃ ^–, Ca, Mg and K decreased with time and pH increased significantly compared with the unplanted soil. The depletion of N in the soil solution roughly agreed with the amount of N taken up by the plant. The depletions of K from the soil solution amounted to less than 10% of the amount of the K taken up, suggesting intensive replenishment of K from exchange sites in the soil. Depletions of Ca and Mg were several times higher than the amounts taken up, indicating that the depletions resulted from the adsorption of the divalent cations by the soil rather than uptake by plants. Because NO₃ ^– is hardly absorbed by exchange sites in soil and was the dominant anion in solution, it was concluded that NO₃ ^– had a major role in controlling cation concentrations in the soil solution and, consequently, on their availability for uptake by plants as well as their possible leaching loss. ei]H Marschner     

MonitoringAspergillus fumigatus aerosols from a composting facility

The large, outdoor Islip Yard Waste Composting Facility on Long Island, New York was investigated as a source of airborne fungus spores. The Burkard-Hirst volumetric spore trap was used for the first extensive sampling of small mold spores for this application. Samplers were operated continuously from 21 August to 30 November 1992 in the facility and in a suburban community about 540 m from the facility. A control site approximately 10 000 m from the facility was also sampled to establish background levels of fungus spores. The facility site had higher average readings ofAspergillus fumigatus spores than did the community and both were higher than the control.A. fumigatus was the only fungus among 30 categories tracked that differed significantly between the facility and control sites. It was also isolated repeatedly from the compost. Higher average levels ofA. fumigatus were measured in the community when winds blew from the facility, and also during times when the compost was moved or mixed at the facility. No correlation was found between wind direction or work times andA. fumigatus conidia at the control site. The study shows that this compost facility can produce a measurable increase in the number of airborneA. fumigatus conidia both at the edge of the facility and at 540 m downwind. It also demonstrates that the Burkard spore trap can be used for monitoring small, airborne mold spores, but it is a difficult and labor intensive task.     

Enumeration of airborne molds in some indoor environments of Madras city (India) by cultural and non-cultural volumetric samplers

The air mycoflora of six indoor environments in Madras city (India) has been investigated by sampling air with an Andersen sampler and a Burkard personal sampler. Forty-eight species assignable to 24 genera were recorded by Andersen sampler. Spores belonging to 14 genera in addition toPenicillium andAspergillus were identified from Burkard trap slides. Species ofAspergillus, Penicillium, Mucor andRhizopus were most frequently isolated in considerable numbers. As a single genusAspergillus ranked first followed byPenicillium at some sites, andCladosporium at some other sites. The predominance ofPenicillium andAspergillus was also confirmed by Burkard trap data. Spores belonging toGanoderma, Nigrospora, Epicoccum, andTetraploa were recorded only by Burkard sampler, thereby suggesting the necessity of using two complimentary spore traps, cultural and non-cultural, in any aerobiological investigation.     

Deployment of a threshold activated pump sampler in an industrial shock load impact study

Shock loading of toxic substances into natural waterways is apervasive practice which has substantial impacts on their biota.This paper describes the effects of shock (pulse) pollution loadingfrom two major industries on a river and wetland system in southernOntario, Canada. The assessment of shock loading frequencyindicated that sporadic discharges of polluted water occurred onaverage once every other day during the 38 days of monitoring inthe period April, 1986 to November, 1987.To estimate the frequency and intensity of the shock loads, anautomatic pump sampler that was activated by a thresholdconductivity was constructed and deployed. Samples were withdrawnfrom the river when the specific conductivity of the streamexceeded a threshold value of two times background. Backgroundspecific conductivity ranged between 200–250 S cm^-1The impact of these shock load discharges on a downstream aquaticplant community in a Class One (Provincially Significant) wetlandwas examined. The area of Thompsons Creek upstream of the CyanamidChemical Company displayed a normal complement of aquatic organismswhile downstream of the companys main discharges for a distance ofnearly 2 km, the stream was barren of nearly all aquatic life.A reef-like structure in which nickel, chromium, and lead reachedrespectively 2900, 2100 and 2210 mg kg^-1 dry weight ofsediment was located in the Welland River near the outfall of theAtlas-Mansfield storm sewer adjacent to the Atlas Specialty SteelsCompany. The average flow rate at the outfall of theAtlas-Mansfield storm sewer into the Welland River wasapproximately 28400 m³ day-¹ in 1986 (MOE 1987). Asmall area referred to as the Atlas reef because of the high ironconcentrations giving the sediments a cement-like condition, wasdevoid of all higher aquatic plants.     

Zooplankton abundance and diversity in Central Florida grass carp ponds

The effect of the Asian grass carp (Ctenopharyngodon idella Val.) upon the zooplankton in three adjacent experimental ponds (0.139 ha each) was studied for one year. The ponds contained nine species of aquatic macrophytes. Grass carp were stocked into Pond 1 (65 per ha) and Pond 2 (611 per ha) three months after the study was started. At the time of stocking, physichochemical and biological parameters were similar among the ponds.Grass carp did not affect water quality and had little direct or indirect effect upon the zooplankton in the ponds. The abundance and species diversity of zooplankton (number of species, Shannon Index, and Simpson Index) were not significantly different (P < 0.05) between ponds prior to grass carp stocking. After stocking with grass carp, the number of species and species diversity were found to be significantly different (P < 0.05) between Pond 1 (low grass carp stocking rate) and Pond 2 (high grass carp stocking rate). Additionally, significant differences (P < 0.05) in populations between ponds were found for Lecane luna, Monostyla bulla, Lepadella ehrenbergii, Polyarthra sp., and Synchaeta sp. Temporal variation rather than grass carp was probably responsible for those differences. The number of zooplankton per group (Rotifera, Cladocera, and Copepoda) and species diversity were not significantly different (P<0.05) between ponds containing different stocking rates of grass carp.During the study, zooplankton were collected with a shallow-water sampler. No significant differences (P < 0.05) between collections were found for the sampler and a No. 20 mesh nylon zooplankton net.     

A moorable,automated plankton sampler

A moorable, automated plankton sampler is described, designed to obtain series of plankton samples over extended time periods in the absence of a surface vessel. The sampler consists of one or more net-containing boxes, a unit for generating as well as measuring water flow through the net boxes, a programmeable control unit, and a frame. Each net box contains several nets on a vinyl strip, used to move the nets from the storage chamber into the fishing position and then into the preservative chamber. Preservation of samples is in a formalin-brine mixture.Net boxes can be added and the number of nets per box changed; the prototype is described with 1 net box with 10 nets. Volume of water to be filtered, time between sample collections, number of net boxes and the number of nets in each box is programmed into the control unit before sampler deployment. Collections made with the sampler are compared with those made with a SCOR net and a pump.     

Cation exchange properties of porous ceramic cups: Implications for field use

Porous ceramic cup soil-water samplers were treated with solutions containing Na, K, Ca, or Mg to examine any interactions between the cups and the extracted solutions. Acid-washed and non-acid washed cups were evaluated. Results demonstrated simple ion exchange between monovalent and divalent cations on charged sites, and that Na contamination of commercially available cups was effectively removed by acid-washing.     

Bayesian inference for a correlated 2 x 2 table with a structural zero

We develop a new Bayesian approach to interval estimation for both the risk difference and the risk ratio for a 2 x 2 table with a structural zero using Markov chain Monte Carlo (MCMC) methods. We also derive a normal approximation for the risk difference and a gamma approximation for the risk ratio. We then compare the coverage and interval width of our new intervals to the score-based intervals over various parameter and sample-size configurations. Finally, we consider a Bayesian method for sample-size determination.     

Cell culture monitoring via an auto‐sampler and an integrated multi‐functional off‐line analyzer

Mammalian cell‐based bioprocesses are used extensively for production of therapeutic proteins. Off‐line monitoring of such cultivations via manual sampling is often labor‐intensive and can introduce operator‐dependent error into the process. An integrated multi‐functional off‐line analyzer, the BioProfile FLEX (NOVA Biomedical, Waltham MA) has been developed, which combines the functionality of three off‐line analyzers (a cell counter, an osmometer, and a gas/electrolyte & nutrient/metabolite bio‐profile analyzer) into one device. In addition, a novel automated sampling system has also been developed that allows the BioProfile FLEX to automatically analyze the culture conditions in as many as ten bioreactors. This is the first report on the development and function of this integrated analyzer and an auto‐sampler prototype for monitoring of mammalian cell cultures. Evaluation of the BioProfile FLEX was conducted in two separate laboratories and involved two BioProfile FLEX analyzers and two sets of reference analyzers (Nova BioProfile 400, Beckman‐Coulter Vi‐Cell AS, and Advanced Instruments Osmometer 3900), 13 CHO cell lines and over 20 operators. In general, BioProfile FLEX measurements were equivalent to those obtained using reference analyzers, and the auto‐sampler did not alter the samples it provided to the BioProfile FLEX. These results suggest that the system has the potential to dramatically reduce the manual labor involved in monitoring mammalian cell bioprocesses without altering the quality of the data obtained, and integration with a bioreactor control system will allow feedback control of parameters previously available only for off‐line monitoring. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010