Sediment Contamination Research Articles

Microbial communities as indicators of marine ecosystem health: Insights from coastal sediments in the eastern Adriatic Sea

Considering the adaptability and responsiveness of microorganisms to environmental changes, their indicator potential is still not acknowledged in European directives. This comprehensive study examined the changes of microbial communities in sediments and a range of geochemical parameters from pristine and anthropogenically impacted coastal areas in the eastern Adriatic Sea. Various analytical methods found evidence of sediment contamination (high toxicity level, enrichments of metals, tributyltin) in certain areas, leading to the categorization of sediments based on the level of anthropogenic disturbance. Prokaryotes were identified as the most promising group of microbes for further research, with specific bacterial families (Rhodobacteraceae, Ectothiorhodospiraceae, Cyclobacteriaceae) and genera (Boseongicola, B2M28, Subgroup 23, Sva0485, Thiogranum) proposed as potential indicators of environmental status. Finally, predictive models were developed to identify key indicator variables for assessing anthropogenic impact in sediments. This research represents an essential step toward incorporating microbial communities into assessments of benthic environmental health.

Recovery of ecosystems pollution by contaminants of potential concern using phytoremediation techniques.

Phytoremediation is a technology that uses plants to break down, remove, and immobilize contaminants in surface water, shallow groundwater, and sediment to achieve cost savings compared with conventional treatments. This study describes a marshy land on an explosives manufacturing site in India that consistently reported elevated concentrations of nitrates, nitrites, ammonia, perchlorate, and lead (contaminants of potential concern-CoPC). The study also illustrates the potential for addressing the human health and environmental risks associated with the explosives manufacturing industrsy in India using innovative, sustainable, and carbon-neutral techniques. This work focuses on reconstructed marshy lands, desedimentation, microwatershed management, and phytoremediation using Phragmites and Vetiveria species (also known as vetiver) to reduce contaminants in surface water and groundwater, improve stormwater management and carbon capture, and increase natural capital like biodiversity. The results obtained during the trial indicate that the selected indigenous species are effective and can be used to remediate sediment and shallow groundwater for many CoPC in tropical climates. Integr Environ Assess Manag 2024;20:1987-2002. © 2024 SETAC.

Potentially toxic elements contamination and ecological risk assessment in surface sediments of Moulouya Estuary (Northeastern, Morocco)

Potentially toxic elements (PTEs) in aquatic ecosystems are a major environmental concern posing serious risks to aquatic life and human health. Understanding their distribution, sources, and effects is crucial for effective environmental management and the protection of biodiversity and natural resources. This study assessed the variability, bioavailability, contamination degree, and ecological risks of PTEs in surface sediments of the Moulouya Estuary. The levels of PTEs were determined using an inductively coupled plasma-optical emission spectrometry (ICP-OES). The mean concentrations of PTEs can be classified in the following order: Zn > Cr > As > Pb >Cu > Cd. The highest values were found in sites (S2, S4, and S5) that receive metals from anthropogenic activities. The mineralogical study showed that the sediment studied is dominated by Ca, which influences the PTEs mobility and makes them bioavailable in the aquatic environment, which means aquatic organisms can easily assimilate them. The PTEs contamination degree was determined by several pollution indices (CF, CD, PLI, EF, Igeo), which indicate that surface sediment shows low to moderate contamination levels. However, the Potential Ecological Risk indicates a moderate to considerable risk in the study area. The multivariate analysis indicates that As, Zn, Cr, Pb, and Cu are derived from anthropogenic activities (urban wastewater, fertilizers, and fishing boats), while Cd could have mixed sources. The results highlight suggest that human activities pose an ecotoxicological risk in the Moulouya Estuary. To minimize these risks and protect the aquatic ecosystem and human health, periodic monitoring and management strategies should be continued. These measures will enable early detection of changes in PTE levels and the implementation of the necessary interventions to reduce their harmful effects.

Spatial distribution, morphology, and risk assessment of microplastics in sediment from the Pearl River Estuary, China

Microplastics (MPs) (<5 mm) are a growing environmental problem and have garnered significant global interest from scientists and policy makers. Coastal ecosystems are vulnerable to MP pollution, and assessing their sources, fate, and transport in the environment is imperative for marine ecosystem health. Data for marine sediment are still limited, particularly in the Pearl River Estuary (PRE) ecosystem in China. Here, we assessed the abundance, characteristics, and risks of MPs in marine sediment from PRE. MPs abundance ranged from 2.05 × 103 items ·kg−1 to 7.75 × 103 items ·kg−1 (dry weight), and white and black MPs were the dominant colors. The majority (>64.12 %) of detected MPs were <0.85 mm and primarily consisted of pellets (36.84 %) and fragments (29.65 %). Three polymer types of MPs were identified by Fourier Transform Infrared Spectroscopy (FT-IR) including polyethylene (PE), polyethylene terephthalate (PET), and polypropylene (PP). Polyurethane (PU) sponge was reported for the first time in this study area. Observations of the surface morphology of typical MPs using Scanning Electron Microscopy (SEM) showed that all MPs exhibited varying degrees of erosion, characterized by cracks, folds, and bumpy structures. Based on type and quantity of MPs and the polymers identified, we assessed and classified the risk of MP contamination in PRE sediment as category III, indicating severe ecosystem contamination. Our results may serve as an effective model for other estuaries facing similar pollution regimes and provides valuable information for marine sediment risk assessment.

Bioconcentration of Per- and Polyfluoroalkyl Substances and Precursors in Fathead Minnow Tissues Environmentally Exposed to Aqueous Film-Forming Foam-Contaminated Waters.

Exposure to per- and polyfluoroalkyl substances (PFAS) has been associated with toxicity in wildlife and negative health effects in humans. Decades of fire training activity at Joint Base Cape Cod (MA, USA) incorporated the use of aqueous film-forming foam (AFFF), which resulted in long-term PFAS contamination of sediments, groundwater, and hydrologically connected surface waters. To explore the bioconcentration potential of PFAS in complex environmental mixtures, a mobile laboratory was established to evaluate the bioconcentration of PFAS from AFFF-impacted groundwater by flow-through design. Fathead minnows (n = 24) were exposed to PFAS in groundwater over a 21-day period and tissue-specific PFAS burdens in liver, kidney, and gonad were derived at three different time points. The ∑PFAS concentrations in groundwater increased from approximately 10,000 ng/L at day 1 to 36,000 ng/L at day 21. The relative abundance of PFAS in liver, kidney, and gonad shifted temporally from majority perfluoroalkyl sulfonamides (FASAs) to perfluoroalkyl sulfonates (PFSAs). By day 21, mean ∑PFAS concentrations in tissues displayed a predominance in the order of liver > kidney > gonad. Generally, bioconcentration factors (BCFs) for FASAs, perfluoroalkyl carboxylates (PFCAs), and fluorotelomer sulfonates (FTS) increased with degree of fluorinated carbon chain length, but this was not evident for PFSAs. Perfluorooctane sulfonamide (FOSA) displayed the highest mean BCF (8700 L/kg) in day 21 kidney. Suspect screening results revealed the presence of several perfluoroalkyl sulfinate and FASA compounds present in groundwater and in liver for which pseudo-bioconcentration factors are also reported. The bioconcentration observed for precursor compounds and PFSA derivatives detected suggests alternative pathways for terminal PFAS exposure in aquatic wildlife and humans. Environ Toxicol Chem 2024;43:1795-1806. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Sediments contamination from a meander of the Lerma River, Mexico

El objetivo de este trabajo fue determinar el grado de contaminación de sedimentos del cauce aislado del río Lerma que atraviesa la zona metropolitana interestatal La Piedad y Pénjamo para sustentar la toma de decisiones que haya que emprender con respecto a este cuerpo de agua que interactúa con un ambiente urbano. Se evaluaron parámetros fisicoquímicos, microbiológicos, metales pesados y partículas microscópicas de muestras de sedimentos recolectados en siete sitios del área de estudio. En promedio, los sedimentos tuvieron textura franco arenosa, con pH (7.6) neutro y conductividad eléctrica de 868 µS/cm, mostraron ser medianamente ricos en materia orgánica (2.7 %), con ligera carga de coliformes fecales (753 NMP/100 g) y presentaron un factor de enriquecimiento moderado para Zn, Cr y Cu. Se observaron partículas de plancton, pero también partículas con metales pesados. Considerando que los sitios urbanos (5 y 6) mostraron más indicadores fuera de los criterios establecidos es probable que los sedimentos están recibiendo contaminantes derivados de las actividades antropogénicas propias del lugar y no los generados río arriba. En general, la contaminación de los sedimentos fue moderada, no obstante, es imperante limitar que la materia orgánica, microorganismos patógenos y metales tóxicos como el Cr se sigan acumulando en el sedimento y evitar lleguen a un punto crítico. Por lo anterior y con la aplicación de algunas estrategias será posible recuperar y conservar esta área del río como un cuerpo de agua aislado e independiente del cauce original.

Heavy metal(loid)s contamination and ecological-health risk assessment of coastal sediment from Salwa Bay, Saudi Arabia

Salwa Bay is an elongated, narrow bay which extends southwards from the Gulf of Bahrain down to the Saudi-Qatari border, separating the peninsula of Qatar from Saudi Arabia. The present study aims to investigate the degree of heavy metal(loid)s (HMs) contamination and the associated health risks in surface sediments of the Salwa Bay, Saudi Arabia. Thirty samples were collected for analysis of Ni, Cu, Cr, Pb, Zn, and As using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Several contamination and health risk indices, and multivariate analysis were applied. The following order was detected for average concentrations of metal(loid)s (μg/g dry weight): Cr (5.56) > Zn (4.63) > Ni (4.43) > As (2.34) > Pb (1.66) > Cu (1.51). The coastal sediments exhibit a significant enrichment in As, moderate enrichment in Pb, Zn, Cr, and deficiency to minimal enrichment for Ni, and Cu. Sediment quality guidelines indicated that HMs do not pose a risk to the benthic communities in Salwa Bay area. The average hazard index values ranged from 0.00002 to 0.0038 in adults and from 0.0002 to 0.0353 in children. This suggests that there is no significant possibility of non-carcinogenic effects to the people inhabiting the coastline of Salwa Bay. The results of the excess lifetime cancer risk (ELCR) for As, Cr, and Pb were below 1 × 10−4, indicating no carcinogenic health risk except for a few sediment samples showing elevated levels of Cr and As.

Spatial-temporal dynamics of microplastic contamination in marine sediments of Tumaco bay, pacific colombian pacific

Contextualización: La bahía de Tumaco es potencialmente receptora de residuos domésticos, lo que conlleva a que diferentes contaminantes como los microplásticos (&lt;5mm) se acumulen en los sedimentos marinos. Vacío de conocimiento: En el Pacifico colombiano no se ha explorado como la emergencia sanitaria (COVID-19) afectó los patrones de contaminación de microplásticos en sedimentos marinos antes, durante y después de esta. Propósito: El propósito de este estudio fue identificar la presencia, características y variación espaciotemporal de la contaminación por microplásticos (MP) durante los años 2020 y 2021 en la zona interna y externa de la bahía de Tumaco y si ello tuvo alguna relación con la cercanía a la zona costera, la desembocadura de los ríos y el COVID-19. Metodología: Se recolectaron muestras de microplásticos en la zona interna y externa de la bahía de Tumaco, durante las épocas de lluvia y seca en los años 2020 y 2021. Resultados y conclusiones: Resultados y conclusiones: La contaminación por MP fue predominante en la zona interna (721.37 ± 175.96 partículas/kg). A sí mismo; la época de lluvia presentó la mayor contaminación por microplásticos (928.73 ± 220.20 partículas/kg) mientras que la menor se observó en la época seca (440.78 ± 101.54 partículas/kg). Finalmente, se evidencio una disminución de MP de un año a otro, siendo marzo durante la época de lluvia de 2020, el que presentó la mayor contaminación con un promedio de 1543.55 ± 362.92 partículas/kg, este patrón se debe posiblemente a la disminución del turismo en la bahía de Tumaco por la emergencia sanitaria que comenzó en Colombia a mediados de marzo del año 2020 y que se presentó a nivel mundial.

Heavy metal pollution causes mass mortality of fish in a tropical estuary in the southwestern Bay of Bengal

A massive fish mortality of the major species, viz., Mugil cephalus, Chanos chanos, and Oreochromis mossambicus, occurred on November 27, 2017 in the Adyar estuary. This catastrophe followed a spell of heavy rainfall and flash floods. A detailed study of water quality parameters (pH, water temperature, salinity, total suspended matter, dissolved oxygen, biochemical oxygen demand, and nutrients) and heavy metals, i.e., chromium (Cr), copper (Cu), cadmium (Cd), nickel (Ni), lead (Pb), and zinc (Zn), in the sediment and fish tissues were analyzed. Pollution indices like the enrichment factor (EF), geo-accumulation index (Igeo), contamination factor (CF), pollution load index (PLI), potential ecological risk index (PERI), and biota sediment accumulation factor (BSAF) were used to measure heavy metals. The pollution indices revealed that metals were significantly enriched in the sediments. The Igeo indicates that there was moderate contamination by Cd (2.27–3.25), whereas CF shows high contamination by Cd (7.22–9.72) and moderate contamination by Pb (2.5–3.25). The PLI (1.04–1.13) suggests that heavy metal contamination of sediments has occurred. Results showed that high concentrations of the toxic metals Pb and Cd were found in the sediment as well as in fish tissues. Length and weight of fish are significantly correlated (r2 = 0.98, p < 0.05). The study revealed that the mass fish kill was due to impulsive changes in the water quality and heavy metal pollution from untreated urban sewage discharges in this region.

The silent threat of plastics along the coastal frontiers of Bangladesh: Are we concerned enough?

Globally plastic pollution is posing a significant threat to the health and integrity of coastal ecosystems. This study aimed to provide a comprehensive overview of plastic pollution in the coastal areas of Bangladesh by examining land-based macroplastic distribution, exploring microplastic (MP) contamination in the coastal aquatic ecosystem and enhancing our understanding of the potential risks associated with MP contamination. Citizen science based monitoring approach using the android application was applied to understand the land-based plastic pollution in the coastal area of Bangladesh. From December 2022 to December 2023, a total of about 3600 photographs of plastic items from 215 citizen scientists were received from the coastal area of Bangladesh covering 580 km long coast line. Polymer Hazard Index (PHI) and Pollution Load Index (PLI) were also calculated to understand the risk of plastic pollution in sediment, water, aquatic organism, dried fish and sea salt. A total of 43 land-based plastic items reported from the coastal area of Bangladesh. Among these plastic items single use items contributed 58.2 % while disposable plastic items contributed 41.8 %. A strong spatial variability in the distribution of these plastic items was observed. PHI and PLI values suggested hazard category-I for MP contamination in sediment, sea salt, water, commercial fishery resources and dry fish. This study highlighted that coastal land area, sea salt, dried fish, water, sediment and organisms are contaminated with plastics which might have the potential threats to human health. Findings from this study will serve as reference data and also baseline for future research to combat the plastic pollution.

Assessment of Heavy Metal Contamination in the Sediments and Soils in the City of Dubai based on the Geoaccumulation Index

This research assesses heavy metal contamination in surface sediments and soils in Dubai using the geoaccumulation index model. Soil and sediment samples were collected from 19 sites across Dubai, with sampling conducted twice to detect variations in heavy metal concentrations. Eight heavy metals—Silver (Ag), Cadmium (Cd), Chromium (Cr), Copper (Cu), Manganese (Mn), Nickel (Ni), Lead (Pb), and Zinc (Zn)—were analyzed for their environmental impact and abundance.Results showed that the soil was highly polluted with Silver (Ag). Nickel (Ni) concentrations ranged from Unpolluted to Moderately Polluted. Chromium (Cr) levels indicated Unpolluted to Moderately Polluted status, except in Al-Marmoum Heritage Village, Jumeirah Lakes, Al-Mamzar Open Beach, and Remram, which showed higher contamination. Cadmium (Cd) levels varied, with some sites Unpolluted and others Unpolluted to Moderately Polluted. Copper (Cu), Manganese (Mn), Lead (Pb), and Zinc (Zn) levels indicated unpolluted status.Area-wise, Jumeirah Lakes, excluding silver contamination, was generally Unpolluted. Dubai Creek exhibited the highest geoaccumulation index for several metals, including Silver, Cadmium, Chromium, Nickel, and Zinc.

ASSESSMENT OF CONTAMINATION AND POLLUTION RISKS CAUSED BY HEAVY METALS IN FISH POND SEDIMENTS

Pollution by heavy metals poses a significant risk to human health and ecology through the food web. Metal contamination in fish pond sediments can be caused by improper waste management and the overuse of artificial feed to increase output and profit. By using an atomic absorption spectrometer to analyse heavy metals such as Cd, Mn, Pb, and Cr, this study aims to assess the contamination levels and pollution risk from bottom sediment samples taken from 12 different fish ponds in the Rajshahi City of Bangladesh. According to this investigation, the concentrations of the metals Pb, Mn, Cr, and Cd were 0.1188 to 1.5139, 0.1899 to 0.8483, 0.0292 to 0.0395, and 0.3017 to 1.6182 mg/kg, respectively. All results show that the metal contents of all the sediments studied around the area do not exceed the standard limit. The risk assessment of the sediments was evaluated based on the geoaccumulation index, enrichment factor, and contamination factor. The analysisindicated that Cd, Pb, and Cr accumulation are within the acceptable limit except for Mn. This study provides essential baseline data on heavy metal contamination, serving as a foundation for future research by focusing on identifying contamination sources, accumulation pathways, and element mobility from feed to fish and sediment to significantly reduce environmental risks and protect both ecosystem integrity and public health.

Assessment of seasonal fluctuation in heavy metal contamination in sediments and surface water of Narmada River, India

ABSTRACT This study aimed to assess the seasonal fluctuation of heavy metal contamination in the sediments and surface water of the Narmada River. In this context, samples were gathered from six stations along the river in 2021–2022 and their concentrations were determined by utilizing Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). The results in sediments, the average concentrations of As, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were 0.05, 1.03, 2.47, 1.64, 750.17, 17.75, 0.54, 0.13, and 1.12 mg/kg and in water, the average concentrations of Co, Fe, Ni, and Zn were 0.03 μg/l, 0.01 mg/l, 0.08 μg/l, and 0.39 μg/l. Seasonal fluctuation in sediments revealed that concentration of metals As, Cu, Fe, Ni, and Zn peaked during the rainy climate, while Co and Cr peaked during the post-monsoon and Mn and Pb peaked during the summer climate. Seasonal fluctuation in water, Co, Ni, and Zn exhibits their highest concentrations during the post-monsoon. The finding of pollution indices revealed that the contamination level was low to moderate. Cluster analysis revealed anthropogenic and agricultural runoff water as a contributor to contamination. The findings of this research enhance comprehension of heavy metal contamination in sediment and water of the Narmada River.

Spatial distribution of potentially toxic elements pollution and ecotoxicological risk of sediments in the high-altitude lakes ecosystem

Sediments are a sink and source for potentially toxic elements (PTE) contamination in aquatic systems. Among aquatic systems, lakes ecosystem play a significant role in managing, maintaining, and supplying water for several environmental and ecological services. The lake has a slow rate of water inflowing contaminant circulation, building up higher contaminants and hence making it most vulnerable. This study focused on and explored the sediments for PTE concentrations in the high-altitude lakes ecosystem of Swat Valley, northern Pakistan. The sediment samples were collected and analyzed for PTE concentrations. Among PTE, iron (Fe) showed an uppermost level of 1024 ± 94.2 mg/kg in Izmis Lake sediments, while cadmium (Cd) noted with a lowermost of 0.30 ± 0.1 mg/kg in Kandol Lake. PTE concentrations in the high-altitude lakes were noted to be lower than the sediment quality guidelines (SQGs), except for copper (Cu) and cadmium (Cd). The concentrations of PTE were utilized to calculate pollution factors and ecotoxicological risks. The contamination factor (Cf) of sediments in high-altitude lakes observed low to moderate contamination levels and ecotoxicological risks. Among high-altitude lakes, the Izmis Lake showed maximum Cf, pollution load index, and risk values for most of PTE than others. Statistical analyses revealed a significant correlation for most PTE and noted geogenic sources of contamination in sediments of high-altitude lakes.

Accumulation Patterns of Polychlorinated Dibenzo-p-Dioxins, Dibenzofurans and Dioxin-like Polychlorinated Biphenyls in Sediments of the South-Eastern Baltic Sea

The current research paper presents the results of the first regional assessment of sediment contamination by dioxins (polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and dioxin-like polychlorinated biphenyls (dl-PCBs)) in the south-eastern part of the Baltic Sea (Lithuanian and Polish marine areas) during the periods of 2014 and 2019–2020. In total, 143 surface and core sediment samples were taken of existing offshore dredged-soil-disposal sites in the area of the former shipyard in the Port of Gdynia (Poland), as well as in a profile from the nearshore to the deeps of the Gdansk basin, following the natural pattern of sediment migration in the region. The obtained results indicated wide variation in both the total content of the investigated compounds as well as the profiles of congeners, indicating the likely sources of their origin. Based on the obtained concentration characteristic profiles of the congeners, we determined the amount of dioxins and the likely sources of their origin in the Gdansk Basin. The profiles showed elevated contents of octa- and hepta-chlorodibenzodioxins (OCDD and HpCDD) in the sediments, while the fractions of most other toxic congeners were considerably lower. The domination of OCDF in the spectrum of the studied PCDFs suggests the possible contribution of industrial processes. The obtained results have filled the gaps in our knowledge while providing a perfect background for more detailed discussions concerning the accumulation of dioxins in surface sediments from the south-eastern part of the Baltic Sea.

Effects of acid mine drainage and sediment contamination on soil bacterial communities, interaction patterns, and functions in alkaline desert grassland

Acid mine drainage and sediments (AMD-Sed) contamination pose serious ecological and environmental problems. This study investigated the geochemical parameters and bacterial communities in the sediment layer (A) and buried soil layer (B) of desert grassland contaminated with AMD-Sed and compared them to an uncontaminated control soil layer (CK). The results showed that soil pH was significantly lower and iron, sulfur, and electroconductivity levels were significantly higher in the B layer compared to CK. A and B were dominated by Proteobacteria and Actinobacteriota, while CK was dominated by Firmicutes and Bacteroidota. The pH, Fe, S, and potentially toxic elements (PTEs) gradients were key influences on bacterial community variability, with AMD contamination characterization factors (pH, Fe, and S) explaining 48.6 % of bacterial community variation. A bacterial co-occurrence network analysis showed that AMD-Sed contamination significantly affected topological properties, reduced network complexity and stability, and increased the vulnerability of desert grassland soil ecosystems. In addition, AMD-Sed contamination reduced C/N-cycle functioning in B, but increased S-cycle functioning. The results highlight the effects of AMD-Sed contamination on soil bacterial communities and ecological functions in desert grassland and provide a reference basis for the management and restoration of desert grassland ecosystems in their later stages.

ASSESSMENT OF PHYSICOCHEMICAL PARAMETERS AND METAL CONTAMINATION IN SEDIMENTS OF THE PERI-URBAN AMAGBA-OKOROMA RIVER, BENIN CITY, NIGERIA.

The key role of sediments in aquatic systems is widely known, sediments are frequently neglected as a factor in the evaluation of water quality assessment. This study assessed the sediment quality of the Peri-urban Amagba-Okoroma River, Benin City, Nigeria, emphasizing physicochemical parameters and heavy metal contamination. Three sites (Upstream site 1, Midstream site 2 and Downstream site 3) were studied and river sediments were collected from each of these sites using Van veen grab. The sediments were collected three times each in the month of March and July, 2023. The results revealed temperature (25.67°C-26°C), slightly alkaline pH (7.55-7.68), and low electrical conductivity (49.33µS/cm-54.67µS/cm). Heavy metals evaluated were all within threshold/probable effect level guideline: Cd (0.09-0.10 mg/kg), Cr (5.61-6.10mg/kg), Cu (18.62-19.90mg/kg), Pb (0.33t-0.37mg/kg), and Zn (32.47-35.01mg/kg). However, Cu slightly exceeded thresholds-effect level limits at midstream site 2 and downstream site 3, indicating localized pollution sources. Principal component analysis and cluster analysis identified significant correlations between Cd-Cr and Cu-Zn, suggesting shared pollution sources likely from industrial or agricultural runoff. Cluster analysis reveal that sites 2 and 3 are more similar compare to site 1 (upstream). The heavy metal pollution indices collectively indicated no sediment contamination across the sites. Geo-accumulation index values for Cd, Cr, Cu, Pb, and Zn suggested unpolluted conditions across all sampling sites. Contamination factor values corroborated these findings, indicating low contamination levels for all metals. Contamination degree values further confirmed the sediment's low degree of contamination, aligning with Pollution load index values, indicating non-pollution. This study underscores the significance of regular monitoring and targeted mitigation efforts to sustain the ecological health of the river ecosystem amidst potential anthropogenic pressures.

Land-Use–Land Cover Changes in the Urban River’s Buffer Zone and Variability of Discharge, Water, and Sediment Quality—A Case of Urban Catchment of the Ngerengere River in Tanzania

The physical integrity of the Ngerengere River and its three tributaries drains within Morogoro Municipality were evaluated by assessing the variations in land-use–land cover (LULC) in the river’s buffer zone, the discharge, and the contamination of river water and sediment from nutrients and heavy metals. Integrated geospatial techniques were used to classify the LULC in the river’s buffer zone. In contrast, the velocity area method and monitoring data from the Wami-Ruvu Basin were used for the discharge measurements. Furthermore, atomic absorption spectrophotometry was used during the laboratory analysis to determine the level of nutrients and heavy metals in the water and river sediment across the 13 sampling locations. The LULC assessment in the river’s buffer during the sampling year of 2023 showed that bare land and built-up areas dominate the river’s buffer, with a coverage of 28% and 38% of the area distribution. The higher discharge across the sampling stations was in the upstream reaches at 3.73 m3/s and 2.36 m3/s at the confluences. The highest concentrations of heavy metals in the water for the dry and wet seasons were 0.09 ± 0.01, 0.25 ± 0.01, 0.03 ± 0.02, 0.73 ± 0.04, 4.07 ± 0.08, and 3.07 ± 0.04 mg/L, respectively, for Pb, Cr, Cd, Cu, Zn, and Ni. The order of magnitude of the heavy metal concentration in the sediments was Zn &gt; Ni &gt; Cr &gt; Cu &gt; Cd &gt; Pb, while the highest NO2−, NO3−, NH3, and PO43− in the water and sediment were 2.05 ± 0.01, 0.394 ± 0.527 0.66 ± 0.05, and 0.63 ± 0.01 mg/L, and 2.64 ± 0.03, 0.63 ± 0.01, 2.36 ± 0.01, and 48.16 ± 0.01 mg/kg, respectively, across all sampling seasons. This study highlights the significant impact of urbanization on river integrity, revealing elevated levels of heavy metal contamination in both water and sediment, the variability of discharge, and alterations in the LULC in the rivers’ buffer. This study recommends the continuous monitoring of the river water quality and quantity of the urban rivers, and the overall land-use plans for conserving river ecosystems.

Distribution and ecological risk assessment of antibiotics in different freshwater aquaculture ponds in a typical agricultural plain, China

Freshwater aquaculture serves as a significant focal point for antibiotic contamination, yet understanding antibiotic distribution across different aquaculture models and stages remains limited. This study evaluated antibiotic pollution in three distinct freshwater aquaculture models: rice-crayfish coculture, fish aquaculture, and crab-crayfish aquaculture, during various aquaculture stages. Of the 33 target antibiotics, 16 antibiotics were detected, with the total concentrations ranging from 111.81 ng/L to 15,949.05 ng/L in water and 10.11 ng/g to 8986.30 ng/g in sediment. Among these antibiotics, erythromycin and lomefloxacin are prohibited for use in Chinese aquaculture. Dominant antibiotics in water included lincomycin, enrofloxacin, and enoxacin, whereas in sediment, oxytetracycline and erythromycin were predominant. Notably, lincomycin emerged as a dominant antibiotic in aquaculture for the first time. The concentrations of these dominant antibiotics were high compared to other aquaculture settings and exhibited elevated ecological risk. Critical periods for antibiotic contamination in water and sediment were found to be incongruent, occurring during the rainy season in July for water and the dry season in October for sediment. Notably, the rice-crayfish coculture model exerts a good effect in reducing antibiotic pollution. Overall, these findings offer valuable evidence for the healthful and sustainable advancement of aquaculture.

Potentially toxic metals contamination in stream sediments of Mbal area (Pan-African fold belt, Cameroon)

The Mbal area is situated within the Neoproterozoic Lom Basin in Cameroon. The objective of this paper was to determine the level of contamination and risk associated of potentially toxic metals (PTMs) in stream sediments of Mbal. Sampling was performed by panning and collected sediment were analysed using an inductively coupled plasma-mass spectrometer. The sediment samples showed significant enrichment in mercury, above 10000 ppb. The other transition metals including manganese, zinc, lead were also elevated, ranging from 825 to 1950, 50.80 to 97 and 9.80 to 87.20 ppm, respectively. Multivariate statistical analyses revealed that the enrichment of the PTMs were attributed both to geogenic and anthropogenic sources. Pollution indicators such as degree of contamination, modified degree of contamination and pollution load index yielding 10809.33–200005, 982.67–18182.33 and 0.59–1.18 respectively, suggest high degree of sediments contamination from natural and anthropogenic sources. Geo-accumulation index and enrichment factor revealed moderate to extreme levels of metallic pollution. Potential ecological risk indices show extreme ecological risk index of PTMs suggesting ecological effects to biota and humans in the ecosystem. Mercury, lithology, mining, domestic and agricultural activities were major sources of PTMs pollution. Toxic metals may cause chronic health problems such as cardiovascular diseases, nervous system disorder, kidney damage and gastrointestinal disorder. This study underlines the importance of continuous monitoring and adaptive management for the preservation of the biotic and non-biotic environment. The results may assist mining companies and local populations in setting realistic targets for monitoring and remediation programs.