Metal pollutant pathways in cohesive coastal catchments: Influence of flocculation and biopolymers on partitioning and flux

Schindler, Rob; Comber, Sean; Manning, Andrew J.

doi:10.1016/j.scitotenv.2021.148800

Cited by 11 publications

(5 citation statements)

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“…Currently, a large amount of manpower and material resources is invested in dredging projects for reliable navigation conditions, heavy metal‐contaminated sediment remediation, and ecological habitat restoration (Liss et al., 2004; Shen et al., 2018). The transportation and downward flux of SPM in aquatic environments are essential to address those engineering and environmental problems, which are controlled, to a large extent, by the settling velocity of the aggregate (Izquierdo–Ayala et al., 2021; Schindler et al., 2021). Moreover, the settling velocity of widespread biomineral flocs is altered significantly due to the colonizing microorganisms, and thus leads to an obstacle for the accurate prediction of sediment and organic carbon fluxes (Bungartz et al., 2006; Larsen, Harvey, & Crimaldi, 2009, Larsen, Harvey, Noe, & Crimaldi, 2009).…”

Section: Discussionmentioning

confidence: 99%

Biomineral Flocculation of Kaolinite and Microalgae: Laboratory Experiments and Stochastic Modeling

et al. 2022

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The transportation of cohesive sediments has attracted great attention for decades due to the significant influences of sediments on various coastal and offshore engineering (e.g., siltation, dredging, seawall foundation treatment, and riverbed morphology) and environmental (e.g., pollutant transport, phytoplankton photosynthesis, and coastal wetland sustainability) issues (Coats et al., 1989;Edmonds & Slingerland, 2010;Sun et al., 2021;Teisson, 1991). It is a challenge to precisely predict the dynamic processes of cohesive sediments because they exist in the form of flocs (clusters) rather than single particles, which further controls the size and the settling velocity (

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Section: Discussionmentioning

confidence: 99%

Biomineral Flocculation of Kaolinite and Microalgae: Laboratory Experiments and Stochastic Modeling

et al. 2022

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“…The maximum was frequently found at site F6 where the boundary of tidal river reach is located, probably as a result of the flocculation effect [30,31]. The salinity of river water serves as an important controlling factor for the partitioning of heavy metals to sediments, particularly the flocculation process in the lower reaches and estuary of rivers affected the distribution of heavy metals in the river sediments [31]. The concentration at the river mouth (F7) slightly decreased compared with site F6, probably because of resuspension and transportation of contaminated sediments seaward.…”

Section: Spatial and Seasonal Variations In Heavy Metalsmentioning

confidence: 99%

“…where CF i and n are the contamination factor of each heavy metal obtained using the Equation ( 2) and the number of heavy metals studied, respectively. Based on the mCd value, the sediment heavy metal contamination level can be categorized into ultra-high degree (mCd > 32), extremely high degree (16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32), very high degree (8)(9)(10)(11)(12)(13)(14)(15)(16), high degree (4-8), moderate degree (2-4), low degree (1.5-2), and nil to very low degree of contamination (<1.5) [24].…”

Section: Modified Degree Of Contamination (Mcd)mentioning

confidence: 99%

“…Overall, the spatial distribution of heavy metals in the Fengshan River sediments showed a relatively high concentration in the lower reaches (F6, F7). The maximum was frequently found at site F6 where the boundary of tidal river reach is located, probably as a result of the flocculation effect [30,31]. The salinity of river water serves as an important controlling factor for the partitioning of heavy metals to sediments, particularly the flocculation process in the lower reaches and estuary of rivers affected the distribution of heavy metals in the river sediments [31].…”

Section: Spatial and Seasonal Variations In Heavy Metalsmentioning

confidence: 99%

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Spatiotemporal Variation and Ecological Risk Assessment of Heavy Metals in Industrialized Urban River Sediments: Fengshan River in Southern Taiwan as a Case Study

et al. 2022

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The sediment pollution index acts as a useful indicator for assessing anthropogenic pollution within river drainage basins. An industrialized urban river, Fengshan River in Kaohsiung City, southern Taiwan has been suffering heavy metal pollution from surrounding factories. In this study, spatial and seasonal variations in heavy metals in sediments from seven sampling sites of Fengshan River were determined to assess sediment pollution status and potential ecological risk using multiple sediment pollution indices. Results showed that the heavy metal concentrations displayed large spatial variations. Severe contamination of heavy metals, especially for Cr, Hg, and Zn in the lower reaches of Fengshan River, may attribute to wastewater discharges from leather processing and metal finishing factories along the river drainage basin. An increase in metal concentrations from upstream to downstream indicated that heavy metals tend to accumulate in tidal reaches, probably as a result of the flocculation effect. Frequent heavy rainfall in the wet season can enhance surface runoff to discharge metal pollutants from non-point sources (scattered factories) into the river. Assessment of multiple pollution indices showed moderately polluted (mCd = 3.9, PLI = 2.6) and considerable ecological risk (RI = 540, mERMQ = 0.55), indicating Fengshan River sediments, particularly in the lower reaches, are considered toxic and can cause adverse effects to benthic organisms. Organic matters showed a good correlation with heavy metals, which play an important role in the spatiotemporal variations in heavy metal pollutants in the Fengshan River sediments. This study can provide valuable information for river pollution remediation, and urban planning and management.

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“…Large fluvial systems drain the continental surface, gathering erosion products and anthropogenic agents, and form huge deltas that result from transport of sand, but mainly silt and clay [1][2][3]. These fine cohesive sediments (mud) host pollutants and bind important portions of nitrogen (N) and phosphorus (P) and organic carbon (OC) [4][5][6][7][8][9]. Because particles smaller than 32 µm tend to form aggregates (or flocs) [10][11][12], freshwater flocculation likely dictates sediment dynamics in large lowland rivers [13][14][15][16], and thereby, the dispersed particle approach does not appropriately represent the suspended load [17].…”

Section: Introductionmentioning

confidence: 99%

Flocculation Patterns Related to Intra-Annual Hydrodynamics Variability in the Lower Grijalva-Usumacinta System

Izquierdo-Ayala¹,

García-Aragón²,

Castillo-Uzcanga

et al. 2023

Water

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Particle aggregation modifies sediment dynamics, which is a determining factor for morphodynamic and ecological processes in deltaic plains. Here, we investigated the link between intra-annual hydrodynamics variability and flocculation in the Grijalva-Usumacinta system. Monthly (2016–2017) and seasonal (2021–2022) river data was processed using analytical methods and the simplified sonar equation. Flocs were reformed and characterized in the laboratory, validating the in situ settling velocities (0.5–3.8 mm/s) and the existence of large low-density macro-flocs (>300 μm). We verified that flocculation prevailed, exhibiting seasonal patterns; (1) the highest aggregation rates matched the increase in total suspended solids at rising-flow (>100 mg/L), (2) periods of high-flow showed stable aggregation rates, and (3) an influence of marine conditions occurred at low-flow. Particulate phosphorous and organic fraction showed seasonal patterns linked to flocculation. Due to damming, the shear rates varied slightly (7–11 L/s) in the Grijalva, leading to high flocculation intensities affecting the diffusivity ratio. In the Usumacinta, aggregation was limited by shear rates that normally exceed 15 1/s. We found seasonal Rouse parameters representative of sediment dynamics.

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Metal pollutant pathways in cohesive coastal catchments: Influence of flocculation and biopolymers on partitioning and flux

Cited by 11 publications

References 38 publications

Biomineral Flocculation of Kaolinite and Microalgae: Laboratory Experiments and Stochastic Modeling

Biomineral Flocculation of Kaolinite and Microalgae: Laboratory Experiments and Stochastic Modeling

Spatiotemporal Variation and Ecological Risk Assessment of Heavy Metals in Industrialized Urban River Sediments: Fengshan River in Southern Taiwan as a Case Study

Flocculation Patterns Related to Intra-Annual Hydrodynamics Variability in the Lower Grijalva-Usumacinta System

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