Integral assessment of estrogenic potentials in sediment-associated samples

Background, aim, and scope  The enzyme-linked receptor assay (ELRA) detects estrogenic and anti-estrogenic effects at the molecular level of receptor binding and is a useful tool for the integrative assessment of ecotoxicological potentials caused by hormonally active agents (HAA) and endocrine disrupting compounds (EDC). The main advantage of the ELRA is its high sample throughput and its robustness against cytotoxicity and microbial contamination. After a methodological adaptation to salinity of the ELRA, according to the first part of this study, which increased its salinity tolerance and sensitivity for 17-β-estradiol, the optimised ELRA was used to investigate 13 native sediments characterised by different levels of salinity and chemical contamination. The applicability of the ELRA for routine analysis in environmental assessment was evaluated. Salinity is often a critical factor for bioassays in ecotoxicological sediment assessment. Therefore, salinity of the samples was additionally adjusted to different levels to characterise its influence on elution and binding processes of receptor-binding substances. Materials and methods  The ELRA was carried out with the human estrogen receptor α (ER) in a 96-well microplate format using the experimental setup known from the competitive immunoassay based on ligand–protein interaction. It is an important improvement that a physiologically relevant receptor was used as a linking protein instead of an antibody. The microplates were coated with a 17-β-estradiol-BSA conjugate, and dilution series of estradiol and of native sediment samples were added and incubated with the ER. After a washing step, a biotinylated mouse anti-ER antibody was added to each well. Receptor binding to estradiol, agonistic and antagonistic receptor binding, were determined by a streptavidin-POD-biotin complex with subsequent measurement of the peroxidase activity at the wavelength of 450 nm using a commercial ELISA multiplate reader. The sediment elutriates and pore water samples of sediments were tested in a dilution series to evaluate at which dilution step the receptor-binding potential ends. In the elution process (see Section 2.1 to 2.2), a method was developed to adjust the salinity to the levels of the reference testings, which offers an appropriate option to adjust the salinity in both directions. Statistical evaluation was made with a combination of the Mann–Whitney U test and the pT-method. Results  This part of the study characterised the environmental factor ‘salinity’ for prospective applications of the ELRA. Using reference substances such as 17-β-estradiol, the ELRA showed sigmoid concentration-effect relations over a broad range from 0.05 μg/l to 100 μg/l under physiological conditions. After methodological optimisation, both sensitivity and tolerance of the assay against salinity could be significantly raised, and the ELRA became applicable under salinity conditions up to concentrations of 20.5‰. The mean relative inter-test error (n = 3) was around 11% with reference substances and below 5% for single sediments elutriates in three replicates each. For sediment testings, the pore water and different salinity-adjusted elutriates of 13 sediments were used. A clear differentiation of the receptor-binding potential could be reached by application of the pT-method. Thereby, pT-values from one to six could be assigned to the sediments, and the deviation caused by the different salinity conditions was one pT-value. The mean standard deviation in the salinity adaptation procedure of the elutriates was below 5%. Discussion  Although the ELRA has already been used for assessments of wastewater, sludge and soil, its applicability for samples to different salinity levels has not been investigated so far. Even if the ELRA is not as sensitive as the E-screen or the YES-assay, with regard to reference substances like 17-β-estradiol, it is a very useful tool for pre-screening, because it is able to integrate both estrogenic as well as anti-estrogenic receptor-binding effects. According to the results of sediment testing, and given the integrative power to detect different directions of effects, the ELRA shows sufficient sensitivity and salinity tolerance to discriminate receptor-binding potentials in environmental samples. Conclusions  The optimised ELRA assay is a fast, cost-effective, reliable and highly reproducible tool that can be used for high-throughput screening in a microplate format in detecting both estrogenic and anti-estrogenic effects. Additionally, the ELRA is robust against microbial contaminations, and is not susceptible towards cytotoxic interferences like the common cell-culture methods. The general applicability and sufficient sensitivity of the ELRA was shown in freshwater environments. Marine and brackish samples can be measured up to salinity levels of 20.5‰. Recommendations and perspectives  In view of the proven sensitivity, functionality and the fastness of the ELRA, it is recommendable to standardise the test method. At the moment, no adequate in vitro test procedure exists which is standardised to DIN or ISO levels. The E-screen and the yeast estrogen/androgen screens (YES/YAS) sometimes underlie strong cytotoxic effects, as reported in the first part of this study. Further development of an ELRA assay using human androgen receptors appears to be very promising to gain information about androgenic and anti-androgenic effects, too. This would offer a possibility to use the ELRA as a fast and reliable pre-screening tool for the detection of endocrine potentials, thus minimising time and cost-expensive animal experiments.     

Rapid measurement of emissions from military aircraft turbine engines by downstream extractive sampling of aircraft on the ground: Results for C-130 and F-15 aircraft

Aircraft emissions affect air quality on scales from local to global. More than 20% of the jet fuel used in the U.S. is consumed by military aircraft, and emissions from this source are facing increasingly stringent environmental regulations, so improved methods for quickly and accurately determining emissions from existing and new engines are needed. This paper reports results of a study to advance the methods used for detailed characterization of military aircraft emissions, and provides emission factors for two aircraft: the F-15 fighter and the C-130 cargo plane. The measurements involved outdoor ground-level sampling downstream behind operational military aircraft. This permits rapid change-out of the aircraft so that engines can be tested quickly on operational aircraft. Measurements were made at throttle settings from idle to afterburner using a simple extractive probe in the dilute exhaust. Emission factors determined using this approach agree very well with those from the traditional method of extractive sampling at the exhaust exit. Emission factors are reported for CO₂, CO, NO, NO_x, and more than 60 hazardous and/or reactive organic gases. Particle size, mass and composition also were measured and are being reported separately. Comparison of the emissions of nine hazardous air pollutants from these two engines with emissions from nine other aircraft engines is discussed.     

Impact of injection system design on ISCO performance with permanganate--mathematical modeling results

In situ chemical oxidation (ISCO) using permanganate (MnO(4)(-)) can be a very effective technique for remediation of soil and groundwater contaminated with chlorinated solvents. However, many ISCO projects are less effective than desired because of poor delivery of the chemical reagents to the treatment zone. In this work, the numerical model RT3D was modified and applied to evaluate the effect of aquifer characteristics and injection system design on contact and treatment efficiency. MnO(4)(-) consumption was simulated assuming the natural oxidant demand (NOD) is composed of a fraction that reacts instantaneously and a fraction that slowly reacts following a 2nd order relationship where NOD consumption rate increases with increasing MnO(4)(-) concentration. MnO(4)(-) consumption by the contaminant was simulated as an instantaneous reaction. Simulation results indicate that the mass of permanganate and volume of water injected has the greatest impact on aquifer contact efficiency and contaminant treatment efficiency. Several small injection events are not expected to increase contact efficiency compared to a single large injection event, and can increase the amount of un-reacted MnO(4)(-) released down-gradient. High groundwater flow velocities can increase the fraction of aquifer contacted. Initial contaminant concentration and contaminant retardation factor have only a minor impact on volume contact efficiency. Aquifer heterogeneity can have both positive and negative impacts on remediation system performance, depending on the injection system design.     

Genetic engineering of cyanobacteria to enhance biohydrogen production from sunlight and water

To mitigate global warming caused by burning fossil fuels, a renewable energy source available in large quantity is urgently required. We are proposing large-scale photobiological H(2) production by mariculture-raised cyanobacteria where the microbes capture part of the huge amount of solar energy received on earth's surface and use water as the source of electrons to reduce protons. The H(2) production system is based on photosynthetic and nitrogenase activities of cyanobacteria, using uptake hydrogenase mutants that can accumulate H(2) for extended periods even in the presence of evolved O(2). This review summarizes our efforts to improve the rate of photobiological H(2) production through genetic engineering. The challenges yet to be overcome to further increase the conversion efficiency of solar energy to H(2) also are discussed.     

Climate Change and Population Growth in Timor Leste: Implications for Food Security

The climate in Timor Leste (East Timor) is predicted to become about 1.5 °C warmer and about 10 % wetter on average by 2050. By the same year, the population is expected to triple from 1 to 2.5–3 million. This article maps the predicted changes in temperature and rainfall and reviews the implications of climate change and population growth on agricultural systems. Improved cultivars of maize, rice, cassava, sweet potato and peanuts with high yield performance have been introduced, but these will need to be augmented in the future with better adapted cultivars and new crops, such as food and fodder legumes and new management practices. The requirements for fertilizers to boost yields and terracing and/or contour hedgerows to prevent soil erosion of steeply sloping terrain are discussed. Contour hedges can also be used for fodder for improved animal production to provide protein to reduce malnutrition.     

Reducing ammonia emissions from laying-hen houses through dietary manipulation

Feed additives can change the microbiological environment of the animal digestive track, nutrient composition of feces, and its gaseous emissions. This 2-yr field study involving commercial laying-hen houses in central Iowa was conducted to assess the effects of feeding diets containing EcoCal and corn-dried distillers grain with solubles (DDGS) on ammonia (NH3), hydrogen sulfide (H2S), and greenhouse gas (CO2, CH4, and N2O) emissions. Three high-rise layer houses (256,600 W-36 hens per house) received standard industry diet (Control), a diet containing 7% EcoCal (EcoCal) or a diet containing 10% DDGS (DDGS). Gaseous emissions were continuously monitored during the period of December 2007 to December 2009, covering the full production cycle. The 24-month test results revealed that mean NH3 emission rates were 0.58 +/- 0.05, 0.82 +/- 0.04, and 0.96 +/- 0.05 g/hen/day for the EcoCal, DDGS, and Control diet, respectively. Namely, compared to the Control diet, the EcoCal and DDGS diets reduced NH3 emission by an average of 39.2% and 14.3%, respectively. The concurrent H2S emission rates were 5.39 +/- 0.46, 1.91 +/- 0.13, and 1.79 +/- 0.16 mg/ hen/day for the EcoCal, DDGS, and Control diet, respectively. CO2 emission rates were similar for the three diets, 87.3 +/- 1.37, 87.4 +/- 1.26, and 89.6 +/- 1.6 g/hen/day for EcoCal, DDGS, and Control, respectively (P = 0.45). The DDGS and EcoCal houses tended to emit less CH4 than the Control house (0.16 and 0.12 vs. 0.20 g/hen/day) during the monitored summer season. The efficacy of NH3 emission reduction by the EcoCal diet decreased with increasing outside temperature, varying from 72.2% in February 2009 to -7.10% in September 2008. Manure of the EcoCal diet contained 68% higher ammonia nitrogen (NH3-N) and 4.7 times higher sulfur content than that of the Control diet. Manure pH values were 8.0, 8.9, and 9.3 for EcoCal, DDGS, and Control diets, respectively. This extensive field study verifies that dietary manipulation provides a viable means to reduce NH3 emissions from modern laying-hen houses.     

The exposition of a calcareous Mediterranean soil to toxic concentrations of Cr, Cd and Pb produces changes in the microbiota mainly related to differential metal bioavailability

The involvement of the bacterial community of an agricultural Mediterranean calcareous soil in relation to several heavy metals has been studied in microcosms under controlled laboratory conditions. Soil samples were artificially polluted with Cr(VI), Cd(II) and Pb(II) at concentrations ranging from 0.1 to 5000 mg kg⁻¹ and incubated along 28 d. The lowest concentrations with significant effects in soil respirometry were 10 mg kg⁻¹ Cr and 1000 mg kg⁻¹ Cd and Pb. However, only treatments showing more than 40% inhibition of respirometric activity led to significant changes in bacterial composition, as indicated by PCR-DGGE analyses. Presumable Cr- and Cd-resistant bacteria were detected in polluted microcosms, but development of the microbiota was severely impaired at the highest amendments of both metals. Results also showed that bioavailability is an important factor determining the impact of the heavy metals assayed, and even an inverted potential toxicity ranking could be achieved if their soluble fraction is considered instead of the total concentration. Moreover, multiresistant bacteria were isolated from Cr-polluted soil microcosms, some of them showing the capacity to reduce Cr(VI) concentrations between 26% and 84% of the initial value. Potentially useful strains for bioremediation were related to Arthrobacter crystallopoietes, Stenotrophomonas maltophilia and several species of Bacillus.     

Bio-Ethanol Production from Non-Food Parts of Cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz)

Global climate issues and a looming energy crisis put agriculture under pressure in Sub-Saharan Africa. Climate adaptation measures must entail sustainable development benefits, and growing crops for food as well as energy may be a solution, removing people from hunger and poverty without compromising the environment. The present study investigated the feasibility of using non-food parts of cassava for energy production and the promising results revealed that at least 28% of peels and stems comprise dry matter, and 10 g feedstock yields >8.5 g sugar, which in turn produced >60% ethanol, with pH ≈ 2.85, 74-84% light transmittance and a conductivity of 368 mV, indicating a potential use of cassava feedstock for ethanol production. Thus, harnessing cassava for food as well as ethanol production is deemed feasible. Such a system would, however, require supportive policies to acquire a balance between food security and fuel.     

Removal of added nitrate in the single, binary, and ternary systems of cotton burr compost, zerovalent iron, and sediment: Implications for groundwater nitrate remediation using permeable reactive barriers

Recent research has shown that carbonaceous solid materials and zerovalent iron (Fe(0)) may potentially be used as media in permeable reactive barriers (PRBs) to degrade groundwater nitrate via heterotrophic denitrification in the solid carbon system, and via abiotic reduction and autotrophic denitrification in the Fe(0) system. Questions arise as whether the more expensive Fe(0) is more effective than the less expensive carbonaceous solid materials for groundwater nitrate remediation, and whether there is any synergistic effect of mixing the two different types of materials. We carried out batch tests to study the nature and rates of removal of added nitrate in the suspensions of single, binary, and ternary systems of cotton burr compost, Peerless Fe(0), and a sediment low in organic carbon. Cotton burr compost acted as both organic carbon source and supporting material for the growth of indigenous denitrifiers. Batch tests showed that cotton burr compost alone removed added nitrate at a greater rate than did Peerless Fe(0) alone on an equal mass basis with a pseudo-first-order rate constant k=0.0830+/-0.0031 h(-1) for cotton burr compost and a k=0.00223+/-0.00022 h(-1) for Peerless Fe(0); cotton burr compost also removed added nitrate at a faster rate than did cotton burr compost mixed with Peerless Fe(0) and/or the sediment. Furthermore, there was no substantial accumulation of ammonium ions in the cotton burr compost system, in contrast to the systems containing Peerless Fe(0) in which ammonium ions persisted as major products of nitrate reduction. It is concluded that cotton burr compost alone may be used as an excellent denitrification medium in a PRB for groundwater nitrate removal. Further study is needed to evaluate performance of its field applications.     

Laboratory and field evaluation of crystallized DOW 704 oil on the performance of the Well Impactor Ninety-Six fFine particulate matter fractionator

Subsequent to the 1997 promulgation of the Federal Reference Method (FRM) for monitoring fine particulate matter (PM2.5) in ambient air, U.S. Environmental Protection Agency (EPA) received reports that the DOW 704 diffusion oil used in the method's Well Impactor Ninety-Six (WINS) fractionator would occasionally crystallize during field use, particularly under wintertime conditions. Although the frequency of occurrence on a nationwide basis was low, uncertainties existed as to whether crystallization of the DOW 704 oil may adversely affect a sampling event's data quality. In response to these concerns, EPA and the State of Connecticut Department of Environmental Protection jointly conducted a series of specialized tests to determine whether crystallized oil adversely affected the performance of the WINS fractionator. In the laboratory, an experimental setup used dry ice to artificially induce crystallization of the diffusion oil under controlled conditions. Using primary polystyrene latex calibration aerosols, standard size-selective performance tests of the WINS fractionator showed that neither the position nor the shape of the WINS particle size fractionation curve was substantially influenced by the crystallization of the DOW 704 oil. No large particle bounce from the crystallized impaction surface was observed. During wintertime field tests, crystallization of the DOW 704 oil did not adversely affect measured PM2.5 concentrations. Regression of measurements with crystallized DOW 704 versus liquid dioctyl sebacate (DOS) oil produced slope, intercept, and R2 values of 0.98, 0.1, and 0.997 microg/m3, respectively. Additional field tests validated the use of DOS as an effective impaction substrate. As a result of these laboratory and field tests, DOS oil has been approved by EPA as a substitute for DOW 704 oil. Since the field deployment of DOS oil in 2001, users of this alternative oil have not reported any operational problems associated with its use in the PM2.5 FRM. Limited field evaluation of the BGI very sharp cut cyclone indicates that it provides a viable alternative to the WINS fractionator.