The main objective of this study was to investigate the 2019 and 2022 oil spill events that occurred off the coast of the State of Ceará, Northeastern Brazil. To further assess these mysterious oil spills, we investigated whether the oils stranded on the beaches of Ceará in 2019 and 2022 had the same origin, whether their compositional differences were due to weathering processes, and whether the materials from both were natural or industrially processed. We collected oil samples in October 2019 and January 2022, soon after their appearance on the beaches. We applied a forensic environmental geochemistry approach using both one-dimensional and two-dimensional gas chromatography to assess chemical composition. The collected material had characteristics of crude oil and not refined oils. In addition, the 2022 oil samples collected over 130 km of the east coast of Ceará had a similar chemical profile and were thus considered to originate from the same source. However, these oils had distinct biomarker profiles compared to those of the 2019 oils, including resistant terpanes and triaromatic steranes, thus excluding the hypothesis that the oil that reached the coast of Ceará in January 2022 is related to the tragedy that occurred in 2019. From a geochemical perspective, the oil released in 2019 is more thermally mature than that released in 2022, with both having source rocks with distinct types of organic matter and depositional environments. As the coast of Ceará has vast ecological diversity and Marine Protected Areas, the possibility of occasional oil spills in the area causing severe environmental pollution should be investigated from multiple perspectives, including forensic environmental geochemistry.

Adult coho salmon (Oncorhynchus kisutch) prematurely die when they return from the ocean to spawn in urban watersheds throughout northwestern North America. The available evidence suggests the annual mortality events are caused by toxic stormwater runoff. The underlying pathophysiology of the urban spawner mortality syndrome is not known, and it is unclear whether closely related species of Pacific salmon are similarly at risk. The present study co-exposed adult coho and chum (O. keta) salmon to runoff from a high traffic volume urban arterial roadway. The spawners were monitored for the familiar symptoms of the mortality syndrome, including surface swimming, loss of orientation, and loss of equilibrium. Moreover, the hematology of both species was profiled by measuring arterial pH, blood gases, lactate, plasma electrolytes, hematocrit, and glucose. Adult coho developed behavioral symptoms within a few hours of exposure to stormwater. Various measured hematological parameters were significantly altered compared to coho controls, indicating a blood acidosis and ionoregulatory disturbance. By contrast, runoff-exposed chum spawners showed essentially no indications of the mortality syndrome, and measured blood hematological parameters were similar to unexposed chum controls. We conclude that contaminant(s) in urban runoff are the likely cause of the disruption of ion balance and pH in coho but not chum salmon. Among the thousands of chemicals in stormwater, future forensic analyses should focus on the gill or cardiovascular system of coho salmon. Because of their distinctive sensitivity to urban runoff, adult coho remain an important vertebrate indicator species for degraded water quality in freshwater habitats under pressure from human population growth and urbanization.

Polycyclic aromatic hydrocarbons (PAHs) were assessed spatially and temporally within and adjacent to a former coking and steel manufacturing facility in Sydney, Nova Scotia, Canada. Concentrations of PAHs were measured in surface soils, marine and estuary sediments prior to and during remediation of the Sydney Tar Ponds (STPs) site which was contaminated by nearly a century of coking and steel production. Previous studies identified PAHs in surficial marine sediments within Sydney Harbour, which were considered to be derived from STP discharges. Numerous PAH fingerprint techniques (diagnostic ratios, principal component analysis, quantitative and qualitative analysis) were applied to soil and sediment samples from the STPs and surrounding area to identify common source apportionment of PAHs. Results indicate coal combustion (from historical residential, commercial and industrial uses) and coal handling (from historic on-site stockpiling and current coal transfer and shipment facilities) are likely the principal source of PAHs found in urban soils and marine sediments, consistent with current and historical activities near these sites. However, PAH fingerprints associated with STP sediments correlated poorly with those of urban soils and marine sediments, but were similar to coal tar, historically consistent with by-products produced by the former coking operations. This study suggests PAH contamination of Sydney Harbour sediments and urban soils is largely unrelated to historic coking operations or recent remediation of the STPs site, but rather a legacy of extensive use of coal for a variety of activities.

As a result of historical industrial activity, the sediments in the inner harbor of Owen Sound Bay in the northeastern part of Lake Huron in Ontario, Canada are contaminated with organic compounds. The present study showed that the concentrations of Ʃ PAH₁₆₋EPA in all sediments in the inner harbor were above the sediment quality guidelines for the province of Ontario, Canada, with mean Ʃ PAH₁₆₋EPA concentrations at the most contaminated site of 46,000 μg/kg dry weight. The concentrations of polychlorinated biphenyls, brominated diphenyl ethers, and organochlorine compounds were all below sediment quality guidelines. The patterns of PAH and alkyl-PAH compounds in sediment cores indicated that contamination is from mixed sources, with a strong indication of pyrogenic contamination from industries that used to operate in the area, including a coal gasification plant. Other areas of the bay are impacted by petrogenic contamination, potentially from spills of fuel. The even distribution of PAH and alkyl-PAH compounds throughout core profiles at depths up to 25 cm indicates that this is a dynamic system and contaminated sediments are not being covered by deposition of less contaminated sediments. This study illustrates the value of determining the patterns of both PAH and alkyl-PAH compounds in sediments for regulatory purposes and also for forensic source tracking.

In this study, the use of co-occurring discriminators of sewage and manure was assessed as a potential way to disentangle sewage and manure sources. A suite of human and veterinary derived chemical markers, which includes pharmaceuticals and compound such as food additives, has been identified for this purpose. The suite was selected in such a manner as to provide additional source characterisation, e.g. differentiating raw versus treated sewage inputs. An SPE–LC–MS/MS method was developed and validated for the determined suite of chemical markers with a detection limit of up to 50 pg L−1. This represents one of the lowest limits of detection for pharmaceuticals reported in literature. To illustrate the suitability of the proposed method to differentiate sewage and manure inputs to surface water bodies, results from surface water samples collected at monitoring sites corresponding to specific land use types within Ireland are discussed.

A forensic source evaluation of polycyclic aromatic hydrocarbons (PAHs) in nearshore sediments in San Francisco Bay examined total PAH greater than ambient concentrations in sediments, and potential pyrogenic source relationships with respect to PAH compounds typically associated with point and nonpoint pyrogenic source types, including PAHs potentially associated with historical manufactured gas plant (MGP) operations. Diagnostic source ratio analysis was employed for determination of potential PAH source relationships. A two-model approach indicated distinct potential source signatures, as identified from the distributions of higher PAH concentrations in some sediments. Source characterization was aided by Polytopic Vector Analysis (PVA) and data visualization with t-Distributed Stochastic Neighbor Embedding (t-SNE). Two signatures exhibited pyrogenic character likely consistent with historical MGP sources, and one signature was related to creosote. A distinct and significant source of PAHs to the investigation area sediment consisted of ubiquitous nonpoint and potential unidentified point sources is termed “urban influence”.

As microplastic pollution evolved to a well-established research field, microplastic scientists started to explore new avenues in the field. Yet, while a multitude of different types of microplastics (microbeads, fibres, fragments) have been well-documented in microplastic literature, our analysis of this literature shows that glitter particles have been overlooked by the field. However, due to the presence of glitter-based research in forensic science, we explore the idea that glitter may have the potential to act as “flag items” - or markers – of a likely source, due to the often complex and individual composition of glitter particles compared to traditional microplastics, such as microbeads. As such, this article demonstrates glitter has insofar been overlooked as a microplastic particle, and demonstrates that glitter may have an important role in explaining microplastic pollution dynamics from source to sink.

Forensic chemistry assessments documented the presence of Macondo (MC252) oil from the Deepwater Horizon (DWH) spill in offshore water samples collected under Natural Resource Damage Assessment (NRDA) protocols. In ocean depths, oiled water was sampled, observed, photographed, and tracked in dissolved oxygen (DO) and fluorometry profiles. Chemical analyses, sensor records, and observations confirmed the shifting, rising oil plume above the wellhead while smaller, less buoyant droplets were entrapped in a layer at ~1000–1400 m and advected up to 412 km southwest. Near-surface oil samples showed substantial dissolution weathering from oil droplets rising through the water column, as well as enhanced evaporative losses of lighter n-alkanes and aromatic hydrocarbons. Dispersant effects from surface applications and injected at the wellhead were seen in oil profiles as enhanced weathering patterns (increased dissolution), thus implying dispersants were a functionally effective mediation treatment. Forensic assessment methods are detailed in the Supplemental information (SI).

Marine cross-border areas are ideal for monitoring pollutants so as to increase ecosystems protection. This study was conducted at the Romanian-Ukraine border of the Black Sea to reveal evidence of contamination with toxic metals based on biomonitoring of: cadmium, lead, total chromium, nickel and copper at different water depths and prey-predator interactions, combined with environmental forensics techniques of biological sampling and separation in witnesses size groups. The species used were Mytilus galloprovincialis L. and Rapana venosa V. collected at 17.5m, 28m and 35m depth. An atomic absorption spectrometer with a high-resolution continuum source and graphite furnace was used for toxic metals quantification in various samples: sediments, soft tissue, stomach content, muscular leg, hepatopancreas. The best sample type, based on the pathology of metal location and bioaccumulation, is the hepatopancreas from R. venosa that proved a significant decrease of cadmium and lead at lower depths.

There is growing evidence of extensive pollution of the environment by microplastic, with microfibres representing a large proportion of the microplastics seen in marine sediments. Since microfibres are ubiquitous in the environment, present in the laboratory air and water, evaluating microplastic pollution is difficult. Incidental contamination is highly likely unless strict control measures are employed. Here we describe methods developed to minimize the amount of incidental post-sampling contamination when quantifying marine microfibre pollution. We show that our protocol, adapted from the field of forensic fibre examination, reduces fibre abundance by 90% and enables the quick screening of fibre populations. These methods therefore allow an accurate estimate of microplastics polluting marine sediments. In a case study from a series of samples collected on a research vessel, we use these methods to highlight the prevalence of microfibres as marine microplastics.