Trace element fluxes during the "Anthropocene" in a large South American industrial and port area (Santos and São Vicente estuarine system, SE, Brazil).

The worldwide evidence of human activities on the environment led the scientific community to recognize a new geologic time unit known as the "Anthropocene." Since the twentieth century, urbanization and industrialization needs driven by population and economic growth have impacted several ecosystems including the estuaries. To assess the contamination, provenance, and fluxes of trace elements (As, Cr, Cu, Ni, Pb, Sc, V, and Zn) over the last century, a geochemical and chemometric technique was employed in sediment cores of an industrial and port region of international importance, the Santos and São Vicente Estuarine System (SSVES). The results indicated low contamination, with the highest enrichment factors (EFs) for Cu (EF = 3.1), Pb (EF = 2.7), Zn (EF = 2.4), and As (EF = 2.3) found next to the harbor area. The Pre-industrial records confirm the relatively high concentrations of As and its naturally enriched occurrence on the Brazilian shelf. Sediment accumulation rates and trace element fluxes showed a general increase over the years, since the early 1960s, associated with the "Great Acceleration" of the mid-twentieth century. These alterations are human-induced and include urbanization and industrialization. Nonetheless, as the contents and enrichment of trace elements indicate that the region is not severely polluted, we hypothesize that the contamination in the SSVES is likely related to the drainage and erosion of the urbanized adjacent area, rather than direct disposal of inorganic contaminants from the industrial activity.

A TIE Approach to Identify Substances Causing Sediment Pore Water Toxicity After a Major Fire at Fuel Storage Tanks in the Port of Santos (SE, Brazil).

The major fire at the fuel storage tanks of a Chemical Terminal in April 2015 at the Port of Santos (SP), SE Brazil, potentially caused significant environmental impacts to the Santos Estuarine System (SES). The aim of the study was to identify the classes of substances causing pore water toxicity in the SES sediments in the vicinity of the port terminal before and after the incident using the TIE approach. Our results suggest that nonpolar compounds (e.g. PAHs, BTX, oil and grease) from the storage tanks that burned, and surfactants present in the formulation of foam fire extinguishing agents were the responsible for the sediment toxicity observed in the vicinity of the incident site. The contribution of metals to the toxicity related to the incident was ruled out. A long-term monitoring of the environmental effects of the incident is recommended since substances for which evidence of toxicity was found are toxic, persistent and can accumulate in the biota.

Investigating the contaminant transport of heavy metals in estuarine waters.

A three-dimensional contaminant transport model of heavy metal (copper) was coupled with the hydrodynamics and suspended sediment transport module to simulate the transport and distribution of heavy metal (copper) of the Danshui River estuarine system in northern Taiwan. The coupled model was validated with observational data including the water level, tidal current, salinity, suspended sediment concentration, and copper concentration. The model simulation results quantitatively reproduce the measurements. Furthermore, the validated model was employed to explore the influences of the freshwater discharge and suspended sediment on the distribution of copper concentrations in the tidal estuarine system. The results demonstrate that a high freshwater discharge results in a decreasing copper concentration, while a low freshwater discharge raises the copper concentration along the estuarine system. If the suspended sediment transport module was excluded in the model simulations, the predicted copper concentration underestimated the measured data. The distribution of copper concentrations without the suspended sediment transport module was lower than that with the suspended sediment transport module. The simulated results indicate that the freshwater discharge and suspended sediment play crucial roles in affecting the distribution of copper concentrations in the tidal estuarine system.

Empirical estimation of suspended solids concentration in the Indus Delta Region using Landsat-7 ETM+ imagery.

Suspended Solids Concentration (SSC) in water is related to its quality and transparency. Satellite remote sensing has proven to be an efficient means of monitoring water quality in large deltas because in situ sampling methods are costly, laborious, time consuming, and spatially constrained. In this study, the potential of Landsat's Enhanced Thematic Mapper Plus (ETM+) sensor was explored to develop a model for remote sensing-based quantification of SSC within the large, turbid Indus Delta Region (IDR, south of Pakistan). Six scenes were atmospherically corrected using the Dark Object Subtraction (DOS) method, to formulate a model for monitoring water quality of the IDR. An empirical model was developed and validated using in situ SSC measurements (9.4-761.4 mg/L) from several data collection campaigns coinciding (within an 11-day window) with satellite overpasses. It was found that using Band 1 (blue: 450-520 nm), Band 2 (green: 520-600 nm), Band 3 (red: 630-690 nm), and Band 5 (shortwave infrared: 1550-1750 nm) of Landsat-7 ETM + along with the Normalized Difference Suspended Sediment Index (NDSSI) can help in precise and accurate estimation of SSC, resulting in a relatively small Root Mean Square Error of 67.24 mg/L, Mean Absolute Error of 54.75 mg/L, and coefficient of determination of 0.88. Further, it was also evident that residuals do not increase with an increasing time window (0-11 days) between the satellite overpass and in situ data collection. Therefore, the established algorithm can potentially be used for frequent (after 8 days) synoptic mapping of SSC in the IDR and other similar estuarine environments.

Assessment of the climate change impacts on fecal coliform contamination in a tidal estuarine system.

Climate change is one of the key factors affecting the future microbiological water quality in rivers and tidal estuaries. A coupled 3D hydrodynamic and fecal coliform transport model was developed and applied to the Danshuei River estuarine system for predicting the influences of climate change on microbiological water quality. The hydrodynamic and fecal coliform model was validated using observational salinity and fecal coliform distributions. According to the analyses of the statistical error, predictions of the salinity and the fecal coliform concentration from the model simulation quantitatively agreed with the observed data. The validated model was then applied to predict the fecal coliform contamination as a result of climate change, including the change of freshwater discharge and the sea level rise. We found that the reduction of freshwater discharge under climate change scenarios resulted in an increase in the fecal coliform concentration. The sea level rise would decrease fecal coliform distributions because both the water level and the water volume increased. A reduction in freshwater discharge has a negative impact on the fecal coliform concentration, whereas a rising sea level has a positive influence on the fecal coliform contamination. An appropriate strategy for the effective microbiological management in tidal estuaries is required to reveal the persistent trends of climate in the future.

The seasonal distribution of plasticizers in estuarine system: Controlling factors, storage and impact on the ecosystem.

Plasticizers such as phthalate esters (PAEs) are commonly used in various consumer and industrial products. This widespread use raises valid concerns regarding their ubiquity in the environment and potential negative impacts. The present study investigates the distribution of eight common plasticizers in the largest European lagoon (Curonian Lagoon) located in the SE Baltic Sea. The concentration levels of plasticizers in the water column, containing both the dissolved and particulate-bound phases, and in sediments were evaluated to reveal seasonal patterns in distribution and potential effects on the lagoon ecosystem. A total of 24 water samples and 48 sediment samples were collected across all four seasons from the two dominant sedimentary areas within the lagoon. The average concentration of total PAEs in the water column ranged from 1 to 21 µg L-1, whereas sediment concentration varied from 5.0 to 250 ng g-1. The distribution of plasticizers was influenced by the patterns in hydrodynamics and water circulation within the lagoon. The confined south-central area contained a higher amount of PAEs in sediments, accounting for most of the lagoon's plasticizer accumulation. More than 7 tons of plasticizers are stored in the 5 upper centimetres of sediment, with over 3 tons persisting for more than five years. Di(2-ethylhexyl) phthalate (DEHP), Diisobutyl phthalate (DiBP), and Dibutyl phthalate (DnBP) were the most abundant PAE congeners, with DEHP posing the highest risk quotient to algae, based on water column concentration. Several other congeners demonstrated medium to high-risk levels for organisms living in the lagoon.

Long-term trends (1986-2019) in the physicochemical properties of the Sado Estuary (Portugal) driven primarily by changes in river flow and influenced by marine upwelling.

Estuaries are among the most sensitive systems to climate change. Previous studies have suggested that the Sado Estuary (Portugal) has decreasing trends for water temperature, which is uncommon in a global warming scenario. However, no long-term analysis regarding water column conditions has been conducted on this estuary to date. Therefore, the main aim of this study is to understand if and how the properties of this estuary have changed, considering a 34-year trend analysis and an assessment of their main drivers. Water temperature significantly decreased (up to 0.04 °C/year) along with chlorophyll a. Salinity increased and nutrients displayed an overall decrease. These trends were potentially driven by higher influence of upwelled water combined with a reduction of the river flow. Sado appears to have a lower vulnerability to climate change than other estuaries as it does not show a high sensitivity to changes in its water column physicochemical properties.

Spatial and temporal distribution of perfluoroalkyl substances (PFAS) detected after an aqueous film forming foam (AFFF) spill.

In 2015, > 460,000 L of aqueous film-forming foam (AFFF) and fire suppressors containing per- and polyfluoroalkyl substances (PFAS) were used to combat a fire at a petrochemical fuel storage terminal in the Port of Santos (Brazil). Sediments from seven sites were sampled repeatedly from 2 weeks to 1 year after the fire (n = 30). Æ©15PFAS concentrations ranged from 115 to 15,931 pg g-1 dry weight (dw). Perfluorooctane sulfonic acid (PFOS) was the most frequently detected compound with concentrations ranging from 363 to 4517 (average = 1603) pg g-1dw to <47.1 to 642 (average = 401) pg g-1 dw, followed by perfluorohexanoic acid (PFHxA) (from 38.8 to 219 (average = 162) pg g-1 dw after 15 days and from <20.8 to 161 (average = 101) pg g-1 dw one year later). Together, the hydrodynamics and fire events documented in the region were important features explaining the spread of PFAS.

Ecological risk assessment of the Paraíba River estuary (Brazil): Plan for a tier 1 screening phase for the ecotoxicological line of evidence.

The knowledge produced in temperate regions is still used today to evaluate environmental problems in the tropics, without taking into consideration environmental differences, such as local conditions, the sensitivity and ecology of species, and exposure routes of contaminants, essential for understanding and determining the fate and toxicity of chemicals. Considering that Environmental Risk Assessment (ERA) studies for tropical systems are scarce and need to be adjusted, the present study aims at contributing to the awareness and development of tropical ecotoxicology. The estuary of the Paraíba River in Northeast Brazil was selected as a model study-case, as it is a large estuary, subjected to a heavy human pressure due to the numerous social, economic and industrial activities. The present study describes the framework for the problem formulation phase of the ERA process; it first includes a detailed integration of the scientific information available on the study area, to then derive the conceptual model, and finally present the analysis plan for the tier 1 screening phase. The latter is designed to be fundamentally supported by the ecotoxicological line of evidence, to ascertain, without delay, where and why there are environmental problems (i.e., adverse biological effects); ecotoxicological tools developed in temperate climates will be optimized to assess water quality in a tropical system. In addition to its intrinsic value for protecting the study area, the results of the present study are expected to provide an important baseline for conducting ERA in similar tropical aquatic systems across the globe.

Factors controlling dissolved 137Cs activities in coastal waters on the eastern and western sides of Honshu, Japan.

The distributions of dissolved 137Cs in river, nearshore, and offshore waters on the east and west coasts of the Japanese island of Honshu were studied in 2018-2021, 7-10 years after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. On the east side along the north western North Pacific (Fukushima Prefecture), estuarine processes, including desorption from riverine particles and dissolution into pore water from riverine particles that had settled to the seafloor, contributed to the maintenance of high dissolved 137Cs activities in nearshore and offshore waters. A survey and mass-balance calculation in a semi-enclosed estuarine area, the Matsukawa-ura, in the northern part of Fukushima, provided convincing evidence that rivers contributed to the influx of 137Cs to coastal waters. In contrast, the extremely low activities of dissolved and particulate 137Cs in the Tedori River of Ishikawa Prefecture on the western side of Japan along the Japan Sea suggested that inputs of riverine 137Cs made a negligible contribution to the increase of dissolved 137Cs activities in the nearshore and offshore waters. The relatively high dissolved 137Cs activities observed in the offshore waters of the Japan Sea were due to movement of FDNPP-derived 137Cs into the Japan Sea via the Tsushima Warm Current. Mechanisms controlling the distributions of 137Cs activities in coastal waters of the eastern and western sides of Japan therefore differ.

Spatial and temporal changes of dissolved oxygen in waters of the Pajarales complex, Ciénaga Grande de Santa Marta: Two decades of monitoring.

Ciénaga Grande de Santa Marta lagoon complex, located in the Colombian Caribbean, is a highly degraded estuarine system, in which massive deaths of organisms have occurred since the 1990s, causing socioeconomic effects on the inhabitants, who are mostly artisanal fishermen. These deaths have been attributed to the deoxygenation of the water at night, as a result of the eutrophication of the system. To understand the variability of dissolved oxygen and its relationship with other water quality variables, the monthly time series collected between 2001 and 2019, in seven stations of the Pajarales Complex (western side of the estuarine complex), were analyzed. Analyzes showed that there are significant differences between stations, as well as between the surface and the bottom of the water, indicating that the behavior of oxygen in the system is not homogeneous, a product of the hydrodynamics of the system. Also, temporal differences were found related to the periods of rain and drought, even with larger-scale climatic events such as El Niño and La Niña, with the lowest concentrations being recorded during the rainy seasons. On the other hand, the analysis of the time series of the average surface temperature of the seven stations analyzed showed a slight tendency to increase over time. Results indicate that the system is very dynamic and its oxygenation conditions are determined by climatic factors that promote changes in water chemistry, such as variations in salinity, temperature, and pH, and biological activity, determined by the abundance of the organisms. Analysis of this information becomes a tool to propose an alert system that allows reducing the impact of deaths.

Spatial and seasonal variation of microplastics and possible sources in the estuarine system from central west coast of India.

The versatile use of various synthetic polymers, including plastics, generates a large volume of non-degradable waste, which is eventually responsible for forming microplastics (MPs) in aquatic environments. The present study describes the significant spatial and seasonal variation on the abundance of MPs and their physiochemical nature along the Mandovi-Zuari estuarine system of Goa, west coast of India. During the wet season (September), the average abundance of MPs was found relatively higher in water (0.107 particles/m3) and sediment (7314 particles/kg) than those found in the dry season (April) (0.099 particles/m3 in water and 4873 particles/kg in sediment). During the wet season, heavy rain and excessive riverine freshwater influx carry more terrestrial plastic debris in the estuarine system which causes higher averages MPs density in surface water and sediment. <300 µm sized particles and black colored MPs were predominant equally in water and sediment during both seasons. MPs of different shapes like fragments, fibres, films and beads accounted for most collected samples. The Micro-Fourier Transform Infrared Spectroscopy (µ-FTIR) based compositional analysis identified approximately 33 types of polymers, of which polyacrylamide (PAM), polyacetylene, polyamide (PA), polyvinyl pyrrolidone (PVP), polyvinyl chloride (PVC), and polyimide (PI) were abundant. Fragmentation of larger plastic particles due to mismanaged treated and untreated STPs and washing machine effluents are the primary sources of these MPs in the estuarine system. Moreover, these estuaries also receive a variety of domestic, industrial and other wastes from local cities, ports, and fishing jetties. Thus the present study enlightens the current distribution of MPs and their sources in the Mandovi-Zuari estuarine system and thus provides very useful information to the stakeholder and concerned departments for initiating the mitigation measures.

Geochemical background indicators within a tropical estuarine system influenced by a port-industrial complex.

This study aims to determine the background values for metals in the Suape estuarine system, Brazil, and to identify contamination caused by anthropogenic sources. Two cores were sampled. Sedimentation rates and metal content were analysed. The Al-normalized method was used to infer the background values, and to identify anthropic influences, the enrichment and contamination factors and the geoaccumulation index were employed. The results revealed an Mn, Ni, Zn, Ga, Pb, Sr, Ti, Mg, V and Fe content (mg kg-1) of 101.8, 5.7, 24.4, 8.3, 14.5, 41.9, 2744.6, 4581, 14.9 and ~ 1% respectively. After the installation of the Suape port, an increase in metal contents and in fluxes were recorded. Increases in Zn, Ga, V and Pb are supported by the indexes showing moderate contamination, enrichment and suggest an area moderately polluted. The other studied metals do not reflect an anthropogenic impact, with low values of contamination, enrichment factors and geoaccumulation indexes.

Tracking the historical sewage input in South American subtropical estuarine systems based on faecal sterols and bulk organic matter stable isotopes (δ13C and δ15N).

Faecal sterols and stable isotopes (δ13C and δ15N) from bulk organic matter (OM) were analysed in three sedimentary cores collected in two subtropical bays located in the South Atlantic to evaluate historical trends in the sewage input and to track possible changes in the bulk isotopic composition of OM in recent decades. The values of δ13C and δ15N ranged from -27.4 to -25.0‰ and from 0.5 to 3.9‰, respectively, without a clear trend in the variation over the whole period covered by sediment cores and with no conclusive interpretation of a specific range value typically related to the sewage input for these areas. The maximum coprostanol concentration was 0.19 µg g-1 in the upper 4 cm of one core, which was not considered contaminated by evaluation of the sterols diagnostic ratios. Even at low levels, the coprostanol concentrations followed variations in urban and economical regional development. Baseline values for faecal sterols (in average between 0.03 and 0.05 µg g-1), which may represent a previous non-impacted environment scenarios, were calculated for use in comparative perspectives for future evaluations of the sewage input and contamination.

Seawater intrusion and resuspension of surface sediment control mercury (Hg) distribution and its bioavailability in water column of a monsoonal estuarine system.

There is limited knowledge regarding seawater intrusion on Hg distribution in monsoon fed tropical estuarine systems during dry season (February to May). This study examined the influence of resuspension of estuarine sediment and intrusion of Hg bound SPM (HgSPM) (by the tide) from the outside of an estuary in controlling distribution, mobility, and bioavailability of Hg within the estuarine systems during the dry season. This investigation was carried out in the Mandovi estuary, a monsoon fed tropical estuary from the central west coast of India. Total Hg concentrations in the water column showed an increasing trend from upstream to downstream of the estuary. The concentration of Hg in the water column of the estuary was much below the concentration recommended by the EPA for aquatic life ambient water quality. Dissolved Hg (HgDissolved) was found to associate mainly with the higher molecular weight fraction of dissolved organic matter (DOM). A significant portion of the total Hg in the water column was present as HgSPM. The average bio-accumulated Hg concentration in edible oyster was high (collected from the estuary) during the dry season compared to the wet season (June to September). This study reveals that resuspension of Hg associated finer sediment particles and intrusion of HgSPM from the outside of the estuary may increase bioavailability of Hg in the Mandovi estuarine systems during the dry season. It is suggested that Hg bioaccumulation in commercially important biological species from different tropical estuarine system may increase during the dry season. The outcome of this research can be useful for policy making and to take proper decision to reduce and control Hg/toxic metals pollution (if any) in tropical estuarine system.

Environmental quality survey of an industrialized estuary and an Atlantic Forest Biosphere Reserve through a comparative appraisal of organic pollutants.

An evaluation of the concentrations, bioavailability and sources of polycyclic aromatic hydrocarbons (PAHs) and persistent organic pollutants (POPs) was performed in the industrialized estuary of Santos-São Vicente and in the Cananéia-Iguape estuarine lagoon system, considered an Atlantic forest biosphere reserve, using different approaches. Semipermeable membrane devices (SPMDs) and bivalves (Crassostrea brasiliana) were deployed in both estuarine systems. Samples of water, suspended particulate material (PM), and sediments were also collected in these regions. The concentrations of PAHs in the water and in the PM from both estuarine systems were similar. In the sediment, the concentrations of PAHs and POPs were higher in the estuary of Santos-São Vicente than in the Cananéia-Iguape estuarine lagoon system. The accumulation of PAHs and POPs by the SPMD and C. brasiliana revealed that in both regions the bioavailability of contaminants was similar. Because of the hydrophobicity of the organic compounds, each matrix responded in a different manner to the source of the contaminants; C. brasiliana and sediment were primarily associated with 4-5 ring-PAHs that represent pyrolytic sources of hydrocarbons, whereas water and the SPMDs were correlated with the 2-3 ring-PAHs, which represent petrogenic sources. The PM produced an intermediated concentration among these compartments and was related to the concentration of POPs. Because no significant differences between the mean concentrations of contaminants in both studied regions were observed, anthropogenic effects currently impact the Cananéia-Iguape lagoon system, which was initially considered a pristine area.

Hexadecane biodegradation of high efficiency by bacterial isolates from Santos Basin sediments.

The aim of the study was the investigation of bacterial diversity from sediments collected at Santos Estuarine System, regarding to their abilities for hexadecane biotransformation. Hexadecane is a medium-chain linear alkane, considered as a model molecule for hydrocarbon biodegradation studies. It is a component from aliphatic fraction of crude petroleum, commonly related to environmental contamination by diesel oil. Santos Basin is an area with historical petroleum contamination. In the present work, sediment samples from this area were inoculated in artificial seawater (ASW), containing hexadecane as carbon source. Six bacterial isolates were selected as resistant to hexadecane. Chromatographic results showed biodegradation indexes above 97%. After 48 h of culture, five of them could degrade >80% of the initial hexadecane added. These isolates were characterized by 16S rDNA gene sequencing analysis. The following species were found: Bacillus amyloliquefaciens, Staphylococcus epidermidis, Micrococcus luteus, Nitratireductor aquimarinus, and Bacillus pumilus.

Common snook juveniles, Centropomus undecimalis, as biomonitor organisms to evaluate cytogenotoxicity effects of surface estuarine water from Southern Brazil.

Centropomus undecimalis fish inhabit the highly contaminated Santos-São Vicente Estuarine System (SESS) and could be a good biomonitor of contaminants. This study aimed to investigate the cytogenotoxic potential of superficial water from SESS using C. undecimalis as a biomonitoring model and to validate the use of farmed fish as controls. Using biochemical (DNA damage and Lipid Peroxidation - LPO), cellular (erythrocyte nuclear abnormality - ENA) and tissue (8-OHdG immunoexpression) biomarkers, our results showed fish from SEES had higher LPO concentration in gills and higher frequency of reniform, lobed and total ENA in erythrocytes when compared with control farmed fish. Thus, SESS surface water are cytogenotoxic for blood and gills cells of fishes. C. undecimalis has shown to be a good biomonitor model and farmed fish can be used as control only if livers were not the target organs of study since the dietary food from farmed fish causes steatosis.

Insights about sources, distribution, and degradation of sewage and biogenic molecular markers in surficial sediments and suspended particulate matter from a human-impacted subtropical estuary.

The molecular markers sterols and linear alkylbenzenes (LABs) were analyzed in the surficial sediments and suspended particulate matter (SPM) of a subtropical estuary in South Atlantic (Paranaguá Estuarine System). The purpose of this study was identify the spatial distribution of sewage and the input of biogenic organic matter (OM) and to provide comparative insights about their behavior, compositions, and sources. The concentration of coprostanol ranged from < DL (detection limit) to 2.67 µg g-1 in SPM and from < DL to 0.94 µg g-1 in sediments. Total LABs ranged from 43.8 to 480.0 ng g-1 in SPM and from < DL to 21.0 ng g-1 in sediments. LABs homologs composition varied between the two matrices. The local hydrodynamic pattern may promote water column homogenization, dispersion, and dilution of sewage particles, and preferential sedimentation in fluvial and mixture zones. Results suggest that SPM is a good matrix for larger spatial and short time scale evaluation while sediments may help to define hot spot areas of input and final deposition of sewage particles. Marine sterols predominated in SPM while no dominance patterns of marine/terrestrial sterols occurred in surficial sediments. The higher degradation rates of sterols and LABs in the water column must be the main factor for the sharp drop in concentration towards the sediment and the variation of the preferential composition of these markers between compartments.

Ancistrosyllis matlaensis n. sp. (Polychaeta: Pilargidae) from the Sundarban Estuarine System, India.

A new species of family Pilargidae, Ancistrosyllis matlaensis n. sp. is described from the Sundarban Estuarine System, India. The new species can be distinguished from its congeners by a combination of characters: absence of median antenna and eyes, shape of tentacular and dorsal cirri, structure of notopodia and neuropodia, and first appearance of notopodial hooks. The new species closely resembles Ancistrosyllis falcata.