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.     

A grain-size correction for metal pollution indexes in river sediments

According to the List of Hazardous Substances of the Agency of the Toxic Substances and Disease Registry(ATSDR 2017),some metallic elements such as Pb or Cd are still considered as the most polluting elements in the world.These elements accumulate in sediments,and there are various methods available that differentiate lithogenic sources from anthropogenic sources.For that,the natural geochemical background is required,however,its definition is far from unanimous:it can be a global or local value,single or statistically estimated value,depending on the studies.Our study is focused on the Suba
e River in the state of Bahia,Northeastern Brazil,which was historically contaminated by lead metallurgy.The river sediments were sampled at 21 locations:one at the discharge point of the plant's rainwater basin,ten upstream,and ten downstream.The total contents of Fe,Ti,Mn,Pb,Zn,Cu,Cr,particle-size distribution,and organic matter were analyzed.The conventional geochemical indexes,i.e.,the pollution degree(mCd),pollution load index,and enrichment factor indicated contamination by Zn,Pb,Cr,and Cu.Then,a new enrichment factor is introduced,assuming that the sediments come from erosion of soils in the watershed.After obtaining the natural concentrations of metals in the clay,silt,and sand fractions of uncontaminated reference soils,we corrected the pollution indexes by calculating a new individual background in each sediment sample,according to its grain size distribution.This new approach provided more precise indexes in the assessment of sediment pollution,by highlighting higher contamination of Zn and Pb(around 50%)and at the same time the absence of Cr and Cu contamination,two metals not involved with the metallurgical activity.     

Arsenic and trace metal contents in sediment profiles from the Admiralty Bay, King George Island, Antarctica

Admiralty Bay (Antarctica) hosts three scientific stations (Ferraz, Arctowski and Macchu Picchu), which require the use of fossil fuel as an energy source. Fossil fuels are also considered the main source of pollution in the area, representing important inputs of major pollutants (organic compounds) and trace metals and metalloids of environmental interest. Accordingly, this work presents the results of As, Cd, Cr, Cu, Ni, Pb and Zn in sediment profiles from Admiralty Bay. The sediment results from Ferraz station were slightly higher than the other sampling sites. The highest contents were observed for Cu and Zn (from 44 to 89 mg kg⁻¹). Otherwise, by using enrichment factors and geochronology analysis, the most relevant enrichment was observed for As in the samples collected close to the Ferraz station, indicating that increasing As content may be associated with the activities associated with this site.     

Nutrient,heavy metal and organic pollutant composition of suspended and bed sediments in the Rhone River

The environmental quality of the Rhone River (Switzerland-France) has been assessed with a geochemical survey of the pollutants bound to suspended sediments. Ten samples were collected between Lake Geneva and the Mediterranean Sea in Nobember 1989 by continuous flow centrifugation and analysed for grain size distribution, carbonate, organic C, N, forms of particulate P, trace metals, and organic compounds (chlorobenzenes, organochlorine pesticides, PCBs, and PAHs). Four bed sediment samples were also studied for comparative purposes. The suspended solids provide lower variance by parameter than the bed sediments and are clearly most suitable for synoptic monitoring.The Upper Rhone River carries a glacial derived sediment with a low nutrient content, the stretch from Geneva to Lyon provides a sediment dominated by carbonate, and in the Lower Rhone the organic matter and phosphorus are relatively increased, mainly due to wastewater effluents and to an industrial P source. High concentrations of metals and organic micropollutants downstream of Lyon indicate a multiple contamination in the Lower Rhone, whereas more specific inputs are located downstream of Geneva and Arles.The comparison with data from other polluted major systems, the Rhine, the Niagara and the Detroit rivers, shows on overall similarity confirming that the Rhone quality is degraded downstream of Lyon. The levels of particular concern are for Hg, DDT metabolites which reveal a recent release in the basin, PCBs with a likely high chlorine content, and PAHs.The statistical evaluation of the compositional variables indicates a limited number of well defined associations, suggesting that the contamination of the suspended sediments results from the combination of numerous and intermittent point and diffuse sources in the Rhone River basin.     

Geochemical baselines of major, minor and trace elements in the tropical sediments of the Terengganu River basin, Malaysia

The geochemical baselines and distribution of 31 elements (Al, Fe, K, Na, Mg, Ca, Mn, Ba, Cr, Zr, Ni, Sr, Zn, Y, Li, Cu, Mo, Nb, Th, Co, Ga, W, Ta, Be, Ti, Ge, Se, Bi, Te, Sc and Re) and physico-chemical parameters of the tropical surface sediments of the Terengganu River basin, Malaysia, are reported. Sediments are sandy loam to sand in texture consisting of mostly quartz, low organic matter content (average-2.68%), low CEC (average-2.02 cmol(+)/kg) and mildly acidic pH1:5 (average-5.91). Concentrations of Mn, Fe, Ba, Cr, Ni, Cu, Mo and Se were measured to be above the environmental sediment quality criteria at various locations. Lake sediments registered significantly higher Al, Fe, Ti, Mg, Ca, Mn, Te and Sc concentrations as compared to the river sediments. Most of the elements investigated showed an association with silt size fraction (2-63 μm). Among the investigated metals, Mo and Fe concentrations showed an increasing (5-fold) and decreasing (3-fold) trend, respectively, along the river path from the upstream to the downstream depending on the stream pH-redox conditions. The enrichment factor values (EF 5) of Cr, Ni, Mo and Se indicated enrichment from anthropogenic activities. Alkali and alkali earth metals registered a significant depletion (EF values 0.7) as compared to the Earth's crust. Principal component analysis of the two main components (PC1, 87.4% and PC2, 8.7%) revealed a well-defined group of estuary sediments. Lake and river sediment sampling locations did not form defined groups revealing heterogeneity in the origin of geologic material and the in-stream geochemical processes. However, Cr, Ni, Mo and Se formed a separate group with elevated concentrations (e.g. Cr1,000 mg/kg) indicating contamination of sediments. This work presents the geochemical baselines of the tropical sediments as industrial development and urbanization along the north east coast of Peninsular Malaysia are advancing rapidly.     

Distribution, enrichment and accumulation of heavy metals in coastal sediments of Alang-Sosiya ship scrapping yard, India

Since its inception in 1982, the Alang-Sosiya yard has become the largest ship scrapping works in the world. Several hundreds of ships arrive every year. The degree of heavy metal contamination has been studied in bulk and fine sediments from the intertidal zone of this ship scrapping yard, two stations, one on either side at 5 km distance and one reference station 60 km distance near Mahuva, towards the south. The samples have been subjected to a total digestion technique and analysed for elements: Cd, Co, Cu, Cr, Fe, Mn, Ni, Pb, Zn and Al, and %TOC. The absolute metal concentrations reflected variations in BF and FF sediment samples with organic matter content. Enrichment factors (EF) and geoaccumulation indices (Igeo) have been calculated and the relative contamination levels are assessed at these sites. At Alang-Sosiya, the enrichment of heavy metals has been observed to be relatively high.     

Unusual grain size effect on trace metals and organic matter in contaminated sediments

Grain size effect on trace metals (cadmium, copper, lead, zinc, and iron) and total organic content distribution in various fractions (<0.063, 0.063–0.105, 0.105–0.250, 0.250–0.500, and 0.500–1.000 mm) of contaminated sediment has been studied. Selective partitioning of the studied contaminants in sediment fractions was observed, with a minimum content in the fine sand fraction of grain size 0.125–0.250 mm. Anomalously high concentrations of trace metals and organic matter content in the medium and coarse sediment fractions (>0.250 mm) was explained by the formation of large agglomerates (clusters) during the generally recommended drying procedures. These large agglomerates, formed from smaller sediment fraction particles enriched by various contaminants kept on their large specific area by adsorption forces, have been observed in photographs of the medium and coarse sediment fractions only. The formed agglomerates consist of small particles cemented either by dissolved organic matter or by sea salts present in the marine sediment. The formation of such agglomerates should be taken into consideration when conducting metal contamination studies on sediments.     

The dynamics of sediment‐associated contaminants over a transition from drought to multiple flood events in a lowland UK catchment

Fine sediment in suspended form, recently deposited overbank and in temporary storage on or in channel beds, was collected in the Nene basin during a period of drought through to a period of four high flows. The sediment was analysed for arsenic, copper, lead, phosphorus and zinc concentrations with the aim of investigating their sources, movement, temporary storage and potential for environmental harm. Copper, lead and zinc probably originated from urban street dusts, phosphorus (originally in dissolved form) from sewage effluent and arsenic from natural soils developed over ironstone. There was little difference in the metal or arsenic concentrations in the sediment under different flow conditions; instead, proximity to pollutant sources appeared to control their concentrations. Phosphorus in tributary sub‐catchments probably adsorbed to sediment during periods of low flow but these sediments were flushed away during high flows and replaced by sediment with lower concentrations. However, concentrations of all pollutants in overbank sediments along the Nene's main channel were not reduced in successive flood events, suggesting no first flush effect. Only phosphorus accumulated on sediment at concentrations exceeding those of its catchment‐based sources (e.g. street dusts, channel banks and catchment soils). This scavenging of aqueous phosphate by sediment explained the difference in behaviour between phosphorus, arsenic and heavy metals. The surface area and organic matter content were shown to have a small effect on contaminant concentrations. Street dust contaminants only exceeded predicted effect levels in close proximity to urban areas, suggesting a small potential for harm to the aquatic environment. Arsenic concentrations exceeded predicted effect levels in most sediment samples. However, it has been shown to be largely non‐bioavailable in previously published research on the Nene, limiting its potential for significant environmental harm. Phosphorus concentrations in river sediments are high in comparison to the soils in the catchment and in comparison with sediment–P concentrations in other published lowland catchment studies, indicating a large potential for eutrophication should the Phosphorus be, or become, bioavailable. Copyright © 2015 John Wiley & Sons, Ltd.     

In-channel surficial fine-grained sediment laminae. Part II: Chemical characteristics and implications for contaminant transport in fluvial systems

Samples of surficial fine-grained laminae (SFGL) were collected in three south-western Ontario rivers. Each sediment sample was subjected to a sequential extraction procedure designed to partition particulate metals (Cd, Pb, Cu, Zn) into five operationally defined fractions: (1) exchangeable; (2) bound to carbonates; (3) bound to Fe-Mn oxides; (4) bound to organic matter; and (5) residual. Particulate phosphus was sequentially extracted from the sediment samples into three fractions: (1) non-apatite inorganic P; (2) apatite P; and (3) organic P. The major accumulate phases of trace metals in SFGL are carbonates, Fe-Mn oxides and organic matter. The content of NAIP in SFGL ranged from 17 to 38% of total particulate P. Compared with suspended and bed sediments, levels of P and trace metals in SFGL were lower at the study sites. A conceptual overview of physical, chemical and biological processes influencing formation of SFGL and the potential role of this fine-grained sediment for contaminant transport in fluvial systems is presented.     

Evaluation of metal contamination in coastal sediments of the Bay of Bengal, India: geochemical and statistical approaches

Surface sediment samples collected from the inner shelf region of the Bay of Bengal, were analysed for the major elements and total and acetic acid available trace elements (Al, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Pb, Si, Zn) to evaluate geochemical processes influencing their distribution. Major elemental analysis showed that the sediments had high concentrations of Si and relatively low concentrations of Al and Fe. Both major elemental and trace metal concentrations indicated that the sediments represent weathered products of granite and charnockite. Normalization of metals to Al indicated relatively high enrichment factors for Pb, Cd, Zn and Cr. The higher proportions of nondetrital Pb (66%), Cd (41%) and Co (28%) reveal metal contamination due to anthropogenic inputs. Factor analysis (FA) identified six possible types of sedimentological and geochemical associations. The dominant factor accounting for 26.9% of the total variance identifies an anthropogenic input and accumulation of nondetrital Cd, Co, Cr, Ni and Pb. Association of these metals with CaCO3 reveals that shell fragments in the surface sediments are likely act as a carrier phase for nondetrital metals. The results are discussed in the context of the sources and pathways of elements in the Bay of Bengal.     

Assessment of the historical trace metal contamination of sediments in the Elizabeth River, Virginia

Two sediment cores (Southern Branch, PC-1, and Western Branch, WB-2) were taken from the highly industrialized Elizabeth River, Virginia. The concentrations of trace metals cadmium, cobalt, chromium, copper, nickel, lead and zinc, major elements iron, manganese and aluminum, organic carbon content and the specific surface area of the sediments were determined in each of the cores. Down-core variations in metals varied significantly in each core with maximum contamination events occurring at different times in different portions of the river. In PC-1, maximum metal concentrations were seen after the appearance of (137)Cs. In contrast, the highest levels in WB-2 occurred well before the appearance of (137)Cs. Although stricter environmental regulations have caused a decrease in metal concentrations since the 1980s, the concentrations in the surface sediments of many trace metals were elevated to levels 2-5 times higher than the levels at the bottom of the cores in both the Southern and Western Branches of the river.     

苏州河网区河道沉积物重金属的污染特征

分析测定了苏州河网区河道底泥十个剖面样点60个样品中Cu、Pb、Zn、Cr、Al、Fe、K、Mn、有机质、TP、TN、粒度、pH及含水量,采用地累积指数、生态风险指数和相关分析等方法研究其重金属污染特征.结果表明:Cu和Zn处于中或中-强度污染,Pb处于无-中污染,没有Cr污染;垂直分布特征显示:Cu和Zn污染逐年变化较为一致,Pb污染有逐年加重趋势;重金属潜在生态风险处于轻微污染状态;相关性分析显示,有机质是影响其分布的重要因素,Mn、Cr、Cu、Zn、Pb五种重金属相关性显著;通过与国内外河流、水库和湖泊沉积物中重金属含量比较,苏州河网区河道重金属的累积受多种因素影响.     

Effects of varying estuarine conditions on the sorption of phenanthrene to sediment particles of Yangtze Estuary

The sorption of phenanthrene on the Yangtze Estuary sediment was studied under varying conditions of particle size, sediment organic contents, salinity, and dissolved organic matter (DOM) concentrations. Small sediment particles showed higher trapping capacity for phenanthrene due to the higher organic contents associated. The organic carbon-based partition coefficient of phenanthrene to the Yangtze Estuary sediment was obtained as 7120 L/kg, lower than the values for other soils or sediments reported in previous studies. The magnitude and direction of the salt effect were complicated by the specific DOM studied. The sediment sorption capacity was greatly increased in saline water in the absence of DOM but decreased in the presence of DOM. Given the conditions in the Yangtze Estuary, the equilibrium sorption of phenanthrene would be decreased with increasing salinity. Overall, the nature and content of both sediment-bound and dissolved organic matter dominate the sorption of hydrophobic organic contaminants in the estuary.     

Heavy Metals in Bottom Sediment in the Upper and Lower Volga

Heavy metal concentrations in bottom sediment in some reaches of the Upper (the Ivankovo Reservoir) and Lower Volga (from Volgograd to the mouth offshore area). The bottom sediment in the Ivankovo Reservoir are shown to be heavily polluted by Cu and Zn and to a lesser extent, by Co and Ni; heavy pollution with Ni and Cr and moderate pollution with Zn and Mn were recorded in the Lower Volga. Principal component procedure was used to assess bottom sediment pollution. The role of organic matter in the formation of the Ivankovo Reservoir bottom sediment pollution with heavy metals is shown to be moderate because of the weak correlation between heavy metal concentration and organic matter content of bottom sediment. The same is true for the Lower Volga because of low organic matter content of bottom sediment. The major role in the redox cycle of elements is shown to belong to Fe in the Ivankovo Reservoir and Mn in the Lower Volga.     

Magnetic signature of hydrocarbon-contaminated soils and sediments at the former oil field H?nigsen, Germany

Magnetic properties of hydrocarbon (HC) containing soils and sediments from two sites (Site A and B) of the former oil-field H?nigsen were analyzed in order to determine whether magnetic methods can be employed to delineate HC contamination of soils and sediments. Magnetic parameters such as magnetic susceptibility and induced isothermal remanent magnetizations, as well as soil and sediment properties such as pH, iron content and water content, HC content and most probable number counts of iron-metabolizing microorganisms were determined. The magnetic concentration-dependent parameters for HC contaminated samples were 25 times higher in soils from Site A than in sediment samples from Site B. However, at Site B the magnetic susceptibility was still four times higher in comparison to lithologically similar non-contaminated sediment samples from a third Site C. Newly formed magnetite containing mainly single domain particles was responsible for the magnetic enhancement, whereas superparamagnetic grains represented only a minor component. Site A had an acidic pH compared to neutral pH at Site B, and a higher crystalline and bioavailable total iron content. Nevertheless, Site B samples contained significant numbers of both iron(II)-oxidizing and iron(III)-reducing microorganisms indicating that microbial iron cycling might have taken place at this site and potentially played a role for iron mineral transformation, including magnetite (trans)formation. The content of total non-polar hydrocarbons (TNPH) at Site A was one order of magnitude higher than at Site B. Only at Site A magnetic susceptibility correlated well with TNPH. Our results demonstrate that HC contaminated samples had an enhanced magnetite content compared to non-contaminated soils and sediments. Therefore, magnetic methods may provide a quick and cost-effective way to assess HC contamination in soils and sediments. However, more field sites and laboratory investigations are needed to reveal the complex nature of the processes involved.     

太湖流域滆湖底泥重金属赋存特征及其生物有效性

为了探讨太湖流域滆湖底泥重金属(Cd、Cr、Cu、Zn、Ni和Pb)的赋存特征及其生物有效性,对底泥重金属总量、形态以及生物富集量进行了分析.结果表明,6种重金属含量的空间分布表现为北部湖区最高,其次为南部湖区,中部湖区最低,重金属Ni、Cu、Zn和Pb含量显著高于沉积物背景值,分别是背景值的4.77、3.89、2.96和2.76倍,重金属总量与沉积物中的黏土成分含量具有显著相关性.采用三级四部提取法对重金属形态进行分析表明,6种重金属的生物有效态(弱酸结合态、可还原态和可氧化态之和)含量顺序为CdCuZnPbNiCr,其中Cd、Cu、Zn和Pb的生物有效态含量分别占总量的84.15%、78.47%、76.50%和64.29%.Cu和Zn在铜锈环棱螺中富集含量要显著高于其他金属元素.相关性分析表明,6种重金属中仅Cr和Pb的生物富集量与有效态含量具有显著相关性,这表明,重金属在生物体内的富集不仅与有效态含量有关,还与底泥重金属总量有关.因此,评价滆湖重金属的生态风险时需要综合考虑重金属的总量及生物有效态含量.     

Distribution and fate of metals in the Montenegrin part of Lake Skadar

Skadar Lake,the largest lake on the Balkan Peninsula,is famous for a wide range of endemic and rare,or even endangered plant and animal species.Different anthropogenic pressures have,however,influenced the fragile equilibria of the lake ecosystem,with metal pollution as one of the primary concerns.Therefore,this study investigated spatial distribution of metal pollutants in the water and sediment phase of Skadar Lake,and anthropogenic and environmental factors affecting this distribution.A sieving analysis showed that sediment in Skadar Lake is mainly distributed in the three smallest fractions（colloid,clay and silt）.Eleven metals were analyzed in the lake surface and bottom water,and only six of them were detected：potassium,magnesium,calcium,nickel,aluminum and manganese.They were all present at low concentrations.In contrast,sediments contained elevated levels of some metals with concentrations between 28.1-126.8 mg kg~（-1） for Ni,23.6-79.2 mg kg~（-1） for Cr,9.2-36.9 mg kg~（-1） for Cu,199-878 mg kg~（-1） for Mn and 9.6-23.1 g kg~（-1） for Fe.Nickel exceeded consensus-based guidelines for safety towards freshwater dwelling organisms.The organic matter content of the sediment fluctuated between 4.7 and 21.5%.No correlations were found between metal concentrations,organic matter and sediment particle size fractions,suggesting that the latter are not the main factors controlling metal accumulation in Skadar Lake.     

The effects of sewage organic matter on biogeochemical processes within mid-shelf sediments offshore Sydney, Australia

A laboratory incubation experiment was conducted using replicate cores collected from a muddy-sand sediment facies offshore Sydney, Australia to determine what components and processes would be affected by the addition of sewage organic matter. Sewage effluent has a solid phase composition of 40% carbon (35% organic carbon), 5% nitrogen, 1% phosphorus and 5% silicate. The molecular C:N:P ratio is 92:10:1, compared to the Redfield ratio of 106:16:1 in marine phytoplankton. Sediment cores were incubated at in situ temperature in a darkened room for periods up to 95 days. Sewage organic matter was added to the cores at three different loads equivalent to 0 (T0), 65 (T1) and 130 (T2) g m⁻² of sediment. Following the addition of sewage organic matter, fluxes of oxygen (into the sediments), ammonia and phosphate (from the sediments) increased, reflecting an enhanced organic carbon supply to the sediments. Oxygen penetrated to a depth of 6 mm in the ambient cores, but the sediment oxygen content was severely depleted following the addition of the sewage-derived organic matter. Sediment porewater data, together with nutrient flux data indicate that oxygen reduction, nitrate reduction and sulphate reduction occurs within these sediments. Following the addition of sewage organic matter, increases in total nitrogen, total phosphate and total organic carbon were measured to depths of 5 cm in the sediments, suggesting that bioturbation influences nutrient and organic carbon distributions. Additionally, irrigation of the surficial sediments may play an important role in the metabolism of organic matter. These results indicate that oxygen penetration, oxygen fluxes, nitrate concentrations within porewaters, ammonia flux rates, and solid phase concentrations of total organic carbon and nutrients may be useful indicators of sediments affected by high rates of organic matter deposition onto Sydney's offshore sediments. The EPA has recently predicted maximum deposition rates of sewage particulate matter to be approximately 1 g m⁻² day⁻¹. Because of the similarities in CNP ratios of sewage organic matter and marine organic matter, the effects of sewage organic matter and marine organic matter inputs to coastal sediments may not be easily distinguishable.     

Spatial and temporal variations of heavy metal contamination in sediments of a mangrove swamp in Hong Kong

Spatial and temporal variations of heavy metal contamination in sediments of a small mangrove stand in Hong Kong were examined by laying two transects perpendicular across the shore. Surface sediment samples were taken along the two transects running landward to seaward at intervals of 5 or 10 m during December 1989, and March, July and September 1990. Total concentrations of Cu, Zn, Mn and Pb did not show any specific trend along each transect, although the maximum concentration of heavy metals tended to occur at the landward edge. There was a high level of variability among locations within each transect; for instance, the Cu concentrations fluctuated from 1 to 42 μg g⁻¹. Certain sites contained exceptionally high levels of total metals. Total concentrations of Cu, Zn, Mn and Pb as high as 42, 150, 640 and 650 μg g⁻¹, respectively, were recorded, implying contaminated sediment. A comparison of the two transects indicated that the sediments of Transect B seemed to contain higher total Zn but lower Cu and Mn concentrations than those of Transect A. Most of the heavy metals accumulated in the sediments were not extractable with ammonium acetate and no Cu or Pb was detected in these extracts. The concentrations of extractable Zn and Mn were low, less than 10% of the total metal concentration in the sediment, and appeared to decrease from the landward to seaward samples. For both total and extractable metals, there were significant seasonal fluctuations for both transects, but no specific trends could be identified. These spatial and temporal variations suggest that the scale and representativeness of sampling require careful planning, and a single sample might not give a satisfactory evaluation of the levels of heavy metal contamination in mangrove ecosystems.     

Characterization and composition of heavy metals and persistent organic pollutants in water and estuarine sediments from Gao-ping River,Taiwan

The objective of this study was to determine the concentrations and possible sources of heavy metals and persistent organic pollutants (POPs) in water and estuarine sediments from Gao-ping River in order to evaluate the environmental quality of aquatic system in southern Taiwan. High concentrations of heavy metals including Cr, Zn, Ni, Cu and As, ranging from 10.7 to 180 mg/kg-dry weight (dw), were detected in sediments from Gao-ping River. When normalized to the principal component analysis (PCA), swinery and electroplating wastewaters were found to be the most important pollution sources for heavy metals. Of various organochlorine pesticide (OCP) residues detected, aldrin and total-hexachlorocyclohexane (HCH) were frequently found in sediments. The total concentrations of OCPs were in the range 0.47–47.4 ng/g-dw. Also, the total-HCH, total-cyclodiene, and total-dichlorodiphenyltrichloroethane (DDT) were in the range 0.37–36.3, 0.21–19.0, and 0.44–1.88 ng/g-dw, respectively. The polychlorinated biphenyl (PCB) concentrations in sediments from Gao-ping River ranged between 0.37 and 5.89 ng/g-dw. The PCB concentrations are positively correlated to the organic contents of the sediment particles. α-HCH was found to be the dominant compound of HCH in the sediments, showing that long-range transport may be the possible source for the contamination of HCH in sediments from Gao-ping River. In summary, trace amounts of POPs in estuarine sediments from Gao-ping River were detected, showing that there still exist a wide variety of POP residues in the river sediments in Taiwan. These POP residues may be mainly from long-range transport and weathered agricultural soils, while heavy metal contamination is primarily from the swinery and industrial wastewaters.