Jerome M. Diamond

Characterizing and Comparing Bioassessment Methods and Their Results: A Perspective

Most of the many bioassessment methods currently in use in the United States produce data of unknown quality. The results are: 1) uncertainty as to which methods yield accurate information for a given type of site, and 2) missed opportunities to share data among different programs or organizations having potentially comparable methods and data quality. Using a performance-based methods system (PBMS) and benthic macroinvertebrate assessment methods as examples, we offer a framework for characterizing the data quality achieved by a collection-and-analysis method and for determining the comparability of different methods. This framework incorporates 3 steps that: 1) quantify method precision and bias for a single site, using different field personnel and different site classes; 2) quantify method precision, bias, and performance range using multiple reference sites within at least 2 different site classes; and 3) quantify method sensitivity, bias, performance range, and--indirectly--accuracy, using test sites (with different levels or types of probable impairment) as well as reference sites. Comparability of methods is judged by the degree of similarity in their performance characteristics rather than in their respective scores or metric values. The PBMS framework could yield several benefits including: documentation of personnel training in the field; realistic requirements for data quality in bioassessment methods so that information gathered is likely to meet program or project needs; greater flexibility in choice of method used; refinement of methods by agencies responsible for long-term monitoring without the loss of historical data; and more sharing of bioassessment information across political boundaries, thus reducing duplication of efforts.

Prioritizing contaminants of emerging concern for ecological screening assessments

More than 40,000 organic chemicals have been identified as contaminants of emerging concern (CECs). Compared to population numbers and national debts, this may not initially appear to be a staggering number; yet, when considering rapid and often unbridled advances in technology, manufacturing, and agricultural practices worldwide—all of which use and then discard waste into the environment—the number takes on more meaning. Even exhaled human breath includes a few hundred volatile organic compounds. Indeed, thousands of organic chemicals are produced or imported annually into the U.S. and other industrialized nations. Furthermore, 40,000 is a conservative estimate that does not account for associated break-down products in the environment.

Toxicity of cobalt to freshwater indicator species as a function of water hardness

Abstract Although generally rare in natural aquatic systems, cobalt concentrations can be elevated through ore and coal mining operations and discharges of certain textile dyes. The U.S. Environmental Protection Agency does not have an ambient water quality criterion for cobalt due to a lack of toxicological data. The present study determined whether freshwater acute and chronic cobalt toxicity were dependent on dilution water hardness. We specifically examined the relative toxicity of cobalt at high water hardness (≥ 200 mg/l as CaCO3) because cobalt often occurs in carbonate ores. Acute and chronic toxicity tests using both Ceriodaphnia dubia and Pimephales promelas were performed using four different synthetic waters: 50,200. 400, and 800 mg/l hardness as CaCO3. Diluent hardness appeared to have no effect on measured cobalt concentrations. Dissolved cobalt in water samples during testing was similar to the corresponding total recoverable cobalt in this study suggesting that most of the cobalt was in a soluble and presumably bioavailable form. LC50 values for P. promelas could not be calculated owing to their low sensitivity to high cobalt concentrations (≥ 5 mg/l) over a 48 h period. Regression analysis of P. promelas acute NOEC values and test water hardness indicated an R2 = 0.94 suggesting a direct relationship between water hardness and acute toxicity to cobalt for this species. C. dubia acute tests indicated water hardness effects after 48 h of exposure and non-linear dose responses in hard water (≥ 200 mg/l). Regression analysis of C. dubia 24 h LC50 values and test water hardness indicated an R2 = 0.91. For both cases, a simple power function gave the best regression fit. C. dubia appeared to be more sensitive than P. promelas at hardness ≥ 200 mg/l but the reverse was true in soft water ( ≤ 50 mg/l). The 7 d P. promelas chronic NOEC increased from 1232 μg/l cobalt (50 mg/l hardness) to ≥ 3833 μg/l (800 mg/l hardness). Effects were on fish survival and not growth. Regression analysis yielded an R2 = 0.97 based on the fish survival NOECs and the natural log of hardness. C. dubia chronic tests were inconclusive due to poor survival and reproduction in the synthetic waters. Available data suggest that within 50–200 mg/l water hardness, cobalt acute toxicily is inversely related to water hardness. Tentative cobalt acute criteria, based on power functions, are 288 μg/l and 873 μg/l for soft and hard water, respectively. Available chronic toxicity data suggest that daphnids are more sensitive to cobalt than other genera. Chronic endpoints for both P. promelus and D. magna were similar in soft and hard water (≤ 400 mg/l hardness) suggesting that chronic toxicity is not hardness-dependent over this range. However, chronic cndpoints at 800 mg/l hardness were 3.1 and ≥ 12 times higher than endpoints observed under soft water conditions for P. promelas and C. dubia respectively suggesting that very hard waters may significantly reduce chronic toxicity potential of cobalt.

Use of man-made impoundment in mitigating acid mine drainage in the North Branch Potomac River

The US Department of the Army, Baltimore District Corps of Engineers, oversees a long-term monitoring study to assess and evaluate effects of the Jennings-Randolph reservoir on biota in the North Branch Potomac River. The reservoir was intended, in part, to mitigate effects of acid mine drainage originating in upstream and headwater areas. The present study assessed recovery of benthos and fish in this system, six years after completion of the reservoir. Higher pH and lower iron and sulfate concentrations were observed upstream of the reservoir compared to preimpoundment conditions, suggesting better overall water quality in the upper North Branch. Water quality improved slightly directly downstream of the reservoir. However, the reservoir itself was poorly colonized by macrophytes and benthic organisms, and plankton composition suggested either metal toxicity and/or nutrient limitation. One large tributary to the North Branch and the reservoir (Stony River) was shown to have high (and possibly toxic) levels of manganese, iron, zinc, and aluminum due to subsurface coal mine drainage. Macroinvertebrate diversity and number of taxa were higher in sites downstream of the reservoir in the present study. Compared with previous years, the present study suggested relatively rapid recovery in the lower North Branch due to colonization from two major unimpacted tributaries in this system: Savage River and South Branch Potomac. Abundance of certain mayfly species across sites provided the most clear evidence of longitudinal gradients in water quality parameters and geomorphology. Fish data were consistent with macroinvertebrate results, but site-to-site variation in species composition was greater. Data collected between 1982 and 1987 suggested that certain fish species have unsuccessfully attempted to colonize sites directly downstream of the reservoir despite the more neutral pH water there. Our results show that recovery of biota in the North Branch Potomac was attributed to decreased acid inputs from mining operations and dilution from the Savage River, which contributed better water quality. Continued improvement of North Branch Potomac biota may not be expected unless additional mitigation attempts, either within the reservoir or upstream, are undertaken.

Use of prospective and retrospective risk assessment methods that simplify chemical mixtures associated with treated domestic wastewater discharges

A framework is presented that is intended to facilitate the evaluation of potential aquatic ecological risks resulting from discharges of down-the-drain chemicals. A scenario is presented using representatives of many of the types of chemicals that are treated domestically. Predicted environmental chemical concentrations are based on reported loading rates and routine removal rates for 3 types of treatment: trickling filter, activated sludge secondary treatment, and activated sludge plus advanced oxidation process as well as instream effluent dilution. In tier I, predicted effluent concentrations were compared with the lowest predicted-no-effect concentration (PNEC) obtained from the literature using safety factors as needed. A cumulative risk characterization ratio (cumRCR) < 1.0 indicates that risk is unlikely and no further action is needed. Otherwise, a tier 2 assessment is used, in which PNECs are based on trophic level. If tier 2 indicates a possible risk, then a retrospective assessment is recommended. In tier 1, the cumRCR was > 1.0 for all 3 treatment types in our scenario, even though no chemical exceeded a hazard quotient of 1.0 in activated sludge or advanced oxidation process. In tier 2, activated sludge yielded a lower cumRCR than trickling filter because of higher removal rates, and the cumRCR in the advanced oxidation process was << 1.0. Based on the maximum cumulative risk ratio (MCR), more than one-third of the predicted risk was accounted for by one chemical, and at least 90% was accounted for by 3 chemicals, indicating that few chemicals influenced the mixture risk in our scenario. We show how a retrospective assessment can test whether certain chemicals hypothesized as potential drivers in the prospective assessment could have, or are having, deleterious effects on aquatic life. Environ Toxicol Chem 2018;37:690-702.

Prospective mixture risk assessment and management prioritizations for river catchments with diverse land uses

Abstract Ecological risk assessment increasingly focuses on risks from chemical mixtures and multiple stressors because ecosystems are commonly exposed to a plethora of contaminants and nonchemical stressors. To simplify the task of assessing potential mixture effects, we explored 3 land use–related chemical emission scenarios. We applied a tiered methodology to judge the implications of the emissions of chemicals from agricultural practices, domestic discharges, and urban runoff in a quantitative model. The results showed land use–dependent mixture exposures, clearly discriminating downstream effects of land uses, with unique chemical “signatures” regarding composition, concentration, and temporal patterns. Associated risks were characterized in relation to the land‐use scenarios. Comparisons to measured environmental concentrations and predicted impacts showed relatively good similarity. The results suggest that the land uses imply exceedances of regulatory protective environmental quality standards, varying over time in relation to rain events and associated flow and dilution variation. Higher‐tier analyses using ecotoxicological effect criteria confirmed that species assemblages may be affected by exposures exceeding no‐effect levels and that mixture exposure could be associated with predicted species loss under certain situations. The model outcomes can inform various types of prioritization to support risk management, including a ranking across land uses as a whole, a ranking on characteristics of exposure times and frequencies, and various rankings of the relative role of individual chemicals. Though all results are based on in silico assessments, the prospective land use–based approach applied in the present study yields useful insights for simplifying and assessing potential ecological risks of chemical mixtures and can therefore be useful for catchment‐management decisions. Environ Toxicol Chem 2018;37:715–728.

Whole Effluent Toxicity Testing:Study Plan for Field Validation

Under the National Pollution Discharge Elimination System (NPDES), many municipal and industrial wastewater treatment facilities must perform Whole Effluent Toxicity (WET) Testing. Regulatory agencies determine the level of compliance of each facility by making inferences about the results of these tests. There has been some concern regarding appropriate ways to integrate WET tests into NPDES permits. The central issue of this concern involves determining the relationship between WET tests and instream biological conditions. Previous research (WERF project 95-HHE-1) has examined this issue using historical data. Because of issues with data comparability, i.e. questionable data quality, and project design, results were inconclusive. This study plan was designed to collect new data on method performance for both WET and bioassessment that would help answer the outstanding question. The study plan was designed using a Data Quality Objective (DQO) approach in which DQOs and MQOs were defined. These DQOs and MQOs were characterized using technical input from many scientists from federal, state, and private organizations. It was through this effort that certain technical design issues arose that needed further investigation before implementing the definitive study. Among these issues were determining if DQOs and MQOs were achievable, and determining appropriate biological assessment methods for various ecoregions (e.g. effluent dependent streams in the arid west). In order to appropriately address these issues, it was determined that a pilot study would be implemented before the definitive study. The pilot study is designed as a one-year study in which participating facilities will perform quarterly WET tests (Ceriodaphnia, P. promelas, Selenastrum) and at least one bioassessment (macroinvertebrate, fish, algae) as well as providing other prescribed data requirements. Results of the pilot will provide answers to technique design issues and will ultimately determine the most appropriate study design for the definitive study. This title belongs to WERF Research Report Series ISBN: 9781843396673 (Print) ISBN: 9781780403182 (eBook)

Effluent Limits for Fluctuating Discharges: Phase II - Alternate Frameworks for Water Quality Criteria

This research evaluated appropriate methodologies to calculate water quality criteria for exposure concentrations that vary in frequency, magnitude and duration. We reviewed over 30 toxicological studies that used either time-dose response or pulsed/intermittent exposure designs representing over 15 contaminants and 10 species. Most of these studies were conducted using freshwater species. Many workers demonstrated a relationship between organism response and internal contaminant concentration, independent of the exposure regime. Internal contaminant concentration has been used to predict organism responses in various models. Results of many laboratory studies indicate that for brief, episodic or high magnitude pollutant events, higher acute toxicity (or lower LC50s), is likely as compared to that predicted based on the averaged or long-term concentration. Our literature search, and evaluation of five case studies, revealed some cautions in using chemical benchmark (criteria) values and simple worst case dilution analysis to evaluate effluent compliance. Our results indicate that magnitude or peak concentration, not duration above a certain threshold, was most important in predicting chronic toxicity to Ceriodaphnia. The relatively infrequent pollutant monitoring in National Pollutant Discharge Elimination System (NPDES) permits, and the general lack of instream contaminant data, means that chemical exceedance duration, or a time-integration approach to permit compliance, is unlikely if not infeasible. Analysis of case studies illustrated the difficulties in using real world data to test alternate criteria approaches. To help address this problem, we designed and conducted several pulsed exposure chronic toxicity tests (based on standard EPA protocols), using Ceriodaphnia and fathead minnow. Testing used copper, acid (nitric), cadmium, sodium chloride, and Chlorpyrifos, all of which occur in wastewater effluents. For many of these chemicals, we observed little difference in acute and chronic toxicity thresholds, as measured by standard toxicity tests on sensitive species. This means that permit exceedences with a magnitude <5 times the chronic limit, may not yield chronic biological effects if relatively short in duration (<2 days). Furthermore, multiple exceedences of a chronic limit may not result in discernable biological effects or biological effects will be predictable based upon expected effects of each exceedance individually. Simulation modeling indicated that both mortality and biomass results from chronic fathead minnow tests and cadmium were well described by an extended Mancini-Breck model, which was developed for acute toxicity effects. Thus, for a number of common wastewater pollutants, a kinetics-based approach to criteria may be a reasonable and worthwhile goal. However, fluctuations close to the chronic limit may not have systematic effects because exposures are within the error limits of chronic test methods. Our research suggests that wastewater plants may have much to gain by implementing front-end equalization because: (1) it will reduce final effluent chemical fluctuations and therefore, permit exceedences; and (2) a more consistent quality effluent means a lower coefficient of variation for chemical concentration over time, which could, using a statistical approach to deriving permit limits, translate to a higher effluent limit. This title belongs to WERF Research Report Series ISBN: 9781843396499 (Print) ISBN: 9781780403205 (eBook)

Evaluation of WET Testing as an Indicator of Aquatic Health

This project evaluated the quality of data needed to determine relationships between chronic Whole Effluent Toxicity (WET) test results and instream biological condition. A data quality objectives approach was used, which included several proposed measurement quality objectives (MQOs) that specified desired precision, bias, and sensitivity of methods used. Six facilities (four eastern and two western U.S.) participated in this study, all having design effluent concentrations > 60% of the stream flow. In accordance with a Quality Assurance Project Plan most of the facilities completed four quarters of chronic Ceriodaphnia dubia, and Pimephales promelas (fathead minnow) WET tests, and three quarters of Selenastrum capricornutum (green algae) WET testing following the most recent USEPA methods. Several other WET tests were conducted to address MQOs including splits, duplicates, and blind positive and negative controls. Macroinvertebrate, fish, and periphyton bioassessments were conducted at multiple locations up and downstream of each facility following the most recent USEPA Office of Water bioassessment protocols. Test acceptance criteria were met for most WET tests, however, this study demonstrated the need to incorporate other MQOs in a full study (such as minimum and maximum percent significant differences and performance on blind samples) to ensure accurate interpretation of effluent toxicity. More false positives, lower test endpoint (i.e., higher toxicity), and more “failed” (non-compliant) tests were observed using No Observed Effect Concentrations (NOEC) as compared to IC25s (concentration causing = 25% decrease in organism response compared to controls). Algae tests often yielded the most effluent toxicity in this study, however, this test was most susceptible to false positives and high inter-laboratory variability. WET test results exhibited few relationships with bioassessment results, even when incorporating actual effluent dilution. Neither frequency of WET non-compliance nor magnitude of WET were clearly related to differences in biological condition up and downstream of a discharge for the most part. Macroinvertebrate assessments were most able to discriminate small changes downstream of the effluent, followed by periphyton and then fish. The sampling methods used were robust but a full study should collect more field replicates up and downstream of each discharge to increase detection power. Macroinvertebrate and periphyton assessments together appeared to be sufficient to address project objectives. Fish assessments could be useful as well but would entail more effort and cost per site than expended in this project to be useful. This title belongs to WERF Research Report Series ISBN: 9781843397687 (Print) ISBN: 9781780403793 (eBook)