Joseph P. Essien

Erratum to: Distribution and ecotoxicological significance of polycyclic aromatic hydrocarbons in sediments from Iko River estuary mangrove ecosystem.

The distribution of polycyclic aromatic hydrocarbons (PAHs) in epipelic and benthic sediments from Iko River estuary mangrove ecosystem has been investigated. Total PAHs ranged from 6.10 to 35.27 mg/kg dry weight. Quantitative difference between the total PAHs in epipelic and benthic sediments showed that the benthic sediment known for higher capability to serve as sink for chemical pollutants accumulated less PAHs. This implies that PAHs in the epipelic sediment may plausibly be from industrial sources via runoff and/or of biogenic origin. A strong pyrolytic source fingerprint has been detected with slight influence of petrogenic sources. Total organic carbon normalized PAHs (sum of 16 PAHs, 59.7 to 372.4 mg/kg OC) were under (except for ES3 and BS3) the threshold effects concentrations (TEC, 290 mg/kg OC). Total PAHs in Iko River estuary sediments were in the range between ERL and ERM.

Microalgae biodiversity and biomass status in Qua Iboe Estuary mangrove swamp, Nigeria

Microalgae composition, abundance, diversity and biomass of the Qua Iboe Estuary mangrove swamp were studied. The results revealed the rich assemblage of the brackish ecosystem. Six major taxanomic classes were encountered. These were the Bacillariophyceae, Cyanophyceae, Chlorophyceae, Chrysophyceae, Euglenophyceae and Phaeophyceae. Their composition, abundance and diversity exhibits strong seasonal variation. Variations between pelagic and sedimentary habitats were also noticed. The diatoms (Bacillariophyceae) dominated the habitats. Actinoptychus undalatus, Navicula radiosa and Amphora ovalis co-dominated the pelagic water column; while the epipellic (intertidal) and benthic (subtidal) sediments were co-dominated by A. ovalis and Actinoptychus undulatus. Analyses of the Shannon’s index of general diversity (H1), McArthur-Terborgh species equitability index (E) and Simpson’s index of dominance (D) of the microalgae communities revealed that A. ovalis with a mean H1-value of 0.25, E-value of 0.08 and D-value of 0.05 was the most prevalent genus in the mangrove ecosystem despite its uneven distribution. The densities of the microalgae communities corresponded with their biomass statuses and were seriously impacted by oil spillage. This forms the basis of concern because the estuary is associated with a high probability of major oil pollution with serious consequences for ecological stability and fisheries.

Source Evaluation and Trace Metal Contamination in Benthic Sediments from Equatorial Ecosystems Using Multivariate Statistical Techniques.

Trace metals (Cd, Cr, Cu, Ni and Pb) concentrations in benthic sediments were analyzed through multi-step fractionation scheme to assess the levels and sources of contamination in estuarine, riverine and freshwater ecosystems in Niger Delta (Nigeria). The degree of contamination was assessed using the individual contamination factors (ICF) and global contamination factor (GCF). Multivariate statistical approaches including principal component analysis (PCA), cluster analysis and correlation test were employed to evaluate the interrelationships and associated sources of contamination. The spatial distribution of metal concentrations followed the pattern Pb>Cu>Cr>Cd>Ni. Ecological risk index by ICF showed significant potential mobility and bioavailability for Cu, Cu and Ni. The ICF contamination trend in the benthic sediments at all studied sites was Cu>Cr>Ni>Cd>Pb. The principal component and agglomerative clustering analyses indicate that trace metals contamination in the ecosystems was influenced by multiple pollution sources.

Hydrocarbons contamination and microbial degradation in mangrove sediments of the Niger Delta region (Nigeria)

The distribution of aliphatic hydrocarbons and polycyclic aromatic hydrocarbons (PAHs), and their degradability by bacteria in epipelic and benthic sediments from Qua Iboe Estuary mangrove ecosystem and associated creeks were investigated. The research findings revealed that total aliphatic hydrocarbons in sediments ranged from 16.82 mg·kg −1 to 210 mg kg −1, wheras total PAHs ranged from 6.30 to 35.55 mg·kg −1 dry weight of sediment. Low molecular mass (i.e. the 2–3-ring) PAHs were predominant in almost all the sampling points, whereas the higher molecular masses (4-, 5- and 6-ring PAHs) had the lowest concentrations. In general, the sediment samples ES 2 (39.7%), ES 3 (24.8%), BS 1 (46.7%), BS 2 (49.9%) and BS 3 (44.2%) showed<50% contributions of Σ combustion–derived PAH (COMP-PAH) concentration to the Σ PAH concentrations, whereas ES 1 (57%) contained>50% of COMP-PAHs. Our results have also shown that many mangrove bacteria have strong capacity to utilise Qua Iboe Light (QL) crude oil as the sole source of carbon and energy, while lower number of bacterial species including Bacillus sp., Micrococcus sp., Pseudomonas aeruginosa, Alcaligenes sp. and Flavobacterium sp. exhibited detectable PAHs degradability; and as such may serve as efficient degraders of QL crude oil contamination of mangrove ecosystem.

Seasonal dynamics of physicochemical properties and heavy metal burdens in Mangrove sediments and surface water of the brackish Qua Iboe Estuary, Nigeria

The physicochemical properties and concentrations of heavy metals were determined in surface water, intertidal mudflats (epipellic) and benthic sediments obtained from the mangrove swamp ecosystem of the Qua Iboe Estuary, Nigeria. The monthly concentrations of the nutritive salts revealed that the sediments are halomorphic. Heavy metal concentrations in benthic sediments and surface water were generally lower than the values recorded for the intertidal mudflats. The mean concentrations of heavy metals obtained from estuarine surface water and intertidal and subtidal sediments were highly variable and seasonally dependent. The levels of heavy metals in the intertidal sediments were comparatively higher in the wet than the dry season. The range of concentration over the months increased by 1.3% (Cr), 1.6% (Pb), 6.0% (V), 7.5% (Ni), 10.5% (Fe), 12.0% (Zn), and 15.0% (Cu). Cr, Pb, Zn, and V concentrations in intertidal and subtidal sediments were below the Sediment Quality Guidelines (SQGs). However, Cu and Ni concentrations exceeded these effect levels, indicating potential ecological effects on local benthic, pelagic and benthopelagic communities of the estuary. Linear relationships and coefficients for concentrations of heavy metals in surface water, intertidal and subtidal sediments during wet and dry seasons were calculated. Moreover, the results indicated a common anthropogenic pollution origin for the heavy metals.

Distribution and risk assessment of trace metals in Leptodius exarata, surface water and sediments from Douglas Creek in the Qua Iboe Estuary

Abstract Five trace metals in Leptodius exarata, epipellic sediments and surface water from an intertidal ecosystem in the Niger Delta (Nigeria) were studied to evaluate their spatial distributions, degrees of contamination, and associated ecological and health risks. The results show that the Cd (cadmium), Cr (chromium), Ni (nickel), Pb (lead) and Zn (zinc) concentrations in sediment range from 0.550–1.142, 9.57–15.95, 9.15–13.96, 2.00–8.90 and 91.5–121.6 mg kg−1 dw, respectively, while the L. exarata tissue metal content varies from 0.162–0.931, 3.81–8.62, 4.45–17.15, 1.90–7.35, and 125.55–269.75 mg kg−1 dw, respectively. The bioconcentration factor ranking for trace metals was found to follow the Zn > Ni > Pb > Cr > Cd sequence. The high biota to sediment accumulation factor (BSAF) found for L. exarata reveals a sentinel metal bioindicator. Sediments from most sites were found to be uncontaminated to moderately contaminated (geoaccumulation, Igeo > 0), with Cd and Zn associated with anthropogenic intrusions. Low mean-ERM (effect range-median) and mean-PEL (probable effect level) quotients of sediments were found, indicating low–moderate degrees of contamination with 30% and 21% probabilities of toxicity. The multi-metal potential ecological risk index (RI) for the intertidal ecosystem denotes low–moderate risk. Health risks associated with crab (L. exarata) consumption are more significant for children than for adults.

Hydrobiological constraints of trace metals in surface water, coastal sediment and water lily of Calabar River, Nigeria

Trace metals concentrations in surface water, sediment and water lily (Nymphaea lotus) samples from the banks of Calabar River, a major tributary of Cross River Estuary, Nigeria were determined. The results revealed average concentrations 0.017, 0.010, 37.08 and 0.025 mg/l, respectively, for As, Cd, Fe and Pb in surface water samples, which exceeded Federal Environmental Protection Agency (FEPA) maximum guideline values. Elevated levels of heavy metals (As, 1.251 mg/kg; Cd, 0.038 mg/kg; Co, 0.509 mg/kg; Cu, 3.78 mg/kg; Fe, 35.48 mg/kg; Mn, 10.72 mg/kg; Ni, 0.732 mg/kg; Pb, 1.355 mg/kg; V, 0.427 mg/kg; and Zn, 8.665 mg/kg) in sediment samples indicated anthropogenic influences while, measured concentrations in N. lotus were typical of a growing plant.

Distribution and Significance of Epipsammic Algae in the Coastal Shore (Ibeno Beach) of Qua Iboe River Estuary, Nigeria

The distribution of epipsammic phytoplankton in the coastal shore (Ibeno beach) of Qua Iboe River estuary was studied in the early summer (between October and December) of 1998. The results revealed the presence of Actinoptychus undulatus, Aphanizomenon flos-aquae, Astasia fustis, Chromulina globosa, Cocconeis pediculus, Cymatopleura solea, Cymbella lanceolata, Euglena intermedia, Lyngbya majusculata, Microcystis sp., Nodularia spumigena, Navicular rhynocephala, Oscillatoria nigroviridis, Pinnularia viridis, Rhoicosphenia curvata, Trachelomonas volvocina and Urceolus cyclostomus in the sandy beach. The mean species density of the epipsammic algae encountered in the beach ranged from 16 to 7600 organisms per hectare. The density, however, decreased with increase in sampling distance from the low tide level. Actinoptychus undulatus was the most abundant and widely distributed phytoplankton while Aphanizomenon flos-aquae was the least encountered species. The occurrence of A. flos-aquae and other toxin producing cyanobacterial species of Lyngbya majusculata, Microcystis sp., N.spumigena and O. nigroviridis in the sandy beach are of serious health significance.

Assessment of the Occurrence and Risks of Emerging Organic Pollutants (EOPs) in Ikpa River Basin Freshwater Ecosystem, Niger Delta-Nigeria

Abstract The levels of some emerging organic pollutants (EOPs) including endocrine disrupting compounds, pharmaceuticals and personal care products were quantified in surface water of a freshwater ecosystem, the Ikpa River Basin, Nigeria using liquid chromatography/high resolution tandem mass spectrometry (LC–MS/MS). In addition, leachates and storm water samples collected from nearby dumpsites were also analysed to assess the effect on water quality. Seventeen compounds were detected at the nanogramme-per-litre levels and the ecological risks of selected compounds assessed based on predicted no-effect concentrations derived from comparison of toxicity data recorded for green algae, fish and invertebrate with the maximum measured environmental concentrations, to obtain risk quotients. Some of the compounds showed some level of widespread occurrence or persistence. Also, bisphenol A, chloramphenicol, erythromycin, triclocarban and triclosan were the most important EOPs detected in the study area that may pose detrimental effects to the aquatic organisms based on the outcome of the risk assessment.

Petroleum hydrocarbons and trace metal loads in the mangrove oyster (Crassostrea rhizophorae) from the Qua Iboe Estuary and adjoining creeks in Nigeria

The mangrove oyster Crassostrea rhizophorae was harvested from clutches associated with mangroves in the Qua Iboe Estuary and adjoining creeks to determine the concentrations of total petroleum hydrocarbons (TPH) and trace metals (Fe, Ni, Pb, Cr, V, Cu and Zn) and to understand their bioaccumulation status. The mean concentrations of trace metals in C. rhizophorae were 36.06 mg·kg− 1 for Fe, 0.58 mg·kg− 1 for Ni, 0.05 mg·kg− 1 for Pb, 0.66 mg·kg− 1 for Cr, 0.32 mg·kg− 1 for V, 6.70 mg·kg− 1 for Cu and 3.93 mg·kg− 1 for Zn. The oysters demonstrated relative affinity for accumulation of Fe, Cu and Zn and the relative status of the metals accumulated, in comparison with the background trace metal load, revealed bio-concentration factors of 0.024, 0.016, 0.004, 0.213, 0.037, 0.302 and 0.036 for Fe, Ni, Pb, Cr, V, Cu and Zn, respectively. The concentrations of TPH in the oyster were highly variable and ranged between 6.37 and 8.44 mg·kg− 1 dry weight of C. rhizophorae. Although the correlation between TPH levels in intertidal (epipelic) sediment and oyster specimens was positive (r = 0.097), it was not significant (p>0.05). However, the relationship between TPH and trace metal levels in C. rhizophorae revealed well-fitting linear models that indicated that the trace metals originated from petrogenic sources. Although the levels of TPH and trace metals in the oyster were within permissible levels, they might affect calcium metabolism and the general productivity of the shellfish. The recorded levels are also indicative of long-term and chronic accumulation of hydrocarbons in the estuarine ecosystem and potential risk to human health.