Polarization Characterization of Porous Particles Based on DDA Simulation and Multi-Angle Polarization Measurements.

Porous suspended particles are hazardous to human health due to their strong absorption capacity for toxic substances. A fast, accurate, in situ and high-throughput method to characterize the microporous structure of porous particles has extensive application value. The polarization changes during the light scattering of aerosol particles are highly sensitive to their microstructural properties, such as pore size and porosity. In this study, we propose an overlapping sphere model based on the discrete dipole approximation (DDA) to calculate the polarization scattering characteristics of porous particles. By combining scattering calculations with multi-dimensional polarization indexes measured by a multi-angle polarized scattering vector detection system, we achieve the identification and classification of pore-type components in suspended particles. The maximum deviation based on multiple indexes is less than 0.16% for the proportion analysis of mixed particles. Simultaneously, we develop a quantitative inversion algorithm on pore size and porosity. The inversion results of the three porous polymer particles support the validity and feasibility of our method, where the inversion error of partial particles is less than 4% for pore size and less than 6% for porosity. The study demonstrates the potential of polarization measurements and index systems applied in characterizing the micropore structure of suspended particles.

Advancing sustainable seawater disinfection: Enhanced inactivation and mechanism of pulsed UV-LEDs irradiation on Tetraselmis sp.

Ultraviolet light-emitting diodes (UV-LEDs), as a novel ultraviolet light source with flexible pulse mode, has gained significant attention for applications in water disinfection and food sterilization. This study investigated the comparative inactivation efficiency of Tetraselmis sp. with continuous and pulsed UV-LEDs irradiation, exploring different wavelengths, duty rates and pulse frequencies. The results reveal a significant enhancement in inactivation efficiency (p < 0.05) under pulsed conditions even at the same UV dose, with inactivation efficiency increasing as duty rate or pulse frequency decreases. The optimal conditions for achieving peak inactivation efficacy are identified as a duty rate of 50% and a pulse frequency of 5 Hz. Within this parameter space, pulsed irradiation leads to a remarkable 1.7-fold increase in inactivation efficiency at UV265 nm and a 1.5-fold increase at UV285 nm compared to continuous irradiation, respectively. Additionally, the disruptive impacts on photosynthetic performance are more pronounced with pulsed irradiation, particularly at the 5 Hz pulse frequency. In shed of these findings, the application of pulsed UV-LEDs irradiation emerges as a promising alternative to the conventional continuous UV disinfection methods in the area of seawater disinfection, offering higher disinfection efficacy and energy consumption.

The hidden risk of microplastic-associated pathogens in aquatic environments.

Increasing studies of plastisphere have raised public concern about microplastics (MPs) as vectors for pathogens, especially in aquatic environments. However, the extent to which pathogens affect human health through MPs remains unclear, as controversies persist regarding the distinct pathogen colonization on MPs as well as the transmission routes and infection probability of MP-associated pathogens from water to humans. In this review, we critically discuss whether and how pathogens approach humans via MPs, shedding light on the potential health risks involved. Drawing on cutting-edge multidisciplinary research, we show that some MPs may facilitate the growth and long-range transmission of specific pathogens in aquatic environments, ultimately increasing the risk of infection in humans. We identify MP- and pathogen-rich settings, such as wastewater treatment plants, aquaculture farms, and swimming pools, as possible sites for human exposure to MP-associated pathogens. This review emphasizes the need for further research and targeted interventions to better understand and mitigate the potential health risks associated with MP-mediated pathogen transmission.

Application of tea polyphenols as additives in brown fermented milk: Potential analysis of mitigating Maillard reaction products.

Brown fermented milk (BFM) is favored by consumers in the dairy market for its unique burnt flavor and brown color. However, Maillard reaction products (MRP) from high-temperature baking are also noteworthy. In this study, tea polyphenols (TP) were initially developed as potential inhibitors of MRP formation in BFM. The results showed that the flavor profile of BFM did not change after adding 0.08% (wt/wt) of TP, and its inhibition rates on 5-hydroxymethyl-2-furaldehyde (5-HMF), glyoxal (GO), methylglyoxal (MGO), Nε-carboxymethyl lysine (CML), and Nε-carboxyethyl lysine (CEL) were 60.8%, 27.12%, 23.44%, 57.7%, and 31.28%, respectively. After 21 d of storage, the levels of 5-HMF, GO, MGO, CML, and CEL in BFM with TP were 46.3%, 9.7%, 20.6%, 5.2%, and 24.7% lower than the control group, respectively. Moreover, a smaller change occurred in their color and the browning index was lower than that of the control group. The significance of this study was to develop TP as additives to inhibit the production of MRP in brown fermented yogurt without changing color and flavors, thereby making dairy products safer for consumers.

Extensive hydrolysis of milk protein and its peptidomic antigenicity analysis by LC-MS/MS.

Milk protein concentrate (MPC) is considered an ideal substitute of cow milk because of its similar protein and nutrition. In this study, MPC was hydrolyzed to peptides by alcalase and neutrase, and the properties of hydrolysate were evaluated. When MPC was hydrolyzed at the ratio of alcalase and neutrase of 1:1 and enzyme to substrate ratio of 6000 U/g MPC at 50°C, pH 8.5 for 3 h, the proportion of peptides with molecular weights <1 kDa was 85.31%, and the antigenicity reduction rates of casein and ß-lactoglobulin were 33.76% and 22.38%, respectively. Moreover, LC-MS/MS peptide identification revealed that the alcalase and neutrase disrupted a total of 65 epitopes of casein and 21 epitopes of whey protein, which further elucidated the mechanism of complex enzyme hydrolysis to reduce milk protein allergenicity.

Evaluating disinfection performance of ultraviolet light-emitting diodes against the microalga Tetraselmis sp.: Assay methods, inactivation efficiencies, and action spectrum.

Ultraviolet light-emitting diodes (UV-LEDs) are among the most compact devices and safest technologies in water disinfection systems. However, the validation of different assay methods to evaluate the disinfection performance of different wavelengths (265, 280, 285, and 300 nm) of UV-LEDs toward marine microalgae remains poorly characterized. In this study, several detection assays, namely the culture-based most probable number (MPN) assay, membrane integrity-based vital stain (VS) assay, chlorophyll fluorescence assay, and photochemical efficiency assay, were compared to assess the viability of the marine microalga Tetraselmis sp., with results indicating the MPN assay to be the most sensitive. In addition, this study compared the inactivation kinetics, inactivation efficiency, and energy efficiency of Tetraselmis sp. under different UV wavelengths, as assessed by the VS and MPN assays. The fluence-response curves of Tetraselmis sp. varied with assay and wavelength, with Geeraerd's model fitting all fluence-response microalgal inactivation curves. The results showed a non-significant difference in inactivation efficiency among different wavelengths of UV-LEDs (except for 300 nm) when using the VS assay. On the contrary, significant differences among all wavelengths were observed with respect to inactivation efficiency when using the MPN assay. The wavelength of 265 nm exhibited maximum inactivation efficiency, whereas 285 nm achieved optimal energy efficiency. The UV action spectrum of Tetraselmis sp. exhibited the peak at 265 nm, a finding which matched well with the absorbance spectrum of DNA. The observations from this study provide a theoretical basis and technical support for the application of the emerging UV-LED light sources in the algicidal treatment of marine water.

Combined toxicity of polystyrene microplastics and ammonium perfluorooctanoate to Daphnia magna: Mediation of intestinal blockage.

Microplastics (MPs) have worldwide accumulated in aquatic environments and coexisted with various water contaminants including perfluorinated compounds (PFCs) that are frequently detected. The adverse effects of individual MPs or PFCs on aquatic organisms have been extensively reported; however, the combined toxicity of MPs and PFCs remains unknown. This study evaluated the combined toxicity of MPs [pristine and aged polystyrene (PS)] and a PFC [ammonium perfluorooctanoate (APFO)] to Daphnia magna under different concentration ratios by three classic methods: toxicity unit, additive index, and mixed toxicity index. The adsorption kinetics of APFO on MPs, aggregation of MPs in exposure medium, MP gut fullness of daphnids, intestinal histology, and lipid peroxidation were analyzed to reveal the mechanism underlying the combined toxicity. Our results showed that the combined toxic modes varied with the concentration ratios of MPs to APFO (antagonism at 4:1 and 1:4, synergism at 3:1, 1:2, and 1:3, and partial addition/antagonism at 2:1 and 1:1 for pristine PS + APFO; antagonism at all ratios except partial addition/antagonism at 3:1 and 1:3 for aged PS + APFO), which could be attributed to the alteration of MP aggregation and thus MP gut fullness in the daphnids. The combined toxicity was further confirmed to occur in the daphnid's gut, which was reflected in physiological and biochemical responses mediated by intestinal blockage. Observable intestinal damages under co-exposures at µg•L-1 levels indicated the risks from future long-term exposure to MPs and PFCs in aquatic environments. This work demonstrates the necessity of assessing combined toxicity with different concentration ratios and provides new insights into the potential risks of MPs in aquatic environments.

Toxicity of 17 Disinfection By-products to Different Trophic Levels of Aquatic Organisms: Ecological Risks and Mechanisms.

Intensified disinfection of wastewater during the COVID-19 pandemic increased the release of toxic disinfection by-products (DBPs). However, studies relating to the ecological impacts of DBPs on the aquatic environment remain insufficient. In this study, we comparatively investigated the toxicities and ecological risks of 17 typical, halogenated DBPs to three trophic levels of organisms in the freshwater ecosystem, including phytoplankton (Scenedesmus sp.), zooplankton (Daphnia magna), and fish (Danio rerio). Toxicity of DBPs was found to be species-specific: Scenedesmus sp. was the most sensitive to haloacetic acids, while D. magna was the most sensitive to haloacetonitriles and trihalomethanes. Specific to each DBP, toxicities were also related to their classes and substituted halogen atoms. Damage to photosystems and oxidative stress served as the potential mechanisms for DBPs toxicity to microalgae. The different sensitivities to DBPs indicate that a battery of bioassays with organisms at different trophic levels is necessary to determine the ecotoxicity of DBPs. Furthermore, the ecological risks of DBPs were assessed by calculating the risk quotients (RQs) based on toxicity data from multiple bioassays. The cumulative RQs of DBPs to all the organisms were greater than 1.0, indicating high ecological risks of DBPs in wastewater effluents.

How do humans recognize and face challenges of microplastic pollution in marine environments? A bibliometric analysis.

Microplastics (MPs) are abundant in marine environments, drawing global attention from scientists and rendering it significant to review the research progress and predict future trends of this field. To achieve that, we collected 1898 publications on marine MPs from Web of Science and performed a bibliometric analysis by CiteSpace and VOSviewer. Additionally, we utilized an unrestricted retrieval of literature from ScienceDirect to supplement our major findings. Trends in publication numbers show the growth in study from the initial stage ( 2012 and before), when microplastic (MP) occurrence, abundance, and distribution were primarily investigated. Throughout the ascent stage (between 2013-2016), when diverse sampling and analytical methods were applied to capture and identify MPs from the ocean, baseline data have been gleaned on physiochemical properties of MPs. The research focus then shifted to the bioaccumulation and ecotoxicological effects of MPs on marine biota, further highlighting their potential deleterious impacts on human health via dietary exposure, and this period was defined as the exploration stage (2017 and onwards). Nevertheless, key challenges including the lack of standard procedures for MP sampling, technical limitations in MP detecting and identification, and controversy about the underlying effects on the marine ecosystems and humans have also been arisen in the last decade. The present study elucidates how we gradually recognize MP pollution in marine environments and what challenges we face, suggesting future avenues for MP research.

Recovery of Alexandrium tamarense under chronic exposure of TiO2 nanoparticles and possible mechanisms.

Harmful algal blooms (HAB), heavily influenced by human activities, pose serious hazard to aquatic ecology and human health. In this study, we monitored the physiological responses and paralytic shellfish poisoning toxins (PSTs) of the toxin-producing HAB species Alexandrium tamarense under titanium dioxide nanoparticles (nTiO2) exposure in the concentration range of 2-320 mg L-1 over a period of 13 days. The results showed the acute inhibition of nTiO2 on the algal growth, photosynthetic efficiency and esterase activity at all concentrations except 2 mg L-1. Nonetheless, they recovered after 13 days nTiO2 exposure from 20 to 80 mg L-1. The EC50 value increased from 85.1 mg L-1 in Day 4 to 140.9 mg L-1 in Day 13. The physiological recovery after prolonged exposure may result from the elimination of excess reactive oxygen species (ROS), a combined outcome of increased nTiO2 aggregation and algal antioxidant defense mechanisms. This observation is supported by the immediately increased antioxidant enzyme activities, including the superoxide dismutase (SOD) and catalase (CAT) activities upon nTiO2 exposure. Moreover, the production of PSTs in A. tamarense significantly increased by 1.41-1.76 folds after chronic nTiO2 exposure at all tested concentrations (p < 0.05), which might also be an adaptive response for the microalgae to overcome the stresses. In particular, the proportions of highly-toxic PSTs analogues GTX2/3, STX and dcSTX were significantly increased upon nTiO2 exposure (p < 0.05). Hence, the chronic nTiO2 exposure might aggravate the ecological impact of HABs. Furthermore investigations on different HAB species, especially those toxin-producing ones, and detail physiological responses are obviously needed.

Effects of Carbon Quantum Dots on Aquatic Environments: Comparison of Toxicity to Organisms at Different Trophic Levels.

Carbon quantum dots (CQDs) have high hydrophilicity, high cell permeability, and are frequently used in water-based and biorelated applications, yet studies concerning the ecological risks of CQDs in aquatic environments are largely insufficient. In the present study, the toxicity of CQDs to zebrafish ( Danio rerio), zooplankton ( Daphnia magna), and phytoplankton ( Scenedesmus obliquus) were assessed for the first time. The results indicated that CQDs (up to 200 mg/L) could be depurated by D. rerio with negligible toxicity. In comparison, CQDs induced mortality and immobility in D. magna with a 48-h EC50 value and LC50 value of 97.5 and 160.3 mg/L, respectively. In S. obliquus, CQDs inhibited photosynthesis and nutrition absorption in a dose- and time-dependent manner, and the growth of algae was also inhibited with a 96-h EC50 value of 74.8 mg/L, suggesting that S. obliquus, the lowest trophic level in this study, was most sensitive to CQDs exposure. Further investigations revealed that CQDs induced an increase in oxidative stress in algae cells and a decrease in pH value of an algae medium, indicating that oxidative stress and water acidification may be the mechanisms underlying the toxicity of CQDs to S. obliquus.

Graphene oxide in the marine environment: Toxicity to Artemia salina with and without the presence of Phe and Cd2.

Given the increasing potential of graphene oxide entering marine environments, it is imperative to assess the risks of GO on marine ecosystem, including its direct toxicity to marine organisms and indirect toxicity brought by co-existing aquatic pollutants, as a result of the remarkable adsorption capacity of GO. In the present study, the acute toxicity of GO, Phe, Cd2+, GO-Phe, and GO-Cd2+ to Artemia salina were systemically assessed and compared for the first time. Although the lethal effects of GO alone to A. salina only appeared at high GO dose (500 mg/L), its sublethal toxicity (growth inhibition) at concentrations as low as 1 mg/L was observed by microscopy, which was likely closely related to the GO-induced oxidative stress in A. salina. Compared with the toxicity of Phe alone, GO-Phe exhibited a synergistic effect to A. salina at a high GO concentration. For GO-Cd2+, the toxicity was positively correlated with both GO dose and Cd2+ dose. The increased toxicity of GO-Phe or GO-Cd2+ at high doses might be attributed to the promoted bioaccumulation of toxicants by GO, as the adhesion of GO complexes to intestinal tract of A. salina was observed during the toxicity tests, which probably resulted in further toxicological effects.

A mechanism study on toxicity of graphene oxide to Daphnia magna: Direct link between bioaccumulation and oxidative stress.

Graphene oxide (GO) possesses versatile applicability and high hydrophilicity, thus may have frequent contact with aquatic organisms. However, the ecological risks of GO in aquatic ecosystems remain largely unexplored currently. This study evaluated the comprehensive toxicological effects of GO on Daphnia magna, a key species in fresh water ecosystem. The results revealed nonsevere acute toxicities, including immobility (72 h EC50: 44.3 mg/L) and mortality (72 h LC50: 45.4 mg/L), of GO on D. magna. To understand the underlying mechanism of GO exposure, changes in superoxide dismutase (SOD) and lipid peroxidation (LPO) of D. magna exposed to GO were correlated, which revealed elevated GO-mediated oxidative stress and damages, especially in the long-time and high-dose exposure groups. The observations of in vivo fluorescence labeled with 2', 7'-dichlorofluorescin further demonstrated that reactive oxygen species were concentrated in daphnia guts, which corresponded with the high bioaccumulation level (5 mg/L, 24 h body burden: 107.9 g/kg) of GO in daphnia guts. However, depuration of GO from daphnia was not difficult. Daphnia almost released all GO within 24 h after it was transferred to clean water. These results hence suggest that GO could accumulate and induce significant oxidative stress in the gut of D. magna, while D. daphnia can also relieve the acute toxicity by depurating GO.

[Effects of Manganese on the Growth and Fluorescence Induction Kinetics of Conticribra weissflogii].

The manganese (Mn4) cluster, as a part of the oxygen-evolving complex (OEC) in the photosystemⅡ (PS Ⅱ) of microalgae and plants, assists in the electrolysis of water to oxygen, protons, and electrons. To examine the relationships among manganese (Mn) concentrations in the culture medium, algae growth, and chlorophyll fluorescence characteristics, we exposed the diatom Conticribra weissflogii to a broad range of Mn concentrations from 0 to 9000 nmol·L-1. Chlorophyll fluorescence induction dynamics analysis, an effective way to investigate photosynthetic characteristics, can be used as indicator of the photosynthetic apparatus of photosynthesizers under different stressors. Here, we studied the effects of Mn exposure on C. weissflogii using this fluorescence analysis method. The results show that the growth of C. weissflogii is independent of the Mn exposure at concentrations below 9000 nmol·L-1. Moreover, chlorophyll fluorescence parameters of C. weissflogii respond to exposed Mn concentrations, whereby the strongest induction occurred at 90 nmol·L-1 Mn and the responses are enhanced over time. Although Mn in culture media may not be a major limiting factor of the growth of C. weissflogii, it significantly enhances the photosynthesis of C. weissflogii via two ways. First, Mn improves the integrity of the OEC structure and electron transfer from OEC to Tyr on the donor side of PS Ⅱ; second, Mn also enhances the energy transfer and electron transport after reaching the primary quinone acceptor (QA) on the acceptor side of PS Ⅱ. Energy transfer-related fluorescence parameters are positively correlated with the level of ROS in C. weissflogii, indicating that Mn plays an important role in both photosynthesis processes and reactive oxygen species(ROS)production.

Impact of Flue Gas Compounds on Microalgae and Mechanisms for Carbon Assimilation and Utilization.

To shift the world to a more sustainable future, it is necessary to phase out the use of fossil fuels and focus on the development of low-carbon alternatives. However, this transition has been slow, so there is still a large dependence on fossil-derived power, and therefore, carbon dioxide is released continuously. Owing to the potential for assimilating and utilizing carbon dioxide to generate carbon-neutral products, such as biodiesel, the application of microalgae technology to capture CO2 from flue gases has gained significant attention over the past decade. Microalgae offer a more sustainable source of biomass, which can be converted into energy, over conventional fuel crops because they grow more quickly and do not adversely affect the food supply. This review focuses on the technical feasibility of combined carbon fixation and microalgae cultivation for carbon reuse. A range of different carbon metabolisms and the impact of flue gas compounds on microalgae are appraised. Fixation of flue gas carbon dioxide is dependent on the selected microalgae strain and on flue gas compounds/concentrations. Additionally, current pilot-scale demonstrations of microalgae technology for carbon dioxide capture are assessed and its future prospects are discussed. Practical implementation of this technology at an industrial scale still requires significant research, which necessitates multidisciplinary research and development to demonstrate its viability for carbon dioxide capture from flue gases at the commercial level.

Exposure of engineered nanoparticles to Alexandrium tamarense (Dinophyceae): Healthy impacts of nanoparticles via toxin-producing dinoflagellate.

Human activities can enhance the frequency, intensity and occurrence of harmful algal blooms (HABs). Engineered nanoparticles (ENPs), contained in many materials, will inevitably enter coastal waters and thus cause unpredictable impacts on aquatic organisms. However, knowledge of the influence of ENPs on HAB species is still lacking. In this study, we examined the effects of titanium dioxide nanoparticles (nTiO2), zinc oxide nanoparticles (nZnO) and aluminum oxide nanoparticles (nAl2O3) on physiological changes and paralytic shellfish poisoning toxins (PSTs) production of Alexandrium tamarense. We found a dose-dependent decrease in photosynthetic activity of A. tamarense under all three ENPs and a significant growth inhibition induced by nZnO. The largest reactive oxygen species (ROS) production was induced by nTiO2, followed by nZnO and nAl2O3. Moreover, the PSTs production rate increased by 3.9-fold for nTiO2 (p<0.01) and 4.5-fold for nAl2O3 (p<0.01) at a concentration of 200mgL-1. The major component, C2 was transformed to its epimer C1 and the proportion of decarbamoyl toxins increased under 200mgL-1 of nZnO and nAl2O3. In addition, the proportion of carbamate toxins increased upon exposure to 2mgL-1 ENPs, while decreased upon exposure to 200mgL-1 ENPs. The changes in PSTs production and composition might be an adaptive response for A. tamarense to overcome the stress of ENPs exposure. This work brings the first evidence that ENP would affect PSTs production and profiles.

Mechanisms underlying the acute toxicity of fullerene to Daphnia magna: Energy acquisition restriction and oxidative stress.

The toxicity of fullerene (C60) to Daphnia magna has been a subject with increasing concerns. Nevertheless, the underlying mechanisms are still poorly understood. In the present study, we evaluated various aspects of the toxicological impacts of C60 on daphnia. After a 72-h exposure, the 50% effective concentration of C60 was 14.9 mg/L for immobilization, and 16.3 mg/L for mortality. Daphnia exhibited a quick uptake of C60 with a body burden value of 413 µg/g in wet weight in the 1 mg/L C60 treatment group. Transmission electron microscopy observations revealed that C60 had mainly accumulated in the guts of organisms. The feeding rate, gut ultra-structural alterations, and digestive enzyme activities of daphnia in response to C60 treatment were evaluated. The results revealed a significant reduction in the digestion and filtration rates, as well as gut impairment and inhibition of digestive enzymes (cellulose, amylase, trypsin, and ß-galactosidase) activity of C60 exposed daphnia. In addition, the changes in superoxide dismutase (SOD) and malondialdehyde (MDA) levels in daphnia under C60 exposures were also discovered. These results, for the first time, provide systematic evidence that C60 caused a restriction in energy acquisition and increased oxidative damage in daphnia, which might be related to the bioaccumulation of C60 and finally led to the immobility and mortality.

[Behaviors of engineered nanoparticles in aquatic environments and impacts on marine phytoplankton].

Engineered nanoparticles (ENPs) have shown invaluable societal benefits and applications in drug targeting, biological imaging and industrial products. ENPs enter the water body through various paths during the processes of production, usage and emission, therefore the behavior and the biosafety of ENPs in water bodies have attracted increasing attention. As the primary producer of ecosystems, phytoplankton provide nutrients, energy and oxygen for both themselves and organisms at higher trophic levels in the aquatic ecosystems. These primary producers may be exposed to the biological and unpredictable effects of this emergent pollutant to the aquatic ecosystems. Numerous studies have proved the toxic effects of ENPs on phytoplankton, but the mechanisms of entry into the aquatic organisms as well as the stability, fate and biotransformation in phytoplankton still remain unclear. Here, we present a review of the pathways of ENPs entering the water, the subsequent behavior and biological effects of ENPs on phytoplankton with an emphasis on latest findings and current knowledge. Future research and endeavors shall focus further on the understanding of mechanisms, fate and transport of ENPs in the aquatic ecosystems.

Effects of fluctuating temperature and silicate supply on the growth, biochemical composition and lipid accumulation of Nitzschia sp.

Nitzschia sp. (Bacillariophyceae) was grown under temperature and photoperiods mimicking those, typical during summer, spring/fall and winter conditions in the southern United States, and using five silicate (Si) concentrations. In general, higher Si concentrations resulted in higher growth rates in summer and spring/fall conditions and lower organic content. Si-deficient Nitzschia sp. had higher levels of neutral lipid compared to those growing in Si replete media. Under summer conditions, the proportion of saturated fatty acids (SFA) and monounsaturated fatty acids (MUFA) was relatively stable compared with spring/fall and winter conditions, and the proportion of polyunsaturated fatty acids (PUFA) was low. In the winter condition, SFA and MUFA showed a gradient of decreasing abundance while PUFA gradients increased with increasing Si concentrations in the medium. Cumulative productivity (optimization of growth and lipid content) would be best in the spring/fall but less so in the other conditions for this strain of Nitzschia sp.