BCR Sequential Extraction Research Articles

Speciation of heavy metals Cu, Ni and Zn by modified BCR sequential extraction procedure in sediments from Banten Bay, Banten Province, Indonesia

Banten Bay is categorized as a marine area that is busy with marine tourism activities, settlements and also industries. One potential impact of the condition is the occurrence of pollution from both industrial and domestic sources, erosion and sedimentation in the coastal environment. Samples were collected from 25 representative stations in April 2016. Chemical speciation of three heavy metals (Cu, Ni, and Zn) was studied using a modified sequential extraction procedure proposed by the European Standard, Measurements and Testing (SM&T) program, formerly the Community Bureau of Reference (BCR). The aims of this study are to determine geochemical speciation of 4 bounds of metal: acid-soluble, reducible, oxidizable and residual, and to assess their impacts in the sediments of Banten Bay, Indonesia. The result shows that the percentage of Copper (45.90-83.75%), Nickel (18.28-65.66%), and Zinc (30.45-79.51%) were mostly accumulated in residual fraction of the total concentrations. The Risk Assessment Code (RAC) reveals that about 0-7.07% of Copper and 1.11-24.35 % of Zinc at sites exist in exchangeable fraction and therefore, they are in low risk category. While 7.34-34.90 of Ni at sites exists in exchangeable fraction and therefore, it is in medium risk category to aquatic environment.

Validation of the BCR sequential extraction procedure for natural radionuclides

Determining the availability of natural radionuclides in environmental conditions is increasingly important in order to evaluate their toxicity. A validated procedure is necessary to ensure the comparability and accuracy of the results obtained by different laboratories. For that, an optimised BCR sequential extraction procedure has been applied to the certified reference material (CRM), coded as BCR-701, and their resulting liquid and solid fractions were subjected to an exhaustive chemical and radioactivity characterisation. In this sense, several material characterisation techniques were used for chemical, mineralogical, and radioactive characterisation, in order to gain basic information about the obtained fractions. In accordance with the results of this work, the BCR sequential extraction procedure has been validated for the most significant alpha-emitter natural radionuclides (210Po, 234U, 238U, 230Th, 232Th, and 226Ra). It has been demonstrated that their mobility is related to the speciation under environmental conditions and the type of radionuclide; we have even found differences between radionuclides of the same element, such as the cases of the pairs 234U238U and 230Th232Th, for the BCR-701. In addition, we found that radium was mainly bound to the reducible fraction (Fe and Mn-oxyhydroxides), uranium to the oxidizable fraction (organic matter and sulphides), and that the polonium and thorium isotopes had a high affinity with the particulate phase (non-mobile fraction).

ARSENIC AND TRACE METALS IN WATER AND SEDIMENT OF THE VELHAS RIVER, SOUTHEASTERN IRON QUADRANGLE REGION, MINAS GERAIS, BRAZIL

This work was undertaken in the Velhas River Basin, in the municipalities of Rio Acima, Nova Lima, Raposos and Sabara, upstream of the city of Belo Horizonte in Minas Gerais State, Brazil. Velhas River provides the public water supply for much of this region. The gold and iron mining activities in the Velhas River yield considerable amounts of suspended solids as well as metals to the hydrological system of the region. Thus, the present study sought to evaluate the concentrations of arsenic and trace metals in the waters and their distribution and mobility in sediment by BCR sequential extraction. Arsenic concentrations in the water samples were between 78.1 and 85.3 μg L-1, which exceeded 10 μg L-1 (maximum limit permitted by Brazilian environmental regulations for water destined to human consumption, CONAMA Resolution 357/2005). The sequential extraction of the sediment showed considerable amounts of As (20%), Cd (55%), Co (56%), Cr (16%), Cu (23%), Ni (29%), Pb (47%) and Zn (71%) associated with the geochemical fractions considered potentially available for the remobilization to the aquatic environment. The presence of the elements in these fractions indicated high ecotoxicological risk and potential harm to the health of the local population.

Cylindrical Electrolyser Enhanced Electrokinetic Remediation of Municipal Solid Waste Incineration Fly Ashes

The paper discusses enhancement and efficiency of removing spiked heavy metal (HM) contaminants from the municipal solid waste incineration (MSWI) fly ashes in the cylindrical electrolyser device. The characterization parameters of the electrolyte solution pH, electric current, electrical conductivity, voltage gradient were discussed after the experiment. The chemical speciation of HMs was analysed between the original samples and remediated ones by BCR sequential extraction. The detoxification efficiencies of Zn, Pb, Cu and Cd in the column-uniform device were compared with that in the traditional rectangular apparatus. The pH value changed smoothly with small amplitude of oscillation in general in cathode and anode compartments except the initial break. The electrical current rapidly increased on the first day of the experiment and steadily declined after that and the electrical conductivity presented a clear rising trend. The residual partition of detoxified samples were obviously lifted which was much higher than the analysis data of the raw materials. The pH and the electrical conductivity in sample region were distributed more uniformly and the blind area was effectively eliminated in the electrolytic cells which was indirectly validated by the contrastive detoxification result of the spiked HMs between the rectangular and cylindrical devices.

TRACE ELEMENTS IN RIVER WATERS AND SEDIMENTS BEFORE AND AFTER A MINING DAM BREACH (BENTO RODRIGUES, BRAZIL)

On November 5, 2015, the Fundao dam ruptured which caused the spill of a large quantity of tailings from the extraction of iron ores to the Gualaxo do Norte, Carmo and Doce Rivers. Seven months prior to the rupture, our group had collected water and sediment samples at 13 points along the Tripui Creek and the entire length of the Carmo River. Six months after deposition of the mud, new samples were collected in the Carmo River. Thus, the present study sought to evaluate the concentrations of trace elements in the waters and their distribution and mobility in sediment by BCR sequential extraction before and after the deposition of the tailings mud. Arsenic concentrations in the water samples were between 10.4 and 50.4 µg L-1, which exceeded 10 ug L-1 (maximum limit permitted by Brazilian environmental regulations for water destined for human consumption) . The tailing mud layer on the sediments caused concentration increases of As (20%), Cd (13%), Co (5%), Cr (9%), Cu (11%), Ni (4%), Pb (7%) and Zn (19%) in the easily remobilized fractions. The presence of the elements in these fractions was indicative of high ecotoxicological risk and potential harm to the health of the local population.

Speciation of nickel and enzyme activities in fluvo-aquic soil under organic amendments treatment

To investigate the efficacy of humic acid and cow dung for nickel (Ni) immobilisation and detoxification in fluvo-aquic soil, the Ni-polluted soil was mixed with amendments of humic acid and cow dung. The Ni speciation (modified BCR sequential extraction method) and enzyme activities were scrutinised. As the humic acid concentration increased (0 to 12 g kg–1), the amount of Ni in the acetic acid-soluble fraction (the bioavailable fraction with high environmental risk) first decreased and then increased. In contrast, the amount of Ni in this fraction continued to decrease as the cow dung concentration increased (P < 0.05). The Ni in the acetic acid-soluble and residual fractions transformed to the oxidisable fraction, leading to lower environmental risk. The fluorescein diacetate hydrolysis and alkaline phosphatase activity were negatively correlated with the amount of Ni in the acetic acid-soluble fraction (r = –0.695 and –0.773, respectively, P < 0.01), indicating that Ni in the acetic acid-soluble fraction was toxic and led to enzyme activity inhibition, and the amendments could reduce subsequent damage. When humic acid concentration ranged from 5.01 to 6.47 g kg–1, the acetic acid-soluble Ni level reached the minimum, while the fluorescein diacetate hydrolysis and the alkaline phosphatase activity reached their maxima. In conclusion, humic acid and cow dung are effective amendments for Ni immobilisation and reduce devastation of soil enzymes. The humic acid concentration should be between 5.01 and 6.47 g kg–1 to achieve the optimum efficacy.

Physico-chemical forms of copper in water and sediments of Lake Pontchartrain basin, USA

In this study, one of the largest estuaries in the Gulf Coast of USA was investigated for Cu forms and fractionations. Both the water and sediment samples in subsegments of the Lake Pontchartrain basin were collected and Cu forms in dissolved phase and sediment phase were analyzed. The BCR sequential extraction procedure was used to extract Cu in exchangeable, reducible, oxidizable and residual fractions in sediments. The results showed that the residual fraction of Cu was a major contributor in Tangipahoa River and I-10 Bridge sediments, while the residual and oxidizable fractions in the case of oil refinery sediments. Cu partitioning in Lake Pontchartrain basin water showed the decreasing trend of inert > labile > organic in both spring and summer. The release of Cu from the sediments into the water column was greater in summer as compared to spring and vice versa. Lower temperature helps in the adsorption of Cu on the surface of sediments in early spring due to low disturbance and temperature.

Comparison of palygorskite and struvite supported palygorskite derived from phosphate recovery in wastewater for in-situ immobilization of Cu, Pb and Cd in contaminated soil

A phosphorus-bearing product S-PAL obtained from nutrient-rich wastewater was reused as ameliorant for Cu, Pb and Cd immobilization in contaminated soil with three different rates (1%, 5% and 10% w/w). The 0.01 mol/L CaCl2 -extractability of metals significantly reduced with increasing rate of PAL and S-PAL in the first 7-day immobilization and insignificantly changed after 14-day immobilization. Compared with PAL, the lower metal extractability was observed after S-PAL addition. The BCR sequential extraction results showed that both of amendments were beneficial to transform acid soluble fraction to residual fraction. The XRD patterns of soil samples after immobilization evidenced that the formation of metal-bearing phosphate precipitates and the combination between functional groups such as Si-OH and metals played a key role for metal immobilization by S-PAL and PAL. Dominant phyla across all samples were Fusobacteria, Proteobacteria and Actinobacteria, and the relative abundance of Fusobacteria decreased under S-PAL treatment. The pH-dependent leaching test indicated that the metal release at a defined pH was not affected by the presence of PAL. Compared with S-PAL, the metals amended by PAL in soil were easier to release at acidic pH since the combination between functional groups and metals instead the formation of new metal-bearing precipitate.

Risk assessment of toxic metals in marine sediments from the Arctic Ocean using a modified BCR sequential extraction procedure

ABSTRACTSurface sediment samples were collected from the Pacific sector of the Arctic Ocean during the 6th Chinese National Arctic Research Expedition (CHINARE), 2014. Concentrations and extractabilities of six toxic metals (Cd, Cr, Cu, Ni, Pb, and Zn) were determined using a modified sequential extraction procedure as described by the European Community Bureau of Reference (BCR). A new analytical hierarchy approach to risk assessment, involving sediment quality guidelines and risk-assessment codes, is described for metals in marine sediments from the Arctic Ocean. Results indicate a mobility order of Pb > Cd > Cu > Zn > Ni > Cr with mean liable fraction (F1+F2+F3) being 83.0%, 81.6%, 62.0%, 47.1%, 42.1%, and 15.6%, respectively. Ni presents the most serious ecological risk in the study area, with most samples (93.9%) indicating medium risk, followed by Cu (54.5%) and Zn (27.3%). For Ni and Zn, there are also samples showing high ecological risk (Ni at site NB02, northern Bering Sea; Zn at R07, northern Chukchi Sea). The ecological risk for Cr indicates low ecological risk (93.9%) and some medium risk (6.1%). All Cd assessments indicate low ecological risk, while most Pb assessments indicate zero (33.3%) to low risk. The new ecological risk assessment method improves on assessments based on metal mobility or concentration alone.

Investigation of microrubbers, microplastics and heavy metals in street dust: a study in Bushehr city, Iran

This study aimed to (1) investigate microrubbers (MRs) for the first time and identify microplastics (MPs) in street dust, (2) determine the physicochemical and mineralogical characteristics and morphology of dust particles, (3) understand the concentration and the possible source(s) of heavy metals/metalloids, (4) identify the chemical speciation and mobility potential of trace metals in urban street dusts, and (5) determine adverse health effects of street dust on children and adults living in the city of Bushehr in southwestern Iran. Generally, twenty four street dust samples were collected and analyzed. Calculated enrichment factors indicate high levels of contamination. Statistical analysis reveals that the two main sources of trace elements include road traffic emissions (Cu, Zn, Sb, Hg, Pb, Mo) and re-suspended soil particles (Al, Mn, Ni, Ti, Cd, Co). BCR sequential extraction results indicated that As, Zn, Cu, and Pb mainly occur in the exchangeable fraction and hence are highly bioavailable. X-ray powder diffraction analysis revealed the presence of calcite, dolomite, quartz, and magnetite. The size distribution of dust particles was also investigated using a scanning electron microscope (SEM), while elemental distribution was analyzed using an attached energy dispersive X-ray spectrometer (SEM–EDS) unit. Dust particles from heavy traffic areas are much finer compared with other investigated areas. MPs and MRs, mostly fibers and fragments, were detected in all samples [ranging from 210 to 1658 (MPs) and 44 to 782 (MRs) items/10 g dust] using fluorescence microscopy. The hazard index for As is higher than 10−4 for children and adults indicative of high risk. According to the calculated potential ecological risk index, Hg indicated moderate ecological risk in the street dust of the study area.

Heavy-metal speciation redistribution in solid phase and potential environmental risk assessment during the conversion of MSW incineration fly ash into molten slag.

The alkalinity (AKash), BCR sequential extraction method, and principle component analysis (PCA) were adopted to investigate the heavy-metal partitioning and their speciation redistribution in solid phase in ash-melting process. The results indicated that the conversion of Zn-OXI (oxidisable fraction) into Zn-RES (residual fraction) and the decomposition of Cu-OXI fraction were prevailing in solid-phase reaction. Moreover, the alkalinity reduction from AKash = 2.0 to AKash = 1.2 had positive implications for the concentration reduction of As-RED (reducible fraction), Zn-RED, and Pb-RES fractions in slags. The modified synthesis toxicity index (STIM) calculation model was introduced to investigate the potential ecological risk (PEI) of heavy metals in the recycling and utilization of molten slag. Based on STIM calculation model, PEI of heavy metal in hazardous materials was classified into five ranks, such as serious pollution (STIM > 462), heavy pollution (330 < STIM < 462), moderate pollution (132 < STIM < 330), mild pollution (0 < STIM < 132), and no pollution (STIM = 0). The molten slags produced from fly ash can be directly reused as building materials like freestone and ceramics due to the mild PEI.

Heavy metal distribution in Tiaoxi River's sediment.

According to current study, seven surface sediments and three sediment cores were collected from three typical areas of Tiaoxi River, which were living area, agricultural area, and industrial area. The water quantity into the Lake Taihu from the Tiaoxi River accounted for almost one third of the total water quantity by all rivers into the Lake Taihu. To study geochemical features and pollution history of heavy metals in three typical areas of Tiaoxi River, total content and chemical fractionations of Cu, Pb, Cd, Cr, Mn, Zn, Fe, As, and Hg were analyzed for surface and core sediments using the speciation extraction procedure, proposed by the Commission of the European Communities Bureau of Reference (BCR), together with grain size and organic carbon measurements. The results showed that the concentration of nine heavy metals and the variation characteristics of Zn, Cu, Fe, Mn, and Cr are different among five cores, which has shown that the river responses to natural and anthropogenic activities were dissimilar in various areas. BCR sequential extraction showed contents of Cr, Fe, and Cu were dominated in the remaining parts. Non-residual fractions for Zn and Mn contained major portions. Based on RAC (risk assessment core), the risk of Mn was high to very high in the three typical areas, and the risk of Zn was medium in the three typical areas.

Spatial distributions, fractionation characteristics, and ecological risk assessment of trace elements in sediments of Chaohu Lake, a large eutrophic freshwater lake in eastern China.

The concentrations, spatial distribution, fractionation characteristics, and potential ecological risks of trace elements (Cu, Pb, Zn, Cr, Ni, and Co) in the surface sediment samples collected from 32 sites in Chaohu Lake were investigated. The improved BCR sequential extraction procedure was applied to analyze the chemical forms of trace elements in sediments. The enrichment factor (EF), sediment quality guidelines (SQGs), potential ecological risk index (PERI), and risk assessment code (RAC) were employed to evaluate the pollution levels and the potential ecological risks. The results found that the concentrations of Cu, Pb, Zn, Cr, Ni, and Co in the surface sediments were 78.59, 36.91, 161.84, 98.87, 38.92, and 10.09mgkg-1, respectively. The lower concentrations of Cu, Pb, Zn, Cr, and Ni were almost found in the middle part of the lake, while Co increased from the western toward the eastern parts of the lake. Cr, Ni, Co, and Zn predominantly existed in the residual fractions, with the average values of 76.35, 59.22, 45.60, and 44.30%, respectively. Cu and Pb were mainly combined with Fe/Mn oxides in reducible fraction, with the average values of 66.4 and 69.1%, respectively. The pollution levels were different among the selected elements. Cu had the highest potential ecological risk, while Cr had the lowest potential ecological risk.

Risk assessment and chemical fractionation of selected elements in surface sediments from Lake Qarun, Egypt using modified BCR technique

In this study, spatial distribution and chemical fractionation were conducted to appraise the overall classification of Al, B, Cd, Cr, and Pb as well as their ecological risks in Lake Qarun sediments. Also, the other chemical components (CaCO3, TOC, SO42−, SiO32−, PO43−, F, Ca, and Mg) that represented the chemical composition of the sediments were determined. Modified BCR sequential extraction technique was used to evaluate the four (acid soluble, reducible, oxidizable and residual) fractions of the surface sediments. The association of Cd was found the highest with acid-soluble fraction (12.16–77.42%), while, Al (89.92–96.83%), B (42.32–93.93%), Cr (86.35–97.42%) and Pb (31.98–86.26%) were reside in residual phase. The degree of surface sediment contamination was computed by risk assessment code (RAC), individual contamination factor (ICF) and Global contamination factor (GCF). Risk assessment code classification showed that the relative amounts of easily dissolved phase of the investigated elements in the sediments are in the order of: Cd > Pb > B > Cr > Al. As a result, Cd had the highest risk to Lake Qarun. This study is a first approach of chemical fractionation of Al, B, Cd, Cr, and Pb in one of the most ecologically important Protectorates declared in the framework of Law 102 of year 1983. Information of this study constitutes a baseline of elements fractionation in Lake Qarun sediments and should be used as a reference for future studies on the changes of labile and residual elements fractions over time.

Fractionation of Pb and Cu in the fine fraction (

The fractionation of metals in the fine fraction (<10 mm) of excavated waste from an Estonian landfill was carried out to evaluate the metal (Pb and Cu) contents and their potential towards not only mobility but also possibilities of recovery/extraction. The fractionation followed the BCR (Community Bureau of Reference) sequential extraction, and the exchangeable (F1), reducible (F2), oxidizable (F3) and residual fractions were determined. The results showed that Pb was highly associated with the reducible (F2) and oxidizable (F3) fractions, suggesting the potential mobility of this metal mainly when in contact with oxygen, despite the low association with the exchangeable fraction (F1). Cu has also shown the potential for mobility when in contact with oxygen, since high associations with the oxidizable fraction (F3) were observed. On the other hand, the mobility of metals in excavated waste can be seen as beneficial considering the circular economy and recovery of such valuables back into the economy. To conclude, not only the total concentration of metals but also a better understanding of fractionation and in which form metals are bound is very important to bring information on how to manage the fine fraction from excavated waste both in terms of environmental impacts and also recovery of such valuables in the economy.

Fractionation of potentially toxic elements (PTE) in soils irrigated with wastewater using modified BCR sequential extraction procedure

Fractionation of potentially toxic elements (PTE) in soils irrigated with wastewater using modified BCR sequential extraction procedure

Chemical speciation, vertical profile and human health risk assessment of heavy metals in soils from coal-mine brownfield, Beijing, China

The characterization of the concentration and chemical speciation of heavy metals in surface and vertical profile soils is a necessary for pollution monitoring and the potential risk assessment of the heavy metals (HMs) to animal and human health. Surface soil samples (n=14) and vertical profile soil samples (n=36) from selected sites (n=6) were collected from coal-mine brownfield in the Qingshui River Basin, in which the concentrations and chemical speciation of HMs (Cd, Cr, Cu, Mn, Ni, Pb, Zn) in surface soils and HM concentrations in vertical profile soils were determined by ICP-OES and analyzed using methods of geo-accumulation index (Igeo), Tucker 3 model and health risk assessment. The chemical fractions of HMs were extracted by BCR-sequential extraction procedure. Results show that HMs in surface soils accumulate in descending order of Cd>Pb>Cu>Ni>Mn>Zn>Cr. All HMs are associated with residue fraction to different degrees. Manganese and Ni are closely related to extractable BCR fractions and turn to be the severer pollutants in some sites. The Igeo values of HMs in vertical profile soils indicate ‘uncontaminated’. Whereas coal mining activities with long history increase HM concentrations in subsurface soils at the coal mine former site. The non-carcinogenic risk posed by HM extractable fractions to children and adults fall below the safe level of 1. Lead extractable fraction exhibits the highest risk value in the case of children. The levels of carcinogenic risk posed by Cr and Ni extractable fractions are above that of the United States Environmental Protection Agency (USEPA) acceptable level (1×10−6). Nickel extractable fraction exhibits the highest carcinogenic risk values for children with exceeding that of the maximum USEPA acceptable level (1×10−4).

Fractionation of Heavy Metals in Fly Ash from Wood Biomass Using the BCR Sequential Extraction Procedure.

The aim of this study was to extract the wood biomass fly ash fractions by a three-stage sequential extraction method for acetic acid and ion exchangeable (BCR 1), hydroxylamine hydrochloride reduction (BCR 2), and hydrogen peroxide oxidation (BCR 3) fractions in order to access the leaching behavior of this residue. The fly ash was collected as a by-product from the processing of mixed wood biomass in Udbina combustion facility, Croatia. Concentrations of several elements (As, Cd, Cr, Cu, Ni, Pb and Zn) in all extracts were determined by inductively coupled plasma atomic emission spectrometry. The acidic exchangeable form of the metals was used to evaluate the potential ecological risk of biomass fly ash. According to calculated potential ecological risk index, it is confirmed that mobility of Ni and As has major environmental impact. However the results of potential ecological risk show that biomass fly ash had a low risk.

Effect heating dwell time has on the retention of heavy metals in the structure of lightweight aggregates manufactured from wastes

ABSTRACTThe main objective of this paper was to study how effective thermal treatment is in the retention of different heavy metals (HMs) within the structure of artificial lightweight aggregates (LWAs). These LWAs were manufactured by washing aggregate sludge and sewage sludge. The consequence of increasing the heating dwell time whilst manufacturing these LWAs was also determined. Partitioning of the HMs (Cr, Ni, Cu, Zn, Cd and Pb) was studied by means of the optimized BCR sequential extraction procedure. Then, the leaching ratio (LRx,y) was calculated. Thermal treatment was totally effective for immobilizing most of the elements studied except for a part of the non-residual Zn and Cd fraction which could volatilize, and the fractions of Pb which were water- and acid-soluble, weakly adsorbed, exchangeable, and oxidable. These were more highly concentrated in the LWAs than in the initial waste mixture. The effect of increasing heating dwell time on the retention of heavy metals in the LWAs depended on both the chemical element studied and the heating dwell time. This study is very important since certain rises in the heating dwell time caused a decrease in retention of some specific heavy metals in the LWAs.Abbreviations: BCR-SEP: optimized BCR sequential extraction procedure; b.d.l: below the detection limit; F1: weakly adsorbed, exchangeable and water- and acid- soluble fraction; F2: reducible fraction; F3: oxidable fraction; F4: residual fraction; HM: heavy metal; ICP-MS: inductively coupled plasma-mass spectroscopy; LOI: loss on ignition; LWA: lightweight aggregate; LWA-5: lightweight aggregate sintered for 5 min; LWA-10: lightweight aggregate sintered for 10 min; LWA-20: lightweight aggregate sintered for 20 min; LWA-30: lightweight aggregate sintered for 30 min; LRx,y: leaching ratio of the element x in the fraction y; n.e: not established; S: compressive strength; SS: sewage sludge; WA24h: water absorption after 24 hours; WAS: washing aggregate sludge; W75S25: mixture of 75% (wt) of the dried washing aggregate sludge and 25% (wt) of the dried sewage sludge; ρb: loose bulk density; ρd: dry particle density; ∑1 + 2 + 3: non-residual fraction; ∑1 + 2 + 3 + 4: total concentration; ∑2 + 3: reducible and oxidable fractions.

Inhibitory effects of rice residues amendment on Cd phytoavailability: A matter of Cd-organic matter interactions?

Incorporating crop residues into soils, a most common way of organic input into farmland soils, is being encouraged in many parts of the world, while its potential impacts on Cd phytoavailability are not well understood. Here, a Cd-contaminated soil was amended with rice residues (RR, i.e., straw + root mixture) or not (Control) and incubated for 81 days under laboratory-controlled conditions. During the incubation, key soil parameters (e.g., dissolved organic carbon and pH), Cd geochemical fractionation (by BCR sequential extraction), and CaCl2 extracted Cd in soils (by 0.01 M CaCl2 extraction) were quantified to explain the effects of RR amendment on Cd phytoavailability (assessed by 7 day-cultivation of rice seedling in soils). Besides, hydroponic experiments were designed to explore the effects of D-RR-OM (dissolved-RR-organic matter) on the uptake of Cd by rice seedlings (quantified by uptake constant rate, ku, using stable isotope tracing technique). Our results demonstrated that RR amendment reduced Cd phytoavailability by 17–92% compared with Control during incubation, which might be explained by the interactions between Cd and RR-OM (RR-organic matter) in soil or porewater: (1) Cd immobilization due to its association with solid-RR-OM in soils, (2) Cd mobilization by D-RR-OM, and (3) Cd complexation with D-RR-OM in porewater, and thus reduced ku of Cd. Our results suggested that dynamics of RR-OM (e.g., dissolution, decomposition and transformation) in soils, and thus interactions between Cd and solid/dissolved-RR-OM may control Cd phytoavailability under RR amendment. Information gained in this study would further our understanding about Cd phytoavailability in farming soils.