Yonghong Zou - Academia.edu (original) (raw)

Papers by Yonghong Zou

Environmental science & technology, Jan 7, 2016

A previously generated data set for polybrominated diphenyl ethers (PBDEs) in dated sediment core... more A previously generated data set for polybrominated diphenyl ethers (PBDEs) in dated sediment cores of West Lake of El Dorado (AED), Calion Lake (ACL), and the lagoon of Magnolia Wastewater Treatment Facility (AMW) from Southern Arkansas is examined by a weighted chemical mass balance (CMB) model and positive matrix factorization (PMF) in order to quantify PBDE sources and debromination. DNA extraction and pyrosequencing were done on several core sections in order to investigate microbial debromination. CMB and PMF analyses indicate that deca technical mixtures are the dominant PBDE input (> 99% in mole fraction in AED and ACL, and 94.7% in AMW). Minor contributions of penta and octa technical mixtures were found in all three water bodies (< 1% in AED and ACL; and 1.1% and 4.1% in AMW, respectively). Results suggest that debromination takes place in all three lakes, but is more intense in AMW. In-situ microbial debromination was supported by the microorganism analysis. The PMF ...

Environmental pollution (Barking, Essex : 1987), 2015

This work intended to explain the challenges of the fingerprints based source apportionment metho... more This work intended to explain the challenges of the fingerprints based source apportionment method for polycyclic aromatic hydrocarbons (PAH) in the aquatic environment, and to illustrate a practical and robust solution. The PAH data detected in the sediment cores from the Illinois River provide the basis of this study. Principal component analysis (PCA) separates PAH compounds into two groups reflecting their possible airborne transport patterns; but it is not able to suggest specific sources. Not all positive matrix factorization (PMF) determined sources are distinguishable due to the variability of source fingerprints. However, they constitute useful suggestions for inputs for a Bayesian chemical mass balance (CMB) analysis. The Bayesian CMB analysis takes into account the measurement errors as well as the variations of source fingerprints, and provides a credible source apportionment. Major PAH sources for Illinois River sediments are traffic (35%), coke oven (24%), coal combust...

Chemosphere, 2014

A stochastic process was developed to simulate the stepwise debromination pathways for polybromin... more A stochastic process was developed to simulate the stepwise debromination pathways for polybrominated diphenyl ethers (PBDEs). The stochastic process uses an analogue Markov Chain Monte Carlo (AMCMC) algorithm to generate PBDE debromination profiles. The acceptance or rejection of the randomly drawn stepwise debromination reactions was determined by a maximum likelihood function. The experimental observations at certain time points were used as target profiles; therefore, the stochastic processes are capable of presenting the effects of reaction conditions on the selection of debromination pathways. The application of the model is illustrated by adopting the experimental results of decabromodiphenyl ether (BDE209) in hexane exposed to sunlight. Inferences that were not obvious from experimental data were suggested by model simulations. For example, BDE206 has much higher accumulation at the first 30 min of sunlight exposure. By contrast, model simulation suggests that, BDE206 and BD...

Journal of Hazardous Materials, 2013

Irrigation with concentrated animal feeding operation (CAFO) wastewater on croplands has been ide... more Irrigation with concentrated animal feeding operation (CAFO) wastewater on croplands has been identified as a major source discharging steroid hormones into the environment. To assess the potential risks on this irrigation practice, the degradation kinetics and mechanisms of 17α-estradiol-3-sulfate were systematically investigated in aqueous solutions blended with dairy wastewater. Dissipation of the conjugated estrogen was dominated by biodegradation under both aerobic and anaerobic conditions. The half-lives for the biodegradation of 17α-estradiol-3-sulfate under aerobic and anaerobic conditions from 15 to 45°C varied from 1.70 to 415 d and 22.5 to 724 d, respectively. Under the same incubation conditions, anaerobic degradation rates of 17α-estradiol-3-sulfate were significantly less than aerobic degradation rates, suggesting that this hormone contaminant may accumulate in anaerobic or anoxic environments. Three degradation products were characterized under both aerobic and anaerobic conditions at 25°C, with estrone-3-sulfate and 17α-estradiol identified as primary metabolites and estrone identified as a secondary metabolite. However, the major degradation mechanisms under aerobic and anaerobic conditions were distinctly different. For aerobic degradation, oxidation at position C17 of the 17α-estradiol-3-sulfate ring was a major degradation mechanism. In contrast, deconjugation of the 17α-estradiol-3-sulfate thio-ester bond at position C3 was a major process initiating degradation under anaerobic conditions.

Journal of Great Lakes Research, 2011

Previously determined PCB concentrations in 10 dated sediment cores from Lakes Michigan, Huron, E... more Previously determined PCB concentrations in 10 dated sediment cores from Lakes Michigan, Huron, Erie, and Ontario are analyzed by positive matrix factorization in order to find characteristic congener patterns including signs of anaerobic dechlorination. Three or four factors are sufficient to describe the PCB data for each lake. All four lakes are dominated by Aroclors 1248A, 1248G, 1254A, and 1254G. Aroclor 1260 is only a significant factor in Lake Michigan prior to 1975, reflecting in part a usage patterns of heavy chlorinated Aroclors early and less chlorinated Aroclors in the phase-out years in the 1970s. Dated records of factors or sources indicate clear PCB concentration maxima for Lakes Erie (1981) and Ontario(1968), while redistribution of PCBs in the less contaminated Lakes Michigan and Huron has occurred after 1980. Using a single data matrix for all four lakes provides a common basis and possibility to examine low degrees of dechlorination, while individual data matrices for each lake provide more accurate results and better separation of factors. Lakes Ontario, Michigan, and Huron undergo dechlorination via reactions such as 66(24-34) → 25(24-3) and 18(25-2) → 4(2-2) consistent with reactions H' + M, while Lake Erie appears to be dominated by 18(25-2) → 4(2-2) and 53(25-26) → 19(26-2) that are typical for processes M + Q.

Journal of Environmental Engineering, 2012

Recent concerns about excessive algal (Cladophora) growth in the nearshore area have prompted a c... more Recent concerns about excessive algal (Cladophora) growth in the nearshore area have prompted a comprehensive study of phosphorus concentrations and loads in the Milwaukee watershed (2000-2008). During this period, total phosphorus (TP) decreased slightly for Outer Harbor water monitoring Station 1 (OH-1) representing the confluence of the three rivers into the Outer Harbor; whereas TP remained the same or slightly increased for Outer Harbor water monitoring Station 2 (OH-2) near the Jones Island Water Reclamation Facility (WRF) outfall. Concentrations of TP at OH-2 (0:095 AE 0:005 mg=L) are higher than at OH-1 (0:073 AE 0:006 mg=L). Years with high rainfall and river discharge during May through June produce high daily and annual average TP loads. This appears to be caused by resuspension and erosion of sediments containing TP in the river beds. Jones Island WRF contributes 39;500 kg=year or less than 34% of the total load to the Harbor. An estimate of TP load to Lake Michigan from rivers is 76;500 kg=year (65.7%). Stepwise regression results show that total soluble phosphorus (TSP), total suspended solids (TSS), and biochemical oxygen demand (BOD), in that order, are important predictors of TP except for Station OH-2.

Environmetrics, 2013

A new idea in receptor modeling is proposed, which utilizes a geometric eigenspace projection com... more A new idea in receptor modeling is proposed, which utilizes a geometric eigenspace projection combined with a mild alternative matrix updating technique. The eigenspace projection determines the sources or characteristic patterns as vertices that can span all measurements in a multidimensional eigenspace. The mild alternative matrix updating algorithm refines the results determined by the eigenspace projection to generate the optimized source profiles. Positive matrix factorization (PMF) analysis was adopted to suggest initial characteristic patterns. The advantage of the eigenspace projection method, compared with a purely computational matrix updating method, is that it can substantially avoid rotational ambiguity. The matrix refining step can effectively minimize data uncertainties. The application of this method has been illustrated step by step through a case study on determination of polybromodiphenyl ether (PBDE) characteristic congener patterns in the sediments of the Laurentian Great Lakes of North America. The number of factors was determined to be five for the Great Lakes PBDE 2002 data set. The sum of squares of error and coefficient of determination (r 2) suggested that the results obtained using this method are better than those from three known sources or the initial application of PMF. The factors represent deca (Saytex 102E), penta (DE-71), and octa (DE-79) technical PBDE mixtures as sources and two degradation factors that may have been generated by both photolysis and biological debromination.

Environmental Science & Technology, 2012

South-central Arkansas (AR) is home to major manufacturing facilities for brominated flame retard... more South-central Arkansas (AR) is home to major manufacturing facilities for brominated flame retardant chemicals (BFRs) in the U.S. Unintended release during production may have caused accumulation of the BFRs in the local environment. In this work, sediment cores were collected from six water bodies in AR, including three located close to the BFR manufacturing facilities in El Dorado and Magnolia, to investigate past and recent deposition histories. A total of 49 polybromodiphenyl ethers (PBDEs) and decabromodiphenyl ethane (DBDPE) were detected, with concentrations as high as 57 000 and 2400 ng/g dry weight for decabromodiphenyl ether (BDE209) and DBDPE, respectively. Log−log regression of BDE209 and DBDPE surface concentrations versus distance to known BFR manufacturing facilities fit the Gaussian Plume Dispersion model, and showed that, if the distance is shortened by half, concentrations of BDE209 and DBDPE would increase by 5-fold. The spatial distribution and temporal trend of the contamination indicate that the manufacturing of PBDEs and DBDPE is the primary source for these compounds in the environment of southern Arkansas. Interestingly, the occurrence of debromination of PBDEs in the sediments of a previously used wastewater sludge retention pond in Magnolia is indicated by the presence of congeners that had not been detected in any commercial PBDE mixtures and by increased fractions of lower brominated congeners relative to higher brominated congeners. Two unknown brominated compounds were detected in the sediments, and identified as nonabromodiphenyl ethanes.

Environmental Pollution, 2013

The objective of this work is to identify the photolytic debromination pathways of polybrominated... more The objective of this work is to identify the photolytic debromination pathways of polybrominated diphenyl ethers (PBDEs).

Environmental Science Technology, Apr 22, 2013

Concentrated animal feeding operations (CAFOs) have been identified as one of the most important ... more Concentrated animal feeding operations (CAFOs) have been identified as one of the most important sources for the release of animal hormones and veterinary antibiotics into the aquatic environment. Funded by a USDA (United States Department of Agriculture) research grant, Dr. Wei Zheng set out to identify and quantify the environmental fate and transport of several commonly-occurring steroid hormones, veterinary antibiotics, and their metabolites.