Chemical speciation and bioavailability of potentially toxic elements in surface sediment from the Huaihe River, Anhui Province, China

Chemical Speciation, Leaching Behavior, and Environmental Risk Assessment of Trace Elements in the Bottom Ash from Biomass Power Plant

“…According to the research of Tessier et al the chemical speciation of trace elements can be divided into five forms: exchangeable fraction, carbonate fraction, Fe/Mn oxide fraction, organic matter fraction, and residual fraction. Different forms exhibit different biological toxicity and environmental behaviors . Exchangeable and carbonate bound states have weaker binding with soil, making them more susceptible to being released and migrated.…”

“…Different forms exhibit different biological toxicity and environmental behaviors. 31 Exchangeable and carbonate bound states have weaker binding with soil, making them more susceptible to being released and migrated. Trace elements bound to iron and manganese oxides are more easily released under reducing conditions, while organic bound states are more prone to decomposition and gradual release in oxidizing environments.…”

Speciation Characteristics and Contamination Degree of Trace Elements in Coal Gangue Hill of a Mining Area in Huainan Coalfield, China

“…In the present study, the Huainan soil background values of heavy metals were adopted as the B i value, and the background value for Cd, Cr, Cu, Mn, Ni, Pb, V and Zn are 0.06, 64.93, 24.16, 416, 25.74, 30.47, 96.03 and 80.81 mg/kg, respectively [28]. Seven grades of I geo were defined for the classification [16]: uncontaminated (I geo ≤0); uncontaminated to moderately contaminated (0<I geo ≤1); moderately contaminated (1<I geo ≤2); moderately contaminated to heavily contaminated (2<I geo ≤3); heavily contaminated (3<I geo ≤4); heavily to extremely contaminated (4<I geo ≤5); extremely contaminated (I geo >5).…”

“…By contrast, the residue state (F5) is a stable state, which can exist stably for a long time without any bioavailability. As such, it is considered as a non-hazardous substance to the environment [16]. The average percentage of trace elements in different forms of coal gangue in the study area was shown in Fig.…”

“…The total amount of trace elements in coal gangue may not provide enough information for evaluating its environmental effects [12]. Therefore, it is of great significance to conduct the chemical speciation of the trace elements and evaluate its mobility and bioavailability [16]. The occurrence state of trace elements determines their migration and transformation pathways in the environment and in the process of utilization [12], affecting the ease of release into the environment [17].…”