Base Neutral Compounds Research Articles

Benzene contamination at a metal plating facility

A metal plating facility in central Kentucky was required to complete a RCRA Facility Investigation to address a number of Solid Waste Management Units at the site. Twenty monitoring wells were installed at the facility. Ground water from the wells was sampled for total and dissolved metals, polychlorinated biphenyls, acid extractable compounds, base neutral compounds, and volatile organic compounds. Unexpectedly, relatively large concentrations of benzene, up to 120 μg/l, were detected in samples from some of the wells, including wells that should have been hydraulically upgradient from the facility. As a result of the detection of benzene, the facility completed an investigation to identify the source. A nearby facility had completed a gasoline underground storage tank (UST) closure at about the time of the installation of the 20 wells. Reportedly the UST had small holes when removed. Three potential pathways of migration (a ditch, sanitary sewer, and a sink hole) from the nearby facility to the metal-plating facility and residual soils with very large concentrations of benzene, toluene, ethylbenzene, and xylenes have been identified.

An assessment of the bioavailability of persistent organic pollutants from contaminated soil

A procedure to assess the bioavailability of persistent organic pollutants (POPs) from soil samples has been developed. The procedure is based on the use of simulated in vitro gastrointestinal extraction to remove POPs from soil matrices. The level of recovery, using this approach, is assessed following liquid-liquid extraction (LLE) and analysis by gas chromatography-mass selective detection (GC-MSD). The remaining soil residue is then extracted using pressurised fluid extraction (PFE) followed by GC-MSD analysis to assess the residual fraction. The residual fraction is monitored to determine the unavailable fraction i.e. not available for absorption in the gastrointestinal tract of humans. The procedure was applied to four soil samples i.e. an aged, spiked soil and three certified reference materials (CRMs) contaminated with POPs. Recoveries of pesticides (lindane, endosulfan I, endrin, DDE, DDD and endosulfan II), phenols (cresol, TCP and PCP), and base neutral compounds (hexachloroethane, acenaphthene, dibenzofuran, fluorene and hexachlorobenzene) from aged, spiked soil following extraction with gastric fluid ranged from 0.8 to 8.3% while following intestinal extraction ranged from 5.5 to 13.5%, irrespective of POP. Recoveries of pesticides (lindane, endosulfan I, endrin, DDE, DDD and endosulfan II) from CRM 805-050 following extraction with gastric fluid were below the limit of detection while following intestinal extraction ranged from 5.3 to 12.8%. Recoveries of phenols (cresol, TCP and PCP) from CRM 401-225 following extraction with gastric fluid ranged from 1.6 to 2.0% while following intestinal extraction ranged from 4.1 to 5.4%. Recoveries of base neutral acid analytes (hexachloroethane, acenaphthene, dibenzofuran, fluorene and hexachlorobenzene) from CRM 107-100 following extraction with gastric fluid ranged from 1.4 to 4.0% while following intestinal extraction ranged from 6.6 to 12.7%. It has been found that the majority of POPs present i.e. >75%, would be excreted if consumed and not be absorbed in the gastrointestinal tract of humans.

Water quality assessment for indirect potable reuse: a new methodology for controlling trace organic compounds at the West Basin Water Recycling Plant (California, USA)

The West Basin Water Recycling plant (California; USA) was built to increase the region's water resource availability. The plant influent is produced at Los Angeles Hyperion wastewater treatment plant and is treated through two parallel treatment processes depending on the end use: (1) Title 22 water for industrial and urban use, and (2) barrier treatment for groundwater recharge. A new methodology was applied to monitor the fate of base neutral compounds in the water barrier treatment train. The methodology included large sample volumes coupled with integrated chromatographic analysis (ICA). Data indicated a 25% increase in concentration of base neutral compounds after RO pretreatment, followed by a 70% removal efficiency after RO. The increase in concentration after RO pretreatment appears to be linked to the use of lime clarification.

Retene and resin acid concentrations in sediment profiles of a lake recovering from exposure to pulp mill effluents

The stratigraphy of resin acids (pimaric, isopimaric, sandaracopimaric, dehydroabietic and abietic acids) and base neutral compounds (retene, tetrahydroretene, dehydroabietin and fichtelite) in sediments of a lake recovering after the mill closure from exposure to effluents from sulphite pulp mill was studied. The highest concentrations of these compounds were detected 1.5 km downstream from the effluent pipe in sediment depth of 7–11 cm. This sediment layer is approximately 30 yrs old. The highest concentration of resin acids was 1100 and of retene 3300 μg/g d.w. The retene concentration observed is the highest reported in the literature so far. The results imply that high concentrations of retene may be common in sediments of Finnish lakes polluted by pulp mill effluents.

Treatment of Trace Organic Compounds by Membrane Processes: At the Lake Arrowhead Water Reuse Pilot Plant

Organic and trace organic performance data for ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) at the Lake Arrowhead water reclamation pilot plant are analyzed to determine the treatment efficiency of these processes in an indirect potable reuse design. Four organic parameters were studied: dissolved organic carbon (DOC), ultra-violet absorbance at 254 nm (UV-254), SUVA and base neutral analysis (BNA). UF and NF removed the larger compounds from the influent, but had no significant impact on the base neutral fraction with the exception of sterols. The RO process removed DOC and UV-absorbance compounds from the effluent to their respective detection limits. Base neutral compounds were significantly removed by RO, leaving at extremely low concentrations small molecular weight compounds, indicating indirect potable reuse is technically feasible.

Treatment of trace organic compounds by membrane processes: At the Lake Arrowhead water reuse pilot plant

Organic and trace organic performance data for ultrafiltration (UF), nanofiltration (NF) and reverse osmosis (RO) at the Lake Arrowhead water reclamation pilot plant are analyzed to determine the treatment efficiency of these processes in an indirect potable reuse design. Four organic parameters were studied: dissolved organic carbon (DOC), ultra-violet absorbance at 254 nm (UV-254), SUVA and base neutral analysis (BNA).UF and NF removed the larger compounds from the influent, but had no significant impact on the base neutral fraction with the exception of sterols. The RO process removed DOC and UV-absorbance compounds from the effluent to their respective detection limits. Base neutral compounds were significantly removed by RO, leaving at extremely low concentrations small molecular weight compounds, indicating indirect potable reuse is technically feasible.

The fate of resin acids-1. The biotransformation and degradation of deuterium labelled dehydroabietic acid in anaerobic sediments

A lake sediment was collected downstream from the discharge from a bleached kraft pulp and paper mill, spiked with 6- d 2-dehydroabietic acid and anaerobically incubated for 264 days. The concentrations of the deuterium label, 6- d 2-dehydroabietic acid and resulting biotransformation products were monitored periodically. The 6- d 2-dehydroabietic acid transformed to d-tetrahydroretene (62 % conversion), and 6- d 2-dehydroabietin (1 % conversion). Towards the end of the study, minor quantities of d-retene and methyl d-tetrahydrophenanthrene were observed. Based on the appearance and disappearance of these and other compounds and mass balances for labelled and unlabelled components, a pathway for the conversion of dehydroabietic acid to several derived base neutrals was proposed. This is the first conclusive study indicating that in resin acid enriched sediments, anaerobic processes form resin acid derived base neutral compounds.

Sample preparation techniques for determining semi-volatile organic compounds in nuclear defense materials production waste

Extraction techniques for semi-volatile organic compounds in caustic and high-ionic-strength nuclear defense material production waste stored is presented. It was demonstrated that the nitrite ions in extracts caused degradation of chromatographic columns. Liquid-liquid extraction, ion-exchange and two types of solid-phase extraction (SPE) adsorbent supports were investigated in this study. The SPE media were styrene-divinylbenzene and alumina. Three classes of compounds were used: acids, base/neutral, paraffinic hydrocarbons and alkyl phosphates. SPE was able to extract semi-volatile organic compounds in simulated waste samples without significant carry-over of nitrate ion. Extraction yields ranged from 2.3 to 97.6% (12% R.S.D.). The range of yields for each chemical class was 0–4.1%, 6.4–79.9%, 14.3–68.3% and 91.1–97.6% for the acid, base/neutral, paraffinic hydrocarbons and alkyl phosphate compounds, respectively. Compounds of regulatory interest, organic semi-volatile acid and base neutral compounds were found to be unstable in the waste samples.

Economics of screening in the detection of organics in ground water

Rajagopal, R., 1990. Economics of screening in the detection of organics in ground water. Chemometrics and Intelligent Laboratory Systems, 9: 261–272. Screening may be defined as the use of efficient test procedures to determine and/or to quantify the presence or absence of contaminants in samples. In support of screening, many commercial laboratories offer price-breaks when analysis for only a few compounds are sought instead of a standard scan (such as those required under a governmental regulatory program). Screening is a step-wise or a decision tree approach to sampling and analysis. For a fixed number of compounds in a screen, a model to maximize the total expected number of positive determinations (detections) of organic compounds in ground water samples is developed and evaluated. This model is tested with extensive data on organic measurements obtained from ground-water samples at hazardous waste sites. The economic viability of the model is evaluated within the context of price-breaks in analytical services offered by commercial laboratories. For a set of price-breaks assumptions, screening is shown to be far superior in the detection of pesticide, acid, and base neutral compounds than in the detection of volatile organic compounds in ground water at hazardous waste sites. By incorporating relevant QA/QC costs, it is further shown that screening is a cost-effective alternative for all groups of organic compounds. A few promising avenues for further research are also outlined.