Macroalgae mitigation potential for fish aquaculture effluents: an approach coupling nitrogen uptake and metabolic pathways using Ulva rigida and Enteromorpha clathrata

Aquaculture effluents are rich in nitrogen compounds that may enhance local primary productivity, leading to the development of algae blooms. The goal of this study was to assess the potential use of naturally occurring green macroalgae (Ulva and Enteromorpha) as bioremediators for nitrogen-rich effluents from a fish aquaculture plant, by evaluating their respective uptake dynamics under controlled conditions. Ulva and Enteromorpha were incubated separately in aquaculture effluent from a local pilot station. Algae tissue and water samples were collected periodically along 4 h. For each sample, nitrate, nitrite, and ammonia concentrations were quantified in the effluent, while internal algae reserve pools and nitrate reductase activity (NRA) were determined within the algae tissues. Both macroalgae absorbed all dissolved inorganic nitrogen compounds in less than 1 h, favoring ammonia over nitrate. Ulva stored nitrate temporarily as an internal reserve and only used it after ammonia availability decreased, whereas Enteromorpha stored and metabolized ammonia and nitrate simultaneously. These distinct dynamics of ammonia and nitrate uptake supported an increase in NRA during the experiment. This study supports the hypothesis that Ulva or Enteromorpha can be used as bioremediators in aquaculture effluents to mitigate excess of dissolved inorganic nitrogen.     

The possible role of the seaweed Ulva fasciata on ameliorating hyperthyroidism-associated heart inflammations in a rat model

Environmental Science and Pollution Research - Cardiovascular diseases are key complications primarily associated with hyperthyroidism disorders. The present study sought to ameliorate...     

The effects of the nitrofuran furaltadone on Ulva lactuca

The use of pharmaceuticals in the food production industry as prophylatic and therapeutic agents is necessary to promote animal health, but may entail significant consequences to natural ecosystems, especially in the cases of overdosing and use of banned pharmaceuticals. The vast effects that antibiotics released into the environment have on non-target organisms are already under the scope of researchers but little attention has been given to primary producers such as macroalgae. The present study assessed furaltadone’s, an antibacterial agent illegally used for veterinary purposes, uptake capacity by Ulva lactuca and its effect in the growth of this cosmopolitan macroalgae. Differences in macroalgal growth were shown when submitted to prophylactic and therapeutic concentrations of furaltadone in the water (16 and 32 μg mL⁻¹, respectively). The therapeutic concentration caused higher growth impairment than the prophylactic treatment did, with 87.5% and 58% reductions respectively. Furthermore, together with data collected from the accumulation assays, with values of internal concentrations as high as 18.84 μg g⁻¹ WW, suggest that the macroalgae U. lactuca should be included in field surveys as a biomonitor for the detection of nitrofurans.     

Ecotoxicity of nanoparticles of CuO and ZnO in natural water

The acute toxicity of CuO and ZnO nanoparticles in artificial freshwater (AFW) and in natural waters to crustaceans Daphnia magna and Thamnocephalus platyurus and protozoan Tetrahymena thermophila was compared. The L(E)C₅₀ values of nanoCuO for both crustaceans in natural water ranged from 90 to 224 mg Cu/l and were about 10-fold lower than L(E)C₅₀ values of bulk CuO. In all test media, the L(E)C₅₀ values for both bulk and nanoZnO (1.1-16 mg Zn/l) were considerably lower than those of nanoCuO. The natural waters remarkably (up to 140-fold) decreased the toxicity of nanoCuO (but not that of nanoZnO) to crustaceans depending mainly on the concentration of dissolved organic carbon (DOC). The toxicity of both nanoCuO and nanoZnO was mostly due to the solubilised ions as determined by specific metal-sensing bacteria.     

Influence of synthetic surfactants on the uptake of Pd, Cd and Pb by the marine macroalga, Ulva lactuca

Uptake of Pd, Cd and Pb by the marine macroalga, Ulva lactuca, has been studied in the presence of an anionic (sodium dodecyl sulphate, SDS), cationic (hexadecyltrimethylammonium bromide; HDTMA) and non-ionic (Triton X-100; TX) surfactant. Compared with the surfactant-free system, metal sorption was reduced in the presence of SDS or TX. Neither surfactant, however, had any measurable impact on cell membrane permeability, determined by leakage of dissolved free amino acids (DFAA), or on metal internalisation. We attribute these observations to the stabilisation of aqueous Cd and Pb by SDS and the shielding of otherwise amenable sorption sites by TX. Presence of HDTMA resulted in a reduction in the extent of both sorption and internalisation of all metals and a significant increase in the leakage of DFAA. Thus, by enhancing membrane permeability, HDTMA exerts the greatest influence on metal behaviour in the presence of U. lactuca.     

Accumulation of Cu and Zn from antifouling paint particles by the marine macroalga,Ulva lactuca

The marine macroalga, Ulva lactuca, has been exposed to different concentrations of antifouling paint particles (4–200 mg L^?1) in the presence of a fixed quantity of clean estuarine sediment and its photosynthetic response and accumulation of Cu and Zn monitored over a period of 2 days. An immediate (<2 h) toxic effect was elicited under all experimental conditions that was quantitatively related to the concentration of contaminated particles present. Likewise, the rate of leaching of both Cu and Zn was correlated with the concentration of paint particles added. Copper accumulation by the alga increased linearly with aqueous Cu concentration, largely through adsorption to the cell surface, but significant accumulation of Zn was not observed. Thus, in coastal environments where boat maintenance is practiced, discarded antifouling paint particles are an important source of Cu, but not Zn, to U. lactuca.     

花生壳吸附Cu^2＋的动力学和热力学研究

采用平衡吸附法,研究了pH、时间及温度对花生壳吸附水溶液中Cu2 的影响.结果表明,pH显著影响花生壳对Cu2 的吸附,pH为3.00～5.00时,吸附效果最好;初始吸附过程非常快,30 min时即达到最大吸附量的97%左右,其动力学行为更好地符合Lagergren准二级反应动力学模型,随着温度增加,初始吸附速率和平衡吸附量增加.吸附过程的表观活化能(Ea)为17.02 kJ/mol,表明花生壳吸附水溶液中Cu2 是吸热的化学过程.吸附活化熵为负值,表明Cu2 从水溶液本体中溶解的自由状态到被吸附的状态是有序增加的过程.吸附活化焓呈正值,意味着升温有利于吸附.花生壳对Cu2 的吸附较好地符合Langmuir吸附等温线.吸附过程中吉布斯自由能变化呈负值,说明吸附过程为自发的过程.     

阿特拉津在水环境中的残留及其毒理效应研究进展

阿特拉津是中国及世界上广泛使用的一种除草剂,目前已存在于某些地区的湖泊和地下水中,并对生态环境和人类饮用水源造成潜在威胁.介绍了阿特拉津的应用概况,综述了阿特拉津在水环境中的残留状况及其对生物的生理生化毒性和遗传毒性研究进展.并在此基础上,提出应加强阿特拉津对生物的"三致"(致癌、致畸、致突变)作用、生殖毒性、蓄积毒性和毒性作用机制的研究,以及阿特拉津与其他污染物对生物的联合毒性作用和毒性作用机制的研究.     

Bioconcentration and uptake kinetics of chlorobenzenes in soy-bean roots

Excised soy-beanroots were exposed to an aqueous solution of five homologous chlorobenzenes in constant concentration. The results were in general agreement with water-lipid partitioning. The relationship between the bioconcentration factor and the octanol-water partition coëfficiënt (K_OW) can be used to estimate bioconcentration. Effective equilibrium was reached within 2.5 hours for 1,2-di-, 1,3,5-tri- and 1,2,3,4-hexachlorobenzene and after a mean of 10.1 and 17.9 hours for penta- and hexachlorobenzene respectively. For 1,2-dichlorobenzene, 1,3,5-trichlorobenzene and 1,2,3,4-tetrachlorobenzene the elimination rate constant was > 4.1, and 0.46 and 0.30 hr⁻¹ for penta- respectively hexachlorobenzene. In the range log K_ow 4.56–5.77, k₂ was negatively correlated with log K_OW but k₁ was not correlated with log K_OW..     

Study of sorption kinetics of some ionic liquids on different soil types

In the present contribution sorption kinetics experiments under static conditions were utilized in three selected ionic liquids cations (1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, 1-hexyl-3-methylimidazolium chlorides) study with five type of soil, differing in total organic carbon (TOC) content. The experimental results indicate the sorption capacity growth with increase in TOC content and hydrophobicity of ionic liquid cation. The obtained kinetic sorption parameters as well as distribution coefficients (K_d) were used to estimate the sorption properties of the soil types towards the ionic liquids in question. The Gibbs free energy values indicate that ionic liquid cations sorption on soils could be generally considered as a physical adsorption with exothermic effect. But the values of −dG for studied cations sorption on soil with very high of TOC content in soil (45%) may testify to nature of chemical adsorption. Sorption of the analyzed compounds occurs probably by means of hydrogen bonds, electrostatic and π  π interaction with the organic matter and the clay minerals of the soils.     

Effect of alginate on the aggregation kinetics of copper oxide nanoparticles (CuO NPs): bridging interaction and hetero-aggregation induced by Ca<Superscript>2+</Superscript>

The stability of CuO nanoparticles (NPs) is expected to play a key role in the environmental risk assessment of nanotoxicity in aquatic systems. In this study, the effect of alginate (model polysaccharides) on the stability of CuO NPs in various environmentally relevant ionic strength conditions was investigated by using time-resolved dynamic light scattering. Significant aggregation of CuO NPs was observed in the presence of both monovalent and divalent cations. The critical coagulation concentrations (CCC) were 54.5 and 2.9 mM for NaNO₃ and Ca(NO₃)₂, respectively. The presence of alginate slowed nano-CuO aggregation rates over the entire NaNO₃ concentration range due to the combined electrostatic and steric effect. High concentrations of Ca²⁺ (>6 mM) resulted in stronger adsorption of alginate onto CuO NPs; however, enhanced aggregation of CuO NPs occurred simultaneously under the same conditions. Spectroscopic analysis revealed that the bridging interaction of alginate with Ca²⁺ might be an important mechanism for the enhanced aggregation. Furthermore, significant coagulation of the alginate molecules was observed in solutions of high Ca²⁺ concentrations, indicating a hetero-aggregation mechanism between the alginate-covered CuO NPs and the unabsorbed alginate. These results suggested a different aggregation mechanism of NPs might co-exist in aqueous systems enriched with natural organic matter, which should be taken into consideration in future studies.

Open image in new window

Graphical abstract Hetero-aggregation mechanism of CuO nanoparticles and alginate under high concentration of Ca²⁺

     

Polymer coating of copper oxide nanoparticles increases nanoparticles uptake and toxicity in the green alga Chlamydomonas reinhardtii

Copper oxide nanoparticles (CuO NPs) are frequently used in a polymer-coated form, to be included in paints or fabrics for antimicrobial properties. Their application in antifouling paints may lead to the contamination of aquatic ecosystems. However, the toxicological risk of NPs in the environment is hard to evaluate due to a lack of knowledge on the mechanisms of NP interaction with biological systems. In this study, we investigated the effect of polymer coating on CuO NP toxicity in the green alga Chlamydomonas reinhardtii by comparing bare and polymer-coated CuO NPs prepared from the same CuO nanopowder. Both CuO NP suspensions were toxic to C. reinhardtii after 6 h treatment to concentrations of 0.005-0.04 g L⁻¹. Bare and polymer-coated CuO NPs induced a decrease of Photosystem II activity and the formation of reactive oxygen species. Polymer-coated CuO NP was found to be more toxic than the uncoated CuO NP. The higher toxicity of CS-CuO NP was mainly associated with the increased capacity of polymer-coated CuO NP to penetrate the cell compared to bare CuO NPs. These results indicates that the high toxicity of polymer-coated CuO NPs in algal cells results of intracellular interactions between NPs and the cellular system.     

Influence of dissolved oxygen on aggregation kinetics of citrate-coated silver nanoparticles

Aggregation, an important environmental behavior of silver nanoparticles (AgNPs) influences their bioavailability and cytotoxicity. The work studied the influence of dissolved oxygen (DO) or the redox potential on the stability of AgNPs in aqueous environments. This study employed time-resolved dynamic light scattering (TR-DLS) to investigate the aggregation kinetics of citrate-coated AgNPs. Our results demonstrated that when DO was present, the aggregation rates became much faster (e.g., 3-8 times) than those without DO. The hydrodynamic sizes of AgNPs had a linear growth within the initial 4-6 h and after the linear growth, the hydrodynamic sizes became random for AgNPs in the presence of DO, whereas in the absence of DO the hydrodynamic sizes grew smoothly and steadily. Furthermore, the effects of primary particles sizes (20, 40, and 80 nm) and initial concentrations (300 and 600 μg/L) of AgNPs on aggregation kinetics were also investigated.     

Trophic transfer of CuO nanoparticles from brine shrimp (Artemia salina) nauplii to convict cichlid (Amatitlania nigrofasciata) larvae: uptake,accumulation and elimination

Environmental Science and Pollution Research - We investigated the trophic transfer potential of CuO-NPs from Artemia salina to Amatitlania nigrofasciata. The Cu uptake was investigated by exposure...     

Seasonal and local variation of Cr, Ni and Co concentrations in Ulva rigida C. Agardh and Enteromorpha linza (Linnaeus) from Thermaikos Gulf, Greece

Cobalt, nickel and chromium concentrations were determined in Enteromorpha linza and Ulva rigida in seawater and sediment after seasonal collection from Thermaikos Gulf, Greece. Industrial waste and sewage is poured into this Gulf. The relative abundance of metals in the seaweeds and seawater decreased in the order Ni > Cr > Co, whereas in the sediment the order was Cr > Ni > Co. The two seaweeds bioaccumulated similar metal concentrations. The seasonal variation of metals in the two algae was not significant, but seemed to depend on the growth dynamics, the age of the tissue, the metal concentrations in the environment and the abiotic factors (such as salinity and temperature). Only Cr concentrations in E. linza showed significant local variation which depended on the area into which the industrial and domestic wastes were discharged and on their transport by sea currents. Nickel and chromium concentrations in U. rigida and Cr concentrations in E. linza displayed significant positive correlation with their concentrations in the seawater. Concentrations of the three metals in the seaweeds and seawater of Thermaikos Gulf generally exceeded the 'background' levels.     

Elemental uptake by seaweed, Plocamium corallorhirza along the Kwazulu-natal coast of Indian Ocean, South Africa

This study reports the elemental uptake by Plocamium corallorhiza, a Rhodophyta class of coralline alga grown richly along KwaZulu-Natal coastline. The uptake of seven important elements, namely Fe, Mn, As, B, Ti, Zn and Hg, selected based on their abundance in the samples, were investigated for a one-year cycle, from June 2002 to May 2003, at four chosen sites located along the KwaZulu-Natal coastline. The sites spread over 150 km from North to South Coast are Zinkwasi, Ballito, Treasure Beach and Park Rynie. P. corallorhiza possess good manganese and arsenic-accumulating ability and has potential to be an excellent indicator for most of the metals studied. A typical P. corallorhiza sample at Park Rynie (winter) recorded Mn (14 ppm), Fe (6.02 ppm), As (8.4 ppm), B (1580 ppb), Zn (234 ppb), Ti (751 ppb) and Hg (15.8 ppb). The general trend found at all sites was a large decrease in iron concentration in spring and summer and increase in winter. Mercury uptake was lowest in winter and autumn at all sites. The highest mercury levels in the seaweeds were recorded during spring or summer.     

Copper kinetics and internal distribution in the marbled crayfish (Procambarus sp.)

Metal pollution e.g. copper, in water bodies occurs worldwide. Although copper is an essential trace metal, at certain levels it is still considered as pollutant. The aim of this study was to investigate the effect of exposure concentration on copper bioaccumulation in marbled crayfish (Procambarus sp.) by determining uptake and elimination kinetics. Crayfish were exposed to sub-lethal copper concentrations (average measured concentrations of 0.031 and 0.38 mg Cu L⁻¹) for 14 d and transferred to copper-free water for another 14 d. At different time points during the uptake and elimination phases copper concentrations were measured in five organs (exoskeleton, gills, muscle, ovaries and hepatopancreas). At 0.031 mg Cu L⁻¹, copper levels in the crayfish organs were not significantly increased compared to the control animals, suggesting effective regulation. Exposure to 0.38 mg Cu L⁻¹ did lead to not significantly increased copper levels in muscles and ovaries, while the gills and exoskeleton, which are in direct contact with the water, showed significantly higher copper concentrations. In these four organs, copper showed fast uptake kinetics with equilibrium reached within 10 d of exposure. Copper accumulation was highest in the hepatopancreas; uptake in this storage organ steadily increased with time and did not reach equilibrium within the 14-d exposure period. Copper accumulation levels in the marbled crayfish found in this study were hepatopancreas > gills > exoskeleton > muscle.     

Sorption kinetics and its effects on retention and leaching.

Sorption of pesticides to substrates used in biopurification systems is important as it controls the system's efficiency. Ideally, pesticide sorption should occur fast so that leaching of the pesticide in the biopurification system is minimized. Although modeling of pesticide transport commonly assumes equilibrium, this may not always be true in practice. Sorption kinetics have to be taken into account. This study investigated the batch sorption kinetics of linuron, isoproturon, metalaxyl, isoxaben and lenacil on substrates commonly used in a biopurification system, i.e. cow manure, straw, willow chopping, sandy loam soil, coconut chips, garden waste compost and peat mix. The first-order sorption kinetics model was fitted to the observed pesticide concentrations versus time resulting in an estimated kinetic rate constant alpha. Sorption appeared to be fast for the pesticides linuron and isoxaben, pesticides which were classified as immobile, while less mobile pesticides displayed an overall slower sorption. However, the substrate does not seem to be the main parameter influencing the sorption kinetics. Coconut chips, which is a substrate with a high organic matter content showed slow sorption for most of the pesticides. The effect of different estimated alpha values on the breakthrough of pesticides through a biopurification system was evaluated using the HYDRUS 1D model. Significant differences in leaching behavior were observed as a result of the obtained differences in sorption kinetics.     

Examining the uptake and bioaccumulation of molybdenum nanoparticles and their effect on antioxidant activities in growing rice seedlings

Environmental Science and Pollution Research - The synthesized α-MoO3 and MoS2 NPs had nanosheet and nanoflower-like structures with crystallite size of 21.34 nm and 4.32 nm, respectively. The...