The pollution of the marine environment by plastic debris: a review

The deleterious effects of plastic debris on the marine environment were reviewed by bringing together most of the literature published so far on the topic. A large number of marine species is known to be harmed and/or killed by plastic debris, which could jeopardize their survival, especially since many are already endangered by other forms of anthropogenic activities. Marine animals are mostly affected through entanglement in and ingestion of plastic litter. Other less known threats include the use of plastic debris by "invader" species and the absorption of polychlorinated biphenyls from ingested plastics. Less conspicuous forms, such as plastic pellets and "scrubbers" are also hazardous. To address the problem of plastic debris in the oceans is a difficult task, and a variety of approaches are urgently required. Some of the ways to mitigate the problem are discussed.     

Distribution and accumulation of heavy metals in carbonate and reducible fractions of marine sediment from offshore mid-western Taiwan

Two marine sediment cores from offshore mid-western Taiwan were subsampled and pre-treated using a sequential extraction procedure to separate carbonate and reducible fractions. Aliquots of these extracts were analyzed to determine their chemical composition to evaluate the geochemical processes responsible for heavy metal distribution and accumulation in the coastal environment. Our data demonstrate that sedimentation rates derived from excess ²¹⁰Pb associated with metal fluxes show large increases circa A.D. 1990. A well-synchronized increase in metal flux in both geochemical fractions was found and validated by Pearson’s correlation. Principal component analysis revealed the heavy metal fluxes to be highly correlated with the sediment deposition rate, with metal contamination potentially driven by a sole contributor. This study emphasizes the changes in sedimentation rate is potentially caused by activities associated with the inland economic development during this time, rather than by raising heavy metal pollution dominated the accumulation offshore mid-western Taiwan.     

A literature review on trace metals and organic compounds of anthropogenic origin in the Wider Caribbean Region

About 30 studies from the published literature were reviewed to determine the pollution status regarding heavy metals and organic compounds of the Wider Caribbean Region (WCR). The literature revealed that most studies were performed in the South and Central American Caribbean Region with sparse reports on the small island states. Collectively, the most frequently analyzed heavy metals were Pb, Cu, Zn, Fe, Cd, Ni, Mn and Cr while DDT and its metabolites were the most frequently reported organic pollutants. The samples which were analyzed vary in terms of sampling schemes, parameters and analytical techniques, as well as differences in data reporting presentation (i.e. dry weight versus wet weight, sediment fraction analyzed, or % lipids). These differences make meaningful comparisons of the available data very difficult. Furthermore, there is limited data available for most of these contaminants from the majority of nations in the WCR. Therefore, any attempt to create a regional scale assessment from contaminants data available in the open literature is limited by the scarcity of available information.     

Bioremediation of petroleum hydrocarbons in anoxic marine sediments: Consequences on the speciation of heavy metals

We investigated the effects of biostimulation and bioagumentation strategies applied to harbor sediments displaying reducing conditions and high concentrations of petroleum hydrocarbons and heavy metals. We compared the microbial efficiency of hydrocarbon removal from sediments maintained for 60 days in anoxic conditions and inoculated with acetate, sulfate-reducing bacterial strains and acetate and sulfate-reducing bacteria. All treatments determined a significant increase in the microbial growth and significant decreases of hydrocarbon contents and of redox potential values. The addition of sulfate-reducing bacterial strains to the sediment was the most efficient treatment for the hydrocarbon removal. In all experiments, significant changes of the heavy metals’ phase repartition were observed. The results reported here suggest that the biodegradation of petroleum hydrocarbons in anoxic marine sediments may be enhanced by stimulating microbial anaerobic metabolism, but care should be applied to monitor the potential changes in the mobility and bioavailability of heavy metals induced by bio-treatments.     

Distribution and pollution assessment of heavy metals in surface sediments in the Yellow Sea

Heavy metal concentrations in surface sediments at 56 stations during two cruises in the Yellow Sea in summer and winter, 2011 were analyzed by inductively coupled plasma-mass spectrometry. The pollution status was assessed via the Geoaccumulation index and Hankanson potential ecological risk index. Higher concentrations of heavy metals (except for Mn) were found in the central Southern Yellow Sea and the western Northern Yellow Sea. The higher contents of Mn were much closer to Shandong Peninsula. Correlation analyses indicated that Pb, Cu, Fe, Ni, Zn and Co probably had the same origin and were controlled by grain size and total organic carbon. Pollution assessment showed that most areas of the Yellow Sea were not or lowly contaminated with the exception of the northwest and south parts of the Southern Yellow Sea showing Cd-contamination. The pollution status of the Yellow Sea in summer was worse than that in winter.     

Adsorption behaviour of dibutyl phthalate on marine sediments

Laboratory experiments were carried out to investigate the adsorption behaviour of dibutyl phthalate (DBP) on marine sediments collected from five different sites in Victoria Harbour, Hong Kong. DBP adsorption can be well described by the Langmuir isotherm. The maximum DBP adsorption capacity (Q(max)) of the marine sediments ranges from 53 to 79 mg g(-1), which has a positive correlation with their organic content. Around 90% of the organic can be removed from the sediments with treatment by H(2)O(2) oxidation, and the Q(max) then decreases to a range between 13 and 22 mg g(-1). The black carbon content of the sediments has a much greater DBP adsorption capacity than does the natural organic matter of the sediments. The amount of DBP adsorbed on the sediments increases as the salinity of the marine water increases.     

巢湖沉积物重金属富集特征与人为污染评价

本文分析了巢湖主要入湖河流河口区表层沉积物及西部湖心区沉积岩芯中Al、Fe、Ni、Cr、Cu、Zn、Pb、Li、V等金属元素变化特征,采用地球化学方法对金属元素变化的"粒度效应"进行矫正,并以Li、V为参照元素对矫正结果进行检验;参考历史沉积物,对河口区及西部湖心区沉积物重金属人为污染特征进行分析;结合沉积岩芯210Pb年代结果,估算西部湖心区近150a来Ni、Cr、Cu、Zn、Pb等重金属元素的人为污染贡献量.结果表明,河口表层沉积物重金属污染具有显著的空间差异,南淝河河口重金属人为污染最重,其中Ni、Cr、Cu、Zn、Pb的人为污染贡献量分别为12.2、32.2、25.3、479.9和76.0 mg/kg,分别占总含量的35%、37%、64%、92%和77%;其次是柘皋河河口,主要重金属污染元素为Cu、Zn和Pb,人为污染贡献量达57.6、57.0和19.5 mg/kg,分别占总含量的73%、47%和36%;而派河、白石山河、杭埠河等河口表层沉积物中重金属元素人为污染程度较弱.巢湖西部湖心区主要污染元素为Cu、Zn、Pb,人为污染开始于1950s,1980年以来其人为污染贡献量显著增加,平均为16.2、245.6、47.8 mg/(m2.a),分别占各元素沉积通量的23%、61%和37%;Ni人为污染开始于1980s初期,人为污染贡献量平均为12.6 mg/(m2.a),占其沉积通量的13%左右;Cr基本未受人为污染影响.西部湖心区沉积岩芯及南淝河河口表层沉积物中重金属污染程度均表现为Zn>Pb>Cu,而且南淝河河口沉积物重金属污染程度显著高于西部湖心区.结合主要入湖河流径流量与河口沉积物重金属污染特征,认为巢湖西部湖心区重金属污染主要通过南淝河输入,来自合肥等城市的废水是主要的污染源.     

Sedimentation and chronology of heavy metal pollution in Oslo harbor, Norway

Stratigraphic profiles of Cu, Cd and Hg in ten sediment cores from the Oslo harbor, Norway, combined with results of radiometric dating demonstrate that pollution by these metals peaked between 1940 and 1970. Dating results indicate that Hg discharges peaked between 1940 and 1950, Cd reached maximum ca. 1955-1960, and Cu has the highest concentration in sediment interval corresponding to ca. 1970. Geochemical profiles and maxima of Cu, Cd and Hg concentrations can be used as chronostratigraphic markers for sediment cores from the Oslo harbor. Acoustic backscatter and sediment core data indicate that propeller wash affects the seabed in the Oslo harbor. The propeller-induced turbulence causes erosion, and in places exposes and remobilizes contaminated sediments that accumulated in the harbor during previous decades. Such re-exposure of contaminated sediments could be detrimental to local ecosystems and offset remediation efforts, warranting further impact studies and potential mitigation strategies to prevent redistribution.     

鄱阳湖流域乐安河重金属污染水平

乐安河是鄱阳湖五大入湖水系中重金属污染最严重的水域.为研究其污染现状,于2003-2004年度对乐安河水体、底泥及水生生物的重金属污染进行了调查与分析.结果表明,乐安河水体中的重金属除Cu的含量超出地表水环境质量标准Ⅲ类标准外,其它各项监测指标均能达到地表水环境质量Ⅲ类标准.乐安河底泥的重金属含量平均值与国家土壤环境质量相比,Cu的平均值超出了三级标准,而Pb和Zn的含量指标均符合三级标准;通过地质累积指数评价结果表明,乐安河底泥中Cu为严重污染,Pb为偏中度污染,Zn为中度污染.乐安河水生植物对Cu,Pb,Zn都有不同程度的富集,根据富集系数评价表明,植物对Cu的平均富集能力相对较强,其次是Pb和Zn.浮游动物、植物和底栖动物也受到不同程度的污染,其分布和数量因河段水质变化的影响也出现类似的波动.     

Environmental pollution in the Gulf of Guinea--a regional approach

Environmental pollution in the Gulf of Guinea (GOG) coastal zone has caused eutrophication and oxygen depletion in the lagoon systems, particularly around the urban centres, resulting in decreased fish (reproduction) levels and waterborne diseases. A pollution sources assessment was undertaken by six countries in the region as a first step in defining a region-wide Environmental Management Plan. Results show that households produce 90% of solid waste. Industry, however, is responsible for substantial amounts of hazardous waste, specifically the Nigerian petroleum industry. The latter is also responsible for the spilling of large amounts of oil. BOD load from industrial effluents is slightly larger than domestic loads in the industrialised coastal zone. Wastewater treatment systems are either absent or inadequate. Apart from large-scale gas flaring in Nigeria, air pollution, in terms of COx, HC, NOx and SO2 emissions, is contributed mainly by traffic. Particulates, originate mainly from industries and domestic biomass burning.     

Baseline metals pollution profile of tropical estuaries and coastal waters of the Straits of Malacca

The status report on metal pollution in tropical estuaries and coastal waters is important to understand potential environmental health hazards. Detailed baseline measurements were made on physicochemical parameters (pH, temperature, redox potential, electrical conductivity, salinity, dissolved oxygen, total dissolved solid), major ions (Na, Ca, Mg, K, HCO₃, Cl, SO₄ and NO₃) and metals concentrations (²⁷Al, ⁷⁵As, ¹³⁸Ba, ⁹Be, ¹¹¹Cd, ⁵⁹Co, ⁶³Cu, ⁵²Cr, ⁵⁷Fe, ⁵⁵Mn, ⁶⁰Ni, ²⁰⁸Pb, ⁸⁰Se, ⁶⁶Zn) at estuaries and coastal waters along the Straits of Malacca. Principal component analysis (PCA) was employed to reveal potential pollution sources. Seven principal components were extracted with relation to pollution contribution from minerals-related parameters, natural and anthropogenic sources. The output from this study will generate a profound understanding on the metal pollution status and pollution risk of the estuaries and coastal system.     

A general integrated ecotoxicological method for marine sediment quality assessment: application to sediments from littoral ecosystems on Southern Spain's Atlantic coast

In the last few decades, several integrated methods for marine sediment quality evaluation have been developed and applied to many coastal sites. This paper describes the development of a general integrated method based on the determination of organic and inorganic sediment contamination, lethal and sublethal toxicity assessments, in situ benthonic community structure alteration and bioaccumulation of contaminants. The proposed method was applied to sediments from Southern Spain's Atlantic coast where six rivers (Guadiana, Carreras, Piedras, Tinto, Odiel and Guadalquivir) drain pollutants from various anthropogenic sources. A series of experiments was conducted to determine the characteristics of the sediments: granulometry, organic matter content, etc. (1); metal contamination of sediments and Chamelea gallina (bivalves widely distributed in the area studied) (2); lethal and sublethal toxicity by a series of biological tests (3); and macrofauna distribution at the 16 stations included in the study (4). Ratio-to-reference values (RTR) calculated for each parameter were used to determine the organic and inorganic contamination indices, the lethal and sublethal toxicity indices, the index of bioavailability of metals in the organisms analyzed and the macrobenthic alteration index. The data were plotted on six-axis plots to describe better the relations between the physical, chemical and biological properties studied. A general integrated sediment quality index (ISQI) was determined and used as an indicator of pollution-induced degradation. The ISQI values summarize the main characteristics of the environmental situation at each sampling point and can be used for purposes of comparison.     

Spatial distribution of heavy metals in Hong Kong's marine sediments and their human impacts: a GIS-based chemometric approach

A geographic information system (GIS)-based chemometric approach was applied to investigate the spatial distribution patterns of heavy metals in marine sediments and to identify spatial human impacts on global and local scales. Twelve metals (Zn, V, Ni, Mn, Pb, Cu, Cd, Ba, Hg, Fe, Cr and Al) were surveyed twice annually at 59 sites in Hong Kong from 1998 to 2004. Cluster analysis classified the entire coastal area into three areas on a global scale, representing different pollution levels. Backward discriminant analysis, with 84.5% correct assignments, identified Zn, Pb, Cu, Cd, V, and Fe as significant variables affecting spatial variation on a local scale. Enrichment factors indicated that Cu, Cr, and Zn were derived from human impacts while Al, Ba, Mn, V and Fe originated from rock weathering. Principal component analysis further subdivided human impacts and their affected areas in each area, explaining 87%, 84% and 87% of the total variances, respectively. The primary anthropogenic sources in the three areas were (i) anti-fouling paint and domestic sewage; (ii) surface runoff, wastewater, vehicle emissions and marine transportation; and (iii) ship repainting, dental clinics, electronic/chemical industries and leaded fuel, respectively. Moreover, GIS-based spatial analysis facilitated chemometric methods.     

Assessment of heavy metal contamination in the surficial sediments from the lower Meghna River estuary,Noakhali coast,Bangladesh

Sediment samples were collected from ten selected sites of the lower Meghna River estuary,and six heavy metals were analyzed with Atomic Absorption Spectrophotometry(AAS)to assess the contamination level and the metals’association with sediment grain size.The current results revealed that the mean concentrations of the studied metals were ranked in descending order of iron(Fe)(1.29×103 mg/kg)>zinc(Zn)(42.41 mg/kg)>lead(Pb)(12.48 mg/kg)>chromium(Cr)(10.59 mg/kg)>copper(Cu)(6.22 mg/kg)>cadmium(Cd)(0.28 mg/kg).The geo-accumulation,contamination,and pollution load indexes suggested that the lower Meghna river estuary was not contaminated by Fe,Zn,Pb,Cr,and Cu.The mean size of the sediment ranged from 28.92 to 126.2 mm,and the Pearson correlation coefficient showed a significant association between Fe and Pb(coefficient of determination,r2=0.836;p<0.05),and no significant correlation was found between individual metals and grain size,indicating no or low influence on the metals distribution.     

Ingestion of marine debris by loggerhead sea turtles, Caretta caretta, in the Adriatic Sea

We examined the occurrence of marine debris in the gastrointestinal tract of 54 loggerhead sea turtles (Caretta caretta) found stranded or incidentally captured dead by fisheries in the Adriatic Sea, with a curved carapace length of 25.0-79.2 cm. Marine debris was present in 35.2% of turtles and included soft plastic, ropes, Styrofoam and monofilament lines found in 68.4%, 42.1%, 15.8% and 5.3% of loggerheads that have ingested debris, respectively. The dry mass of debris per turtle was low, ranging from <0.01 to 0.71 g, and the ingestion was not significantly affected by sex or body size (all p > 0.05). Marine debris averaged 2.2 ± 8.0% of dry mass of gut content, with a maximum of 35% found in a juvenile turtle that most likely died due to debris ingestion. Considering the relatively high occurrence of debris intake and possible sub-lethal effects of even small quantities of marine debris, this can be an additional factor of concern for loggerheads in the Adriatic Sea.     

Investigations into the bioavailability and bioaccumulation of mercury and other trace metals to the sea cucumber, Sclerodactyla briareus, using in vitro solubilization

The in vitro solubilization and bioaccumulation of mercury and other trace metals by the intestinal fluid of the sea cucumber, Sclerodactyla briareus, was investigated. Sediments were incubated with intestinal fluid and the intestinal fluid was analyzed for the in vitro experiments. Experiments examined both procedural effects of in vitro solubilization and bioaccumulation of trace metals by the sea cucumber. Both solubilization and bioaccumulation were compared among the different metals. This comparison revealed that monomethylmercury (MMHg) solubilization and bioaccumulation is greater than Hg_I; Cd solubilization is higher than MMHg and Hg_I; and Cu and Pb solubilization is similar to MMHg and slightly higher than Hg_I. Solubilization and bioaccumulation was found to be very low, except for Cd, which had high relative solubilization but low bioaccumulation. It was concluded that while solubilization could be the rate-limiting step for certain metals, other factors, such as depuration and membrane transport, may influence overall bioaccumulation of the other metals.     

Concentrations and transport of trace metals in the St. Lawrence River

Samples of raw water were collected in the St. Lawrence River during six sampling trips from August 1990 to April 1992. Water samples were analyzed for both dissolved and particulate phases for five trace metals. Partition coefficients (Kd) and metal fluxes were calculated in order to determine metal transport. A mass balance equation was used for the determination of the major metal sources to the St. Lawrence River and an estimation of metal loadings to the estuary was made. Average dissolved metal concentrations were found to be Cd 10 ng/L, Co 74 ng/L, Cu 64 ng/L, Fe 69 µg/L and Mn 700 ng/L. Particulate concentrations were (in µg/g) 1.68 for Cd, 31 for Co, 73 for Cu, 25 mg/g for Fe and 1.69 mg/g for Mn. Co, Fe and Mn were transported essentially in the particulate phase while Cd and Cu were predominantly found in the dissolved phase at 56% and 48% of the total metal concentration respectively. Log Kd values varied from 5.1 (for Cu) to 6.8 (for Mn). In the dissolved phase the major sources were found to be the Great Lakes and the Ottawa River whereas in the particulate phase Québec tributaries appear to be the most important. Industrial inputs are quite important in both the dissolved and the particulate phases for Cd, whereas other sources are very variable, especially for the dissolved phase.     

The effect of an oil drilling operation on the trace metal concentrations in offshore bottom sediments of the Campos Basin oil field,SE Brazil

The concentrations of Al, Fe, Mn, Zn, Cu, Pb, Ni, Cr, Ba, V, Sn and As in offshore bottom sediments from the Bacia de Campos oil field, SE Brazil, were measured at the beginning and at 7 months after completion of the drilling operation. Concentrations of Al, Fe, Ba, Cr, Ni and Zn were significantly higher closer to the drilling site compared to stations far from the site. Average concentrations of Al, Cu, and in particular of Ni, were significantly higher at the end of the drilling operation than at the beginning. Comparison between drilling area sediments with control sediments of the continental platform, however, showed no significant difference in trace metal concentrations. Under the operation conditions of this drilling event, the results show that while changes in some trace metal concentrations do occur during drilling operations, they are not significantly large to be distinguished from natural variability of the local background concentrations.     

Trace metals in the living and nonliving components of scleractinian corals

Trace metals in coral tissue and skeleton have been investigated in various ways since the early seventies. More recently it has been suggested that the symbiotic zooxanthellae may play an important role in the accumulation and regulation of trace metals. Furthermore gamete development and mucus production may influence the metal accumulation and loss in corals. Many studies have attempted to use the annual growth bands in coral skeletons to investigate historical pollution events. However the relationship between the metal concentrations in the surrounding environment and the incorporation of this into coral skeleton is not well understood. This paper explains a method for investigating metal loads in coral tissue, zooxanthellae and skeleton. Furthermore, it presents new information suggesting that zooxanthellae accumulate most metals (Al, Fe, As, Mn, Ni, Cu, Zn, Cd, Pb) in greater concentrations than the coral tissue. Coral skeletons had consistently lower metal concentration than the zooxanthellae, tissue and gametes. The loss of zooxanthellae during stress events may have a significant contribution to the total metal loads in corals. The use of corals as biomonitors should carefully factor in zooxanthellae densities and gamete development before conclusions are drawn.