Towards a systematic method for assessing the impact of chemical pollution on ecosystem services of water systems

Petroleum refinery effluent contribution to chemical mixture toxic pressure in the environment

Petroleum refinery effluents (PRE) are wastewaters from industries associated with oil refining. Within Europe, PREs are regulated through local discharge permits and receive substantial treatment before emission. After treatment, PREs can still contain low levels of various pollutants potentially toxic to organisms. Earlier work, including whole-effluent toxicity assessments, has shown that the toxicity of permitted PREs is often limited. However, the extent to which PREs contribute to chemical pollution already present in the receiving environment is unknown. Therefore, our study aimed to assess the contribution of PREs to mixture toxic pressure in the environment, using the multi-substance potentially affected fraction of species (msPAF) as an indicator. Based on measured chemical concentrations, compiled species sensitivity distributions (SSD) and a mechanistic solubility model, msPAF levels were estimated for undiluted effluents at discharge points and diluted effluents downstream in receiving waters. Median msPAF-chronic and msPAF-acute levels of PREs at discharge points were 74% (P50) and 40% (P95), respectively. The calculated msPAF levels were reduced substantially to <5% downstream for most effluents (82%), indicating low to negligible toxicity of PREs in receiving environments beyond the initial mixing zone. Regardless of differences in endpoints and locations, hydrocarbons (mainly total petroleum hydrocarbons) and inorganics (mainly ammonia) explained at least 85% of the mixture toxic pressure. The msPAF levels of PREs were on average 2.5-4.5 orders of magnitude lower than msPAF levels derived from background pollution levels, suggesting that PREs were minor contributors to the toxic pressure in the environment. This study presents a generic methodology for quantifying the potential toxic pressure of PREs in the environment, identifying hotspots where more effective wastewater treatment could be needed. We explicitly discuss the uncertainties for further refinement and development of the method.

Streambed pollution: A comprehensive review of its sources, eco-hydro-geo-chemical impacts, assessment, and mitigation strategies

Streambeds are an integral part of the river ecosystem. They provide habitat to a vast array of aquatic and benthic organisms as well as facilitate the bio-degradation and transformation of organic matter and vital nutrients. Increasing anthropogenic influence introduces multiple stressors to the stream networks resulting in pollution of streambeds, which in turn, have detrimental effects on the overall stream ecosystem health. There is a huge gap in the current understanding of streambed pollution and its impacts, and the widely practiced streambed pollution mitigation strategies lack a holistic approach. In this comprehensive review, we first synthesize the state-of-the-art knowledge of conventional and emerging forms of contaminants, their overall impacts on stream ecosystem functions, and present future directions to comprehend the problem of streambed pollution. We highlight that fine sediments and plastics (found especially in urban streambeds) are among the major physical pollutants causing streambed pollution and the chemical pollutants generally comprise hydrophobic compounds including various legacy contaminants such as polychlorinated biphenyl (PCB), dichlorodiphenyltrichloroethane (DDT), a wide range of pesticides and a variety of heavy metals. Moreover, in recent years, highly polar and hydrophilic emerging contaminants such as micro-plastics, pharmaceutical waste and personal care products have been identified in riverbeds and streambeds across the world. We stress that the impacts of streambed pollution have been largely studied with discipline-driven perspectives amongst which the ecological impacts have received a lot of attention in the past. To present a comprehensive outlook, this review also synthesizes and discusses most of the understudied hydrological, geomorphological and biochemical impacts of different forms of streambed pollution. Subsequently, we also present a global inventory by compiling information from the published literature to highlight the status of streambed pollution around the globe. In the end, we endorse the positive and negative aspects of the current impact assessment methodologies and also highlight various physical, chemical and biological remediation measures that could be undertaken to alleviate streambed pollution.

The impact of imidacloprid and thiacloprid on the mean species abundance in aquatic ecosystems

Neonicotinoids are currently the most widely used and sold insecticides in the world, providing effective pest control. Risk assessment of these and other pesticides by lab-based indicators is common. Yet, empirically and theoretically underpinning of extrapolation to indicators used in field surveys is severely limited. Consequently, the aim of our study was to quantify the toxicological and ecological impact of the neonicotinoids imidacloprid and thiacloprid to aquatic invertebrates. We derived Species Sensitivity Distributions (SSDs) based on chronic LC₅₀ data and Mean Species Abundance Relationships (MSARs), comparing these lab-based approaches to field data as well. MSARs are changes in mean species abundance (MSA) as a function of chemical exposure, providing insight into the overall decline of a community. The MSA expresses the mean abundance of species in disturbed conditions relative to their abundance in undisturbed habitat. The medians of the SSD of imidacloprid and thiacloprid for the different species were 16.45 μg/L and 26.40 μg/L, respectively. HC₅₀s of the MSAR of imidacloprid and thiacloprid were 4.25 μg/L and 5.12 μg/L, respectively. The three taxonomic groups tested (insects, crustaceans and mollusks) did not differ significantly in sensitivity for imidacloprid and thiacloprid, both according to the SSDs and MSARs derived. Quantile exposure-response curves (99%-tile) were plotted showing the relative abundance (RA) of aquatic invertebrate species at increasing imidacloprid levels. The 99%-tile of the Relative Abundances (RA₉₉) of species and corresponding imidacloprid concentrations monitored in field surveys in the Netherlands was significantly lower than the Potentially Affected Fraction (PAF) calculated from the SSD. Yet, the MSA was similar to the RA₉₉, suggesting that MSAR is an ecologically meaningful relationship for toxic stress estimated from lab data. Future efforts should be directed to additional empirical underpinning as well as determining the relationship of PAF to other metrics for ecosystem diversity and productivity.

New implication of pesticide regulatory management in soils: Average vs ceiling legal limits

To help regulatory agencies better interpret pesticide soil standards (PSSs) and promote pesticide soil regulations, this study revealed new PSS implications by introducing the average (i.e., PSS_AC) and ceiling (i.e., PSS_CC) legal limits of pesticides. The PSS_AC indicates the average legal limit of a pesticide in the soil over a duration (e.g., annual or monthly average), ensuring that no adverse human health effects can occur. The PSS_CC indicates the ceiling legal limit that cannot be exceeded by pesticide concentrations in the soil, which was introduced to comply with pesticide application in real-world scenarios. We introduced the regulatory ceiling factor (RCF) to screen whether a pesticide in the surface soil could be regulated using the PSS_AC and PSS_CC values. The results indicated that except for some pesticides with high lipophilicity and low degradability (e.g., legacy pesticides), many pesticides were eligible to be regulated by both average and ceiling legal limits. In addition, we conducted a case study to evaluate chlorpyrifos soil standards via a four-step regulatory procedure; the results indicated that our new interpretation using the simulated PSS_AC and PSS_CC values of chlorpyrifos demonstrated that most current chlorpyrifos soil standards can protect population health, which is in contrast to the findings of current regulatory studies. Furthermore, based on the new implication of PSSs interpreted in this study, we recommend that regulatory agencies clarify PSSs to avoid confusion and promote cost-efficient remediations, and recommend improving the regulatory communication between environmental agencies and pesticide manufacturers to define a comprehensive policy integrating PSSs and application patterns.

Floodplain soils contamination assessment using the sequential extraction method of heavy metals from past mining activities

Floodplains are among the most precious and threatened ecosystems in the world. The study deals with floodplain soil contamination caused by 8 heavy metals (HMs) (Cd, Co, Cr, Cu, Mo, Ni, Pb, Zn) originating and transported from old mine works along the Štiavnica River in Slovakia. We determined the total HMs content and the HM fractions using BCR sequential extraction method. We selected 12 alluvial sites (AS), two contaminated sites (CS), and one reference site (RS). The sampling points were located within the riparian zones (RZ), arable lands (AL), and grasslands (GL). We confirmed soil contamination by HMs and the related ecological risk by different factors. The contamination by HMs at many AS localities was similar or even higher than at CS localities. The highest contamination factor was calculated for Cu (39.8), followed by Pb (27.4), Zn (18.2), and Cd (7.2). The HMs partitioning in the different fractions at the CS and AS localities revealed that Cd, Zn, and Pb were mainly associated with the exchangeable and reducible fractions, while Cu was mainly associated with the oxidisable fraction. The soil properties were selectively correlated with the HM fractions. Based on the ANOVA results, the effect of different ecosystem types on HM fractions was revealed.

One planet: one health. A call to support the initiative on a global science-policy body on chemicals and waste

The chemical pollution crisis severely threatens human and environmental health globally. To tackle this challenge the establishment of an overarching international science-policy body has recently been suggested. We strongly support this initiative based on the awareness that humanity has already likely left the safe operating space within planetary boundaries for novel entities including chemical pollution. Immediate action is essential and needs to be informed by sound scientific knowledge and data compiled and critically evaluated by an overarching science-policy interface body. Major challenges for such a body are (i) to foster global knowledge production on exposure, impacts and governance going beyond data-rich regions (e.g., Europe and North America), (ii) to cover the entirety of hazardous chemicals, mixtures and wastes, (iii) to follow a one-health perspective considering the risks posed by chemicals and waste on ecosystem and human health, and (iv) to strive for solution-oriented assessments based on systems thinking. Based on multiple evidence on urgent action on a global scale, we call scientists and practitioners to mobilize their scientific networks and to intensify science-policy interaction with national governments to support the negotiations on the establishment of an intergovernmental body based on scientific knowledge explaining the anticipated benefit for human and environmental health.

Biocellulose for Treatment of Wastewaters Generated by Energy Consuming Industries: A Review

Water and energy are two of the most important resources used by humanity. Discharging highly polluting wastewater without prior treatment is known to adversely affect water potability, agriculture, aquatic life and even society. One of the greatest threats to water sources are contaminated effluents, which can be of residential or industrial origin and whose disposal in nature must comply with specific laws aimed at reducing their environmental impact. As the oil industry is closely related to energy consumption, it is among the sectors most responsible for global pollution. The damage caused by this industrial sector is present in all countries, whose legislations require companies to carry out wastewater treatment before disposal or recycling in their production process. Bacterial cellulose membranes have been shown to be efficient as filters for the removal of various contaminants, including biological and chemical agents or heavy metals. Therefore, their use could make an important contribution to bio-based technological development in the circular economy. Moreover, they can be used to produce new materials for industry, taking into consideration current environmental preservation policies aimed at a more efficient use of energy. This review aims to compare and describe the applications of cellulose membranes in the treatment of these effluents.