Municipal Outfalls Research Articles

Controlling mechanisms of sediment-driven dissolved oxygen dynamics in New Bedford Outer Harbour

A summer-long monitoring programme investigated mechanisms controlling near-bottom dissolved oxygen (DO) concentrations in New Bedford Outer Harbor, a shallow embayment on the southern Massachusetts coast that receives discharge from a 1.3 m3 s-1 municipal sewage outfall. Continuously recording meters and hydrographic cruises measured DO, temperature, salinity, meteorology, waves and/or currents. The programme quantified the magnitude, spatial extent and duration of oxygen undersaturation in the bottom waters. Summer stratification of New Bedford Outer Harbor reduced reaeration of the bottom waters. Depletion of near-bottom DO was strongly correlated with the presence and duration (though not intensity) of stratification. Stratification is typically thermal, a result of seasonal warming of the water surface, although it can become enhanced (and somewhat salinity driven) owing to the influx of cold saline bottom water following major storm events. Destratification is caused by high wind speed or a drop in 24-h average air temperatures below the water temperature. The decrease in DO concentrations when the water column is stratified is directly related to local sediment oxygen demand. In general, DO dynamics were found to be local and fundamentally one dimensional.

Effects of an oil and gas-production effluent on the colonization potential of giant kelp (Macrocystis pyrifera) zoospores

Point sources of pollution (e.g. industrial and municipal outfalls) may produce ecological impacts at distant locations if pollutants affect dispersive propagules. We used laboratory experiments to determine how water-column exposure to produced water (=the aqueous fraction of oil and gas production that is typically discharged into coastal waters) influences the colonization potential of giant kelp (Macrocystis pyrifera) zoospores on the bottom. Zoospores were maintained in suspension at relatively low densities in 18-liter containers and exposed to one of five concentrations of produced water for varying amounts of time. Zoospore swimming generally decreased with increasing produced-water concentration and exposure duration; however, the specific pattern of decrease differed between experimental trials done on different dates. The effect of exposure duration on the ability of swimming zoospores to attach to plastic dishes placed on the bottom varied with produced-water concentration. Zoospores placed in produced-water concentrations of 1 and 10% showed a steady decline in their ability to attach with increased exposure; lower concentrations of produced water had no such effects. The percentage of zoospores that germinated after attachment varied tremendously with exposure duration and date of experimental trial. Zoospores that settled during the first 12 h after release had very poor rates of germination, indicative of a short precompetent period. Surprisingly, exposure of suspended zoospores to high concentrations of produced water during the first 12 h reduced this precompetent period and greatly improved germination success on the bottom. The magnitude of this enhancement, however, varied among dates. The results suggest that adverse effects of discharging produced water on planktonic zoospores of giant kelp would most likely be limited to the immediate vicinity of the outfall.

Effects of reservoir-dam, urban, industrial, and sewage treatment run-off on the presence of oxygen and organic compounds in the Bow River

Because of persistent complaints by downstream users about the deterioration of water quality, the Bow River waters near Calgary, Alberta, were examined for the occurrence and presence of organic compounds. The overall water quality was determined by studying the effects of reservoir-dam, urban, industrial and municipal outfall on the river as it enters and leaves the Calgary city limits. The reservoir-dam and urban run-off do not affect the Bow River water quality. The industrial and municipal outfall, although contributing slightly higher levels of organic carbon compounds to the river, have minimal impact on its water quality. This was indicated by the fact that concentrations of organic compounds in the river waters leaving the Calgary city limits were in the range of those for pristine waters of Alberta. Thus, in terms of organic compounds, the Bow River water quality poses no problem to the downstream users of the river.

Zooplankton Distribution in Three Estuarine Bayous with Different Types of Anthropogenic Influence

Zooplankton was sampled in three tributaries of the Calcasieu Estuary: one flowing through an area of petrochemical industries, one through a municipal area, and one through an agricultural area. Synoptic comparisons among the bayous were made on eight trips over a two-year period. Additionally, each bayou was sampled intensively for small-scale distribution on four occasions. Numbers of all zooplankton taxa were consistently higher in the agricultural bayou than in either of the other bayous. Patterns of small-scale spatial variability also differed among the bayous. The agricultural bayou appeared to be a relatively healthy estuarine tributary. The municipal bayou was probably subjected to chronic environmental stress that is very severe in the vicinity of the municipal sewage and storm-drain outfalls. Evidence indicated that the industrial bayou suffered from frequent, but not continuous, episodes of environmental stress throughout its length.

Chlorophenols and Chlorinated Hydrocarbons in Starry Flounder (Platichthys stellatus) and Contaminants in Estuarine Sediments near a Large Municipal Outfall

Abstract Starry flounders, collected near a large municipal sewage outfall in the Fraser River Estuary, between March 1984 and April 1985, were quantified for chlorophenols, DDTs, and PCBs. Sediments from the polluted zone were analyzed for EPA Priority Pollutants and herbicides. Muscle tissue contained maximum chlorophenol levels about one half the Canadian limit and one tenth the limit for PCBs in edible fish tissue. Contaminants in matched tissue samples from the polluted zone and an adjacent control area showed statistically significant higher levels of all target compounds in muscle tissue from the outfall area except for DDD which was greater in the control. Bone and liver tissue were rich in PCBs and DDTs. The sediments contained phthalate esters, PCBs, PAHs and phenol. However the levels of pesticides, chlorophenols and herbicides were close to or below the detection limits. The sediment data were compared with values from nine other sites in the estuary.

Municipal wastewater contamination in the southern california bight: Part I—metal and organic contaminants in sediments and organisms

Sediments and organisms were examined for concentrations of organic and metal contaminants from near the Los Angeles County (JWPCP) municipal outfall at Palos Verdes (PV) station 7-3, the Los Angeles City (Hyperion) municipal outfall at Santa Monica Bay (SMB) station 6-4 and reference station SMB 2–3 near Malibu Beach. Flows and mass emission rates of suspended solids, PCBs, Cd and Zn were similar at the two outfalls. Mass emission rate of copper was almost twice as high from Hyperion as from JWPCP, while mass emission rate of DDTs was an order or magnitude higher from JWPCP than from Hyperion. Surficial sediments at PV 7-3 were enriched in most contaminants relative to SMB 6-4 and relative to the mass emission rates of contaminants from the JGVPCP and Hyperion outfalls. Some of this enrichment could be accounted for by the greater accumulation of organic material, measured as total volatile solids, at PV 7-3 relative to SMB 6-4. Some might be accounted for by resurfacing of more contaminated historical deposits buried at PV 7-3. Some of the enrichment of DDTs relative to PCBs could be accounted for by the greater abundance of oxygenated metabolites of PCBs (PCBols) relative to DDTs (DDTols) in sediments. The degree of contamination of organisms by DDTs increased with proximity to PV 7-3 but contamination by PCBs was similar at PV 7-3 and SMB 6-4. DDT concentrations in fish livers ranged from 12 ± 4 ( x ± SE: n = 4 ) mg/wet kg in longspine combfish from SMB 2–3 to 610 ± 105 ( n = 5) mg/wet kg in Pacific sanddab from PV 7-3. DDT concentrations in fish gonads ranged from 0·003 ± 0·003 ( n = 5) mg/wet kg in yellowchin sculpin from SMB 6-4 to 1.5 ± 6 ( n = 3) mg/wet kg in Pacific sanddabs from PV 7-3. PCB concentrations in fish livers ranged from 1·2 ± 0·4 ( n = 4) mg/wet kg in yellowchin sculpin from SMB 2–3 to 16 ± 3 ( n = 6) in Pacific Sanddab from SMB 6-4. DDT and PCB concentrations in invertebrate hepatopancreas were only slightly lower than those in fish livers. DDTols and PCBoIs comprised an average of 91 % of the total of parent compounds and oxygenated metabolites in sediments and 66 % in livers and hepatopancreas. Trace metals were frequently decreased in livers and hepatopancreas from near outfalls even though they were highly elevated in sediments. Comparison of sediment and tissue chlorinated hydrocarbon data with that from Elliot and Commencement Bays, Puget Sound, indicated that none of the southern California coastal stations considered in this study were sufficiently lacking contamination to be considered as adequate control sites.

Xenobiotic organics and biological effects in scorpionfish caged near a major southern California municipal outfall

Xenobiotic organics and biological effects in scorpionfish caged near a major southern California municipal outfall

Metals in seafood organisms near a large California municipal outfall

With the possible exception of copper and zinc, eight trace metals in muscle tissue of five popular benthic-feeding sportsfishes caught near the Los Angeles County municipal wastewater outfalls were not concentrated above levels measured in island and coastal control specimens. In contrast, the edible portions of five invertebrate seafood organisms collected from the highly contaminated bottom sediments in this discharge zone did concentrate some of the metals several-fold above control values. The maximum contamination observed was a 10-fold elevation of chromium in abalone and scallop muscle.

Metals in marine sediments near a large California municipal outfall

Elevated concentrations of trace metals in surficial sediments off Palos Verdes Peninsula, site of the Los Angeles County outfall system, clearly reflect the submarine discharge of treated municipal (domestic and industrial) wastewater. The following contamination factors (median outfall/median baseline) were obtained for the eight metals measured in a 45 km 2 region of the outfall monitoring zone: Ag-27; Cd-36; Cr-12; Cu-20; Hg-23; Ni-5.4; Pb-17; Zn-7.7.

DDT and PCB in flatfish around southern California municipal outfalls

DDT and PCB in flatfish around southern California municipal outfalls