Risk of acute toxicity for fish during aluminium application to hardwater lakes

Isolation and Optimization of Culture Conditions of a Bioflocculant-Producing Fungi from Kombucha Tea SCOBY

Biolocculants are gaining attention in research due to their environmental friendliness and innocuousness to human in comparison to the conventional flocculants. The present study aimed to investigate the ability of fungi from Kombucha tea SCOBY to produce effective bioflocculant in bulk. A 16S rRNA gene sequence analysis was utilized to identify the isolate. The medium composition (carbon and nitrogen sources) and culture conditions (inoculum size, temperature, shaking speed, pH, and time) were optimized using one-factor-at-a-time method. The functional groups, morphology, and crystallinity of the bioflocculant were evaluated using Fourier transform infrared (FT-IR), scan electron microscope (SEM) and X-ray diffractometry (XRD). The fungus was found to be Pichia kudriavzevii MH545928.1. It produced a bioflocculant with flocculating activity of 99.1% under optimum conditions; 1% (v/v) inoculum size, glucose and peptone as nutrient sources, 35 °C, pH 7 and the shaking speed of 140 rpm for 60 h. A cumulus-like structure was revealed by SEM; FT-IR displayed the presence of hydroxyl, carboxyl, amine, and thiocynates. The XRD analysis demonstrated the bioflocculant to have big particles with diffraction peaks at 10° and 40° indicating its crystallinity. Based on the obtained results, P. kudriavzevii MH545928.1 has potential industrial applicability as a bioflocculant producer.

Banded tetra (Astyanax aeneus) as bioindicator of trace metals in aquatic ecosystems of the Yucatan Peninsula, Mexico: Experimental biomarkers validation and wild populations biomonitoring

Bioindicator organisms are important tools in environmental monitoring studies. Understanding this, the overall goal of the present study was to evaluate the sensitivity and viability of the native fish species Banded tetra, (Astyanax aeneus; Günther, 1860), widely spread in the aquatic ecosystems of the Yucatan Peninsula in Mexico, as a bioindicator organism. In order to do this, we performed a bioassay at sublethal concentrations using copper (CuSO₄) to experimentally evaluate and validate the relationship between the trace metals and oxidative stress biomarkers response [(catalase (CAT), lipoperoxidation content (LPO)], detoxification [(glutathione S-transferase (GST), metallothionein content (MT)] and neurotoxicity (AChE) in muscle of A. aeneus. Results showed changes in biomarkers after 96 h: Catalase activity (CAT) was significantly higher above 1.5 and 2 mg/L (154.35 and 172.50% increase, respectively); lipid peroxidation contents (TBARS), GST activity, and MT content were very similar to CAT activity at 1.5 and 2 mg/L of Cu. In terms of neurotoxicity, AChE activity was significantly inhibited at 0.1 mg/L (64%; p < 0.001) and 0.5 mg/L (44%; p < 0.001) of Cu. Based on the bioassay results, we performed a trace metal monitoring campaign in muscle of A. aeneus caught in 15 sites with different anthropogenic activities, during the summer of 2017, to establish a baseline of trace metals pollution in the state of Campeche. A. aeneus showed the highest trace metal accumulation in the following order: Al > Fe > Mn > Zn > Cu > Hg > Cr > Pb > Cd > V > As, while sites were arrange as follows: Xnoha lagoon > Palizada River > Candelaria River > Ululmal > Maravillas > López Mateos. PCA showed a cluster between biomarkers (GST, CAT, TBARS, and MT) and concentration of metals (Cd, Cu, Fe, Zn, Hg and Cr). Conversely, AChE inhibition was not related to a specific metal, but highest inhibitions (>50%) were present in those sites with intensive agricultural practices. These results determined that, based on its physiological response and trace metal bioaccumulation, Astyanax aeneus can be considered a good bioindicator for evaluating the presence of trace metals in tropical aquatic systems of the Yucatan Peninsula.

Human health risk associated with the management of phosphorus in freshwaters using lanthanum and aluminium

The use of geo-engineering materials to manage phosphorus in lakes has increased in recent years with aluminium and lanthanum based materials being most commonly applied. Hence the potential impact of the use of these compounds on human health is receiving growing interest. This review seeks to understand, evaluate and compare potential unintended consequences on human health and ecotoxicological risks associated with the use of lanthanum- and aluminium-based materials to modify chemical and ecological conditions in water bodies. In addition to their therapeutic use for the reduction of intestinal phosphate absorption in patients with impaired renal function, the phosphate binding capacity of aluminium and lanthanum also led to the development of materials used for water treatment. Although lanthanum and aluminium share physicochemical similarities and have many common applications, their uptake and kinetics within the human body and living organisms importantly differ from each other which is reflected in a different toxicity profile. Whilst a causal role in the development of neurological pathologies, skeletal lesions, hematopoietic disorders and respiratory effects has unequivocally been demonstrated with increased exposure to aluminium, studies until now have failed to find such a clear association after exposure to lanthanum although caution is warranted. Our review indicates that lanthanum and aluminium have a distinctly different profile with respect to their potential effects on human health. Regular monitoring of both aluminium and lanthanum concentrations in lanthanum-/aluminium-treated water by the responsible authorities is recommended to avoid acute accidental or chronic low level accumulation.

Microbial Flocculants as an Alternative to Synthetic Polymers for Wastewater Treatment: A Review

Microorganisms such as bacteria, fungi, and microalgae have been used to produce bioflocculants with various structures. These polymers are active substances that are biodegradable, environmentally harmless, and have flocculation characteristics. Most of the developed microbial bioflocculants displayed significant flocculating activity (FA > 70–90%) depending on the strain used and on the operating parameters. These biopolymers have been investigated and successfully used for wastewater depollution in the laboratory. In various cases, selected efficient microbial flocculants could reduce significantly suspended solids (SS), turbidity, chemical oxygen demand (COD), total nitrogen (Nt), dye, and heavy metals, with removal percentages exceeding 90% depending on the bioflocculating materials and on the wastewater characteristics. Moreover, bioflocculants showed acceptable results for sludge conditioning (accepted levels of dry solids, specific resistance to filtration, moisture, etc.) compared to chemicals. This paper explores various bioflocculants produced by numerous microbial strains. Their production procedures and flocculating performance will be included. Furthermore, their efficiency in the depollution of wastewater will be discussed.

Toxic and heavy metals as a cause of crayfish mass mortality from acidified headwater streams

Mining activities are responsible for high concentrations of metals in river networks in many parts of the world. Mining activities and the resulting high loads of heavy metals interact with intensive acid rain, and often have great consequences for biodiversity. However, considering the frequently episodic nature of these heavy acid rains, there is little detailed evidence of direct impacts. In 2011 we observed a massive mortality of noble crayfish and stone crayfish in Padrťsko Special Area of Conservation (SAC) in the Brdy Mountain region of the Czech Republic. Based on concentrations of metals (Al, Fe, As, Cd, Pb, Cu, Zn and Hg) in various tissues (gills, hepatopancreas, muscle) of both dead and live crayfish in this locality compared to reference populations, these crayfish had experienced long-term exposure to increased levels of these metals. Here we give detailed documentation of crayfish mortality associated with high metal concentrations in the gills and other tissues of these endangered invertebrates.

Aluminium sulfate exposure: A set of effects on hydrolases from brain, muscle and digestive tract of juvenile Nile tilapia (Oreochromis niloticus)

Aluminium is a major pollutant due to its constant disposal in aquatic environments through anthropogenic activities. The physiological effects of this metal in fish are still scarce in the literature. This study investigated the in vivo and in vitro effects of aluminium sulfate on the activity of enzymes from Nile tilapia (Oreochromis niloticus): brain acetylcholinesterase (AChE), muscle cholinesterases (AChE-like and BChE-like activities), pepsin, trypsin, chymotrypsin and amylase. Fish were in vivo exposed during 14days when the following experimental groups were assayed: control group (CG), exposure to Al₂(SO₄)₃ at 1μg·mL^-1 (G1) and 3μg·mL^-1 (G3) (concentrations compatible with the use of aluminium sulfate as coagulant in water treatment). In vitro exposure was performed using animals of CG treatment. Both in vivo and in vitro exposure increased cholinesterase activity in relation to controls. The highest cholinesterase activity was observed for muscle BChE-like enzyme in G3. In contrast, the digestive enzymes showed decreased activity in both in vivo and in vitro exposures. The highest inhibitory effect was observed for pepsin activity. The inhibition of serine proteases was also quantitatively analyzed in zymograms using pixel optical densitometry as area under the peaks (AUP) and integrated density (ID). These results suggest that the inhibition of digestive enzymes in combination with activation of cholinesterases in O. niloticus is a set of biochemical effects that evidence the presence of aluminium in the aquatic environment. Moreover, these enzymatic alterations may support further studies on physiological changes in this species with implications for its neurological and digestive metabolisms.

Algal bloom sedimentation induces variable control of lake eutrophication by phosphorus inactivating agents

Lake eutrophication typically occurs with a syndrome of algae breeding and biomass accumulation (e.g., algal blooms). Therefore, the effect of algal bloom sedimentation on eutrophication control by phosphorus (P) inactivating agents was assessed herein. Three commercial products, including aluminum (Al) sulfate, iron (Fe) sulfate, and a lanthanum-modified clay (Phoslock®), as well as one easily available by-product, drinking water treatment residue (DWTR), were selected. The most important finding was that during algae sedimentation, P immobilization from the overlying water by Al, Phoslock®, and DWTR was dominated by a long-term slow phase (>150d), while Fe has limited effectiveness on the immobilization. Further analysis indicated that the algae sedimentation effect was mainly due to the slow release of P from algae, leading to relatively limited P available for the inactivating agents. Then, a more unfavorable effect on the P immobilization capability of inactivating agents was caused by the induced anaerobic conditions, the released organic matter from algae, and the increased sulfide in the overlying water and sediments during sedimentation. Overall, algae sedimentation induced variable control of eutrophication by P inactivating agents. Accordingly, recommendations for future works about algal lake restoration were also proposed.

Density functional theory studies on the structures and water-exchange reactions of aqueous Al(III)-oxalate complexes

The structures and water-exchange reactions of aqueous aluminum-oxalate complexes are investigated using density functional theory. The present work includes (1) The structures of Al(C(2)O(4))(H(2)O)(4)(+) and Al(C(2)O(4))(2)(H(2)O)(2)(-) were optimized at the level of B3LYP/6-311+G(d,p). The geometries obtained suggest that the Al-OH(2) bond lengths trans to C(2)O(4)(2-) ligand in Al(C(2)O(4))(H(2)O)(4)(+) are much longer than the Al-OH(2) bond lengths cis to C(2)O(4)(2-). For Al(C(2)O(4))(2)(H(2)O)(2)(-), the close energies between cis and trans isomers imply the coexistence in aqueous solution. The (27)Al NMR and (13)C NMR chemical shifts computed with the consideration of sufficient solvent effect using HF GIAO method and 6-311+G(d,p) basis set are in agreement with the experimental values available, indicating the appropriateness of the applied models; (2) The water-exchange reactions of Al(III)-oxalate complexes were simulated at the same computational level. The results show that water exchange proceeds via dissociative pathway and the activation energy barriers are sensitive to the solvent effect. The energy barriers obtained indicate that the coordinated H(2)O cis to C(2)O(4)(2-) in Al(C(2)O(4))(H(2)O)(4)(+) is more labile than trans H(2)O. The water-exchange rate constants (k(ex)) of trans- and cis-Al(C(2)O(4))(2)(H(2)O)(2)(-) were estimated by four methods and their respective characteristics were explored; (3) The significance of the study on the aqueous aluminum-oxalate complexes to environmental chemistry is discussed. The influences of ubiquitous organic ligands in environment on aluminum chemistry behavior can be elucidated by extending this study to a series of Al(III)-organic system.

Toxicity of raw and neutralized bauxite refinery residue liquors to the freshwater cladoceran Ceriodaphnia dubia and the marine amphipod Paracalliope australis

The extraction of alumina from bauxite produces a highly toxic residue, termed bauxite refinery residue (BRR) or red mud. The toxicity of this material is due to chemical and biological effects of high pH, alkalinity, electrical conductivity (EC), and Na(+) and Al(3+) concentrations. Several neutralization techniques may allow BRR to be used for environmental remediation. The present study investigated standardized 48-h acute toxicity tests with a freshwater cladoceran, Ceriodaphnia dubia, and a marine amphipod, Paracalliope australis, against raw supernatant BRR liquor (RL) versus liquors neutralized with acid (ANL), CO(2) (CNL), seawater (SNL), and a hybrid method (HNL). Based on 48-h LC50 values, the toxicity of the liquors to C. dubia increased in the following order; HNL ≤ SNL< ANL ≤ CNL < RL, with comparable responses from P. australis. The high toxicity of RL likely is due to high pH (≈ 12), alkalinity, and Al concentration. Toxicity of CNL likely is due to high EC and alkalinity. Sulfate and Na(+) concentrations are considered sources of toxicity in ANL. Seawater-neutralized liquor and HNL were considerably less toxic to both test species. These data provide evidence of the acute lethal toxicity of raw supernatant liquor from BRR and four neutralized supernatant liquors to the freshwater cladoceran C. dubia and the marine amphipod P. australis, providing valuable baselines for further ecotoxicological investigations of BRR materials in aquatic environments.