Nutrient Concentrations Research Articles

Integrating physical and biogeochemical processes and oceanic exchanges at a coastal lagoon in Southern West Europe

Coastal lagoons are highly productive systems and the quantification of mass fluxes, which is of paramount importance for the sustainable management of these systems, remains poorly studied. In this context, a detailed study was conducted to better understand the exchanges between the productive coastal lagoon Ria Formosa (South-West Europe) and the ocean. The exchanges of water, nutrients, chlorophyll-a and suspended solids between the main inlets (Faro-Olhão inlet - BFO; Armona inlet - BAR; and Ancão inlet - BAN) and adjacent channels (Faro - CF and Olhão - CO) and the adjacent ocean were estimated along complete semidiurnal tidal cycles, under extreme fortnightly tidal ranges and different seasonal and environmental/oceanographic conditions. The net tidal prism was highest during spring tides. Among the three inlets, BFO was the most important in terms of exchange, followed by BAR and BAN. Net transport at BFO was lowest during the Summer campaign, although it exported material that fertilised the adjacent coast. The persistent net export of suspended solids and ammonium suggests the higher biological productivity of Ria Formosa compared to that found in coastal waters. In the Winter campaign, after a period of rainfall and increased land runoff, there was a remarkable export of matter, on which, ammonium and suspended particles exported can exceed 0.3 times and almost 0.9 times, respectively, those imported from coastal water. However, the import of phosphate and nitrate can be attributed to a weak coastal upwelling event, as well to low consumption and nitrification at this period of low temperature. During the Spring and Autumn campaigns, the Ria Formosa was fertilised either by upwelling events or due to rapid consumption of nutrients by phytoplankton in this shallow system. BFO and the other two inlets of the western sector of Ria Formosa are interconnected by CF and CO. The higher nutrient transport was recorded at CF, despite the highest nutrients concentrations was recorded at CO. The data show the strong link between physical and biogeochemical processes with meteorological/oceanographic factors. The study showed that associated biological processes are superimposed on the tidal effect in this system. Data from this study could be used as a reference, particularly important for management of Ria Formosa, a productive system where bivalves production depends deeply on water quality. In addition, the nutrient concentrations and mass exchanges resulting from the different processes can be used as a reference for other lagoon systems where shellfish production is practised.

Elevated concentrations of soil carbon dioxide with partial root-zone drying enhance drought tolerance and agro-physiological characteristics by regulating the expression of genes related to aquaporin and stress response in cucumber plants

Water scarcity and soil carbon dioxide elevation in arid regions are considered the most serious factors affecting crop growth and productivity. This study aimed to investigate the impacts of elevated CO2 levels (eCO2 at rates of 700 and 1000 ppm) on agro-physiological attributes to induce drought tolerance in cucumbers by activating the expression of genes related to aquaporin and stress response, which improved the yield of cucumber under two levels of irrigation water conditions [75% and 100% crop evapotranspiration (ETc)]. Therefore, two field experiments were conducted in a greenhouse with controlled internal climate conditions, at the Mohamed Naguib sector of the national company for protected agriculture, during the winter seasons of 2021–2022 and 2022–2023. The treatments included eCO2 in soil under normal and partial root zoon drying (PRD, 100% ETc Full irrigations, and 75% ETc). All the applied treatments were organized as a randomized complete block design (RCBD) and each treatment was replicated six times. Untreated plants were designed as control treatment (CO2 concentration was 400 ppm). The results of this study showed that elevating CO2 at 700 and 1000 ppm in soil significantly increased plant growth parameters, photosynthesis measurements, and phytohormones [indole acetic acid (IAA) and gibberellic acid (GA3)], under partial root-zone drying (75% ETc) and full irrigation conditions (100% ETc). Under PRD condition, eCO2 at 700 ppm significantly improved plant height (13.68%), number of shoots (19.88%), Leaf greenness index (SPAD value, 16.60%), root length (24.88%), fresh weight (64.77%) and dry weight (61.25%) of cucumber plant, when compared to untreated plants. The pervious treatment also increased photosynthesis rate, stomatal conductance, and intercellular CO2 concentration by 50.65%, 15.30% and 12.18%; respectively, compared to the control treatment. Similar findings were observed in nutrient concentration, carbohydrate content, Proline, total antioxidants in the leaf, and nutrients. In contrast, eCO2 at 700 ppm in the soil reduced the values of transpiration rate (6.33%) and Abscisic acid (ABA, 34.03%) content in cucumber leaves compared to untreated plants under both water levels. Furthermore, the results revealed that the gene transcript levels of the aquaporin-related genes (CsPIP1-2 and CsTIP4) significantly increased compared with a well-watered condition. The transcript levels of CsPIP improved the contribution rate of cell water transportation (intermediated by aquaporin’s genes) and root or leaf hydraulic conductivity. The quantitative real-time PCR expression results revealed the upregulation of CsAGO1 stress-response genes in plants exposed to 700 ppm CO2. In conclusion, elevating CO2 at 700 ppm in the soil might be a promising technique to enhance the growth and productivity of cucumber plants in addition to alleviating the adverse effects of drought stresses.

Concentrations and predictors of select nutrients in Canadian human milk samples from the Maternal-Infant Research on Environmental Chemicals pregnancy cohort

BackgroundHuman milk (HM) composition data are widely used in clinical, regulatory, and public health initiatives. The existing HM profiles in United States and Canadian nutrient databanks are outdated and now considered inappropriate to estimate current nutrient intakes. Recent reviews have underscored the limited North American data available to generate a new profile. ObjectivesTo describe concentrations and sources of variability of nutrients in HM from a large cohort collected in Canada. MethodsThe Maternal-Infant Research on Environmental Chemicals (MIREC) study recruited participants in the first trimester of pregnancy from 10 Canadian cities between 2008 and 2011. HM samples (n = 559–835, depending on nutrient) were collected 3–10 wk postpartum and analyzed for minerals (calcium, magnesium, phosphorus, potassium, sodium, manganese, molybdenum, zinc, copper, iodine, selenium), vitamin D [vitamin D3, 25-hydroxyvitamin D3], folate vitamers (folic acid, 5-methyltetrahydrofolate, total folates), and fatty acids (panel). We examined associations between participant characteristics and log-transformed nutrient concentrations using linear regression. ResultsConcentrations of HM components in MIREC samples were within the range observed in literature except for manganese, which was >100-fold lower than the value in the existing Canadian nutrient databank profile [2.43 (standard deviation 2.84) compared with 260 ng/g]. In multivariable models, concentrations of folate vitamers, vitamin D, and fatty acids demonstrated greater variability with maternal and sample characteristics than minerals. Factors such as relevant supplement use, body mass index, and for vitamin D, skin color and season, had a larger impact on nutrient concentrations than characteristics typically standardized in HM research, such as maternal or infant health, and method of collection. ConclusionsHM mineral concentrations from this study meet the methodological inclusion criteria for updating nutrient databank values and dietary reference intakes. Consideration of factors such as diet, skin color, and BMI will be important for selecting studies for developing representative reference values based on HM.

Pulsed wind-driven control of phytoplankton biomass at a groundwater-enriched nearshore environment

Along some Mediterranean coastal areas and other world regions, nutrient and chlorophyll concentrations often show gradient increases of up to one order of magnitude perpendicular to the coast. This nearshore stripe, extending a few hundred meters from the coast, is enriched by submarine groundwater discharges (SGD) containing elevated nutrient concentrations that may eventually sustain high biomass phytoplankton blooms. During a survey carried out in the summer of 2018, we examined the short-term (hours) variability of the phytoplankton biomass (measured as chlorophyll; Chl) in response to environmental changes associated with SGD and wind forcing in the nearshore waters of Palma Beach (Mediterranean Sea). Continuous CTD records revealed a general salinity decline indicative of SGD along the shoreline. Large and pulsed salinity fluctuations (i.e. 2–3 psu variations, 1–4 h) were observed each day that were consistent with offshore advection episodes of the lower salinity water retained in the nearshore (peak crosshore velocity 5–6 cm s−1). Chl near the shoreline was markedly higher than offshore (3.55 ± 1.29 and 0.68 ± 0.27 mg m−3 respectively) but recurrently fluctuated in the afternoon to up to >7 mg m−3. Primary production estimations showed that despite the higher production in the nearshore (50.29 ± 10.98 μmol O2 L−1 d−1, 4-fold offshore values) productivity per unit chlorophyll did not significantly vary (p > 0.01) therefore suggesting that, at this time scales, high biomass episodes in the nearshore are driven by an accumulation mechanism. Statistical analysis (CCA) demonstrates that Chl variability is largely explained (93 %) by variations in wind and current velocity. Our results provide evidence that the dynamics of this nearshore environment are modulated by the interplay between the shoreward wind-induced flow and the offshore directed density flow. This mechanism could explain the occurrence and episodic nature of high biomass blooms in the nearshore, as well as be an important factor influencing the microbial community structure at the coastal zone.

Long-term interaction of metals and phosphate with ferrihydrite in artificial seawater and implications for past and present environments

The FeIII hydroxide ferrihydrite (Fh) is highly reactive towards dissolved metals and other aqueous compounds. This reactivity suggests a possible role for Fh in environmental remediation and in controlling ambient concentrations of metals and nutrients in both modern and ancient aqueous environments. Though the reactivity of Fh towards a variety of aqueous compounds has been determined in previous studies, its reactivity under seawater-like conditions has not been systematically explored. Since solution chemistry can have a profound effect on the uptake of metals and oxyions through its effects on the surface chemistry of Fh and the speciation of metals in solution, the dearth of experiments under seawater-like conditions translates into a knowledge gap of metal-Fh interactions in natural marine systems. Furthermore, metal- and nutrient-Fh interactions have been investigated under dissimilar conditions, making a quantitative comparison of these interactions difficult. Lastly, the fate of the aqueous metals and nutrients taken up by Fh upon its aging has been examined in only a few studies and mostly for a duration up to ∼8 months.We bridged these gaps in a series of adsorption and co-precipitation experiments of various metals and phosphate with Fh, in seawater-analog solutions, at circumneutral pH (pH 7.5 and 8.0) and 25 °C. We quantified the effect of interaction with Fh on the aqueous concentrations of CdII, CoII, CrVI, CuII, MnII, MoVI, NiII, VV, UVI, ZnII, and phosphate (PO43−). The experimental results are provided as uptake percentages (quantified as the metal:Fe ratio in the solid phase relative to the metal:Fe ratio added) at different metal:Fe ratios and as a series of partition coefficients of the studied metals and PO43− between aqueous solution and Fh. Additionally, aging experiments of up to ∼4 years in duration were used to determine the potential effects of grain coarsening, surface modification and mineral transformation on the uptake of the metals and PO43−. Uptake of CrVI, MoVI and UVI was negligible in both the adsorption and co-precipitation experiments. Uptake of VV and PO43− by co-precipitation was as much as twice their uptake by adsorption, and we suggest that stabilization of colloidal Fh with a large surface area explains these findings. For CuII, NiII, CoII, MnII, and CdII differences in uptake between the co-precipitation and adsorption experiments were less pronounced, and we ascribe these differences to relatively minor incorporation of these metals into Fh. No significant transformation of Fh to more stable phases was observed under our experimental conditions and duration. Nevertheless, the uptake of several metals and phosphate was affected by Fh aging. Approximately 75% of the PO43− initially taken up by co-precipitation with Fh was released, as was approximately 30% of the VV. A pronounced increase in the uptake of MnII may be related to its oxidation and precipitation as MnIII,IV oxides. For other metals the changes in uptake were less pronounced.We discuss the mechanisms of metal and PO43− uptake by Fh, the effects of solution composition on uptake, and the implications of our findings for modern and ancient natural environments and for environmental remediation.

Study on the Microbial Mechanisms of Enhancing Agaricus bisporus Growth through Inoculation with Pseudomonas putida

Introducing Pseudomonas putida optimizes the microbial community within the casing layer, thereby enhancing Agaricus bisporus growth. Nevertheless, the underlying mechanisms governing microbial community succession within the casing layer following microbial agent introduction remained elusive. This study delineated the interplay among microbial populations in the casing layer across the growth cycle of A. bisporus, comparing cohorts treated with P. putida (AP) against untreated controls (CK). The inoculation with Pseudomonas promoted the growth of A. bisporus, shortened its growth cycle, and linearly enhanced the relative abundance of key bacterial genera integral to its growth, including Flavobacterium, Rhodoferax, Pseudarthrobacter, and Vogesella (adjusted R2=0.238-0.866). Importantly, a positive correlation was identified between the proliferation of these beneficial bacteria and positive community cohesion (adjusted R2=0.353-0.838). Additionally, analysis of the symbiotic network topology within the AP group indicated a more stable community following inoculation. The niche results (AP=11.7672±1.8938, CK=11.0481±3.1273, P<0.05) underscored the positive impact of Pseudomonas inoculation on ecosystem dynamics. Concentrations of essential nutrients for A. bisporus growth, notably readily available phosphorus (On day 17, the AP group was 78.8333±1.26623 mg/kg, while the CK group was 30.0333±0.98658 mg/kg) and readily available potassium (On day 17, the AP group was 2693.9±14.79561 mg/kg, while the CK group was 1646.9333±10.71276mg/kg), were significantly elevated in the AP group. These enhancements strongly correlated with the increased abundance of pivotal microbial populations. Our research provided insights into the application of microbial inoculants to enhance the production of edible fungi.

Riverine connectivity modulates elemental fluxes through a 200- year period of intensive anthropic change in the Magdalena River floodplains, Colombia

Tropical floodplain lakes are increasingly impacted by human activities, yet their pathways of spatial and temporal degradation, particularly under varying hydrological connectivity regimes and climate change, remain poorly understood. This study examines surface-sediment samples and 210Pb-dated sediment cores from six floodplain lakes, representing a gradient in hydrological connectivity in the lower Magdalena River Basin, Colombia. We analysed temporal and spatial variations in several sediment biogeochemical indicators: the concentration and flux of nutrients, heavy metals, and organic matter (OM), and redox conditions, flooding and erosion. Multiple factor analysis (MFA) of surface-sediments identified redox conditions, OM, flooding, heavy metals and lake connectivity as the main contributors to spatial variability within- and between-lakes sediments, accounting for 48% of the total variation. Additionally, no clear distinction was found between littoral and open-water sediment characteristics. Isolated lakes sediments exhibited reductive conditions rich in OM and nutrients, whereas connected lakes sediments showed greater heavy metal enrichment and higher concentrations of coarse river-fed material. Generalised additive models identified significant changes in the biogeochemical indicators since the late 1800s, that accelerated post-1980s. Shifts in OM, erosion, flooding, redox conditions, land-cover change, heavy metals and climate were identified by MFA as the main drivers of change, explaining 60%-71% of the variation in the connected lakes and 53%-72% in the isolated lakes. Post-1980s, connected lakes transitioned from conditions of higher accumulation of OM and little erosion to higher accumulation of heavy metals and river-fed material. Conversely, isolated lakes, shifted from detrital-heavy metal-rich sediments to OM-, and nutrient-rich, reductive sediments. Sedimentation rates also surged post-1980s, particularly in highly connected lakes, from 0.14 ± 0.07 g cm² yr⁻¹ to 0.5 ± 0.5 g cm² yr⁻¹, with elevated fluxes of metals, OM and nutrients. These changes in sediment biogeochemistry align with deforestation, river regulation and prolonged dry periods, highlighting the complexities behind establishing reliable reference conditions for pollution assessments in large, human-impacted tropical river systems.

Assessment of the chemical composition of buriti (Mauritia flexuosa Liliopsida) and cassava (Manihot esculenta Crantz) residues and their possible application in the bioproduction of coconut aroma (6 pentyl-α-pyrone).

This work aimed to define strategies to increase the bioproduction of 6 pentyl-α-pyrone (bioaroma). As first strategy, fermentations were carried out in the solid state, with agro-industrial residues: Mauritia flexuosa Liliopsida. and Manihot esculenta Crantz in isolation, conducting them with different nutrient solutions having Trichoderma harzianum as a fermenting fungus. Physicochemical characterizations, centesimal composition, lignocellulosic and mineral content and antimicrobial activity were required. Fermentations were conducted under different humidification conditions (water, nutrient solution without additives and nutrient solutions with glucose or sucrose) for 9days. Bioaroma was quantified by gas chromatography, assisted by solid-phase microextraction. The results showed the low production of this compound in fermentations conducted with sweet cassava (around 6ppm (w/w)). The low bioproduction with sweet cassava residues can probably be related to its starch-rich composition, homogeneous substrate, and low concentration of nutrients. Already using buriti, the absence of aroma production was detected. Probably the presence of silicon and high lignin content in buriti minimized the fungal activity, making it difficult to obtain the aroma of interest. Given the characteristics presented by the waste, a new strategy was chosen: mixing waste in a 1:1 ratio. This fermentation resulted in the production of 156.24ppm (w/w) of aroma using the nutrient solution added with glucose. This combination, therefore, promoted more favorable environment for the process, possibly due to the presence of fermentable sugars from sweet cassava and fatty acids from the buriti peel, thus proving the possibility of an increase of around 2500% in the bioproduction of coconut aroma.

Estimation of Staphylococcus total viable count in different contamination states of central venous catheters in hemodialysis centers based on tunable diode laser wavelength‐modulation spectroscopy

AbstractThe surveillance and assessment of the total viable count (TVC) of Staphylococcus under different levels of catheter contamination are crucial for the prevention and evaluation of catheter‐related infections in hemodialysis (HD). This paper demonstrates the noninvasive and accurate measurement of the TVC of Staphylococcus using wavelength‐modulated tunable diode laser absorption spectroscopy (WMAS). The tunable distributed feedback laser with a central wavelength of 2004 nm was employed and the detection limit of 22.5 ppm for carbon dioxide (CO2) produced by Staphylococcus epidermidis was obtained. The growth of Staphylococcus under different medium concentrations was studied, and the results indicated a strong correlation between the growth rate and final TVC of S. epidermidis with the medium concentration. When the degree of catheter contamination was low, resulting in minimal residual nutrient concentration within the catheter, the bacterial growth rate and TVC were effectively suppressed. Therefore, it is proven that WMAS is a user‐friendly, noninvasive, and high signal‐to‐noise ratio technique for monitoring Staphylococcus, making it an effective tool for assessing Staphylococcus growth in HD catheter surveillance.

The Critical Role of Hydrological Distance in Shaping Nutrient Dynamics Along the Watershed‐Lake Continuum

AbstractTerrestrial hydrological and nutrient cycles are subjected to major disturbances by agricultural operations and urbanization that profoundly influence freshwater resources. Non‐point source pollution is one of the primary causes for water quality deterioration, and thus an emerging imperative in limnology is establishing empirical models that connect watershed attributes and hydrological drivers with lake nutrient dynamics. Here, we compiled three nation‐wide nutrient, meteorological, and watershed‐landscape data sets, to develop Generalized Linear Models that predict lake phosphorus and nitrogen concentrations as a function of the surrounding watershed characteristics within various hydrological distances across 104 Chinese lakes and reservoirs. Our national‐scale investigation revealed that lake nutrient concentrations can be satisfactorily predicted by proxies of natural drivers and anthropogenic activities, reflecting the properties of the surrounding watershed. Counter to previous studies, we found that China's lake nutrient concentrations strongly depend on watershed characteristics within a hydrological distance of less than 45 km rather than the entire watershed. Furthermore, extensive human activities in watersheds not only compromise our predictive capacity, but also increase the hydrological distance that is relevant to predict lake nutrients. This national‐scale characterization can inform one of the most contentious issues in the context of China's lake management, that is, the determination of the extent of the nearshore area, where nutrient control should be prioritized. As far as we know, our study represents the first attempt to apply the concept of hydrological distance and establish statistical models that can delineate the critical spatial domain primarily responsible for the nutrient conditions along the watershed‐lake continuum.

Inter-annual variability in the phytoplankton abundance and community structure of a tropical monsoonal estuary in response to variable monsoonal patterns

The study elucidates the inter-annual and seasonal variability in the phytoplankton abundance and community structure concurrent to variable rainfall patterns in Chettuva, a tropical monsoonal estuary along the southwest coast of India. The phytoplankton community exhibited statistically significant inter-annual variation with a 1.2-fold increase in abundance (av. 19.44 ×104cellsL-1) in 2021 in comparison with 2019 (av. 15.30 ×104cellsL-1). A total of 87 phytoplankton species were observed during the study, among which Bacillariophyceae dominated with 52 species, followed by Dinophyceae (20 species), and to a lesser extent by Chlorophyceae (11 species) and Cyanophyceae (2 species). Phytoplankton community structure also showed variation, with 71 species contributing to the diversity in 2021 and 62 species in 2019. Though Bacillariophycea dominated during both years, the community was more diverse in 2021comparatively a more saline year Biddulphia sp. Coscinodiscus sp., Cyclotella striata, Melosira sulcata, Pleurosigma sp., and Skeletonema costatum were the diatoms common to both the years, though with varied abundance. Dinophyceae did not show a conspicuous change in community structure in both years, with mostly the same species contributing to the total phytoplankton population but showed slight variation in abundance. Cyanophycea was observed exclusively during the year 2021. The abundance and community structure of the species varied from year to year, but they also changed seasonally, with lower numbers observed during the monsoon compared to the post-monsoon period in both years. CCA analysis identified two groups of phytoplankton assemblages in relation to the prevailing environmental conditions. The Group I species preferred lower temperature and salinity and elevated nutrient concentrations and they dominated during the monsoon season. Group II species preferred high saline well oxygenated, nutrient-poor waters and they dominated during the post-monsoon. Furthermore, the trophic state index analysis indicated mesotrophic conditions during the monsoon, while eutrophic conditions were observed in the post-monsoon period.

Towards the development of a ‘land-river-lake’ two-stage deep learning model for water quality prediction and its application in a large plateau lake

Accurate prediction of water quality that is essential for effective lake management requires a comprehensive understanding of influential factors in the ’land-river-lake’ continuum. We develop a novel deep learning model employing a Long Short-Term Memory (LSTM) model for predicting water quality, and apply it for a large plateau lake, Lake Dianchi. The model comprises two stages: the first establishes a correlation between land and rivers by predicting nutrient loads, incorporating socioeconomic and meteorological features. The second establishes a correlation between feeding rivers and the lake by predicting nutrient concentrations, taking water quality, meteorological conditions, riverine import, and agricultural Non-Point Source (NPS) loads into consideration. Compared to single-stage deep learning models developed using classical methods, the two-stage model reduces Mean Absolute Percentage Error (MAPE), Mean Absolute Error (MAE), and Root Mean Square Error (RMSE), indicating enhanced prediction accuracy. Shapley Additive Explanation (SHAP) analysis is further employed to identify key contributing features. Precipitation emerges as the primary feature in the first stage, while in the second stage, disparities in the most contributing features for two zones of the lake are revealed due to dam isolation and water diversion projects. In the main zone, the primary predicting features are temperature and agricultural NPS features, while in the dam-isolated zone, Secchi depth is the key predictor, highlighting spatial–temporal variations in driving features. Our model contributes a novel deep learning framework and valuable insights for water quality management in large lakes, emphasizing the importance of considering the dynamic interplay of features or factors in the ’land-river-lake’ system.

Hydromorphological pressure explains the status of macrophytes and phytoplankton less effectively than eutrophication but contributes to water quality deterioration

Hydromorphological alterations are among the human-induced pressures that must be considered when assessing the ecological status of aquatic ecosystems. We investigated the effects of hydromorphological pressures on the ecological status of lowland lakes in Poland, focusing particularly on macrophyte and phytoplankton conditions. The analysis was based on biological, hydromorphological, and physicochemical data collected from 30 lowland lakes. Almost all biological and physicochemical indices correlated significantly (Spearman's |R|>0.5) with the hydromorphological index LHMS_PL. Using the variation partitioning method, we found that hydromorphological pressures explained only a small proportion (5.5%) of the variability in ecological status assessed using macrophytes. These pressures had no direct effects on the ecological status assessed using phytoplankton. The shared effects of physicochemistry and hydromorphology explained a large proportion of the variability in ecological status indices based on both phytoplankton and macrophytes. The results demonstrated that in the analysed lakes, hydromorphological alterations were usually accompanied by increased nutrient concentrations. This finding indicates that physical alterations may affect lake biological assemblages not only directly but also indirectly by reducing the ecosystem's natural buffering capacity, thereby promoting the eutrophication process.

Response of Hydroponic Tomato Yield and Yield-correlated Morphological Characteristics to Constant or Growth Stage-based Nutrient Management Strategies

In the United States, the annual revenue attributable to tomato production is $1 billion. However, tomato production can cause negative environmental impacts, such as water pollution, often in the form of eutrophication-causing nutrient pollution. Hydroponic production can decrease excess nutrient leaching; however, optimization of nutrient management and cultivar choices could further decrease excess nutrient discharges. The objectives of this study were as follows: to evaluate and compare the responses of tomato growth characteristics, yield, and yield components to two nutrient management regimes (varying nutrient solution concentrations by growth stage and the use of a constant nutrient solution concentration from transplant to termination), and to analyze the effects of growth habits among six cultivars (Big Beef, Cherokee Purple, Heatmaster, Legend, Mountain Fresh Plus, and Tropic) on tomato yield and yield-correlated morphological characteristics. The nutrient management strategies were applied to tomato plants, and data regarding yield and related morphological characteristics were obtained. Data were analyzed using SAS PROC GLM. An analysis revealed no significant difference in the total fruit weight/plant between nutrient management regimes (P = 0.05); however, the mean fruit weight (164.26 g) and diameter (71.70 mm) were significantly greater (P &lt; 0.0001) for plants that received the constant concentration nutrient regime. Indeterminate plants had a significantly greater (P &lt; 0.0001) mean fruit weight (192.76 g) and mean fruit diameter (76.42 mm). Among cultivars, Big Beef had a significantly greater (P &lt; 0.05) total fruit weight/plant (9.25 kg). Applying a constant nutrient concentration to indeterminate cultivars, particularly Big Beef and Cherokee Purple, improved the factors analyzed and could decrease negative environmental impacts while increasing profits of the producers.

Root puppet masters: Infauna shift trait-productivity relationships in submerged aquatic vegetation communities.

Submerged aquatic vegetation (SAV) growth can be limited by light and nutrient availability. Infauna are common inhabitants of SAV meadows. Their activity increases nutrient mobility, and they can positively affect plant growth, but we do not know their role in plant trait-biomass production relationships. We approached this problem using a 15-week insitu transplant experiment in the Baltic Sea with experimental additions of Macoma balthica, a sedentary bivalve, to experimental SAV communities. Experimental plant communities were tricultures with varying species composition, compiled from a pool of six different species, to create an experimental gradient of trait community weighted means that allowed us to detect changes more clearly in plant trait-biomass production relationships in response to the M. balthica treatment. We evaluated the relationships between plant height, leaf area, maximum root length (MMRL), specific root length (SRL), and SAV biomass production, then compared M. balthica condition index (soft tissue biomass [WW, mg]/valve length [mm]) to plant community leaf tissue nutrient concentrations (N (%DW), δ15N). Community biomass production was significantly related to plant height in the control treatment, but this relationship was decoupled in the M. balthica treatment, where community biomass production was instead significantly related to MMRL and SRL. This suggested a shift in the predominant SAV growth strategy, from height-related to root-related community biomass production. Leaf tissue δ15N was significantly related to M. balthica condition index. The growth of one species, Potamogeton perfoliatus, was significantly inhibited by the M. balthica treatment. Our results show that infauna have an important role in the plant traits related to community biomass production, and they have the potential to shape plant community structure via selective influences on different plant species.

The global process of eutrophication and its features in Arctic lakes as a consequence of climate warming

An analysis of the problem of water bodies eutrophication as a global process is presented. The volumes increasing use of nitrogen and phosphorus on a planetary scale are shown, the dispersion of which leads to an increase in the content of nutrients in lakes and rivers. The results of original studies of remote lakes in the Arctic zone are presented, which showed an increase in the concentrations of nutrients in lakes in recent decades. A tendency has been revealed for an increase in the contents of nitrogen and phosphorus, as well as organic matter in lake waters, even in the absence of anthropogenic influence. It has been established that an increase in temperature and climate warming in the Arctic regions exert the main influence on the increase in the content of nutrients and the trophic status of lakes.

Spatial variability of bacterial biofilm communities in a wastewater effluent-impacted suburban stream ecosystem.

Streams in arid and semi-arid biomes are often dependent on their flow from municipal sources, such as wastewater effluent. However, wastewater has been shown to contain high concentrations of nutrients and chemical pollutants that can potentially harm aquatic ecosystems and their biota. Understanding if and the type of microorganisms that respond to pollution sources, specifically effluent from wastewater treatment facilities, in regions where flow is predominantly from treatment facilities, is critical for developing a predictive monitoring approach for eutrophication or other ecological degradation states for freshwaters.

Phycoremediation of Domestic Waste Water and Biodiesel Extraction from Fresh-Water Microalgae

ABSTRACT: Microalgae have recently drawn attention as a potential source for the sustainable production of biotechnologically valuable resources and improving the environment in various ways. They are widely distributed and can thrive even under extreme circumstances like high temperatures or high salinity. However, producing microalgae takes a lot of nutrients, which may have an adverse impact on the environment and the economy. The use of wastewater, particularly those from agro-industrial facilities, domestic waste waters, and industrial discharges, which often contain high nutrient concentrations, can serve as an alternative to synthetic culture media. Because the composition of wastewater and usual culture media is relatively similar, wastewater can be utilized to both clean itself and culture microalgae at the same time. Utilizing microalgae as wastewater bioremediation agents can efficiently remove N and P from domestic wastewater, maintain dissolved oxygen concentration, and reduce the various disease-causing pathogens and fecal bacteria that are present in domestic wastewater. The potential of microalgae to be used as a feedstock is increased by their ability to change the composition of their biomass under stress and accumulate lipids or carbohydrates that might be used to produce biodiesel. Methyl or ethyl esters of fatty acids produced from triglycerides by transesterification process by using renewable feedstocks are known as biodiesel. The microalgal biomass is considered as the next generation of feedstock for biofuel production. The Dual function of microalgae in domestic wastewater treatment and biomass growth for biodiesel production is outlined and discussed in detail in this review paper.

Omitting the Application of Nitrogen or Potassium Reduced the Growth of Young Chestnut (Castanea sativa) Trees, While a Lack of Boron Decreased Fruit Yield

The chestnut tree (Castanea sativa Mill.) is gaining importance in the mountainous regions of southern Europe due to the high value of its fruits. It is essential to establish effective cultivation protocols, considering that this species is still relatively understudied. In this study, we present the outcomes of the initial establishment of a chestnut orchard conducted through a nutrient omission trial for four years. The treatments included a fertilization plan with nitrogen, phosphorus, potassium, and boron (NPKB), the control, and four other treatments corresponding to the omission of each nutrient (-NPKB, N-PKB, NP-KB, NPK-B). The -NPKB and NP-KB treatments showed significantly lower trunk circumferences and canopy volumes compared to the other treatments. The NPK-B treatment resulted in the lowest fruit production, with a total accumulated yield (2020–2022) of 0.56 kg tree–1, a value significantly lower than that of NPKB (1.12 kg tree–1) and N-PKB (1.19 kg tree–1). The assessment of nutrient concentrations in the leaves revealed plants with deficient levels of B and K in treatments that did not receive these nutrients. Conversely, N levels in the leaves in the -NPKB treatment fell within the sufficiency range (20 to 28 g kg–1). This suggests that the sufficiency range should be adjusted to higher values, given the treatment’s effect on tree growth. It was also observed that the -NPKB treatment led to lower soil organic matter compared to the other treatments, likely due to reduced herbaceous vegetation development under the canopy, leading to decreased organic substrate deposition in the soil. The main findings of this study are that N and K were crucial elements for the optimal growth of chestnut trees, while B played a significant role in fruit production.

Anomalous 2022 deep-water formation and intense phytoplankton bloom in the Cretan area

Abstract. The Mediterranean Sea is a quasi-permanently stratified and oligotrophic basin with intense late-winter and early-spring phytoplankton blooms typically limited to few regions (i.e. northwestern Mediterranean Sea, the southern Adriatic Sea, and the Rhodes Gyre). In these areas, blooms are sustained by nutrient injection to surface layers by winter vertical mixing and convective processes. A markedly intense bloom was predicted in spring 2022 in an unusual area of the southeastern Mediterranean Sea (i.e. southeast of Crete) by the Mediterranean Sea Copernicus Marine Forecasting Centre (MED MFC) system. Combining Copernicus modelling and observation products, the 2022 event and a number of driving and concurrent features have been investigated in a multidisciplinary way. A noticeable cold spell that occurred in Eastern Europe at the beginning of 2022 has been identified as the main driver of an intense deep-water formation event, with associated high nutrient concentrations in the surface layers. Consequently, an extreme phytoplankton bloom that was 50 % more intense than usual occurred in the area southeast of Crete, starting nearly 1 month later than usual and lasting for 3–4 weeks. Impacts on primary production were also relevant in the 2022 event area and were 35 % higher than the climatological annual primary production. Furthermore, the documented link between primary productivity and fishery catches suggests possible consequences along the whole food chain up to the marine ecosystem in the eastern Mediterranean Sea.