Chromium adsorption on surface activated biochar made from tannery liming sludge: A waste-to-wealth approach

In a beamhouse, liming plays a key role in the removal of hair/wool and epidermis, but problems are created when waste liming sludge is discharged to the environment. The treatment of tannery wastewater is another major challenge to the industry. In this study, thermally-activated biochars derived from liming sludge were studied for their effective adsorption of chromium (Cr) from the tannery wastewater. The thermally activated biochars (B500, B550, B600, and B650) were prepared at different temperatures from the liming sludge. Their characteristics before and after the treatment were investigated using Fourier transform infrared spectroscopy, energy dispersive X-ray spectroscopy, Brunauer–Emmett–Teller, and scanning electron microscopy analyses. The related functional groups (C–H, O–H, C–N, and =C–O) and chromium adsorption capacity were determined according to the surface morphology, element contents (C, O, Ca, Na, Al, Mg, and Si), surface area (5.8–9.2 m²/g), pore size (5.22–5.53 nm), and particle size (652–1 034 nm) of the experimental biochars. The biochar originated at 600°C from the tannery liming sludge (B600) had a greater surface area with a chromium adsorption capacity of 99.8% in comparison to B500, B550, and B650 biochars. This study developed an innovative way of utilizing liming sludge waste to minimize the pollution load and wastewater treatment cost in the tannery industry.     

Anaerobic treatment of a medium strength industrial wastewater at low-temperature and short hydraulic retention time: a pilot-scale experience

The aim of this work was to evaluate the performance of a pilot-scale upflow anaerobic sludge blanket (UASB) reactor during the treatment of cereal-processing industry wastewater under low-temperature conditions (17 degrees C) for more than 300 days. The applied organic loading rate (OLR(appl)) was gradually increased from 4 to 6 and 8 kg COD(sol)/m3d by increasing the influent soluble chemical oxygen demand (COD(sol)), while keeping the hydraulic retention time constant (5.2 h). The removal efficiency was high (82 to 92%) and slightly decreased after increasing the influent COD(sol) and the OLR(appl). The highest removed organic loading rate (OLR(rem)) was reached when the UASB reactor was operated at 8 kg COD(sol)/m3d and it was two times higher than that obtained for an OLR(appl) of 4 kg COD(sol)/m3d. Some disturbances were observed during the experimentation. The formation of biogas pockets in the sludge bed significantly complicated the biogas production quantification, but did not affect the reactor performance. The volatile fatty acids in the effluent were low, but increased as the OLR(appl) increased, which caused an increment of the effluent COD(sol). Anaerobic treatment at low temperature was a good option for the biological pre-treatment of cereal processing industry wastewater.     

Enterococcus phages as potential tool for identifying sewage inputs in the Great Lakes region

Bacteriophages are viruses living in bacteria that can be used as a tool to detect fecal contamination in surface waters around the world. However, the lack of a universal host strain makes them unsuitable for tracking fecal sources. We evaluated the suitability of two newly isolated Enterococcus host strains (ENT-49 and ENT-55) capable for identifying sewage contamination in impacted waters by targeting phages specific to these hosts. Both host strains were isolated from wastewater samples and identified as E. faecium by 16S rRNA gene sequencing. Occurrence of Enterococcus phages was evaluated in sewage samples (n = 15) from five wastewater treatment plants and in fecal samples from twenty-two species of wild and domesticated animals (individual samples; n = 22). Levels of Enterococcus phages, F + coliphages, Escherichia coli and enterococci were examined from four rivers, four beaches, and three harbors. Enterococcus phages enumeration was at similar levels (Mean = 6.72 Log PFU/100 mL) to F + coliphages in all wastewater samples, but were absent from all non-human fecal sources tested. The phages infecting Enterococcus spp. and F + coliphages were not detected in the river samples (detection threshold < 10 PFU/100 mL), but were present in the beach and harbor samples (range = 1.83 to 2.86 Log PFU/100 mL). Slightly higher concentrations (range = 3.22 to 3.69 Log MPN/100 mL) of E. coli and enterococci when compared to F + coliphages and Enterococcus phages, were observed in the river, beach and harbor samples. Our findings suggest that the bacteriophages associated with these particular Enterococcus host strains offer potentially sensitive and human-source specific indicators of enteric pathogen risk.     

Variability of light absorption properties in optically complex inland waters of Lake Chaohu,China

Absorption coefficients of phytoplankton, colored detrital matter (CDM), non-algal particles (NAP), colored dissolved organic matter (CDOM), and their relative contributions to total non-water absorption (a_t ? w) are essential variables for bio-optical and radiative transfer models. Light absorption properties showed large range and variability sampled at 194 stations throughout Lake Chaohu between May 2013 and April 2015. The a_t ? w was dominated by phytoplankton absorption (a_ph) and NAP absorption (a_d). The contribution of CDOM absorption to a_t ? w was lower than 30%. Phytoplankton and NAP were the primary sources of spatial and vertical variability in absorption properties. Light absorption by CDOM, though significant in magnitude, was relatively constant. CDM absorption (a_dg) was dominated by NAP. The spatial variation of the absorption coefficients from each of the optically active constituents were driven by several main inflow rivers in the western and middle part of Lake Chaohu. Algal blooms and bottom resuspension contributed to vertical variability as observed by phytoplankton and NAP profiles. Specific absorption of phytoplankton had significant spatial and seasonal variations without vertical variation. The spectral slope of absorption showed no significant spatial variability (p > 0.05). Variations of absorption affected different ranges of remote sensing reflectance (R_rs) spectrum, thereby increasing the difficulty of applying the remote sensing algorithm in optically complex waters. Parameters and relationships presented in this study provide useful information for bio-optical models and remote sensing of lakes similar to Lake Chaohu in terms of optical properties.     

Sediment geochemistry and contributions to carbon and nutrient cycling in a deep meromictic tropical lake: Lake Malawi (East Africa)

The biogeochemical functioning of large tropical lakes differs substantially from temperate lakes, yet remains poorly understood. We characterized the carbon, nitrogen, and phosphorus cycling in the water column and sediments of a deep meromictic tropical Lake Malawi (East Africa) by measuring geochemical distributions and compiling whole-lake geochemical budgets. Four locations (100 to 650 m water depth) were characterized. The results reveal that sediments contribute significantly to lake-wide biogeochemical budgets. Sedimentation rates have significantly increased in recent decades. While the export efficiency of organic matter from photic zone to deep sediments is low (14%), organic carbon is buried in the anoxic sediments with high efficiency (27–46%). Area-specific rates of carbon mineralization (4.1 mmol m^? 2 d^? 1) are similar to those in temperate well-oxygenated large lakes and marine sediments in similar water depths. Ammonium effluxes from sediments (0.44 mmol m^? 2 d^? 1) contribute 29% to the total nitrogen inputs into the water column, while sediment denitrification (0.035 mmol m^? 2 d^? 1) and burial of organic nitrogen (0.27 mmol m^? 2 d^? 1) remove 28% of total inputs in the lake. The recycling efficiency of phosphorus in anoxic sediments is high (73%). P effluxes average 0.037 mmol m^? 2 d^? 1, suggesting a large and previously unquantified contribution (42%) to water column P inputs. The results underscore the importance of sediments in the geochemical budgets of even large lakes and suggest trends in lacustrine carbon cycling that hold across a wide range of environments.     

Chemistry,Mineralogy, and Morphology of Lake Erie Suspended Matter

Suspended matter was collected from different depths at three stations in spring and summer, 1978, in Lake Erie. Chemistry, mineralogy, and morphology of the suspended particles were measured to investigate spatial and temporal changes. The determined elements (Si, Fe, Ca, K, Mn, P, Al, Ti, and Mg) were partitioned between inorganic and biological material and the majority of these elements were present in at least two different chemical forms. Flocculates > 3 μm composed of organic material and mineral fragments were common at the water surface and the middle of the water column. Mineral fragments < 3 μm were the major constituent of suspended matter at the bottom at the deepest sampling station (62 m). The concentration of the major components of the suspended matter, organic material, alumino-silicates, and calcite, varied significantly from spring until later summer. The high concentration of organic material and the fluctuations of calcite concentration result from high rates of photosynthesis and respiration and temperature increases in spring and summer.     

Purification and utilization of garlic processing wastewater in lotus pond wetlands

Based on the experiments of utilization of garlic processing wastewater in a lotus pond, this study demonstrates that lotus pond wetlands have a remarkable ability to remove organic pollutants and decrease chemical oxygen demand(CODCr), biochemical oxygen demand(BOD5), and suspended substances(SS) in garlic processing wastewater. Results also show evident effects of lotus roots on absorption of NH3-N. The pH value in a lotus pond with wastewater discharged was relatively stable. The water quality in the lotus pond reached the class Ⅱ emission standard, according to the Integrated Wastewater Discharge Standard(GB8978-1996), seven days after pretreated garlic processing wastewater had been discharged into the lotus pond. Garlic processing wastewater irrigation does not produce pollution in the pond sediment and has no negative effect on the growth of lotus roots. Due to utilization of garlic processing wastewater, the output of lotus roots increased by 3.0% to 8.3%, and the quality of lotus roots was improved. Therefore, better purification and utilization results can be achieved.     

The spectral characteristics of dissolved organic matter from sediments in Lake Baiyangdian,North China

Dissolved organic matter (DOM) extracted from sediment samples in Lake Baiyangdian was investigated using UV -Vis absorption and fluorescence spectroscopy. Two parameters, the ratios of absorbance and dissolved organic carbon at 254° nm (SUVA₂₅₄) and the integral area from 240° nm to 400° nm (A_{240 -400}), were used to assess the molecular weight and aromaticity of DOM. The surface sediments showed a relatively low aromaticity of DOM due to the impact of environmental pollution. Synchronous fluorescence spectra showed an extremely high fraction of the protein-like region (PLR). Parallel factor analysis (PARAFAC) of excitation -emission matrix spectra revealed four fluorescent components occurring in sediment DOM: two humic-like (C1 and C2) components and two protein-like (C3 and C4) components. The PARAFAC-PCA displayed three PCA factors (factors 1, 2 and 3) which accounted for 48.250%, 25.927% and 25.391%, respectively, of the variance in fluorescent component. The humic-like components 1 and 2 concurrently showed positive factor 1 loadings. Factor 2 was mainly explained by the tryptophan-like component C3. A non-humic component 4, having a low factor loading in the other two factors, showed an extremely high factor 3 loading. The EEM -PARAFAC-PCA showed varying contributions of terrestrial versus autochthonous DOM sources in lake sediments.     

Treatment and valorisation of winery wastewater by a new biophysical process (ECCF).

Taking account of the high specificity of the organic load of winery effluents, a new biophysical treatment using the stripping of ethanol combined with a final concentration by evaporation has been studied. Two options are proposed: full treatment and pre-treatment. The study of the composition of winery wastewater has shown the large, dominant part of ethanol in the organic load (75 to 99% of the COD). According to a linear correlation between COD and ethanol concentration, the determination of ethanol concentration can be used to estimate the organic load of winery wastewater. Full treatment by stripping and concentration at a pilot plant allows the separation of the wastewater into highly purified water (COD elimination > 99%), a concentrated alcoholic solution usable as bio-fuel and a concentrated by-product. Stripping alone represents an advantageous pre-treatment of winery wastewater. The purification rate reaches 78 to 85% and ethanol is recovered. The process facilitates discharge into a sewage system in view of treatment with domestic effluents and can also improve the efficiency of overloaded or old purification plants. The economical approach of this method demonstrates its competitiveness in comparison with biological treatments: low energy consumed, no sludge.     

Precision of Ages Determined from Scales and Opercles for Yellow Perch Perca flavescens

Scales and opercles were used to age yellow perch Perca flavescens collected in 1989 from Lake Madison (South Dakota), Dauphin Lake (Manitoba), and southern Lake Michigan (Indiana). Three readers aged fish from Lake Madison and Dauphin Lake once and two readers aged fish from Lake Michigan twice. The coefficient of variation (CV) was calculated to compare precision. Ages determined from opercles were as precise as those from scales for fish from Lake Madison (CV = 0 for both structures), and more precise than ages from scales for fish from Dauphin Lake (CV_opercle = 14.0, CV_scale = 27.4, p < 0.001) and Lake Michigan (CV _opercle = 10.6, CV_scale = 13.9, p < 0.001). The high precision of scale and opercle ages for yellow perch from Lake Madison can be attributed to the fast growth rate of fish from that lake and also that only age 1 and 2 fish were aged. The greater precision of opercle ages in comparison to scale ages for Dauphin Lake and Lake Michigan yellow perch can be attributed to ease of recognition of false annuli on opercles as well as to difficulty in distinguishing between false and true annuli crowded on the edge of scales from mature, slower growing fish. Because true annuli are more easily recognized on opercles, ages determined from opercles may be more accurate than ages determined from scales for yellow perch growing at slow or moderate rates.     

Influence of physico-chemical treatment on the subsequent biological process treating paper industry wastewater

The present paper presents the main results of the biodegradation study of paper industry wastewater through physico-chemical treatment. Indeed, around 60% of chemical oxygen demand (COD) removal can be achieved by electroflocculation treatment. Furthermore, a removal efficiency of the COD of almost 91% has been obtained by biological treatment, with activated amount of sludge for 24 h of culture. Concerning the physico-chemical pre-treatment of the untreated, filtered and electroflocculated rejection effluents, it has been investigated through the degradation curve of COD studies.     

Estimation of Zooplankton Mean Length for Use in an Index of Fish Community Structure and its Application to Lake Erie

Mills et al. (1987) developed an index of zooplankton mean size to assess the state of fish communities. The use of this index was evaluated in an assessment of the fish community structure in 1993 at nearshore and offshore sites in the three Lake Erie basins. Mills et al.’s index was developed using a 153-μm mesh net, while the samples in this study have been collected with 64-μm and 110-μm mesh size nets. Two methods were used to convert the data to 153-μm equivalent collections: (a) regression relationships based on simultaneous collections with three mesh sizes, and (b) elimination of smaller organisms that would have passed through the 153-μm mesh by determining the minimum length of inclusion (MLI). The regressions employed for the conversion of zooplankton mean length (ZML) between the nets were: ZML₁₅₃ = 0.137 + 0.988 ZML₁₁₀ (mm) (r²= 0.804) (n = 10) and ZML₁₅₃ = 0.042 + 1.330 ZML₆₄ (mm) (r² = 0.931) (n = 9). The MLI that resulted in the same mean length as the 153-μm sample averaged (± 1 SE) 0.267 ± 0.016 mm (n =19).The comparison between zooplankton mean length and fish community structure in the western basin of Lake Erie in 1993 showed good agreement with Mills et al.’s index. However, the same was not true for the 1988 to 1990 data. Reasons for this discrepancy are discussed.     

Silicon Isotopic Fractionation in Lake Tanganyika and Its Main Tributaries

Silicon isotopic measurements in Lake Tanganyika were performed using multiple-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) in dry plasma condition. Isotopic signatures are reported for dissolved ortho-silicic acid [Si(OH)₄] collected during a 1-year-long surface waters survey in the southern basin along with several of the major tributaries. Deep-water Si isotopic profiles from a north-south transect cruise conducted in July 2002 are also described. The nutrient-like shape dissolved Si profiles and the isotopic disequilibrium between surface (δ²⁹Si = 0.87±0.08 ‰) and deep waters (0.61 ± 0.05 ‰) suggest the occurrence of biological isotopic discrimination induced by diatoms biomineralisation in a fresh water system. Short-term surface water Si isotopic and diatom biomass variations obtained during the 1-year bi-weekly monitoring (2002–2003) in the south confirms this biological effect. Five epilimnion biogenic opal samples also were analyzed. Their signature (δ²⁹Si of 0.28 ± 0.12‰) compared to those of surrounding waters are consistent with the diatom isotopic fractionation effect measured on marine tropical diatoms. This demonstrates the species and temperature independent character of the silicon isotope fractionations by diatoms. River signatures present variable dissolved Si concentrations which were positively correlated to δ²⁹Si values in the range of previously published world river data. Because of its fast response to climate variability, nutrient dynamics, and limnological changes, δ²⁹Si in siliceous organisms should be very useful in studying environmental changes and particularly the recent decline of diatom Si utilization in Lake Tanganyika.     

Transport of Fine Sediment Through a Wetland Using Radionuclide Tracers: Old Woman Creek,OH

The Old Woman Creek estuary (OWC), a coastal wetland in Ohio, traps 47% of incoming suspended sediment and has a sedimentation rate of ∼1 cm/yr. Persistence of the OWC wetland and other coastal wetlands with high sedimentation rates seems problematic unless some previously trapped sediment is exported from the wetland.Suspended sediment, ⁷Be, and ²¹⁰Pb_xs budgets for a single runoff event in the OWC wetland were developed to understand short-term sediment dynamics. The budgets were balanced by subtracting the sum of the imports from the sum of the exports and attributing the difference to either deposition on, or resuspension from, the wetland bed. The wetland exported 118 ± 2%, 93 ± 1%, 74 ± 2% of the delivered sediment, ²¹⁰Pb_xs, and ⁷Be, respectively, during the studied event. The ⁷Be/²¹⁰Pb_xs ratios of the total suspended solids and bed sediment were distinct from one anther and used to quantify the relative proportions of recently delivered and resuspended bed material in the sediment efflux from the wetland. The ⁷Be/²¹⁰Pb_xs ratios suggest that 26 ± 20% of the sediment efflux was resuspended from the bed. While the wetland trapped 13 ± 3% of the sediment it received during the runoff event, resuspension and removal of previously deposited sediment in the wetland was sufficiently large to result in a net loss of sediment from the wetland during the event. Thus, the Old Woman Creek wetland is a sediment sink over the long-term, but can be a net exporter of sediment during single events.     

Effects of lake-basin morphological and hydrological characteristics on the eutrophication of shallow lakes in eastern China

The Yangtze River floodplain contains numerous oxbow or riverine lakes, all of which were openly connected with the Yangtze River or its major tributaries prior to 1950s. However, stresses resulting from human settlement and utilization of catchment resources have exerted great pressures on these lake ecosystems changing their morphology, connectivity and trophic state lakes. This study examined the interaction of these changes and their impact on eutrophication for 90 shallow lakes in eastern China in 2008 to 2011. TN and TP in the study lakes had negative relationships with mean water depth (Z_mean), but no single lake-basin characteristic was found to dominate chlorophyll-a (Chl-a) growth. Instead, water depth and surface area were found to interactively affect Chl-a concentrations in smaller lakes. That is, Chl-a concentration in the lakes with Z_mean > 2 m and surface area (SA) ≤ 25 km² was significantly higher than that in relatively larger lakes with Z_mean > 2 m and SA > 25 km² (p-value ≤ 0.038). Chl-a concentration was higher in the lakes located within the lower Yangtze River basin which had longer retention times, than in the lakes located within the middle Yangtze River basin, where flow velocity is relatively larger. As expected, the water quality was found to be better in the lakes hydraulically connected with rivers than in those isolated from the river. This study revealed that lake-basin morphology and hydrology dominated algal blooms in the highly eutrophic shallow lakes in eastern China.     

Legacy polychlorinated organic pollutants in the sediment of the Great Lakes

Legacy, organic pollutants, including polychlorinated biphenyls (PCBs), dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), naphthalenes (PCNs), and diphenyl ethers (PCDEs) were quantified in sediments of the Laurentian Great Lakes of North American. A total of 40 cores (939 core segments) and 198 Ponar surface grab samples were collected from the five Great Lakes between 2010 and 2014. Median concentrations in Ponar grab samples were 8.4, 0.27, 0.05, 0.19 and 0.01 ng/g dry weight (dw) for total-PCBs, ∑₇PCDDs, ∑₁₀PCDFs, ∑₁₂PCNs, and ∑₇PCDEs, respectively. By using Geographic Information Systems Analysis with the inverse distance weight (IDW) interpretation of the spatial distribution of the chemical inventory at coring sites, total mass loads in the five lakes combined were estimated to be 511, 15.3, 5.3, 20.7 and 2.9 t for total-PCBs, ∑₇PCDDs, ∑₁₀PCDFs, ∑₁₂PCNs, and ∑₇PCDEs, respectively. Patterns of spatial distributions revealed pollution hotspots and provided evidence for historical local sources. Concentrations of residues in Ponar grabs and inventories at coring sites, when normalized to concentrations of organic carbon, exhibited statistically significantly correlations with latitude and longitude of the sampling sites for all five chemical groups. At most coring sites, concentrations have been decreasing towards the sediment surface. At locations relatively close to known or suspected sources, estimated half-times for all classes of chemicals were approximately 20 years. The declining trends of PCDDs and PCDFs were unclear at some locations, suggesting the presence of currently active emission sources.     

Influence of temperature and sludge loading on activated sludge settling,especially on Microthrix parvicella

During recent years modern full scale wastewater treatment plants with biological nitrification, denitrification and phosphorus removal have had increasing problems with foam formation on the surfaces of aerobic tanks and with bulking activated sludge. The results of a survey in 1995 (Kunst and Knoop, 1996) showed that most often the filamentous bacterium Microthrix parvicella is responsible for these problems. Up to today there is only little knowledge about its selection criteria in activated sludge. Therefore several expenments were done in full scale activated sludge plants and in laboratory systems under defined conditions to investigate the influence of low (< 0.1 kg/(kg·d)) and high (≤ 0.2 kg/(kg·d)) BOD₅-sludge loading rates on the growth and morphology of M. parvicella and the settlement of activated sludge. Furthermore the influence of temperatures of 5°C, 12°C and 20°C on the growth of M. parvicella was investigated. It was shown that M. parvicella grows at low BOD₅-sludge loading rate and low temperature and is the main causative organism of bulking and foaming sludge in nutrient removal plants. On the basis of this investigation it was concluded that the growth of M. parvicella and the settling problems of the activated sludge resulting from excessive growth of this filament will always appear in modern municipal wastewater treatment plants with BOD₅-sludge loading rate ≤ 0.1 kg/(kg·d) especially under low temperature conditions.     

Fenton氧化预处理磷酸酯阻燃剂生产废水

针对磷酸酯阻燃剂生产废水中COD质量浓度高,含有微生物难降解的成分,是一种难处理的有机废水的现实,利用Fenton氧化工艺对磷酸酯阻燃剂生产废水进行预处理,测定水中COD质量浓度的变化情况,以评价Fenton氧化工艺的处理效果,并考察Fe SO4·7H2O投加量、H2O2投加量及不同酸调节p H值对处理效果的影响。结果表明,最佳工艺条件为:Fe SO4·7H2O加入量为5 g/L,H2O2加入量为5.55 g/L;用硫酸调整p H值优于用盐酸调整p H值。     

Anthropogenic Copper Inventories and Mercury Profiles from Lake Superior: Evidence for Mining Impacts

During the past 150 years, the mining industry discharged more than a billion tons of tailings along Lake Superior shorelines and constructed numerous smelters in the watershed. Given the vast size of Lake Superior, were sediment profiles at locations far offshore impacted by nearshore activities? Did copper and associated precious metal mining modify regional fluxes for copper and mercury? Samples from thirty sediment cores document that background concentrations of copper are high (mean 60.9 ± 7.0 μg/g), due to the proximity of natural ore sources. Anthropogenic inventories uncorrected for focusing also are high, ranging from 20 to 780 μg/cm² (mean 187 ± 54 μg/cm²). Focusing factor corrections decrease the mean estimate and reduce variance (144 ± 24 μg/cm²). Several approaches to estimating inputs suggest that only 6 to 10% of historic copper deposition originated directly from atmospheric sources, emphasizing terrestrial sources. Moreover, coastal sediment cores often show synchronous early increases in copper and mercury with buried maxima. Around the Keweenaw Peninsula, twenty-two cores trace high copper and mercury inventories back to mill and smelting sources. Direct assays of ores from thirteen mine sites confirm a natural amalgam source of mercury in the stamp mill discharges. Core records from inland lakes (Michigamme Project) also reveal patterns of copper and mercury inputs from a variety of mining sources: historic tailing inputs, amalgam assay releases, and atmospheric smelter plumes.     

Accumulation of Contaminant Metals in the Amphipod Diporeia spp. in Western Lake Ontario

Sediment and amphipods (Diporeia spp.) were collected in areas in western Lake Ontario suspected of containing a range of sediment metal contents. The total metal contents (Al, As, Cd, Cr, Cu, Ni, Fe, V, and Zn) of depurated Diporeia tissues were measured and compared to the total metal contents of the surrounding sediment. The fractional bioavailability of As, Cu, Fe, and Zn was determined in those same sediments using a sequential chemical extraction (SCE) procedure and correlated with depurated Diporeia tissue metal contents. Results of these analyses were then used to assess the ability of Diporeia to accumulate sediment metal contamination. A comparison of metal biota-sediment accumulation factors (BSAFs) and sediment metal enrichment factors (EFs) for each metal yielded separate metal groups showing different behavior for tissue accumulation. Aluminum, Cr, Fe, Ni, and V were not enriched in the sediments and were not accumulated in Diporeia tissues, while As, Cd, Cu, and Zn were enriched in the sediments and accumulated in Diporeia tissues. SCE results showed that Cu (3.2 to 8.4 %) and Zn (13 to 19 %) contents in the easily extractable sediment fractions (MgCl₂ and Na-acetate) were significantly correlated with Cu (r = 0.86; P<0.01) and Zn (r = 0.69; P<0.05) contents in depurated Diporeia tissue. In addition, Cu and Zn in Diporeia tissues are also correlated to the total sediment metal content for each respective metal (Cu: r = 0.67, P < 0.05; Zn: r = 0.66, P < 0.05). The high BSAFs for Cu and Zn, in combination with the association of tissue metal contents with easily extracted sediment metal fractions, suggest that Diporeia may be a potential bioindicator for Cu and Zn contamination in sediments.