Harbour Water Research Articles

Study of Atmospheric Forcing Influence on Harbour Water Renewal

In this study, we use observations and numerical simulations to investigate the effect of meteorological parameters such as wind and atmospheric pressure on harbour water exchanges. The modelled information is obtained from the SAMOA (Sistema de Apoyo Meteorológico y Oceanográfico de la Autoridad Portuaria) forecasting system, which is a high-resolution numerical model for coastal and port-scale forecasting. Based on the observations, six events with high renewal times have been proposed for analysis using the SAMOA model. Therefore, the conclusions of this study have been possible due to the combination of observed data from the measurement campaigns and the information provided by the model. The results show that days with higher renewal times coincide with favourable wind-direction events or increases in atmospheric pressure. After analysing these events using model results, it was observed that during these episodes, water inflows were generated, and in some cases, there was a negative difference in levels between inside and outside the harbour produced by atmospheric pressure variations. The latter may be due to the fact that the water in the harbour (having a lower volume) descends faster and, therefore, generates a difference in level between the exterior and the interior and, consequently, inflow currents that imply an increase in the renewal time. These results are a demonstration of how meteorological information (normally available in ports) can be used to estimate currents and water exchanges between ports and their outer harbour area.

Performance analysis of the water quality index model for predicting water state using machine learning techniques

Existing water quality index (WQI) models assess water quality using a range of classification schemes. Consequently, different methods provide a number of interpretations for the same water properties that contribute to a considerable amount of uncertainty in the correct classification of water quality. The aims of this study were to evaluate the performance of the water quality index (WQI) model in order to classify coastal water quality correctly using a completely new classification scheme. Cork Harbour water quality data was used in this study, which was collected by Ireland's environmental protection agency (EPA). In the present study, four machine-learning classifier algorithms, including support vector machines (SVM), Naïve Bayes (NB), random forest (RF), k-nearest neighbour (KNN), and gradient boosting (XGBoost), were utilized to identify the best classifier for predicting water quality classes using widely used seven WQI models, whereas three models are completely new and recently proposed by the authors. The KNN (100% correct and 0% wrong) and XGBoost (99.9% correct and 0.1% wrong) algorithms were outperformed in predicting the water quality accurately for seven WQI models. The model validation results indicate that the XGBoost classifier outperformed, including accuracy (1.0), precision (0.99), sensitivity (0.99), specificity (1.0), and F1 (0.99) score, in order to predict the correct classification of water quality. Moreover, compared to WQI models, higher prediction accuracy, precision, sensitivity, specificity, and F1 score were found for the weighted quadratic mean (WQM) and unweighted root mean square (RMS) WQI models, respectively, for each class. The findings of this study showed that the WQM and RMS models could be effective and reliable for assessing coastal water quality in terms of correct classification. Therefore, this study could be helpful in providing accurate water quality information to researchers, policymakers, and water research personnel for monitoring using the WQI model more effectively.

EVALUATION OF SEDIMENT PARTICLE SIZES OF HEAVY METAL CONTAMINATION IN THE LAGOS INLAND WATER SYSTEM.

Sediments are important in the geochemical cycles of marine and estuarine ecosystems with the ability to influence ecological processes and inhabiting biota. This study evaluated sediment particle sizes of the Lagos Harbour and inland water system with a view to determine their diversity and influence on heavy metal levels. Samples were collected using Van veen grabs, viz; dry season 2013 (DS-1), wet season 2013 (WS) and dry season 2014 (DS-2) for a period of 18 months in the Lagos Lagoon and inland water system. The sediments collected were analysed according to the British Standard (BS 1377-2, 1990) at the instrument Physical Geography Laboratory, University of Portsmouth. The mean clay, silt, course and sand were found to be 6.67± 4.51, 6.0 ± 3.0, 9.17± 3.25 and 0.37 ± 3.06 respectively. The particle size in relation with total metals/metalloids concentration in the sediment revealed positive correlation with significant differences (p<0.05) between clay and Fe (r = 0.391*), clay and Pb (r = 0.40*). While the particle size in relation and recoverable metals/metalloids concentration in the sediment revealed positive correlation with significant differences (p<0.05) between clay and Mn (r = 0.416*), silt and Mn (r = 0.414*). The particle size in relation with bioavailable metals/metalloids concentration in the sediment revealed positive correlation with were significant differences (p<0.05) between silt and Pb (r = 0.426*). This implies that the widespread dredging of the lagoon sediments and artisanal sand mining has had its toll on the structural integrity of the substratum. The strong correlation between the finer particle sizes with total, recoverable and bioavailable fractions of Fe-Mn-Pb in the sediment samples is notable and implies increased chances of retention of pollutants in the sediment matrix. Keywords: Evaluation Techniques, Inland-Lagoons, Sediment texture, Heavy metal/metalloid, Marine pollution.

Simulator Study on Emergency Manoeuvre on Ship Entering Colombo Harbour

Colombo Harbour has had its fair share of ship accidents just like any other port. The Harbour breakwater has a comparatively narrow entrance today as it was built in 1800’s when the ships were much smaller. Since then, ship sizes have continued to increase. There is a race amongst companies to build and own the largest ship. A good recent example is the “Ever Given” 22000 TEU ship which blocked the Suez Canal. Now they build the “Ever Accept” an even larger 24000 TEU ship which still will transit the canal. Risk assessments need to be done for the safety of the ports and the safety of other ships in the port. The Harbour water area in Colombo remains the same has even decreased when privatization of QEQ to SAGT took place, which was a big mistake. Large ships have come into the Colombo harbour and have not been able to stop in time due to various reasons and damaged Jetties and other ships and third-party properties in the harbour. Here we look at how to stop such accidents.

Evaluation of the antifouling efficacy of biogenic constituents of some algal species

Marine macroalgae are good source of biogenic compounds having potent activities such as antimicrobial and antifouling. This work aimed to use the different constituents (water soluble polysaccharides “WSP”, protein, and lipid) of four algal species (Ulva fasciata, Cymodocea nodosa, Padina pavonia, and Colpomenia sinusa) as active biocides in paint formulations for preparing environmentally safe antifouling marine paints. Each type of these algal extracts was mixed solely by 2% (w/w) for WSP and protein and 1% (w/w) for lipid with the prepared paint formulation forming sixteen paint compositions beside the control (prepared paint formulation). They were applied on unprimed steel panels then hanged on a steel frame and immersed in Eastern Harbour (E. H.) water of Alexandria city, Egypt. The panels were followed up by visual and photographic inspections. Besides, the effect of these different marine paint formulations on seawater characteristics was studied through analysis of seawater samples collected on immersion date and on each inspection date. Results showed that, after 171 days of immersion the best results were obtained for the panels coated with the formulations containing hot and cold WSP extracts; the percentages of fouling organisms on the coated panels ranged between 25 and 35% of the panels area. U. fasciata panels in both cases showed the lowest percentages (25 and 30%) of fouling organisms. The panels coated with the formulations containing protein extract of P. pavonia and C. sinusa showed good results as well (35% in each case). Moderate results obtained for protein extract of U. fasciata and lipid extracts of C. nodosa, P. pavonia and C. sinusa (40 and 45%). The measured hydrographical parameters are within the normal range indicating that, these paints are environmentally safe.

An assessment of water quality and pollution in Puranawella fishery harbour, Dewinuwara, Sri Lanka.

Fishery harbours in Sri Lanka have been facing severe pollution problems since recent past. However, a systematic monitoring of the pollutant load has not been done. This study was carried out at Puranawella harbour, located in the southern coast of Sri Lanka, with the objective of assessing the severity of the pollution level. Investigation was carried out at seven sampling stations at three week intervals during the period from December 2010 to February 2011. Spatial and seasonal variations of physico-chemical parameters and phytoplankton abundances were examined together with bacteriological analyses. Among the characteristics studied, significant differences between sampling stations were observed for water transparency, chemical oxygen demand, orthophosphate, nitrite, oil and grease content of surface and bottom water as well as Cu and Pb in water and sediment. Water temperature, pH, salinity, total suspended solids, total dissolved solids, dissolved oxygen, biological oxygen demand, Pb in sediment and phytoplankton abundance showed significant variations among sampling months. Harbour water was characterized significantly by poor transparency (0.35m - 4.00m) and high amount of total suspended solids (0.015 - 0.072 gl-1), total dissolved solids (6.98 - 43.79 gl-1), high biological oxygen demand (0.44 - 8.08 mgl-1), high chemical oxygen demand (0.78 - 23.4 mgl-1), high orthophosphate (0.008 - 1.58 mgl-1) and a high proportion of Nitrite (0.02 - 1.83 mgl-1) indicating a severe eutrophication. Biological oxygen demand close to harbor jetty was 4.46 mgl-1, which exceeded the recommended quality standard. Orthophosphate in surface waters exceeded the limit 0.015 mgl-1, amount necessary for the establishment of heavy algal blooms. Oil and grease content of surface (9 - 82 mgl-1) and bottom water layers (22 - 241 mgl-1) inside the harbour also exceeded the recommended value of 10 mgl-1. The concentration of Cu and Pb in water exceeded the standard value of 0.5 mgl-1. MPN value of total coliforms (per 100 ml) ranged between 5 and 2400, which also exceeded the recommended standards. The phytoplankton density ranged between 16356 and 62500 cells/m3. Results of this study revealed that the water quality of the arbour has been degraded and harbour is subjected to severe oil pollution, organic pollution and microbial contamination. Since this study was carried for only 3 months, a yearlong study is required to come to stronger conclusions.DOI: http://dx.doi.org/10.4038/jur.v1i1.6157 Journal of the University of Ruhuna 2013 1(1): 23-30

Two-layer hydraulic exchange flow through the Burlington Ship Canal

The exchange flow through the Burlington Ship Canal connecting Hamilton Harbour with Lake Ontario is investigated, using a two-layer internal hydraulics model. The summer exchange features an upper layer of polluted Harbour Water flowing from the harbour into the lake, whereas a lower layer of fresh Lake Ontario Water flowing from the lake into the harbour. We predict this exchange, taking into account the effects of both friction and barotropic forcing of multiple frequencies. Predictions of density interface and volume flux compare well with experimental and field data. The interface varies non-linearly with distance along the canal, with and without barotropic forcing. Our results indicate that the exchange flow is highly frictional. The barotropic forcing comprises oscillation modes of different frequency; these individual forcing modes cause the interface and layer velocities to fluctuate significantly in time, but their influence on the time average flows through the canal is minimal.

Integration of numerical modeling and Bayesian analysis for setting water quality criteria in Hamilton Harbour, Ontario, Canada

The credibility of the scientific methodology of mathematical models and their adequacy to form the basis of public policy decisions has frequently been challenged. We believe that the development of novel methods for rigorously assessing model uncertainty should be a top priority of the modeling community. In this regard, we introduce the Bayesian calibration of process-based models as a methodological advancement that warrants consideration in aquatic ecosystem research. This modeling framework combines the advantageous features of both mechanistic and statistical approaches, i.e., mechanistic understanding that remains within the bounds of data-based parameter estimation. Other advantages of the Bayesian approach are the ability to sequentially update “beliefs” as new knowledge is available, the consistency with the scientific process of progressive learning and the policy practice of adaptive management. In this study, the Bayesian calibration framework is used to guide the water quality criteria setting process in Hamilton Harbour, Ontario, Canada. First, we present the results of the Bayesian calibration exercise and examine the ability of the model to adequately reproduce the average observed patterns along with the major cause–effect relationships underlying the Harbour water quality conditions. We then address the following critical questions regarding the future response of the system: How possible is it to meet the objective of delisting the study system as an Area of Concern, if the nutrient loading reductions proposed by the Hamilton Harbour Remedial Action Plan are actually implemented? What additional remedial actions are needed to increase the likelihood of meeting the water quality targets? In this regard, the present modeling study undertakes an estimation of the critical nutrient loads in the Harbour based on acceptable exceedance frequencies and confidence of compliance levels with different water quality criteria, e.g., chlorophyll a, total phosphorus (TP). Our analysis suggests that the water quality goals for TP (17 μg L−1) and chlorophyll a concentrations (5–10 μg L−1) will likely be met, if the recommendation for phosphorus loading at the level of 142 kg day−1 is achieved. We also provide evidence that the anticipated structural shifts of the zooplankton community will determine the restoration rate of the Harbour. Finally, we pinpoint two critical aspects of the system dynamics that invite further investigation and will likely modulate the stability of the new trophic state, i.e., the coupling between the benthic and pelagic habitat and the relative importance of the allochthonous organic matter in sustaining the secondary production in the system.

Eutrophication risk assessment in Hamilton Harbour: System analysis and evaluation of nutrient loading scenarios

Environmental modeling has been an indispensable tool of the Hamilton Harbour restoration efforts, where a variety of data-oriented and process-based models have been used for linking management actions with potential ecosystem responses. In this study, our objective is to develop a biogeochemical model that can effectively describe the interplay among the different ecological mechanisms modulating the eutrophication problems in Hamilton Harbour, Ontario, Canada. First, we provide the rationale for the model structure adopted, the simplifications included, and the formulations used during the development phase of the model. We then present the results of a calibration exercise and examine the ability of the model to sufficiently reproduce the average observed patterns along with the major cause–effect relationships underlying the Harbour water quality conditions. The present modeling study also undertakes an estimation of the critical nutrient loads in the Harbour based on acceptable probabilities of compliance with different water quality criteria (e.g., chlorophyll a, total phosphorus). Our model suggests that the water quality goals for TP (17 μg L − 1) and chlorophyll a concentrations (5–10 μg L − 1) will likely be met, if the Hamilton Harbour RAP phosphorus loading target at the level of 142 kg day − 1 is achieved. We also provide evidence that the anticipated structural shifts of the zooplankton community will determine the restoration rate as well as the stability of the new trophic state in the Harbour.

Dissolved Organic Matter in the Great Lakes: Role and Nature of Allochthonous Material

Dissolved organic matter (DOM) quality and the modifying influence of light on DOM bioavailability were investigated along a natural gradient of allochthonous influence in the lower Great Lakes. Using parallel factor analysis (PARAFAC), three DOM fluorophores were identified. One fluorophore, previously identified as peak C, was of allochthonous (component 1) origin and two previously uncharacterized fluorophores were identified as autochthonous (components 2 and 3). Component 1 was photoreactive and the dominant form in creek water samples while components 2 and 3 were dominant in Hamilton Harbour and lake water samples. Components 2 and 3 showed limited photoreactivity. Exposure to full spectrum irradiance decreased the average molecular weight of DOM (i.e., increased the absorbance ratio (a254:a365)) for all water samples. DOM bioavailability was lowest in creek and highest in lake water samples and was inversely related to DOM average molecular weight. Photomodification of DOM resulted in higher bacterial activity although these differences were not significantly different. This suggests that light plays a significant role in the cycling of terrestrially-derived DOM and to a certain extent autochthonous DOM, potentially increasing metabolism of both terrestrially and microbially derived DOM in the Great Lakes aquatic ecosystems.

A note on the concentrations and bioavailability of selected metals in sediments of Richards Bay Harbour, South Africa

Sediments are considered to be the ultimate sink for most contaminants and therefore pose the highest risk to these aquatic environments. This paper presents the levels of metals in sediments from Richards Bay Harbour, 20 years after the construction of the harbour and studied spatial and temporal, as well as the proportion of the bioavailable metal fraction. Sediment samples were collected from nine sites in Richards Bay Harbour. Sequential extractions of metals were carried out and samples were analysed for aluminium, chromium, copper, iron, manganese and zinc. Metal concentrations in sediment samples varied only slightly between seasons but showed significant spatial variation, which was significantly correlated to sediment particle size composition. Highest metal concentrations were found in sites with substrata dominated by fine mud. Manganese and Zn had more than 50% of this concentrated in the easily reducible fractions. Zinc concentrations were not elevated when compared to historic data. More than 70% of Cr was concentrated in the inert fractions nevertheless concentrations recorded at some sites were still above action levels when considering only the bioavailable fractions. Keywords : sediments, metals, bioavailability, sediment composition, Richards Bay Harbour Water SA Vol. 31(4) 2005: 589-596

Spectral study and antifouling assessment of some thiosemicarbazone derivatives

Three thiosemicarbazone derivatives were synthesised: p‐chlorobenzylideneamino thiosemicarbazone, p‐itrobenzylideneamino thiosemicarbazone and p‐N,N ′‐dimethylminobenzylideneamino thiosemicarbazone. The structures of these compounds were characterised by elemental analysis, IR, 1H NMR and UV spectral measurements. The antifouling properties of the compounds were evaluated through the incorporation of each compound in a marine coating system and testing the system in Alexandria Eastern Harbour water. The results are discussed in the light of the leaching rate of the compounds from their paint films, and their interaction with paint matrix.

Genotoxic and biochemical responses in caged eel ( Anguilla anguilla L.) after short-term exposure to harbour waters

European eel ( Anguilla anguilla L.) were caged and exposed in situ for 8 and 48 h to the Aveiro offward fishing harbour water (HW) and to clean seawater under laboratory conditions (Control). Eel liver biotransformation (Phase I) was measured as ethoxyresorufin- O-deethylase (EROD) activity, cytochrome P450 ( P450) and glutathione S-transferase (GST) activity (Phase II). Genotoxic responses were determined as blood, liver and kidney DNA strand breaks as well as erythrocytic nuclear abnormalities (ENAs). HW failed to significant increase liver EROD, GST activities and ENA frequency. Nevertheless, P450 content was significantly increased after 8 and 48 h exposure. Genotoxicity measured as DNA integrity decrease was found in blood after 8 and 48 h exposure to HW, whereas in liver and kidney, it was observed after 48 h exposure to HW. Blood, kidney and liver genotoxicity may be due to the presence of polycyclic aromatic hydrocarbons (PAHs) which are genotoxic compounds and the main HW organic contaminants.

Factors influencing the short-term variation in phytoplankton composition and biomass in coral reef waters

The short-term temporal dynamics of phytoplankton composition was compared among coral reef waters, the adjacent ocean and polluted harbour water from July until October along the south-western coast of Curacao, southern Caribbean. Temporal variations in phytoplankton pigment 'fingerprints' (zeaxanthin, chlorophyll b, 19′-hexanoyloxyfucoxanthin, fucoxanthin, 19′-butanoyloxyfucoxanthin, chlorophyll c 2 and c 3 relative to chlorophyll a) in the ocean were also observed in waters overlying the reef. However, with respect to specific pigments and algal-size distribution, the algal composition in reef waters was usually slightly different from that in the oceanic water. Phytoplankton biomass (chlorophyll a) was either higher or lower than in the oceanic water. The relative amount of fucoxanthin and peridinin was usually higher, and the relative and absolute amount of zeaxanthin was significantly lower than in oceanic water. Zeaxanthin-containing Synechococci were significantly reduced in reef water. Average algal cell size increased from the open water to the reef and the harbour entrance. Large centric diatoms (>20 m O) were better represented in reef than in oceanic water. In reef-overlying waters, the nitrate and nitrite concentrations were higher than in oceanic water. In front of the town, anthropogenic eutrophication (sewage discharge and ground water seepage) resulted in higher NH4, NO3 and PO4 concentrations than at other reef stations. This concurred with significantly enhanced phytoplankton biomass (chlorophyll a), chlorophyll c 2 and peridinin amounts at Town Reef compared with the other reef stations. Polluted harbour water usually showed the highest phytoplankton biomass of all stations, dominated by diatoms and dinoflagellates. Conditions in reef waters and harbour water promoted the occurrence and the relative abundance of diatoms and dinoflagellates. Harbour water did not influence the phytoplankton composition and biomass at reef stations situated >5 km away from the harbour entrance. We conclude that phytoplankton undergoes a shift in algal composition during transit over the reef. The dominant processes appear to be selective removal of zeaxanthin-containing Synechococcus (by the reef benthos) and (relative) increase in diatoms and dinoflagellates. The difference in the phytoplankton composition between reef and oceanic waters tends to increase with decreasing dilution of reef water with ocean water.

Antifouling Paint Booster Biocides in the UK Coastal Environment and Potential Risks of Biological Effects

In the yachting sector of the UK antifouling market, organic biocides are commonly added to antifouling preparations to boost performance. Few data presently exist for concentrations of these compounds in UK waters. In this study the concentrations of tributyltin (TBT) and eight booster biocides were measured before and during the 1998 yachting season. The Crouch Estuary, Essex, Sutton Harbour, Plymouth and Southampton Water were chosen as representative study sites for comparison with previous surveys of TBT concentrations. Diuron and Irgarol 1051 were the only organic booster biocides found at concentrations above the limits of detection. Diuron was measured at the highest concentrations, whilst detectable concentrations of both Irgarol 1051 and diuron were determined in areas of high yachting activity (e.g. mooring areas and marinas). Maximum measured values were 1421 and 6740 ng/l, respectively. Lower concentrations of both compounds were found in open estuarine areas, although non-antifouling contributions of diuron may contribute to the overall inputs to estuarine systems. TBT was found to be below or near the environmental quality standard (EQS) of 2 ng/l for all samples collected from estuarine areas frequented by pleasure craft alone, but with much higher concentrations measured in some marinas, harbours and in areas frequented by large commercial vessels. Using the limited published environmental fate and toxicity data available for antifouling booster biocides, a comparative assessment to evaluate the risk posed by these compounds to the aquatic environment is described. TBT still exceeds risk quotients by the greatest margins, but widespread effects due to Irgarol 1051 and less so diuron cannot be ruled out (particularly if use patterns change) and more information is required to provide a robust risk assessment.

Marine anti‐corrosion paints based on thiouracil compounds

The inhibition of marine corrosion of steel by 6‐amino‐2‐thiouracil (I) and its derivatives 6‐benzylideneamino‐2‐thiouracil (II) and 6‐p‐chlorobenzylideneamino‐2‐thiouracil (III) has been tested on laboratory scale using electrochemical technique which was performed on mild steel in sea water medium and on field scale through the incorporation of the compounds individually in marine paints compositions. The paints containing the compounds were applied on unprimed steel and the coated panels were tested in Alexandria Eastern Harbour water (Egypt). The electrochemical measurements indicated that both compounds (I) and (III) acted as cathodic‐type inhibitors, but the data of compound (II) showed neither cathodic nor anodic inhibition. Two marine paint compositions were prepared using different binder materials. The three compounds were added individually in both paint compositions. The paint composition based on the soluble resin material as a sole binder and containing compound (I) showed the best corrosion protection of its steel surface till more than two months followed by the paint composition containing compound (III). The same paint containing the compounds showed antifouling property for four months.

Multivariate Analysis of the Hong Kong Victoria Harbour Water Quality Data

Two multivariate techniques (principal components analysis and cluster analysis) are used to analyse Hong Kong Victoria Harbour water quality data. Results show that the sampling stations can be divided into four main groups, which is consistent with the tripartite structure obtained from an environmental approach. Moreover, it is found that the groups produced can be interpreted based on two main features of the data: nutrient level and the algae-faecal pollution.

Review of the Water Environment in Tolo Harbour:A Land-Locked Embayment in North-Eastern Hong Kong

Uncontrolled discharges of municipal sewage, agricultural wastes and industrial effluents in the past decades have upset the ecosystems, caused frequent occurrences of red tides, and resulted in a loss of inland and coastal amenity values of the land-locked embayment of Tolo Harbour and the related river systems. This paper provides a review of the established relevant legislations and sewage management facilities for environmental conservation, and the current status of water environment in the Tolo Harbour Water Control Zone.;Uncontrolled discharges of municipal sewage, agricultural wastes and industrial effluents in the past decades have upset the ecosystems, caused frequent occurrences of red tides, and resulted in a loss of inland and coastal amenity values of the land-locked embayment of Tolo Harbour and the related river systems. This paper provides a review of the established relevant legislations and sewage management facilities for environmental conservation, and the current status of water environment in the Tolo Harbour Water Control Zone.

Isotopic Variations in Hamilton Harbour Water as an Indicator of Lake Ontario Exchange Flow

In September, 1993, and May, 1994, surface water samples were collected from Hamilton Harbour at the western end of Lake Ontario to determine if hydrogen and oxygen isotopes could be used to estimate the volume of lake water entering the harbor through the Burlington Canal, a shipping canal at the harbor's eastern end. In addition, the survey sought to determine if the isotopic variations were significantly different to allow mapping of the lake water plume present within the harbor. The results of this preliminary survey show a west to east enrichment in stable oxygen and hydrogen ratios. This distribution results from mixing via the Burlington Canal of lake water at the eastern end of the harbor that is enriched in 18O and 2H, with harbor water that is depleted in 18O and 2H relative to lake water. The results suggest that variations in the isotopic signature between Lake Ontario and Hamilton Harbour waters differ significantly to allow the use of oxygen and hydrogen isotopes to examine lake water-harbor water mixing relationships. A more detailed sampling will allow the amount of exchange across the Burlington Canal to be calculated, and the extent of the harbor's lake water plume to be determined.

Dissolved Metal Concentrations and Suspended Sediment in Hamilton Harbour

Hamilton Harbour sediments are elevated in metal and organic contaminants, resulting from 75 years of industrial and municipal discharge. These contaminants could be released from the sediments during resuspension events caused by strong winds or dredging operations. We predict the metal concentrations in the water column that would be found during resuspension, using an equilibrium adsorption model. Confirmation of the model was made experimentally using small reactors with spikes of metal added to the aqueous phase. Four different Hamilton Harbour sites were sampled and used in the experiments. The time to reach steady state was determined as 2 days or less after the resuspension event. Results from the experiments yielded aqueous phase concentrations equivalent to or lower than concentrations in Hamilton Harbour water. We conclude that the concentration of metals in the water column of Hamilton Harbour is not elevated by resuspension of surficial sediments.