Introduction

Contaminants of emerging concern (CECs) are either compounds newly introduced into the environment or those that may have been in the environment for years but are just now able to be sampled with current laboratory analytical methods. Natural compounds, such as hormones, and man-made compounds, such as pharmaceuticals, can both be considered CECs. CECs include many categories of compounds. In 2013, Pennsylvania initiated a study of CECs in sediment. Samples have been collected at many sites across the state. This summary encompasses CEC sediment results from 2013 through 2017. A detailed report and data are located on DEP’s website at https://www.dep.pa.gov/Business/Water/CleanWater/WaterQuality/Pages/CECs.aspx at “Sediment Analyses 2013 - 2017” and “Sediment Data 2013 - 2017”.

Methods Summary

Data Collection Protocols

Sediment samples were collected according to DEP’s Sediment Chemistry Data Collection Protocol (Williams 2017) and analyzed for a variety of naturally-occurring metals and hormones, and anthropogenic contaminants, including pesticides, PCBs, wastewater indicator compounds, and hormones.

Sediment was collected at 87 sites throughout Pennsylvania from 2013 through 2017. Typically, sites sampled in any given year were sampled over multiple seasons to allow for seasonal comparisons. Some sites were designated as core sites and were sampled over multiple years.

Use the interactive map below to view each sediment site and information about that site.

Explanatory Variable Analyses

Canonical correspondence analyses (CCAs) were done on anthropogenic, natural, and rock type variables versus concentrations. Anthropogenic variables (percent forested land cover, percent agricultural land cover, and percent developed land cover), natural variables (drainage area, flow, and season), and rock type (dominant lithology and ecoregion) were analyzed as separate variable groups due to their differing influences on contamination. Natural variables were not grouped per watershed since those variables were site specific (flow, drainage area) or independent of watershed boundary (season). Rock and ecoregion variables were only included for metals analyses.

Results

Distribution and Occurrence

From 2013 through 2017, 202 compounds were tested from various CEC groups. The majority of sample results, 72%, were non-detect. However, a large portion of compounds tested were detected at least once (115 out of 202 compounds). Specifically, wastewater compounds, PAHs, metals, and hormones were detected frequently when tested for. Pesticides and PCBs were detected the least frequently. Explore the map below to view percent of compounds detected in different compound categories, per sample. Note: Dots located at a site represent the general area of sampling; locations of dots are jiggled at a site so they do not overlap and are visible.

The table below lists common compounds that were detected greater than 90% of the time in samples.

Compounds Detected >90% of Time, 2013 - 2017
Analyte	Description
Current Pesticide
1-naphthol	metabolite of insecticide carbaryl and photooxidation of naphthalene; used in agrochemical production
Hormone
Cholesterol	ubiquitous, natural sterol produced by animals & plants
Metal
Aluminum
Barium
Calcium
Chromium
Copper
Iron
Lead
Magnesium
Manganese
Nickel
Potassium
Strontium
Zinc
PAH
2,6-dimethylnaphthalene	present in diesel/kerosene (trace in gasoline)
Anthracene	wood preservative, component of coal, tar, diesel, or crude oil
Anthraquinone	coal, manufacturing of dye/textiles, seed treatment, bird repellent
Benzo[a]pyrene	regulated PAH, found in coal tar, tobacco smoke
Fluoranthene	component of coal tar & asphalt (only traces in gasoline or diesel fuel)
Phenanthrene	manufacturing explosives, component of tar, diesel fuel, or crude oil
Pyrene	component of coal tar & asphalt (only traces in gasoline or diesel fuel)
Wastewater
3-methyl-1(h)-indole (skatol)	odor in feces, coal tar; fragrance
Beta-sitosterol	plant sterol
Carbazole	insecticide; manufacturing of dyes, explosives, lubricants; tobacco; coal
Indole	fragrance compound (in coffee); inert ingredient in pesticide; coal
p-cresol	wood preservative; coal

Effects of Explanatory Variables on Sediment Concentrations

Sites were grouped based on the size of the watershed upstream of the sample location. Watersheds were organized into two groups, those >1000 square miles (large drainage areas) and those <1000 square miles (small drainage areas). Analyses were also grouped by early (2013 - 2015) and later (2016 - 2017) datasets if there were differences in testing between these time periods.

Canonical correspondence analyses (CCAs) were done on the anthropogenic, natural, and rock type variables versus concentrations. Several results were statistically significant, although in many cases CCA was not a strong predictor:

Hormone concentrations (anthropogenic variables, large watersheds, 2013 - 2015) were most strongly predicted by percent agricultural land.
Hormone concentrations (anthropogenic variables, small watersheds, 2016 - 2017) were most strongly predicted by percent forested land.
Hormones & wastewater indicator concentrations (natural variables, all watersheds, 2013 - 2015) were most strongly predicted by flow and drainage area.
Wastewater indicator concentrations (anthropogenic variables, small watersheds, all years) were most strongly predicted by percent forested and percent agricultural land.
Wastewater indicator concentrations (anthropogenic variables, large watersheds, all years) were most strongly predicted by percent agricultural land.
Metal concentrations (anthropogenic variables, small watersheds, all years) did not have one variable stronger than others.
Metal concentrations (anthropogenic variables, large watersheds, all years) were most strongly predicted by percent developed land.
Metal concentrations (natural variables, all watersheds, all years) were most strongly predicted by drainage area.
Metal concentrations (rock/ecoregion variables, all watersheds, all years) were most strongly predicted by ecoregion.

Discussion

DEP’s CEC sediment data collection efforts from 2013 through 2017 resulted in detection of 115 of 202 analytes tested across 87 sites. Although 72% of all individual sample results were non-detect, the results indicate that sediment contamination for various analytes, including historical and currently used compounds, is a water quality concern that needs to continue to be monitored and evaluated. More specifically, wastewater compounds, PAHs, metals, and hormones were most frequently detected. Pesticides and PCBs were least frequently detected. CCAs in this study showed varying influences of anthropogenic and natural variables on analyte groups in sediment. Agricultural land cover was related to concentrations in several of the analyses; however, in general, agricultural land cover was not a good predictor of sediment CEC concentrations.

It is recommended that sediment monitoring efforts continue and expand, and that steps are taken to better understand and acknowledge sediment contamination in the development and implementation of water quality standards. Sediment contamination could assist in determining impairment causes in stream aquatic life assessments. Studies on sediment contaminants could be targeted and contaminant-specific, to determine the extent of contamination in surface waters. In addition, DEP will keep up with the current literature documenting effects of sediment contamination on aquatic biota. In the future, sediment sampling could prove to be useful and commonplace in DEP’s work to monitor, assess, restore, and protect water quality in Pennsylvania.

Literature Cited

Williams, A. 2017. Sediment chemistry data collection protocol. Chapter 4.4 in Water Quality Monitoring Protocols for Streams and Rivers (2021). Pennsylvania Department of Environmental Protection. Harrisburg, Pennsylvania.