The ability of water hyacinth (WH) and pondweed (PW) to accumulate mercury from water in gold mine tailing area was studied. Experiments were carried out in the field conditions without using a model system. An approach for mercury fractionation according to its association with various types of biomolecules (water soluble compounds, oxygen-containing ligands such as polycarboxylic acids and cell wall components) was suggested. It is based on sequential extraction of mercury to recover different compounds according to the binding strength. In all cases for WH and PW, the most portion of mercury is bound to the cell wall (63–67 and 54–64 %, for WH and PW, respectively) that works as a physiological barriers and protects the plants from negative impact of mercury ions. An approach based on the ability of plants to extract elements from tailings drainage waters that are characterized by milder conditions in comparison with strongly acidic waste material was suggested. The highest BCF values (66,500 and 32,700 for WH and PW, respectively) were obtained for plants grown in natural stream. At low levels of mercury in water (C Hgwₐₜₑᵣ = 0.01–0.05 ppb) typical for tailing solutions, translocation of the element from roots to shoots decreases as concentration of mercury in WH increases. PW is preferable to use in practice for tailings remediation from mercury contamination since it does not require cultivation in a greenhouse and shows BCF values comparable with WH.

The contamination of soil with heavy metals is a serious agricultural issue. The presence of foods contaminated with heavy metals in the human diet can cause health damages. Metal phytoextraction processes remove soil contaminants through plant absorption; however, plants display different responses to the metal contamination of the soil. Thus, the purposes of this paper were to determine cadmium (Cd), chromium (Cr), and lead (Pb) immobilization in soil mixed with different amounts of stabilized vermicompost (obtained by earthworm composting) and verify if this vermicompost helps in the removal of heavy metal through the phytoextraction technique with black oat (Avena strigosa Schreb cv IAPAR 61) plants. The addition of a high quantity of vermicompost (50, 75, and 100%) to the soil presents similar results to the immobilization of Cd, Cr, and Pb, and a similar trend was observed in lower quantities (0 and 25%) of vermicompost. The addition of vermicompost improves the growth of black oat plants, but only the treatment with 25% of vermicompost showed promising results in the absorption of Cr and Pb, and the treatment with 50% in the absorption of Cd. Finally, we suggest that “IAPAR 61” black oat cultivar is efficient Cd, Cr, and Pb accumulators. However, heavy metal remained mostly in the root, indicating that root-to-shoot translocation was not efficient, hindering its application for phytoremediation strategies.

Chitosan-montmorillonite composite was extensively used for the removal of heavy metals from wastewater. In wastewater, copper (Cu²⁺) usually coexist with the organic ligands, which had unknown effect on Cu²⁺ adsorption by the composite materials. In order to understand further on that, the adsorption of copper by the composite materials must be studied. In the present study, montmorillonite was coated with chitosan, and X-ray diffraction (XRD) patterns of the composite proved the intercalation of chitosan in the montmorillonite. Fourier transform infrared (FTIR) spectra of the composite identified the presence of amino group on the composite, and that of the composite saturated with metals identified the interaction between the amino groups and metals. Langmuir adsorption isotherm indicated that the composite had more capacity to adsorb Cu²⁺ from wastewater than montmorillonite. The adsorption capacity of Cu²⁺ by montmorillonite and chitosan-montmorillonite composite was studied, respectively, as a function of pH and in the presence of acetate. Compared to the montmorillonite at low ligand concentration (0.08 mmol/L) or low pH (<4.0), the coexisting acetate increased more Cu²⁺ adsorption by the composite. The acetate ligand presented less depression on the adsorption by the composite than that by montmorillonite at high ligand concentration (4 mmol/L) or high pH (>4.5). Therefore, the composite is more suitable for removing Cu²⁺ than montmorillonite in acid aqueous medium.

Nanoscale zero-valent iron (NZVI) particles can be used for in situ groundwater remediation. The spatial particle distribution plays a very important role in successful and efficient remediation, especially in heterogeneous systems. Initial sand permeability (k ₀) influences on spatial particle distributions were investigated and quantified in homogeneous and heterogeneous systems within the presented study. Four homogeneously filled column experiments and a heterogeneously filled tank experiment, using different median sand grain diameters (d ₅₀), were performed to determine if NZVI particles were transported into finer sand where contaminants could be trapped. More NZVI particle retention, less particle transport, and faster decrease in k were observed in the column studies using finer sands than in those using coarser sands, reflecting a function of k ₀. In heterogeneous media, NZVI particles were initially transported and deposited in coarse sand areas. Increasing the retained NZVI mass (decreasing k in particle deposition areas) caused NZVI particles to also be transported into finer sand areas, forming an area with a relatively homogeneous particle distribution and converged k values despite the different grain sizes present. The deposited-particle surface area contribution to the increasing of the matrix surface area (θ) was one to two orders of magnitude higher for finer than coarser sand. The dependency of θ on d ₅₀ presumably affects simulated k changes and NZVI distributions in numerical simulations of NZVI injections into heterogeneous aquifers. The results implied that NZVI can in principle also penetrate finer layers.

This paper proposes multilayer perceptron neural network (MLPNN) to predict phycocyanin (PC) pigment using water quality variables as predictor. In the proposed model, four water quality variables that are water temperature, dissolved oxygen, pH, and specific conductance were selected as the inputs for the MLPNN model, and the PC as the output. To demonstrate the capability and the usefulness of the MLPNN model, a total of 15,849 data measured at 15-min (15 min) intervals of time are used for the development of the model. The data are collected at the lower Charles River buoy, and available from the US Environmental Protection Agency (USEPA). For comparison purposes, a multiple linear regression (MLR) model that was frequently used for predicting water quality variables in previous studies is also built. The performances of the models are evaluated using a set of widely used statistical indices. The performance of the MLPNN and MLR models is compared with the measured data. The obtained results show that (i) the all proposed MLPNN models are more accurate than the MLR models and (ii) the results obtained are very promising and encouraging for the development of phycocyanin-predictive models.

The study was aimed to evaluate the selected improvements of nature restoration in a depleted gravel pit. The study site consisted of four water reservoirs of different shapes and sizes, flooded after the gravel extraction ended. Ecological succession monitoring, conducted by the Warsaw University of Life Sciences students associated in the Student Scientific Association of Animal Sciences Faculty since the completion of mining, have focused on amphibians. A twofold approach upheld amphibian species population dynamics, as well as selected habitat elements. The restoration practices dedicated to habitat conditions enhancing have been proved to be definitely effective and useful for similar sites.

Laboratory batch and column experiments were performed to better understand the effects of Ca²⁺, Mg²⁺, and HCO₃ ⁻ on Cr(VI) removal from aqueous systems with pyrite. Batch results show that increasing HCO₃ ⁻ concentration led to an increase in Cr(VI) removal by pyrite due to pH buffering capacity of HCO₃ ⁻. However, while Ca²⁺ and Mg²⁺ individually had no effect on Cr(VI) removal at pH 4, the addition of Ca²⁺ or Mg²⁺ to systems containing HCO₃ ⁻ resulted in a significant decrease in Cr(VI) removal at pH 8 relative to the systems containing HCO₃ ⁻ alone. The XPS data proved that while Ca²⁺ precipitated as CaCO₃₍S₎ onto pyrite surface, Mg²⁺ sorbed and/or accumulated as Mg(OH)₂₍S₎ onto oxidized pyrite surface. The formation of surface precipitates (e.g., CaCO₃) inhibited further Cr(VI) reduction by blocking electron transfer between Cr(VI) and pyritic surface sites. While the precipitation of Ca²⁺ as CaCO₃ led to a significant decrease in effluent pH, the decrease in effluent pH was very low in systems containing Mg²⁺, most probably due to much higher solubility of Mg²⁺ at pH 8. Zeta potential measurements provided further evidence that while Ca²⁺ or Mg²⁺ had no effect on zeta potential of pyrite particles under acidic conditions (e.g., pH < 7), the addition of Ca²⁺ or Mg²⁺ to systems containing Cr(VI) reversed the pyrite surface potential from negative to positive under alkaline pH conditions (e.g., pH > 8) relative to system containing only Cr(VI), suggesting the sorption and/or accumulation of surface precipitates on pyrite surface.

This study aimed to investigate the characteristics of the event mean concentration (EMC) and first flush effect (FFE) during typical rainfall events in outfalls from different drainage systems and functional areas. Stormwater outfall quality data were collected from five outfalls throughout Fuzhou City (China) during 2011–2012. Samples were analyzed for water quality parameters, such as COD, NH₃-N, TP, and SS. Analysis of values indicated that the order of the event mean concentrations (EMCs) in outfalls was intercepting combined system > direct emission combined system > separated system. Most of the rainfall events showed the FFE in all outfalls. The order of strength of the FFE was residential area of direct emission combined system > commercial area of separated system > residential area of intercepting combined system > office area of separated system > residential area of separated system. Results will serve as guide in managing water quality to reduce pollution from drainage systems.

In this study, the effects of cypermethrin (CYP), amitraz (AMT) and combined cypermethrin-amitraz (CYP-AMT) on some serum biochemical, oxidative stress and drug-metabolising parameters were investigated in male Wistar albino rats. CYP, AMT and combined CYP-AMT were administered at doses of 80 mg kg⁻¹ bw⁻¹ of CYP and 170 mg kg⁻¹ bw⁻¹ of AMT for 1 day (single dose), and at doses of 12 mg kg⁻¹ bw⁻¹ of CYP and 25 mg kg⁻¹ bw⁻¹ of AMT for 40 days by oral gavage. Oxidative stress (malondialdehyde (MDA), nitric oxide (NO), superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) and glucose-6-phosphate dehydrogenase (G6PD)), serum biochemical (glucose, triglyceride, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), blood urea nitrogen (BUN), creatinine, asparatate amino transferase (AST), alanine amino transferase (ALT), alkaline phosphatase (ALP), total protein, albumin) in blood/tissues (liver, kidney, brain, spleen and testis) and hepatic drug-metabolising (cytochrome P450 2E1 (CYP2E1), NADH-cytochrome b₅ reductase (CYPb5), NADPH-cytochrome c reductase/NADPH cytocrome P450 reductase (CYTC), glutathione S-transferase (GST), glutathione (GSH)) parameters were measured in liver samples taken on days 1 and 40. In result, it was determined that CYP, AMT and their combinations led to significant changes in the parameters investigated, and it was ascertained that long-term exposure to insecticides and the administration of insecticide combinations produced greater toxic effects in comparison with the administration of insecticides alone.

Combined coagulation and electrochemical treatment processes were used to mineralize the organic load and detoxify a real textile effluent. The coagulation step was investigated for distinct pH values (4 to 11) and Al₂(SO₄)₃ concentrations (0.25 to 9.00 g L⁻¹). Complete turbidity and partial total organic carbon (TOC) removals were attained at pH 5, using 0.50 g L⁻¹Al₂(SO₄)₃. Moreover, the coagulation process totally removed the initial toxicity (100 % mortality) of the effluent, assessed by toxicity tests with the crustacean Artemia salina. The remaining TOC was mineralized by the electrochemical step in a flow cell with a boron-doped diamond (BDD) anode, when the investigated parameters were the BDD boron-doping level (100, 500, 2500 ppm), pH (3, 7, 11, no control), and current density (10, 20, 30 mA cm⁻²). No significant differences in TOC removal were observed when the BDD anode or pH value was changed; however, as the system was under mass transport limitation, mineralization attained at low current densities led to a reasonable current efficiency (∼40 %) and low energy consumption (∼16 kW h m⁻³). The use of the electrochemical method solely led to poor TOC and turbidity removals, thus not being recommended.