Real-time PCR assays using TaqMan or Molecular Beacon probes were developed and optimized for the quantification of total bacteria, the nitrite-oxidizing bacteria Nitrospira, and Nitrosomonas ...oligotropha-like ammonia oxidizing bacteria (AOB) in mixed liquor suspended solids (MLSS) from a municipal wastewater treatment plant (WWTP) using a single-sludge nitrification process. The targets for the real-time PCR assays were the 16S rRNA genes (16S rDNA) for bacteria and Nitrospira spp. and the amoA gene for N. oligotropha. A previously reported assay for AOB 16S rDNA was also tested for its application to activated sludge. The Nitrospira 16S rDNA, AOB 16S rDNA, and N. oligotropha-like amoA assays were log- linear over 6 orders of magnitude and the bacterial 16S rDNA real-time PCR assay was log-linear over 4 orders of magnitude with DNA standards. When these real-time PCR assays were applied to DNA extracted from MLSS, dilution of the DNA extracts was necessary to prevent PCR inhibition. The optimal DNA dilution range was broad for the bacterial 16S rDNA (1000-fold) and Nitrospira 16S rDNA assays (2500-fold) but narrow for the AOB 16S rDNA assay (10-fold) and N. oligotropha- like amoA real-time PCR assay (5-fold). In twelve MLSS samples collected over one year, mean cell per L values were 4.3 ± 2.0 × 1011 for bacteria, 3.7 ± 3.2 × 1010 for Nitrospira, 1.2 ± 0.9 × 1010 for all AOB, and 7.5 ± 6.0 × 109 for N. oligotropha-like AOB. The percent of the nitrifying population was 1.7% N. oligotropha-like AOB based on the N. oligotropha amoA assay, 2.9% total AOB based on the AOB 16S rDNA assay, and 8.6% nitrite-oxidizing bacteria based on the Nitrospira 16S rDNA assay. Ammonia-oxidizing bacteria in the wastewater treatment plant were estimated to oxidize 7.7 ± 6.8 fmol/hr/cell based on the AOB 16S rDNA assay and 12.4 ± 7.3 fmol/hr/cell based on the N. oligotropha amoA assay.
Future bioenergy demand will likely result in the conversion of significant amounts of crop and pasture/hay lands in the mid-south of US. The objective of this research is to analyze the effects of ...the large-scale land use conversion to switchgrass as a bioenergy feedstock on water quality and economic feasibility in Oostanaula Creek watershed in East Tennessee. The soil and water assessment tool (SWAT) model was first used to simulate nutrient loadings of current land use in the watershed. Statistical criteria such as Nash–Suttcliffe efficiency (E) and R2 were calculated for model calibration and validation. The calibrated SWAT model was then used to simulate the effect of the land use conversion from the entire current crop and pasture/hay lands to switchgrass production. Results show that the conversion reduces average annual watershed loadings of sediment, nitrate (NO3), total nitrogen (TN), and total phosphorous (TP) by an estimated 77%, 62%, 34%, and 46%, respectively. Analysis of net present values of ten years of farm profits and cost-effectiveness ratios for abatement of nutrient loadings indicates that the land use conversion is economically feasible.
Purpose
The accurate identification of primary sediment sources in a watershed is necessary to implement targeted management practices that will reduce erosion and restore water quality. Sediment ...fingerprinting is a commonly used tool to accomplish this task. However, the accuracy and precision of different procedures to select tracers for un-mixing sediment sources are still a largely uninvestigated area in relation to sediment fingerprinting. The goal of this research was to validate a sediment fingerprinting methodology by applying it to the Oostanaula Creek watershed in southeast Tennessee, USA.
Materials and methods
We assessed three method protocols (soil digestion procedure, objective source grouping, and tracer selection) that are utilized for assessing the performance of fingerprinting in terms of apportionment outputs. The major and trace elemental composition of sediment source and suspended sediment were determined by total dissolution and nitric acid extraction followed by analysis with inductively coupled plasma-optical emission spectrometry (ICP-OES). The Kruskal-Wallis (KW) test as well as stepwise discriminant function analysis (DFA) was utilized during tracer selection. The source un-mixing model utilized was a Bayesian mathematical model within Stable Isotope Analysis in R (SIAR). Sediment fingerprinting in the Oostanaula watershed proved to be difficult due to the chemical and mineralogical similarities of the potentially erodible source material.
Results and discussion
Upon analysis, it was found that the sediment tracers identified as those with low misclassification during cluster analysis would not guarantee a high degree of accuracy during source apportionment. However, there are certain outputs with low errors as compared with the real proportional contributions in artificial mixtures, for example, findings showed that bank erosion is a primary source of suspended sediment in the Oostanaula Creek.
Conclusions
Source apportionment from sediment fingerprinting was sensitive to the digestion procedure, objective source groupings, and the tracer selection. Our research provides a quantitative approach for assessing the validity of the sediment fingerprinting technique.
Concentrated animal feeding operations typically store livestock waste in clay‐lined ponds. Although these ponds are regulated to include a liner with a small hydraulic conductivity to limit ...leaching, previous studies have traced surface and groundwater contamination from such regulated animal waste ponds. This research examined the transport of 17β‐estradiol (E2) and its primary metabolite, estrone (E1), through soil liners using field‐ and laboratory‐based studies. Additionally, a potential engineering solution to limit hormone transport—applying biochar to new pond liners to act as a retardant—was studied. Soil cores 80 cm in length were collected beneath a mature dairy waste pond and analyzed for moisture content and hormone concentrations. Unsaturated conditions and E2 concentrations of 4 to 250 ng g−1 were detected beneath the waste pond. In the laboratory portion of the study, hand‐packed columns of sand or clay were subjected to infiltration by a 2.3‐m head of dairy waste. A subset of the hand‐packed sand columns was amended with powdered biochar to test its ability to retard E2 and E1. For 3 mo, column leachate was analyzed for hormone concentrations, and at the conclusion of the study E2 and E1 concentrations in the soil were measured. In the 44 d after sealing, the clay, sand, sand with a thin layer of biochar, and sand mixed with a biochar amendment leached a total of 0.54, 1.3, 0.09, and 0.45 μg of E2, respectively. The biochar amendments to the hand‐packed columns considerably minimized E2 in the leachate.
Determining the total elemental concentrations of soils requires a total dissolution method, in which hydrofluoric acid (HF) is commonly used. However, this method is tedious and risky due to the ...dangerous reagent HF. This study compared a single acid extraction technique using a nitric acid (HNO
3
) extraction method to total dissolution (HF + microwave assisted aqua regia) for evaluating the total elemental concentrations in soils and sediments. The two methods were used to analyze the elemental content of soils and sediments from the Oostanaula Creek and Pond Creek watersheds in East Tennessee. Twenty-one elements (Al, Ba, Ca, Co, Cr, Cu, Fe, K, La, Li, Mg, Mn, Nd, P, S, Si, Sr, Ti, V, Zn, and Zr) were subsequently measured using inductively coupled plasma optical emission spectrometry (ICP-OES). The extraction efficiency for HNO
3
relative to the total was compared and discussed. In general, HNO
3
can extract the elements in absorbed phases and those residing in non-silicate minerals. Six elements (Ba, Co, Fe, Ca, Mn, and P) generated significant correlations between total and HNO
3
in both OC and PC watersheds. Finally, the elements were grouped according to the interrelationships of their total elemental concentrations based on the dendrogram plots, suggesting their geochemical association in soils and sediment forming minerals.
Abstract
Research on producer willingness to adopt individual best pasture management practices (BMPs) is extensive, but less attention has been paid to producers simultaneously adopting multiple, ...complementary BMPs. Applications linking primary survey data on BMP adoption to water quality biophysical models are also limited. A choice-experiment survey of livestock producers is analyzed to determine willingness to adopt pasture BMPs. Sediment abatement curves are derived by linking estimates of producer responsiveness to incentives to adopt rotational grazing with a biophysical simulation model. Current cost share rates of $24/acre should yield a 12% decrease in sediment loading from pastures.
The genome of a fecal pollution indicator phage, Bacteroides fragilis ATCC 51477-B1, was sequenced and consisted of 44,929 bases with a G+C content of 38.7%. Forty-six putative open reading frames ...were identified and genes were organized into functional clusters for host specificity, lysis, replication and regulation, and packaging and structural proteins.
Dwindling water resources have drawn global attention to the reuse of treated wastewater (TWW) for irrigation. However, the impact of continuous TWW applications on soil quality and the proper ...quantification and monitoring frameworks have not been well-understood. This study aims to provides an insight into the impact of flood irrigation of urban TWW on soil nutritional-chemical attributes and the potential application of multiple soil quality indices for a corn cropping system. To achieve that goal, we pursued the Total Data Set (TDS) and Minimum Data Set (MDS) approaches, as well as the Integrated Quality Index (IQI) and Nemoro Quality Index (NQI) models. A total of 17 soil nutritional-chemical indicators (0–50 cm depths) were determined for the soils irrigated with TWW (five sites) and well water (one site as control) in West Azerbaijan province in northwestern Iran. Results revealed a significant difference in the majority of soil nutritional-chemical attributes, IQI-TDS, NQI-TDS, IQI-MDS, NQI-MDS, and corn yield between the TWW-irrigated and well-irrigated soils. Irrigation with TWW resulted in a significant increase in the amount of organic matter and cation exchange capacity by 9–17% and 17–26%, respectively, macronutrients (N, P, K, Ca, and Mg) by 22–164%, and the majority of trace metals (Fe, Mn, Zn, and Cu) by 17–175%, suggesting an improvement in soil nutrients and an increase in productivity. Comparing to the soil in control sites, the TWW irrigation caused a notable increase in the values of IQI-TDS, NQI-TDS, IQI-MDS, and NQI-MDS models ranging 14.6–29.5%, 19.1–25.5%, 21.7–33.3%, and 18.4–23.7%, respectively. This implies that soil quality was ameliorated to a significant extent with TWW irrigation. These improvements resulted in a remarkable increase in corn yield ranging from 12.5% to 28.1%. The regression equations revealed that up to 78%, 47%, 72%, and 36% of the variance in the IQI-TDS, NQI-TDS, IQI-MDS, and NQI-MDS models, respectively, could be captured by corn yield. The results of the regression and correlation analyses showed that the IQI-MDS model was more accurate than the other models in assessing soil quality and predicting crop yield. These findings may be an effective and practical tool for policy making, implementation, and management of soil irrigated with TWW.
The focus of this research effort was to develop an autonomous, inducible, lux-based bioluminescent bioreporter for the real-time detection of dichloromethane. Dichloromethane (DCM), also known as ...methylene chloride, is a volatile organic compound and one of the most commonly used halogenated solvents in the U.S., with applications ranging from grease and paint stripping to aerosol propellants and pharmaceutical tablet coatings. Predictably, it is released into the environment where it contaminates air and water resources. Due to its classification as a probable human carcinogen, hepatic toxin, and central nervous system effector, DCM must be carefully monitored and controlled. Methods for DCM detection usually rely on analytical techniques such as solid-phase microextraction (SPME) and capillary gas chromatography or photoacoustic environmental monitors, all of which require trained personnel and/or expensive equipment. To complement conventional monitoring practices, we have created a bioreporter for the self-directed detection of DCM by taking advantage of the evolutionary adaptation of bacteria to recognize and metabolize chemical agents. This bioreporter, Methylobacterium extorquens DCM lux , was engineered to contain a bioluminescent luxCDABE gene cassette derived from Photorhabdus luminescens fused downstream to the dcm dehalogenase operon, which causes the organism to generate visible light when exposed to DCM. We have demonstrated detection limits down to 1.0 ppm under vapor phase exposures and 0.1 ppm under liquid phase exposures with response times of 2.3 and 1.3 h, respectively, and with specificity towards DCM under relevant industrial environmental monitoring conditions.
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