Eutrophication Process Research Articles

Modelling the influence of environmental parameters over marine planktonic microbial communities using artificial neural networks

Guanabara Bay is a tropical estuarine ecosystem that receives massive anthropogenic impacts from the metropolitan region of Rio de Janeiro. This ecosystem suffers from an ongoing eutrophication process that has been shown to promote the emergence of potentially pathogenic bacteria, giving rise to public health concerns. Although previous studies have investigated how environmental parameters influence the microbial community of Guanabara Bay, they often have been limited to small spatial and temporal gradients and have not been integrated into predictive mathematical models. Our objective was to fill this knowledge gap by building models that could predict how temperature, salinity, phosphorus, nitrogen and transparency work together to regulate the abundance of bacteria, chlorophyll and Vibrio (a potential human pathogen) in Guanabara Bay. To that end, we built artificial neural networks to model the associations between these variables. These networks were carefully validated to ensure that they could provide accurate predictions without biases or overfitting. The estimated models displayed high predictive capacity (Pearson correlation coefficients ≥0.67 and root mean square error ≤ 0.55). Our findings showed that temperature and salinity were often the most important factors regulating the abundance of bacteria, chlorophyll and Vibrio (absolute importance ≥5) and that each of these has a unique level of dependence on nitrogen and phosphorus for their growth. These models allowed us to estimate the Guanabara Bay microbiome's response to changes in environmental conditions, which allowed us to propose strategies for the management and remediation of Guanabara Bay.

Freshwater mollusks from Neogene-Quaternary Dniester and Prut riverine deposits as indicator paleoenvironments: chemical composition of shells and its palaeoecological interpretation

The respective environments in two ancient rivers were studied using geochemical methods with paleogeographic reconstructions of fossil material represented by shells of freshwater bivalve mollusks. The studied outcrops are located in the basins of the Dniester and Prut rivers. Materials were collected from two Pliocene (Brînza, Giurgiuleşti) outcrops and the ages of the second group of localities (Sucleia, Slobozia Mare, Gura Bîcului) are from Middle to Late Pleistocene. The determination of the taxonomic position was carried out using standard malacological methods. Geochemical data were used for the environmental reconstruction and included stable isotope ratio and trace element compositions in subfossil freshwater bivalve shell (Bivalvia: Unionoida). Key indicators of paleoenvironments show changes in water temperature. Changes in the taxonomic composition of bivalve mollusk assemblages also occurred. In the present study, increasing the water temperature caused a change of stenobiont species of bivalve mollusks to eurybiont species. Eutrophication of watercourses, caused by anthropogenic pollution and climate change in the direction of warming, has led to the replacement of pearl mussels of the family Margaritiferidae by more eurybiont species of the family Unionidae in the benthic communities of European oligotrophic rivers. These processes are similar to those deduced for the Neogene-Quaternary watercourses of the Prut and Dniester basins, but they proceed at a much faster pace. They are processes of eutrophication of watercourses – the main factor leading to the catastrophically rapid modern reduction of the ranges of pearl mussel.

Reduced phosphorus loads from the Loire and Vilaine rivers were accompanied by increasing eutrophication in the Vilaine Bay (south Brittany, France)

Abstract. The evolution of eutrophication parameters (i.e., nutrients and phytoplankton biomass) during recent decades was examined in coastal waters of the Vilaine Bay (VB, France) in relation to changes in the Loire and Vilaine rivers. Dynamic linear models were used to study long-term trends and seasonality of dissolved inorganic nutrient and chlorophyll a concentrations (Chl a) in rivers and coastal waters. For the period 1997–2013, the reduction in dissolved riverine inorganic phosphorus (DIP) concentrations led to the decrease in their Chl a levels. However, while dissolved inorganic nitrogen (DIN) concentrations decreased only slightly in the Vilaine, they increased in the Loire, specifically in summer. Simultaneously, phytoplankton in the VB underwent profound changes with increase in biomass and change in the timing of the annual peak from spring to summer. The increase in phytoplankton biomass in the VB, manifested particularly by increased summer diatom abundances, was due to enhanced summer DIN loads from the Loire, sustained by internal regeneration of DIP and dissolved silicate (DSi) from sediments. The long-term trajectories of this case study evidence that significant reduction of P inputs without simultaneous N abatement was not yet sufficient to control eutrophication all along the Loire–Vilaine–VB continuum. Upstream rivers reveal indices of recoveries following the significant diminution of P, while eutrophication continues to increase downstream, especially when N is the limiting factor. More N input reduction, paying particular attention to diffuse N sources, is required to control eutrophication in receiving VB coastal waters. Internal benthic DIP and DSi recycling appears to have contributed to the worsening of summer VB water quality, augmenting the effects of anthropogenic DIN inputs. For this coastal ecosystem, nutrient management strategies should consider the role played by internal nutrient loads to tackle eutrophication processes.

Modeling the interaction of light and nutrients as factors driving lake eutrophication

Eutrophication is a major problem in the field of water environments at present, and its main driving factors are light and nutrients. In this paper, the process of eutrophication in small artificial lake is studied, according to the principle of water optics and conservation of mass, the light and the nitrogen and phosphorus in water nutrients were selected as influencing factors, and 16 different scenarios of light-nutrients interaction conditions were designed by orthogonal experiment. Then water eutrophication model was used to analyze the process of eutrophication under different light-nutrient scenarios. According to the comparison of simulation results, if the concentration of nutrients is increased under low light conditions, the growth of algae will be inhibited; And if the light condition is set to a fixed value, the simulation results under different nitrogen and phosphorus concentrations in the water show that the effect of phosphorus on algae growth is greater than that of nitrogen; In addition, comparing the growth of algae under different light and phosphorus scenarios, it can be seen that the light-driven effect is more significant than that of phosphorus. By simulating all the design scenarios and analyzing the results, it can be found that the algae growth rate reaches a maximum when the light intensity and the nitrogen and phosphorus concentration increase to a certain range; while continuing to increase the light and nutrient concentration exceeds a certain threshold range, the rate of algae growth will be inhibited.

Assessing multimetric trophic state variability during an ENSO event in a large estuary (Río de la Plata, South America)

During the “El Niño”- Southern Oscillation (ENSO) event 2009–2010, trophic state uni (TSI’s) and multimetric (TRIX’s) indexes were determined in the north coast of the Río de la Plata (RdlP). The relationships of such indexes with the hydrological, physical and chemical parameters were explored to identify climatic variability or anthropogenic effects on the eutrophication process. Eleven oceanographic sampling campaigns at 25 stations were conducted along the north coast of RdlP from 2009 to 2011. Temperature, salinity and oxygen saturation, water transparency (Secchi depth), chlorophyll (Chl a) content and total nutrient concentrations (total nitrogen and phosphorous) were determined. Trophic indexes (TSI Chl a, TSI TP, TRIX NP-Voll. and TRIX NP-Mvdeo.) were quantified and the RdlP flow was measured. RdlP flow showed significant differences between ENSO phases, with higher values during “El Niño” (EN), negative and significant correlations with salinity, Secchi depth and positive with total nutrients. The trophic status indexes showed spatial and temporal variability and associations with flow, physical and chemical parameters. Trophic state indexes showed spatial and temporal heterogeneity and were strongly associated to environmental conditions (hydrological and seasonal oscillations) during the study period but also to the anthropogenic factors affecting the north coast of RdlP. The system has been classified as mesotrophic to hypertrophic, depending on the selected indicator. According to these results, we suggest the use of a multimetric trophic state indicator, i.e., the TRIX index, as explains better the causes and effects of the eutrophication processes. To implement the TRIX index, (TRIX NP-Mvdeo.) we suggest researchers to consider a large number of local records (Chl a, nutrients, oxygen) at seasonal scales. This index is adapted to the environmental conditions of the study zone and complemented with other community structure indexes, and should be used for eutrophication assessment programs in the north coast of RdlP.

Simulation of the impact of pollution discharged by surface waters from agricultural areas on the water quality of Puck Bay, Baltic Sea

The paper presents the analysis results of the impact of pollution discharged by surface waters on the quality of the Puck Bay waters. Puck Bay is part of the Gulf of Gdansk and belongs to the Baltic Sea. The analysis was carried out using mathematical modeling. A numerical model of part of the Gulf of Gdansk was achieved, taking into account the current bathymetry and the shoreline shape. The pollutants inflow was assumed point-by-point at the mouth of the main watercourses: Plutnica, Gizdepka, Bladzikowski Creek and the Reda River. The hydrodynamic conditions in the Bay were adopted for several scenarios regarding wind speed and direction. In order to determine the velocity distribution, the Ekman model—dedicated to shallow coastal waters—was used. The spread of pollutants in the Bay’s waters was determined by solving a two-dimensional, partial differential, advection–dispersion equation describing the migration of a non-degradable dissolved matter. The finite volume method was used for the solution. As a result, the extent of pollution in the Puck Bay area was obtained in relation to Natura 2000—the European Union’s protected areas. Visible is the necessity of integrating these conclusions into measure aiming at the mitigation of eutrophic processes in the Baltic Sea. The results of this research may be extended to serve other bay regions adjacent to similar substantial agricultural activities.

Application of WASP model for assessment of water quality for eutrophication control for a reservoir in the Peruvian Andes

AbstractWater quality models are important tools for facilitating assessment of the main processes occurring in an aquatic system. To this end, a water quality analysis simulation programme (WASP8) was used to assess the eutrophication process in El Pañe Reservoir. The reservoir has a useful water volume of 99.6 hm3 and is connected to six other reservoirs located in the Chili Basin of the Arequipa Region. El Pañe Reservoir, which is the basin head, has exhibited eutrophication problems since 2014, causing water treatment problems for human consumption and a high probability of cyanotoxin releases from intensive algal blooms. Accordingly, the reservoir was divided into 11 segments, ammonia, nitrate, phosphate, total phosphate, dissolved oxygen, water temperature and chlorophyll‐a being the simulated water quality parameters. The simulations were set in a steady state condition for 3 years from October 2015 to October 2018, subsequently determining aquaculture activity and benthic flux as being meaningful nutrient sources impacting the phytoplankton community. The results of the present study provide necessary evidence of the need to exhaustively quantify both sources in future research, which will aid decision makers in identifying the best management option that can help guarantee the sustainable development of the involved human activities.

Land Uses Simplified Index (LUSI): Determining Land Pressures and Their Link With Coastal Eutrophication

Human activities on land result in the high-level production of nutrients. When these nutrients reach coastal waters, they could drive the eutrophication process. Here we present the Land Uses Simplified Index (LUSI), an easy-to-use tool for assessing continental pressures on coastal waters. This assessment is done by indirectly estimating continental nutrient loads and concentrations and their influence on coastal waters. LUSI is based on systematic information describing both the land uses that influence coastal waters by providing nutrient-rich freshwater inflows (urban, industrial, agricultural, and riverine) and the coastline morphology, which can modify this influence, as it determines the degree of coastal water confinement and therefore the likelihood that these inflows will be diluted. A low LUSI value indicates that coastal waters are not or only slightly influenced by continental pressures and/or that these pressures are diluted. On the contrary, a high LUSI value indicates that coastal waters are strongly influenced by continental pressures and/or that these pressures are not diluted. LUSI fulfils a methodological gap, as a simple method to assess coastal pressures when there is a lack of information. Furthermore, it fulfils the requirement of the Water Framework Directive for a true pressure assessment (i.e. not confounded with impact), which for coastal waters imply using pressure data from land. An additional and important feature of LUSI is that it allows the establishment of pressure-impact relationships with impact indicators, such as those related to the Biological Quality Elements of the above Directive. For example, a relationship based on LUSI, as a proxy of pressure, and on the chlorophyll-a concentration, as a proxy of phytoplanktonic biomass and, thus, of the eutrophication impact. By providing insights into the land uses that trigger eutrophication in coastal waters, LUSI aids in the design of measures aimed at remediating anthropogenic damage caused to the environment.

Distribuição espacial da concentração de nutrientes em sedimentos na Laguna hipersalina de Araruama – RJ, Brasil

The present study was carried out in Laguna de Araruama, Rio de Janeiro. Pollution in the lagoon has hampered the ecosystem structure and caused the eutrophication process to intensify. In order to improve water quality, it is proposed to open channels of the lagoon with the sea, but may result in the remobilization of the nutrients in the sediment to the water column. Considering the importance of sediment as a nutrient storage compartment, the objective of this study was to determine nutrient concentrations in sediments and interstitial water and their distribution in the sediments. Measurements of pH and Eh were made in the sediment, conductivity and temperature along the water column. The granulometry was determined and the concentrations of ammonium, nitrite, nitrate and phosphate in the interstitial water were determined, and the total concentrations of phosphorus, nitrogen and carbon in the sediments. Considering the granulometric results, most of the lagoon has sandy formations. The sediment presented temperatures between 22 °C and 25 °C, basic pH (7.1 - 8.2) and reducing characteristics (-400mV). In the stations near Sao Pedro da Aldeia and Araruama, there are high levels of total nitrogen in the sediment due to the high amount of sewage discharged into the rivers that flow into the lagoon. High concentrations of total phosphorus were also found in the region of the Itajuru Channel, closer to the sea, which due to its lower salinity has higher primary productivity. It is concluded that the lagoon presents a high degree of pollution by nutrients, in specific points, due to the contributions caused by the discharge of sewage

Long-Term Dynamic in Nutrients, Chlorophyll a, and Water Quality Parameters in a Coastal Lagoon During a Process of Eutrophication for Decades, a Sudden Break and a Relatively Rapid Recovery

Coastal lagoons are considered among the marine habitats with the highest biological productivity, and support a great variety of human activities and pressures that make them especially vulnerable to trophic imbalances. While dystrophic crises are common in many lagoons, others like the Mar Menor show homeostatic mechanisms, high resilience, and clear waters. This paper analyses the water column descriptors dynamic during the last 22 years in this coastal lagoon, in the context of a eutrophication process produced by an increase in nutrient inputs, mainly derived from agriculture. Despite water column nitrate concentration increased by one order of magnitude, the lagoon maintained homeostatic regulation for two decades, keeping the water transparency and relatively low levels of nutrients and chlorophyll a (Prebreak phase), followed by a sudden change of state in 2016 with an abrupt increase in average nutrients and chlorophyll a concentration and loss of water transparency (Break phase), and a relatively rapid recovery after the reduction of nutrient discharges (Recovery phase). The activation of the regulation mechanisms seems to manifest through an ammonium production in the water column, as a consequence of the activity in the trophic web. The low correlation between chlorophyll a and nutrients concentration, mainly at small spatio-temporal scales, is in disagreement with eutrophication traditional models, and suggests a rapid response of primary producers to nutrient inputs and a zooplankton control in the short-term, which in turn is controlled by the rest of the trophic web components. Homeostatic properties that in the Mar Menor lagoon have provided resistance to eutrophication are based on several mechanisms: channeling its production toward the benthic system (maintaining high biomasses of primary producers, filter feeders, and detritivores), a top-down control of the pelagic trophic web exerted by ichthyoplankton and jellyfish, and exporting surplus production outside the system. Resilience of the system would be based on the high turnover in the species composition related to the restricted connectivity to the sea, the spatio-temporal variability of the environmental conditions, and the multiplicity of spatial–temporal scales involved in lagoon processes. TRIX index was sensitive to the trophic and water quality changes. However, in our study, its current score does not allow to anticipate or alert the eutrophication risk and the trophic breakpoint of the system.

The estimation of nutrient limit for predicting eutrophication using quantile regression model (case study: aquaculture pond at IBAT Punten, Batu)

Aquaculture can be defined as the cultivation of aquatic organisms, and its systems are usually done in pond. Feeding management in aquaculture pond is very important since it will determine the yield of aquaculture production. Primary food source for most aquatic organism is phytoplankton, which its abundance in aquatic ecosystem is affected by nutrient such as nitrate and phosphate, light availability, temperature, and etc. The nutrient content must be maintained at the level that supports a beneficial phytoplankton abundance and a healthy fishery. Because when the nutrients increasing exceeds the desirable rate, the pond begins the eutrophication process. Eutrophic ponds are often undergo large algal bloom that will causing mass fish mortality and other environmental problem. The relationship between nutrients and phytoplankton abundance conventionally using simple linear regression. However, this method is less informative because it cannot provide the estimation limit of nutrient content to prevent eutrophication. This research proposes quantile regression to fix the flaw. The proposed method is applied to nutrient content and phytoplankton abundance of aquaculture pond at IBAT Punten, Batu. The result shows that the nitrate and phosphate limit are estimated at 0.731 mg/L and 0.022 mg/L respectively.

Enhanced mineralization of sedimentary organic carbon induced by excess carbon from phytoplankton in a eutrophic plateau lake

Large additions of organic carbon (OC) have been introduced into the carbon cycle of lakes from algae during the process of lake eutrophication. The impact of eutrophication on OC burial and CO2 fixing has been widely studied; however, there is still a gap regarding the impact of excess OC from algae on sedimentary OC mineralization. In this study, we aim to fill this gap by analyzing in situ measurements. Three pairs of sediment cores collected from a plateau lake (Dianchi Lake) in 2006 and 2014 were used to estimate the accumulation loss rate (ALR) of OC (and thus the total mineralization rate) in the sediment. n-Alkanes, measured from the same sedimentary cores, were used to identify the source of OC. An OC mineralization experiment in a laboratory was used to confirm the enhanced effect of excess phytoplankton carbon on ALR and reveal the potential influence of microorganisms. The results indicate that the sedimentary core (core 3), with high excess OC from algae (located in an algal bloom area), possessed a higher ALR (85.66%) and a higher attenuation coefficient (0.078), indicating the low burial efficiency and short mineralization duration of OC. Sedimentary core 1, controlled by terrestrial OC, had a relatively lower ALR (64.60%) and lower attenuation coefficient (0.029), indicating a high burial efficiency and long period of OC mineralization. The mineralization of OC in core 2 was impacted by terrestrial and endogenous OC, with an ALR of 72.00% and attenuation coefficient of 0.064, which is between that of cores 1 and 3. Excess OC from algae corresponded to an increase in ALR by 32.60% when comparing core 1 to core 3. The increased ALR and attenuation coefficient could be caused by excess OC from algae. Sedimentary OC mineralization indicates that the ALR with dominantly allochthonous OC (64.60%) is much lower than that controlled by autochthonous OC (85.66%). Excess OC from phytoplankton increases the mineralization of OC: not only via increased ALR but also increased mineralization speed. The laboratory experiment on the mixture of algae and sediment suggested that excess phytoplankton OC increased the emission of CO2 by 20–70% (mineralization rate).

Spatial variability and temporal dynamics of cyanobacteria blooms and water quality parameters in Missisquoi Bay (Lake Champlain)

Abstract Cyanobacteria bloom events have been associated with eutrophication processes, along with hydrologic and climate factors. Missisquoi Bay is a portion of Lake Champlain (USA–Canada) that is highly eutrophic and prone to cyanobacteria blooms and cyanotoxins. This study assessed the spatial–temporal influence of nutrients, turbidity and temperature in cyanobacteria distributions during a bloom event in the summer of 2006. Correlations, generalized linear models (GLMs), geostatistics and local indications of spatial association (LISA) autocorrelation analysis tested the influence of nutrient and non-nutrient explanatory variables in cyanobacteria biovolume. Total phosphorus exhibited a high direct correlation with cyanobacteria biovolume. The best performing GLMs included total phosphorus, total nitrogen, Secchi depth (as turbidity) and temperature as explanatory variables of cyanobacteria biovolume. Variogram analysis of those variables resulted in a better understanding of the underlying spatial variation process of the cyanobacteria bloom event. The LISA test revealed a moderate but stable autocorrelation between cyanobacteria biovolume and total phosphorus from 180 to 1,000 m of weight distance, suggesting the possibility of up-scaling the current results to coarse-resolution satellite imagery for more frequent monitoring of bloom events. The LISA test also revealed the spatial–temporal dynamic (movement of cyanobacteria scums) of high cyanobacteria blooms with high total phosphorus concentration.

Influence of land use on trophic state indexes in northeast Brazilian river basins.

Eutrophication is a natural process within the ecological succession of aquatic ecosystems that results from nutrient inputs to water bodies, especially limiting elements such as phosphorus and nitrogen. However, the anthropogenic activities in river basin influence areas accelerate the eutrophication process of water bodies. Eutrophication is a global problem and considered one of the most relevant reasons of aquatic environments' degradation. In this context, watercourses that make up the Eastern Water Planning and Management Region (RPGA) receive high pollutant contributions due to release of wastewater and agriculture diffuse sources from cities located in influence area. The present study aims to evaluate the land use effect in trophic state of the water bodies in Eastern RPGA basins. The Carlson Trophic State Index in 1977, adjusted by Lamparelli 2004, was used to determine the eutrophication degree of the three river basins (Almada, Cachoeira, and Una) located in the Eastern RPGA. The nutrient and chlorophyll a data were obtained from the Monitoring Program (Monitora) of Environment and Water Resources Institute of Bahia (INEMA), covering the period from 2008 to 2015, at thirteen (13) sampling sites, with quarterly collections. The results showed that, among three basins analyzed, Cachoeira River basin presented the worst values for trophic state index (TSI) due to the high level of anthropization, while best results were found in Una basin. It was verified that land use exerted a significant influence on the water quality of bodies of water evaluated.

Geospatial assessment of the Mokra Sura river ecological condition using remote sensing and in situ monitoring data

The use of remote sensing methods for environmental monitoring of the surface water quality is proved. Regression relationships are consistent with ground-based measurements at sampling sites in water bodies and are an effective tool for assessing the ecological status of water bodies. The state of the water bodies of the Mokra Sura river basin varies considerably. The best is the water quality in the upper part of the Mokra Sura river, the worst – in the middle and lower parts. The factors of water pollution are discharges of not enough treated wastewater of industrial enterprises of the Kamyans’koy and Dniprovs’koy industrial agglomeration. The purpose of our search included the following tasks: (a) calculation of integrated environmental water quality indices; b) obtaining satellite information, processing of multispectral satellite images of water bodies using appropriate applied software techniques; c) establishment of statistical dependencies between water quality indexes obtained for biotopically space images and data of actual in situ measurements. The results of systematic hydrochemical control of the Mokra Sura river basin from 2007 to 2011 years were initial data in 4 control areas located in the Dnipropetrovsk region: 1 – the Sursko-Litovske village; 2 – the Bratske village; 3 – the Novomykolayvka village; 4 – the Novooleksandryvka village. Environmental assessment of the water quality of the Mokra Sura river within the Dnipropetrovsk region was based on the calculation the integrated environmental index ( IEI ). Priority pollutants in this case are oil products and ions 2−SO 4, 2 + Mg , 2 + Zn , 6 + Cr . Two images with a difference in three years in April 2015 and May 2017 were used to determine the current changes in the land cover of the study area. Geomorphological assessment of the water network of the Morka Sura river was performed using satellite radar interferometry. Multispectral images of Landsat 5/TM (2007-2011) and Sentinel 2B/MSI (2017) satellite systems were used forremote assessment of water bodies in the study area of the Mokra Sura river basin. The multispectral index TCW (Tasseled Cap Wetness) was used to measure the spectral reflection of the aquatic environment along of the Mokra Sura river flow. The main advantage of the studies is a demonstration of remote sensing capabilities to estimate Mokra Sura river ecological status not only in individual sites, but also throughout the flow – from source to mouth. Follow the necessity to use water from the Mokra Sura river for irrigation, the level of soil water erosion can only increase and enhance the negative processes of eutrophication of reservoirs. Long term technogenic pollution requires information about the state of surface water of fishery, drinking and municipal water use facilities as an integral part of the aquatic ecosystem, the habitat of aquatic organisms and as a resource of drinking water supply. Over 80% of the Mokra Sura river basin surface (IEI 4-12) belong to the classes with the assessment of dirty, very and extremely dirty. The results of studies using remote sensing indicate the need to reduce the streams of not enough treated wastewater to the the Mokra Sura river. The obtained data can be used for ecological assessment of the current and retrospective state of water bodies, development of forecasts of rivers pollution.

Description of fouling population emerging after the episode of eutrophic crisis in the Mar Menor coastal lagoon

Description of fouling population emerging after the episode of eutrophic crisis in the Mar Menor coastal lagoon

Phytoplankton Productivity and Hydrology in an Impacted Estuarine Complex in Northeastern Brazil

The aim of the current study was to evaluate the productive capacity of the phytoplankton community and other environmental variables in the estuarine area of Suape; while considering the constant morphological, sedimentological and hydrological changes, the site has been facing due to the implementation and expansion of an industrial and port complex. The study comprised 6 campaigns: 3 in the dry season and 3 in the rainy season. Water samples were collected from the surface layer of the internal and external portions of the estuarine bay during low spring tides. The salinity ranged from 32.20 to 37.10, the water temperature ranged from 26.60°C to 29.40°C, and the oxygen saturation rate ranged from 58.5% to 114.5%. There was significant seasonal variation. The nitrite concentration was higher during the rainy season, whereas the ammonia concentration was higher during the dry season; the higher ammonia concentration helped increase chlorophyll-a levels and rates of primary productivity, which ranged from 0.02 - 2.45 mg·m−3 and from 0.34 to 4.32 mg·C·m−3·h−1, respectively. Chlorophyll-a < 20 μm was the fraction of biomass most commonly present in the estuarine ecosystem, accounting for 88.6% of the chlorophyll-a-containing biomass, and this reflected the low nutrient content in the water and indicated that the area was free from eutrophication processes. The decrease of rainfall during the sampling months and the anthropogenic changes in the environment led to reduced continental contributions, increased marine interference, nutrient dilution and loss of phytoplankton production capacity in Suape Bay, which severely damaged other trophic links in the ecosystem.

The use of satellite images to determine the boundaries of water bodies and study the processes of eutrophication

The use of satellite images to determine the boundaries of water bodies and study the processes of eutrophication

Physiological tipping points to light reduction underlie seagrass population collapse and abrupt shift in a shallow coastal lagoon

Physiological tipping points to light reduction underlie seagrass population collapse and abrupt shift in a shallow coastal lagoon

Treatment Wetland effluent quality improvement by usage sorbents of various origin

TWs are finding as low-cost and also effective system to treat domestic wastewater. The aim of this study is to find suitable adsorbing material for application in an additional treatment unit where treatment wetlands do not provide sufficient PO43- reduction level. Material M1 is a fine-grained by-product of thermal treatment of carbonate-siliceous rock (opoka) with high content of calcium carbonate CaCO3 in temperature 700°C. Particular disadvantage of material M1 can be very high level of pH (11-12) and causing alkaline solution. Material M2 is lanthanum-modified bentonite (LMB) and was already used for reducing content of phosphorus compounds in lakes and other water bodies to treat effects of eutrophication process. Lanthanum-modified bentonite consists mostly SiO2 and Al2O3 (~80%). The study was conducted on effluent from small (60 pe) treatment wetland (TW) in northern Poland where Hybrid Treatment Wetland (HTW) system was provided. Sorption capacity of material M1 was low and equal 0.9 mg/g. For material M2 this parameter reached value of 2.1 mg/g. Lanthanum-modified bentonite (M2) has shown better abilities to reduce phosphates from wastewater that material M1 – material containing mostly calcium oxide. Also performed study revealed that presence of others contaminations in wastewater is causing difficulties in phosphates removal.