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Environmental Awareness 1970 – present
The beginning of environmental awareness Although some national legislation addressing the issue of pollution was passed before 1960, Rachel Carson’s book “Silent Spring” published in 1962, brought attention to the problem of pollution. On December 2, 1970, U. S. Environmental Protection Agency was created. A number of environmental laws were enacted in the 1970s (see the Public Health and Legislative section of the timeline).
The sewage problem is improving There has been some remediation of the sewage problem in New Bedford Harbor and surrounding waters. A wastewater treatment plant for New Bedford, with primary treatment of waste, was built in 1974. The outfall is off the end of Clarks Point. Secondary treatment of waste began in 1996, when a new wastewater treatment facility was brought on-line. This has improved the quality of the effluent discharged from the plant; however, untreated wastes are still discharged into the harbor from the combined sewer overflows (CSOs) during periods of heavy rain. A long-term plan to reduce the overflow of raw sewage into New Bedford Harbor through the CSOs was developed in 1990 (Camp, Dresser & McKee, 1990). In the 1990s, $178 million was spent to reduce the volume of waste released through the CSOs and another $200 million was committed for further improvements (personal communication, R. Labelle, New Bedford Department of Public Works, Wastewater Division, Nov. 4, 1999). Since 1990, a number of the CSOs have been eliminated; as of 2006, only 13 (of 24) CSOs remain in upper and lower New Bedford Harbor (Camp, Dresser & McKee, 2006). The Fairhaven Water Pollution Control Facility, built in 1969, empties into the harbor, but has had secondary treatment of waste since it started operation. In April, 2004, the facility started using ultraviolet light treatment, rather than chlorination, to disinfect the effluent before release.
Cleaning up PCBs In 1994 and 1995, the Army Corps of Engineers dredged about 5 acres of sediment (14,000 cubic yards) from the "hot spot," the section of the upper harbor that contained the highest concentrations of PCBs. The dredge spoil was stored in a contained disposal facility (CDF) until a decision was made on how to dispose of this highly contaminated sediment. In 1999-2000 the dredge spoil was dewatering and transported to an off-site landfill that was permitted for toxic waste.
The second phase of the project, dredging about 450,000 cubic yards of PCB-contaminated sediment from 170 acres in the upper and lower harbor, started in 2004 and will continue annually until the project is completed. The $15 million annual funding level allows approximately 40 days of dredging each year. The dredging is performed on a worst-first basis, generally proceeding from north to south, beginning at the former Aerovox plant. The dewatered dredge spoil is sent by rail to a licensed PCB-landfill in Michigan.
For the latest information on the remedial dredging see the "Newsletters & Press" and “Status” sections on the EPA New England (Region 1) New Bedford Harbor web site. Scientists are monitoring New Bedford Harbor for 30 years after the dredging to assess the effects of remediation (see Nelson et al., 1996).
Metal contaminated sediment Some PCB-contaminated sediment is also highly contaminated with metals, therefore, some metal-contaminated sediment is also being removed with the dredging. However, at the present time, there are no plans to deal specifically with sediments contaminated by chemicals other than PCBs. Maintenance dredging of the shipping channels, mentioned in the harbor master plan, will also remove contaminated sediment. An industrial pretreatment program, where industries remove contaminants from their wastes before releasing them into the sewer system, was instituted in 1987, so fewer contaminants are now being discharged through the outfall of the wastewater treatment plant and the CSOs.
Is there evidence that the environmental laws are being effective? Sediments record the history of contamination in estuaries. Contaminants adsorb to sediment particles, which get moved by currents and tides and settle to the bottom in areas of low flow. The contaminants in the surface sediment reflect current time and events, whereas, contaminants found deeper in the sediment correspond to past time and events. Sediment cores from estuaries can be frozen, sliced horizontally into thin slices, and the slices analyzed for various chemicals. Various methods can be used to assign approximates dates to slices down the core. When concentrations of contaminants in slices of the core are plotted by date, the resulting graph (called a sediment profile) shows the history of contamination in the estuary.
Sediment study in New Bedford Harbor A sediment study was conducted in New Bedford Harbor to determine historical changes in the harbor over the past 350 years (Latimer, J.S. et al., 2003). Three sediment cores were taken in the harbor, two in the upper harbor (in 1996) and one in the lower harbor (in 1998), in areas that were relatively undisturbed and where sediment had accumulated. The cores were frozen, sliced horizontally and the slices analyzed for toxic organic compounds, metals, organic carbon content, carbon isotope composition, and biological indicators (dinoflagellate cysts, benthic foraminifera, and pollen). Radionuclides (210Pb and 137Cs) and pollen analyses were used to date the sediment slices. Plotting concentrations by date shows the history of contaminants in New Bedford Harbor sediment from the present at the surface, back in time with depth (see Fig. 16, 18, and 20). Please note, dating methods are not exact, so the dates shown on the sediment profiles are approximate, with less certainty the further back in time.
Contaminants in sediment cores correlated with development All of the contaminants measured (PAHs, PCBs, copper, lead, zinc, cadmium, silver, chromium, and nickel) increased with the urbanization of the New Bedford Harbor watershed. Statistical tests were done to establish when each contaminant increased above background level (the concentration of a chemical in the environment that occurs naturally, not the result of human activity). In the early 1800s (the whaling period), two contaminants, copper (Cu) and lead (Pb), were found at concentrations significantly above background level in the lower harbor, where development initially started (Fig 16). Although these increases were significantly above background, they were substantially lower than concentrations reached later. The shore of lower harbor was the location of foundries, machines shops, casting, plating and metal working businesses that made metal goods needed for whaling, and whale-oil processing businesses (Fig. 17). The metal-related businesses were the most likely sources of copper and lead.
PAHs There was a small, but discernable peak in PAHs (polycyclic aromatic hydrocarbons) in the late 1700s. This peak may reflect the burning, in 1778, of part of New Bedford by the British during the Revolutionary War (see timeline). Major sources of PAHs are the combustion of wood, charcoal, coal, and petroleum products. When PAHs are released to the atmosphere, many of them are attached to particles, which are deposited on land, and later washed into streams, storm drains, and nearby water bodies. PAH concentrations increased significantly above background in the late 1800s. The whale-oil processing and metal-working businesses burned wood, charcoal, and later coal. The whaling-related businesses, which increased in the second half of the 19th century, were the most likely source of PAHs in the lower harbor sediment. By the late 1950s, the concentration of PAHs had started to decrease.
Time lag in upper harbor About 100 years later, in the early 1900s, copper, lead, and PAHs were found to be significantly above background level in the upper harbor cores (Fig. 18). By this time, textile mills and other industries had been built on the shores of the upper harbor (Fig.19). These industries were the most likely source of the contaminants found in upper harbor sediments. The timing of the appearance of contaminants in the sediments followed the development along the shores of New Bedford Harbor: first appearing in the lower harbor where the initial development of wharfs and whaling-related industries occurred, and then later in the upper harbor when the textile mills and other businesses located along that shore.
PCBs in cores PCBs, chemicals which were manufactured for the first time in 1929 (they don’t occur naturally), showed up initially in the upper harbor (near Aerovox, the source of PCBs) in the late 1930s, and in the lower harbor in the early 1940s (Fig. 20). With the uncertainty of dating sediment cores, this difference in dates between upper and lower harbor may not be real. When PCBs enter the harbor waters they are quickly adsorbed onto sediment particles. Sediment particles can be moved by the outgoing tide, settle to the bottom, get resuspended, and then moved further down the harbor (see Fig.13 for distribution of PCBs in harbor).
Sediment profiles show effect of environmental regulations Concentrations of all contaminants measured in this study increased greatly after the turn of the 20th century. After environmental regulations were instituted in the 1970s, concentrations of these contaminants started to decrease, but were still substantially elevated (Fig. 18). The top of the core taken in the lower harbor was apparently lost (perhaps when coring), because the surface slice of the core dates to the middle 1970s, so a decrease is not seen in the concentrations of copper, lead, or PCBs (Fig 16). In the lower harbor, concentrations of PAHs started to decrease in the late 1950s.
Summary The sediment profiles of contaminants in New Bedford Harbor record the history of pollution in the harbor. The increase in contaminants first appeared in the lower harbor sediments adjacent to the area of initial development. Later as development spread northward to the shores of the upper harbor, contaminants appeared in the upper harbor sediments. Contaminants increased with the urbanization of the New Bedford Harbor watershed. With the implementation of environmental legislation in the 1970s, the concentrations of contaminants started to decrease.