Detection of reproductive impacts of effluents from pulp and paper mills: Shifts in issues and potential causes

Triterpene betulin may be involved in the acute effects of pulp and paper mill effluent on testis physiology in zebrafish

Pulp and paper mill effluent can cause changes in the morphology and energy metabolism in the zebrafish (Danio rerio) testis. Betulin, a naturally occurring triterpene is commonly present in this type of effluent and is suspected of being involved in these effects. The aim of this study was to compare the effects pulp and paper mill effluent and betulin on various aspects of testicular physiology in the zebrafish. This included the in vitro effects of effluent and betulin on testicular lactate content and lactate dehydrogenase (LDH) activity. In addition, the effects of betulin on glucose uptake, glycogen, alanine aminotransferase (ALT), reactive oxygen and nitrogen species formation and oxidative damage in the testes were determined. Furthermore, we compared the effects and mechanism of action of betulin and effluent on calcium homeostasis in testes. In vitro exposure to both effluent and betulin decreased lactate and calcium influx, possibly due to the activation of the sodium‑calcium exchanger (NCX) pump. Additionally, betulin-treated testes had higher reactive oxygen species (ROS) and reduced glutathione (GSH) content, as well as increased glutathione transferase (GST) activity and a tendency towards decreased catalase (CAT) activity. Thus, this study shows that alterations in testis physiology caused by the pulp and paper mill effluent in the testis may be due in part to the actions of betulin.

Characterization and spatial distribution of organic-contaminated sediment derived from historical industrial effluents

Organic sediment contaminants [polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans (PCDD/Fs), and polycyclic aromatic hydrocarbons (PAHs)] were assessed using secondary monitoring data from a former tidal estuary (Boat Harbour) impacted by historical industrial effluents. Spatiotemporal characterization of PCDD/Fs and PAHs in sediments was conducted to inform a sediment remediation program designed to return this contaminated aquatic site back to a tidal lagoon. Spatiotemporal variations of sediment PCDD/F and PAH concentrations across Boat Harbour and off-site reference locations were assessed using secondary monitoring data collected between 1992 and 2015. Sediment PCDD/F toxic equivalency (TEQ) and PAH concentrations were compared to sediment quality guidelines. Sediment PCDD/F concentrations exceeded the highest effect thresholds posing severe ecological health risks. High sediment PCDD/F concentrations have persisted in Boat Harbour despite implementation of Pulp and Paper Mill Effluent Chlorinated Dioxins and Furans Regulations in 1992. PAH concentrations varied greatly. Five individual PAH compounds frequently exceeded severe effect thresholds, in contrast to total PAHs, which were below severe effect thresholds. Forensic analysis using PAH diagnostic ratios suggests pyrogenic PAHs derived from wood processes or coal combustion were likely sources. Twenty-five years of monitoring data revealed large data gaps in our understanding of sediment characteristics in Boat Harbour. Gaps included spatial (vertical and horizontal) and temporal variations, presenting challenges for remediation to accurately delineate sediment contaminants. Deeper horizons were poorly characterized compared to shallow sediments (0-15 cm). Historical secondary monitoring data showed that spatial coverage across Boat Harbour was inadequate. Due to severe ecological health risks associated with high sediment PCDD/F concentrations, remediation of the entire sediment inventory is recommended. Detailed vertical and horizontal sampling within Boat Harbour, establishment of local baseline concentrations, and additional sampling in down-gradient-receiving environments for a suite of contaminants are required to better characterize sediments prior to remediation.

Spatiotemporal assessment (quarter century) of pulp mill metal(loid) contaminated sediment to inform remediation decisions

A bleached kraft pulp mill in Nova Scotia has discharged effluent wastewater into Boat Harbour, a former tidal estuary within Pictou Landing First Nation since 1967. Fifty years of effluent discharge into Boat Harbour has created >170,000 m³ of unconsolidated sediment, impacted by inorganic and organic contaminants, including metal[loid]s, polycyclic aromatic hydrocarbons (PAHs), dioxins, and furans. This study aimed to characterize metal(loid)-impacted sediments to inform decisions for a $89 million CAD sediment remediation program. The remediation goals are to return this impacted aquatic site to pre-mill tidal conditions. To understand historical sediment characteristics, spatiotemporal variation covering ~quarter century, of metal(loid) sediment concentrations across 103 Boat Harbour samples from 81 stations and four reference locations, were assessed by reviewing secondary data from 1992 to 2015. Metal(loid) sediment concentrations were compared to current Canadian freshwater and marine sediment quality guidelines (SQGs). Seven metal(loid)s, As, Cd, Cr, Cu, Pb, Hg, and Zn, exceeded low effect freshwater and marine SQGs; six, As, Cd, Cr, Pb, Hg, and Zn, exceeded severe effect freshwater SQGs; and four, Cd, Cu, Hg, and Zn, exceeded severe effect marine SQGs. Metal(loid) concentrations varied widely across three distinct temporal periods. Significantly higher Cd, Cu, Pb, Hg, and Zn concentrations were measured between 1998 and 2000, compared to earlier, 1992-1996 and more recent 2003-2015 data. Most samples, 69%, were shallow (0-15 cm), leaving deeper horizons under-characterized. Geographic information system (GIS) techniques also revealed inadequate spatial coverage, presenting challenges for remedy decisions regarding vertical and horizontal delineation of contaminants. Review of historical monitoring data revealed that gaps still exist in our understanding of sediment characteristics in Boat Harbour, including spatial, vertical and horizontal, and temporal variation of sediment contamination. To help return Boat Harbour to a tidal estuary, more detailed sampling is required to better characterize these sediments and to establish appropriate reference (background) concentrations to help develop cost-effective remediation approaches for this decades-old problem.

Identification of characteristic organic contaminants in wastewaters from modern paper production sites and subsequent tracing in a river

The paper industry is one of the most significant industrial branches that contributes to water pollution. Recent studies regarding the chemical composition of wastewaters from modern paper production sites are sparse, and organic contaminants originating from this source may remain undetected and uncontrolled. Therefore, for this study, non-target screening analyses of wastewaters from five different paper production sites were performed, including an extended analysis of one facility, for the identification of volatile non-polar to semi-polar organic contaminants. The identified contaminants were also traced in the adjacent river. Several specific agents related to paper production, including photoinitiators, ink and thermal paper constituents, were present in most wastewaters and were therefore considered to be characteristic paper industry contaminants. A couple of contaminants identified in this study are being reported for the first time and might be toxic, but have been neglected in previous studies. Bisphenol A and 2,4,7,9-tetramethyl-5-decyne-4,7-diol were found in untreated wastewaters, treated wastewater and in river water. Bisphenol A was present in river water downstream from where the paper industry discharges at a concentration that was reported to affect the reproduction of gastropods. Thus, our findings imply that paper industry discharges pose a risk to the populations of sensitive macroinvertebrates.

Assessment of public perception and environmental compliance at a pulp and paper facility: a Canadian case study

Communities across Canada rely heavily on natural resources for their livelihoods. One such community in Pictou County, Nova Scotia, has both benefited and suffered, because of its proximity to a pulp and paper mill (currently owned by Northern Pulp). Since production began in 1967, there have been increasing impacts to the local environment and human health. Environmental reports funded by the mill were reviewed and compared against provincial and federal regulatory compliance standards. Reports contrasted starkly to societal perceptions of local impacts and independent studies. Most environmental monitoring reports funded by the mill indicate some levels of compliance in atmospheric and effluent emissions, but when compliance targets were not met, there was a lack of regulatory enforcement. After decades of local pollution impacts and lack of environmental compliance, corporate social responsibility initiatives need implementing for the mill to maintain its social licence to operate.

Sources, concentrations, and exposure effects of environmental gestagens on fish and other aquatic wildlife, with an emphasis on reproduction

Fish and other aquatic wildlife, including frogs, turtles, and alligators, have been used as vertebrate sentinels for the effects of endocrine disrupting and other emerging chemicals of concern found in aquatic ecosystems. Research has focused on the effects of estrogenic, androgenic, and thyroidogenic compounds, but there is a growing body of literature on the reproductive health exposure effects of environmental gestagens on aquatic wildlife. Gestagens include native progestogens, such as progesterone, and synthetic progestins, such as gestodene and levonorgestrel, which bind progesterone receptors and have critically important roles in vertebrate physiology, especially reproduction. Roles for progestogen include regulating gamete maturation and orchestrating reproductive behavior, both as circulating hormones and as secreted pheromones. Gestagens enter the aquatic environment through paper mill effluent, wastewater treatment plant effluent, and agricultural runoff. A number of gestagens have been shown to negatively affect reproduction, development, and behavior of exposed fish and other aquatic wildlife at ng/L concentrations, and these compounds have been measured in the environment at single to 375 ng/L. Given the importance of endogenous progestogens in the regulation of gametogenesis, secondary sex characteristics, and reproductive behavior in vertebrates and the documented exposure effects of pharmaceutical progestins and progesterone, environmental gestagens are an emerging class of contaminants that deserve increased attention from researchers and regulators alike. The potential for environmental gestagens to affect the reproductive health of aquatic vertebrates seems evident, but there are a number of important questions for researchers to address in this nascent field. These include identifying biomarkers of gestagen exposure; testing the effects of environmentally relevant mixtures; and determining what other physiological endpoints and taxa might be affected by exposure to environmental gestagens.