Barry G. Oliver

The contribution of humic substances to the acidity of colored natural waters

Abstract An operationally defined carboxyl content of humic substances extracted from rivers, streams, lakes, wetlands, and groundwaters throughout the United States and Canada is reported. Despite the diversity of the samples, only small variations were observed in this humic carboxyl content. The dissociation behavior of two combined fulvic/humic acid extracts was studied and it was found that the dissociation of the humics varied in a predictable manner with pH. Using a carboxyl content of 10 μeq/ mg humic organic carbon, and mass action quotient calculated from sample pH, the ionic balances of three highly colored Nova Scotia rivers were estimated.

History of Lake Ontario Contamination from the Niagara River by Sediment Radiodating and Chlorinated Hydrocarbon Analysis

Contamination of Lake Ontario by persistent organic compounds began with the development of the chemical industry along the Niagara River. These compounds are discharged to the river where they are scavenged from the water column by sedimenting particulates which in turn settle out in depositional areas of Lake Ontario. We have determined 210Pb, 137Cs, and chlorinated hydrocarbon profiles of sediment cores taken about 3 km from the mouth of the Niagara River. Age profiles of the sediments were constructed from the radionuclide measurements and used to determine historic trends of chlorinated hydrocarbon input to Lake Ontario. The historical record found in the sediments for chlorobenzenes, chlorotoluenes, hexachlorobutadiene, octachlorostyrene, mirex, and PCBs is in good agreement with known production and usage patterns of the chemicals. Pollution of Lake Ontario with chlorinated hydrocarbons from the Niagara River is still occurring, but the worst contamination of the lake occurred in the 1960s.

Desorption of chlorinated hydrocarbons from spiked and anthropogenically contaminated sediments

The desorption of 20 chlorinated organics from sediments has been studied using a nitrogen purge/Tenax trap system for separating the dissolved and sorbed fractions in sediment/water slurries. The desorption partition coefficient, K/sub D/, was found to decrease with increasing temperature and suspended sediment concentration. While some differences in K/sub D/ and desorption rates were observed for the study chemicals, considering their wide range of physical/chemical properties such as K/sub ow/, these changes were small. Desorption half-lives averaged about 60d at 4/sup 0/C, 40d at 20/sup 0/C and 10 at 40/sup 0/C under continuous gaseous purging. Estimates of the loadings of chemicals via desorption from bottom sediments in Lake Ontario are compared to loadings of these chemicals to the lake from the Niagara River.

Chlorinated Contaminants in Surficial Sediments of Lakes Huron, St. Clair, and Erie: Implications Regarding Sources Along the St. Clair and Detroit Rivers

Abstract Surficial sediments from southern Lake Huron, Lake St. Clair, and Lake Erie have been analyzed for a broad spectrum of chlorinated organics including PCBs, chlorobenzenes, and several pesticides. The differences between sediment contaminant concentrations in Lake Huron and Lake St. Clair indicated sources of hexachlorobenzene, hexachlorobutadiene, octachlorostyrene, and several other chlorinated benzenes along the St. Clair River. Similar differences between sediment PCB concentrations in Lakes Huron/St. Clair and Lake Erie indicated major PCB sources along the Detroit River. Specific PCB congener analysis revealed that PCBs discharged to the Detroit River contained especially high concentrations of highly chlorinated hexa-, hepta-, and octachloro-biphenyls which are major constituents of the industrial mixture Aroclor 1260. The analysis of individual PCB congeners made it possible to trace PCBs of Detroit River origin to the central and eastern basins of Lake Erie, and to estimate the contribution of the Detroit River to the PCB burden in sediments of these basins.

Chloroform production from the chlorination of aquatic humic material: The effect of molecular weight, environment and season

Humic material from various aqueous environments and from laboratory microbial cultures was segregated into humic and fulvic acid fractions and then each fraction was separated into eight molecular weight ranges by ultrafiltration. The fractionated material was then chlorinated in aqueous solution and the amount of chloroform produced was measured. Chloroform concentration per unit weight humic material passed through a maximum at molecular weight about 20,000–30,000 for the fulvic acids, whereas the CHCl3 concentration decreased with increasing molecular weight above 20,000–30,000 for the humic acids. Only minor fluctuations in chloroform concentrations were apparent for samples from various aqueous environments (lake, river, stream, swamp, microbial) and for samples from a single environment obtained during different seasons of the year. Based on the total amount of material isolated from the original samples and the chloroform production per unit weight, the major chloroform precursors in aquatic humic material were the low molecular weight (< 30,000) fulvic acid fractions. Unfortunately, because of their low molecular weight and high surface activity, these fractions will probably prove to be the most difficult to remove by standard water treatment processes.

Compartmental Distribution of Organochlorine Contaminants in the Niagara River and the Western Basin of Lake Ontario

Abstract Ten chlorobenzenes, hexachlorobutadiene, and PCBs were measured in Niagara River water and suspended solids, and in western Lake Ontario sediments and benthic fauna. High levels of these contaminants were found on all fractions of the river suspended solids, but the larger particles contained much higher concentrations than the smaller particles. A portion of the CBs, HCBD, and PCBs present in the lake sediments was available to benthic organisms. A trend toward greater bioaccumulation for compounds having higher octanol-water partition coefficients was observed at all trophic levels.

Chlorinated contaminants in the Niagara River, 1981-1983

Abstract For the period September 1981 to September 1983, large volume (161) water samples, collected weekly from the Niagara River at Niagara-on-the-Lake (NOTL), were analyzed for 31 chlorinated contaminants. The major class of compounds found were the chlorobenzenes (CBs). The CBs were present at much higher concentration at the river mouth (NOTL) than at the rivers source (Lake Erie), indicating major inputs along the river. A fairly steady background concentration was observed for most compounds, likely due to steady leaching from waste disposal sites along the rivers course. Superimposed on these background levels were numerous unpatterned concentration spikes, indicating direct dumping into the river. Only crude estimates of contaminant loadings from the Niagara River to Lake Ontario could be made because of the large concentration variability in the river.

Extraction and Clean-Up Procedures for Measuring Chlorobenzenes in Sediments and Fish by Capillary Gas Chromatography

A soxhlet extraction technique for recovering chlorobenzenes from sediments and fish is described. The extract is concentrated by evaporation, cleaned up with florisil (sediments) or a combination of alumina, silica gel, florisil and acidified silica gel (fish) before quantitation by capillary gas chromatography with an electron capture detector. Recoveries for all chlorobenzenes are greater than 80%. Detection limits of the technique are approximately 0.05 ng/g (ppb) for penta- and hexachlorobenzene, approximately 0.2 ppb for the tetrachlorobenzenes, approximately 0.4 ppb for the trichlorobenzenes, approximately 5 ppb for the dichlorobenzenes, and approximately 1500 ppb for monochlorobenzene.

Field Testing of a Large Volume Liquid - Liquid Extraction Device for Halogenated Organics in Natural Waters

Abstract The testing of a large volume (200 litre) liquid-liquid extractor for trace organics in the laboratory and in the field is described. The recovery efficiency of the device, as measured by laboratory spiking experiments and field spiking of five surrogate chemicals, was reasonably consistent and in the 40–70% range. Concentration and cleanup procedures for the extract are described in detail. The device reduces the detection limits of the organic chemicals by one or two orders of magnitude over those achieved with conventional small volume (1–10L) samples.

Partitioning Relationships for Chlorinated Organics Between Water and Particulates in the St. Clair, Detroit and Niagara Rivers

The suspended sediment/water partition coefficients have been measured for 19 chlorinated organics in 25 samples from the St. Clair, Detroit and Niagara Rivers. An excellent linear correlation (r2 = 0.87) between the organic-carbon corrected partition coefficient (KOC) and the octanol/water partition coefficient (KOW) was found (log KOC = 0.76 log KOC + 1.66). Using this equation plus another equation developed in this paper it is shown that the percentage of chemical in the “dissolved” and “particulate” phases in the study rivers could be estimated from a chemical’s Kow to within a factor of two. The paper also discusses the time required for equilibrium to be achieved between the “dissolved” and “particulate” phases, and the potential importance of biota such as algae in the partitioning process.