Thomas Belton

Levels and patterns of PCDD and PCDF contamination in fish, crabs, and lobsters from Newark Bay and the New York Bight

Abstract Samples of striped bass, crabs and lobsters were collected in Newark Bay and the New York Bight. The fish muscle and the hepatopancreas and meat from the crabs were subjected to congener specific analysis. All samples were found to be contaminated by 2,3,7,8-tetraCDD and a series of other highly hazardous 2,3,7,8-substituted congeners as well as less hazardous PCDDs and PCDFs. A value exceeding 6000 ppt wet tissue weight of 2,3,7,8-tetraCDD was found in a sample of crab hepatopancreas, which seems to be the highest value so far reported in a food product. The crab meat, on the other hand, contained only 100 ppt. In general the crustaceans contained many congeners, while the fish samples contained only 2,3,7,8-substituted compounds. An unknown compound, possibly a tetrachlorodibenzothiophene, was the dominating peak in most of the crustacean samples.

Managing the Risks of Toxic Exposure

Recent studies have shown that consumption of contaminated fish may be one of the major exposure pathways for environmental toxins in urban populations. In 1976, concerned by the discovery of broad-range polychlorinated biphenyl (PCB) contamination of fish and sediments in the upper Hudson River in New York State, the New Jersey Department of Environmental Protection (DEP) instituted a monitoring program to survey the possibility of similar PCB contamination for finfish and shellfish within the lower Hudson River and throughout the rest of the state. The project was designed with three main objectives: to determine the degree to which aquatic organisms were contaminated, to determine how PCB levels in fish vary with geography, and to assess the suitability of the fish for human consumption.

A diatom-based biological condition gradient (BCG) approach for assessing impairment and developing nutrient criteria for streams.

Over-enrichment leading to excess algal growth is a major problem in rivers and streams. Regulations to protect streams typically incorporate nutrient criteria, concentrations of phosphorus and nitrogen that should not be exceeded in order to protect biological communities. A major challenge has been to develop an approach for both categorizing streams based on their biological conditions and determining scientifically defensible nutrient criteria to protect the biotic integrity of streams in those categories. To address this challenge, we applied the Biological Condition Gradient (BCG) approach to stream diatom assemblages to develop a system for categorizing sites by level of impairment, and then examined the related nutrient concentrations to identify potential nutrient criteria. The six levels of the BCG represent a range of ecological conditions from natural (1) to highly disturbed (6). A group of diatom experts developed a set of rules and a model to assign sites to these levels based on their diatom assemblages. To identify potential numeric nutrient criteria, we explored the relation of assigned BCG levels to nutrient concentrations, other anthropogenic stressors, and possible confounding variables using data for stream sites in New Jersey (n=42) and in surrounding Mid-Atlantic states, USA (n=1443). In both data sets, BCG levels correlated most strongly with total phosphorus and the percentage of forest in the watershed, but were independent of pH. We applied Threshold Indicator Taxa Analysis (TITAN) to determine change-points in the diatom assemblages along the BCG gradient. In both data sets, statistically significant diatom changes occurred between BCG levels 3 and 4. Sites with BCG levels 1 to 3 were dominated by species that grow attached to surfaces, while sites with BCG scores of 4 and above were characterized by motile diatoms. The diatom change-point corresponded with a total phosphorus concentration of about 50μg/L.

Validation of a Macroinvertebrate-Based Index of Nutrient Status in Streams Using Macroinvertebrate, Water-Chemistry, and Diatom Data

Abstract Determination of the causes of water-impairment is a critical part of bioassessment, and it is useful to be able to infer causes from the same sampling data used to assess the impairment. Determination of excess nutrient inputs to a waterbody as a cause of impairment is especially important because of the severity and ubiquity of nutrient-related water-quality problems nationwide. To that end, we tested and validated in New Jersey waters a macroinvertebrate-based nutrient biotic index (NBI) for phosphorus and nitrogen developed by the New York State Department of Environmental Conservation (NYSDEC). We used macroinvertebrate, water-chemistry, and diatom data from New Jersey streams collected in the state biomonitoring program and a study of diatom—nutrient relationships. We calculated tolerance values for widespread taxa based on frequency of occurrence in samples from sites with a range of nutrient concentrations. The NBI of a sample was calculated as a sum of the tolerance values of taxa in a sample weighted by the relative abundances of taxa. We developed tolerance values from the New Jersey data because relatively few taxa present in the New Jersey samples were rated in the New York study. NBIs for the New Jersey data calculated using the New Jersey-based tolerance values were significantly related to nutrient concentrations with correlations similar to, or greater than, those observed in the New York study. For taxa in common, the New Jersey-based tolerance values were only weakly correlated with the analogous New York values. To validate the NBI approach, we calculated NBI scores via a “leave-one-out” procedure for a data set not used to estimate tolerance values. These comparisons yielded statistically significant but weak correlations between the NBIs and nutrient concentrations. Factors that weaken these relationships are related to: (1) the specific data used (e.g., the lack of tolerance values for many taxa in independent data sets and weak temporal matching of macroinvertebrate and nutrient samples), (2) estimation issues (e.g., variability in estimates of tolerance values and NBIs), and (3) problems inherent in the approach (e.g., the effects of other factors on macroinvertebrate relationships). However, for all data sets examined, nitrogen and phosphorus concentrations were positively correlated, as were nitrogen and phosphorus tolerance values for taxa, and nitrogen and phosphorus NBI scores for sites. These correlations need to be considered in the selection of sampling sites for the development of tolerance values, the weighting of taxa in calculation of NBIs, and the interpretation of NBI values for the 2 nutrients.