Low Phosphorus Content Research Articles

Parameters of Drainage Waters Collected during Soilless Tomato Cultivation in Mineral and Organic Substrates

The aim was to determine the suitability of various substrates for application in a closed system of soilless tomato cultivation, based on the potential fitness of drainage waters from these substrates for recirculation. Four substrates were used: rockwool, coir substrate, lignite substrate (Carbomat) and biodegradable organic substrate (Biopot). Tomato plants grown in these substrates were fertilized with the same amount of nutrient solution, containing the same concentration of nutrients. The characteristics of drainage water from these substrates were analyzed during cultivation. The highest amount of drainage water was collected from the lignite substrate Carbomat. However, these leachates showed good properties for further recirculation: low electro conductivity and turbidity, high nutrient content, moderate microbial load with high population of Trichoderma fungi, and being beneficial for plant growth. Moreover, Carbomat produced the highest tomato yield compared to other substrates. This indicates that this organic substrate is an efficient alternative to rockwool and its drainage water may be reused in a recirculation system. On the contrary, the drainage water from the Biopot substrate showed the worst qualities: high pH and low EC, low concentration of nitrate nitrogen and phosphorus, very high turbidity and a high number of microorganisms. These parameters do not qualify Biopot drainage waters for reuse.

Enhanced hydraulic cleanability of biofilms developed under a low phosphorus concentration in reverse osmosis membrane systems

A critical problem in seawater reverse osmosis (RO) filtration processes is biofilm accumulation, which reduces system performance and increases energy requirements. As a result, membrane systems need to be periodically cleaned by combining chemical and physical protocols. Nutrient limitation in the feed water is a strategy to control biofilm formation, lengthening stable membrane system performance. However, the cleanability of biofilms developed under various feed water nutrient conditions is not well understood.This study analyzes the removal efficiency of biofilms grown in membrane fouling simulators (MFSs) supplied with water varying in phosphorus concentrations (3 and 6 μg P·L-1 and with constant biodegradable carbon concentration) by applying hydraulic cleaning after a defined 140% increase in the feed channel pressure drop, through increasing the cross-flow velocity from 0.18 m s-1 to 0.35 m s-1 for 1 h. The two phosphorus concentrations (3 and 6 μg P·L-1) simulate the RO feed water without and with the addition of a phosphorus-based antiscalant, respectively, and were chosen based on measurements at a full-scale seawater RO desalination plant. Biomass quantification parameters performed after membrane autopsies such as total cell count, adenosine triphosphate, total organic carbon, and extracellular polymeric substances were used along with feed channel pressure drop measurements to evaluate biofilm removal efficiency. The outlet water during hydraulic cleaning (1 h) was collected and characterized as well. Optical coherence tomography images were taken before and after hydraulic cleaning for visualization of biofilm morphology.Biofilms grown at 3 μg P·L-1 had an enhanced hydraulic cleanability compared to biofilms grown at 6 μg P·L-1. The higher detachment for biofilms grown at a lower phosphorus concentration was explained by more soluble polymers in the EPS, resulting in a lower biofilm cohesive and adhesive strength. This study confirms that manipulating the feed water nutrient composition can engineer a biofilm that is easier to remove, shifting research focus towards biofilm engineering and more sustainable cleaning strategies.

AURUBIS Cu-PHC

Abstract Aurubis Cu-PHC is a deoxidized, oxygen-free copper with a very low residual phosphorus content. It combines good electrical conductivity with excellent hot and cold formability and excellent joining characteristics. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as heat treating and joining. Filing Code: Cu-915. Producer or source: Aurubis AG.

Lameness in fattening pigs \u2013 Mycoplasma hyosynoviae, osteochondropathy and reduced dietary phosphorus level as three influencing factors: a case report

BackgroundMultiple diagnostic procedures, their results and interpretation in a case with severe lameness in fattening pigs are described. It is shown that selected diagnostic steps lead to identification of various risk factors for disease development in the affected herd. One focus of this case report is the prioritization of diagnostic steps to verify the impact of the different conditions, which finally led to the clinical disorder. Assessing a sufficient dietary phosphorus (P) supply and its impact on disease development proved most difficult. The diagnostic approach based on estimated calculation of phosphorus intake is presented in detail.Case presentationOn a farrow-to-finishing farm, lameness occurred in pigs with 30–70 kg body weight. Necropsy of three diseased pigs revealed claw lesions and alterations at the knee and elbow joints. Histologic findings were characteristic of osteochondrosis. All pigs were positively tested for Mycoplasma hyosynoviae in affected joints. P values in blood did not indicate a P deficiency, while bone ashing in one of three animals resulted in a level indicating an insufficient mineral supply. Analysis of diet composition revealed a low phosphorus content in two diets, which might have led to a marginal P supply in individuals with high average daily gains with respect to development of bone mass and connective tissue prior to presentation of affected animals. Finally, the impact of dietary factors for disease development could not be evidenced in all submitted animals in this case.ConclusionsMycoplasma (M.) hyosynoviae was identified to be an important etiologic factor for disease. Other, non-infectious factors, such as osteochondrosis and claw lesions might have favored development of lameness. In addition, a relevant marginal P supply for pigs was found in a limited time period in a phase of intense growing, but the potential interaction with infection by M. hyosynoviae is unknown.The presented case of severe lameness in fattening pigs revealed that three different influences presumably act in pathogenesis. Focusing only on one factor and ignoring others might be misleading regarding subsequent decision-making for prevention and therapy. Finally, clinical symptoms disappeared after some changes in diet composition and anti-inflammatory treatment of individual animals.

Synthesis of reactive DOPO-based flame retardant and its application in polyurethane elastomers

An inherently flame-retardant polyester diol (FRPE) containing phosphorus was successfully synthesized via condensation polymerization with the commercial reactive flame retardant 9,10-dihydro-10-[2,3-di(hydroxycarbonyl)propyl]-10-phospha-phenanthrene-10-oxide (DDP), adipic acid (AA), ethylene glycol (EG), and 1,4-butanediol (1,4-BDO). Flame-retardant polyurethane elastomers (FR-PUEs) were subsequently produced by employing FRPE, 4,4-diphenylmethane diisocyanate (MDI) and 1,4-BDO. The mechanical and thermal properties and flame retardancy of the resulting FR-PUEs were characterized by tensile tests, thermogravimetric analysis (TGA), differential scanning calorimetric (DSC) analysis, dynamic mechanical analysis (DMA), limiting oxygen index (LOI) analysis, vertical burning tests (UL-94), and cone calorimeter (CC) analysis. It was suggested that DDP would increase the interaction between the hard and soft segments, resulting in FR-PUEs of unexpected higher tensile strengths of up to 40.0 MPa. In addition, it was found that the introduction of DDP can give rise to an increase of the residual char yield and limiting oxygen index (LOI), whereas reduces the total heat release (THR). Especially, using a low phosphorus content of 0.72 wt.%, the vertical burning level and LOI of the resultant FR-PUE reached V-0 and 24% respectively, and reduced THR of 52.6 MJ/m2 was obtained. The flame-retardant mechanism of phosphorus in DDP was proposed both in the gas and condensed phases based on cone calorimeter (CC), residual char analyses and TG-IR analysis.

Low concentrated phosphorus sorption in aqueous medium on aragonite synthesized by carbonation of seashells: Optimization, kinetics, and mechanism study

Phosphorus (P) concentration beyond threshold limit can trigger eutrophication in stagnant water bodies nevertheless it is an indispensable macronutrient for aquatic life. Even in low P concentration (≤1 mg L−1), P can be detrimental for ecosystem's health, but this aspect has not been thoroughly investigated. The elimination of low P content is rather expensive or complex. Therefore, a unique and sustainable approach has been proposed in which valorized bivalve seashells can be used for the removal of low P content. Initially, acicular shaped aragonite particles (~21 μm) with an aspect ratio of around 21 have been synthesized through the wet carbonation process and used to treat aqueous solutions containing P in low concentration (P ≤ 1 mg L−1). Response surface methodology based Box-Behnken design has been employed for optimization study which revealed that with aragonite dosage (140 mg), equilibrium pH (~10.15), and temperature (45 °C), a phosphorus removal efficiency of ~97% can be obtained in 10 h. The kinetics and isotherm studies have also been carried out (within the range P ≤ 1 mg L−1) to investigate a probable removal mechanism. Also, aragonite demonstrates higher selectivity (>70%) towards phosphate with coexisting anions such as nitrate, chloride, sulfate, and carbonate. Through experimental data, elemental mapping, and molecular dynamic simulation, it has been observed that the removal mechanism involved a combination of electrostatic adsorption of Ca2+ ions on aragonite surface and chemical interaction between the calcium and phosphate ions. The present work demonstrates a sustainable and propitious potential of seashell derived aragonite for the removal of low P content in aqueous solution along with its unconventional mechanistic approach.

Analysis of Steel Slag Composition and Properties to Facilitate the Search for Rational Slag Recycling Methods

This paper is devoted to the challenging problem of steel slag recycling. This study considers the composition and properties of steel slag, namely, slag of electric and pneumatic steelmaking. Slag of the pneumatic and electric steelmaking was found to be composed of calcium silicate Ca2SiO4, while phosphorus is represented by a complex calcium silicophosphate. Iron is in oxidized forms of FeO, Fe2O3 and Fe3O4 with the following ratios to the total mass of iron oxides, %: 51.51:37.16:11.33 for pneumatic steelmaking slag, and 75.92:20.90:3.18 for electric steelmaking slag, respectively. Chemical composition study showed the following content of the main elements for electric steelmaking slag, mass %: 31.6 – 33.2 Fe; 0.330 – 0.383 P; 19.15 – 19.2 Ca; 4.62 – 5.39 Si; for pneumatic steelmaking slag, mass %: 18.7 – 20.5 Fe; 0.630 – 0.710 P; 27.8 – 28.0 Ca; 4.73 – 5.04 Si. Electron microprobe analysis of slag samples showed the presence of Fe, C, O, P, Ca, Si, Mn, Ti, Cr, and Mg heterogeneously distributed over the sample crosscut surface. Samples had low content of phosphorus, however, this element was found to be accumulated in clusters together with Si and Ca.

Hydrochemical Structural Patterns of the Lena River–Laptev Sea Mixing Zone in the Autumn Period

This study was based on data obtained during the cruise 63 of the R/V Akademik Mstislav Keldysh in September 2015. We examine the features of the hydrochemical structure of the Lena River–Laptev Sea mixing zone. The studies were carried out in the eastern part of the Laptev Sea on a quasi-meridional transect, with the length of 710 km along 130°30' E. The distribution of dissolved oxygen, pH, alkalinity, major nutrients (phosphates, silicon, nitrate, and ammonium nitrogen), and chlorophyll a was analyzed. The relationship between the main hydrochemical parameters and chlorophyll a was considered. The distribution of hydrochemical parameters is similar to the data of previous studies: significant removal of silicon by waters of the Lena River (66.6 μM) with a moderate nitrate content (3.87 μM) and low concentration of mineral phosphorus (0.08 μM) in the area of strong influence of river runoff (salinity of 3.012 PSU). The presence of a near-bottom stagnant water zone in the part of research area affected by river runoff was detected. It is shown that the influx of mineral forms of nitrogen and phosphorus into the marine region of the Lena River delta occurs mostly as a result of nutrient recycling rather than due to the continental runoff.

Trace Level Direct Determination of Phosphorus in Petroleum Products with High Particulate Content

Petrochemical samples are difficult matrices, as they cover a wide range of volatilities, densities, viscosities, and quantities of particulate matter. The analysis of organic samples has always been a challenge for inductively coupled plasma – optical emission spectrometry (ICP-OES). More volatile than aqueous solutions, an organic matrix affects the plasma robustness and stability and creates complicated spectral backgrounds. As a result, the detection limits in organic as compared to aqueous samples are degraded. The goal of this study was to develop a robust and reliable method for trace level phosphorus determination in petroleum products with high particulate content. Selecting the correct sample introduction system, particularly the nebulizer as its most critical component, and optimization of instrument operating parameters are expected to significantly improve the analytical performance of the developed method. Three nebulizers were evaluated, and the analytical performance for the determination of low phosphorus concentration in a number of challenging petrochemical samples with high particulate content was compared. The evaluation included one concentric and two non-concentric nebulizers specifically designed to handle samples with large particles. In order to achieve the lowest possible quantification limits, the optimization of the dilution ratio was carried out for each studied matrix. The results clearly showed that the lowest quantification limit of 0.08 mg kg−1 at 1:3 dilution ratio as well as accuracy, precision, and ability to handle samples with high particulate content was achieved by using one of the non-concentric nebulizers.

Features of rainbow trout farming technology in PE “Zakhidna Rybna Kompania”, for feeding with Aguafeed Fischfutteer

The production of trout products in ponds and aquaculture farms is based on modern and long-term plans for technology and intensification of production, through the introduction of the latest approaches, by borrowing the experience of leading foreign producers, expanding production areas and sectoral investments. The main indicator that characterizes the efficiency of fisheries and reflects the state of production and the level of its economic indicators. is fish productivity Growing trout in aquaculture in a closed water supply is associated with high planting densities per unit area, the use of high-protein granular feed, which must fully meet the needs of fish in all necessary nutrients to ensure a balanced diet. In modern farms for feeding trout use high-protein feed mixtures in the form of grits and pellets. The dynamics of the intensity of growth and development of rainbow trout mainly depends on the location of the farm, the quality of the water supply source, the feeding regime of fish and the quality of feed. Therefore, the aim of the work was based on a review of literature sources and analysis of economic activity of the studied farm to give a general description of trout feed, Aquafeed Fischfutter, used for fish feeding, and determine their effectiveness, taking into account geographical location and abiotic and biotic factors . In addition, the study fish performance when feeding these feeds. Conduct research on the growth rate of rainbow trout, changes in weight and length of larvae, fry, yearlings and commercial fish, in tray, pool and pond cultivation. Develop a scheme for growing all age groups of trout on these feeds. Establish indicators of quality, nutritional value, feed ratio of starting, growth and production feeds. To give an objective assessment of their impact on the growth of larvae, fry, yearlings and commercial rainbow trout in the conditions of trout farming PE “Zakhidna Rybna Kompania”, Perimyshlyany district, Lviv region. The conducted research gives the basis to claim that this compound feed guarantees high daily gain. Being a high-energy feed, its use does not lead to obesity of fish. With intensive feeding, a good ratio of price and productivity of farmed fish is realized. The risk of contamination of water bodies and fish is very low, due to the low phosphorus content and good digestibility of feed – 1.1 kg of feed/kg of fish growth. The feed corresponds to the best world indicators in accordance with buoyancy and stability in water.

PHOSPHORUS AND POTASSIUM RESERVES IN THE MAIN TYPES OF ZONAL SOILS OF THE CHELYABINSK REGION

One of the most important tasks of land monitoring is to control the content of gross and mobile forms of basic nutrients in soils. The phosphate-potassium regime of the soil depends not only on its type and the geochemical composition of the soil-forming rock, but also on the landscape and the level of chemicalization of the soil. The low content of phosphorus in the soil in the main area of agricultural land limits the productivity of agrocenoses. The reserves of potassium in the soils of the region are quite high. However, monitoring of this indicator is still important. A comparative assessment of the phosphate-potassium regime of arable land and virgin lands under the same soilforming process is of scientific and practical interest. According to the research results, it has been established that black soils have the highest reserves level of gross and mobile forms of phosphorus. Dark gray mountain-forest soils have the lowest one. A widespread decrease in the reserves of mobile phosphorus in agricultural soils was revealed. This tendency is especially pronounced in dark gray mountain forest soils, ordinary and southern black soils. According to the results of monitoring, it was revealed that the reserves of exchangeable potassium in the main area of arable land and virgin land are gradually increased. In the dark gray mountain-forest soils, as well as leached black soils for five rounds of the survey, the reserves of exchangeable potassium decreased. It is necessary to adjust the dose of fertilizers into the farms with updated information on the agrochemical properties of the soil, taking into account the content of phosphorus and potassium in the arable layer. Also it is of great importance to take into account their removal with the crop and the utilization rate of nutrients from the soil and fertilizers.

SUBSTANTIATION OF PHARMACOLOGICAL CORRECTION OF THE MINERAL COMPOSITION OF ANIMAL NUTRITION

The pharmacological correction of the mineral composition of animal nutrition has been substantiated. The analysis of the results of studies of fodder by veterinary laboratories of the Novosibirsk region for the period 2018–2019 was carried out. It has been established that in the production of animal fodder such crops as wheat, barley, oats, millet, corn, peas, and soybeans are used. Cereals make up about 85% of the compound fodder, legumes – 45%. It is noted that the mass fraction of moisture and dry matter in all types of animal fodder is within the permissible ranges of the norm. In winter cows are fed with hay, silage and mixed fodder. So protein deficiency (10.69 ± 0.35%) occurs for milk yield above 10 kg per day. The largest amount of crude protein is contained in the meal (36.48 ± 1.31%), the least is in silage (3.08 ± 0.12%). Crude fat is mainly contained in the millcake (9.68 ± 0.83%), and its minimum content is characterized by feed concentrates (0.49 ± 0.39%). Rough forage – hay and straw are rich in fiber (27.04 ± 0.58 and 36.87 ± 1.29%, respectively). A low level of calcium was found in fodder such as silage and grain used for feed purposes – 2.07 ± 0.11 and 2.22 ± 0.21 g / kg, respectively. Potassium deficiency was detected in compound animal fodder (2.75–3.03 g / kg), which requires correction of the diet. A low phosphorus content is noted in roughage, silage, grain (0.07–0.27%). The forage obtained during the ensiling process is provided with zinc at 8.02 ± 1.51 mg / kg, which is a low figure. The iron content in the compound feed is at an average level of supply – 40–50 mg / kg. Evaluation of the mineral composition of different types of feed showed the highest frequency of deviations in the amount of zinc – 42.5%. There are also significant fluctuations in the content of phosphorus and calcium in feed – 26.25 and 23.75%, respectively.

Organomineral phosphate fertilization in millet in sandy soil

ABSTRACT Evaluation of fertilizers is an important premise, given the need for knowing new alternative sources to increase the efficiency in the use of nutrients, especially phosphorus. The objective of this study was to evaluate the growth of millet cultivated in sandy soil under phosphorus doses and sources. The experiment was carried out in a greenhouse, in Sobral, CE, in soil with low phosphorus concentration in the randomized block experimental design, with two sources (monoammonium phosphate - MAP and organomineral fertilizer prepared with MAP and organic compost of waste from small ruminant production - OMF) and four doses of P2O5 (35, 70, 140 and 210 kg ha-1), plus an additional treatment without phosphate fertilization, with three replicates, conducted in the second half of 2015. The variables measured were dry mass production, phosphorus accumulation in the plant and agronomic, physiological and recovery efficiencies. Evaluations were carried out in two cuts in millet plants(65 and 110 days after germination). The data were subjected to analysis of variance, followed by t-test for the sources and regression analysis for the doses, in addition to the Dunnett’s test to compare the phosphate fertilization with the control. In the first cut, it was observed that even at low doses of P2O5 (35 kg ha-1of P2O5), the biomass increases compared to the control. Increment in phosphorus doses increased the accumulation of this nutrient in millet plants. Considering the total accumulated in the two cuts of millet, the organomineral fertilizer promoted higher nutrient content compared to monoammonium phosphate from 127 kg ha-1 of P2O5.

Soil Assessment in Mount Kasunogan’s West Ridge

The soil remains a fundamental asset to human survival and plant development. Soil degradation is additionally a major agricultural and ecological issue in the Philippines as it incredibly influences soil efficiency. This study focused on the soil in the west ridge of Mount Kasunogan, a notable constraint regarding the mountain’s soil quality. The quality of the soil hindered many people who had been trying to rehabilitate the mountain. This research was conceptualized to determine the soil’s soil content in the west ridge of Mount Kasunogan in terms of soil texture, organic matter content, available phosphorus, and exchangeable potassium. This study utilized simple random sampling to gather the soil samples and performed various soil test methods: Potentiometric Method, Walkley-Black Method, Cold-Sulfuric Acid Method, Olsen Method, and Feel Method. Results have shown that the soil in the west ridge is slightly acidic with a pH level of six and eighty-nine (6.89), has low available phosphorus content with one and four (1.4) ppm, moderately deficient exchangeable potassium content of thirty-eight and thirteen (38.13) ppm, and a low percentage of organic matter with only one and sixty-nine (1.69 %) percent. It was recommended that another soil sampling be done to the areas not covered by this study due to the steepness and vastness of the west ridge of Mount Kasunogan.

Mechanism for phosphorus removal from wastewater with fly ash of municipal solid waste incineration, Seoul, Korea

A novel mechanism that combines adsorption with chemical precipitation is proposed to interpret the removal of phosphorus with fly ash of municipal solid waste incineration. Thermodynamic modeling results demonstrate the vital roles of both Ca2+ and OH− in the chemical precipitation process. The mechanism is dominated by precipitation at low phosphorus concentrations, while under high phosphorus concentrations it is under a mixed control by precipitation and adsorption in the filtered solution of fly ash. By subtracting the thermodynamic modeling value of precipitation at certain equilibrium pH from the total removal rate at the corresponding pH, the contribution of adsorption to the total phosphorus removal is calculated for the first time in the fly ash solution. The removal process of phosphorus with calcium-containing waste materials under ambient atmosphere may involve coupled reactions between Ca(OH)2 dissolution, chemical precipitation of hydroxyapatite, adsorption of phosphorus on the surface, and carbonation. The removal efficiency peaks in the CO2-free atmosphere with 100% phosphate removal and 98.9% carbonate removal.

Poly (vinyl alcohol)-oligophosphonate eco-friendly composites with improved reaction-to-fire properties

Flame retardation of poly (vinyl alcohol) with oligophosphonates, either as singular flame retardant filler or in the presence of intumescent additives, is a key to achieving eco-friendly advanced composites with improved reaction-to-fire properties. Herein, following a facile synthetic approach, PVA/oligophosphonate/ammonium sulfate composites were prepared via casting method. It was demonstrated that a low content of phosphorus led to composites exhibiting improved flame retardant properties. The peak heat release rate was substantially reduced in all the cases, depending on the content of oligophosphonates-based flame retardants or ammonium sulfate intumescent additive. Thermogravimetric data showed that the incorporation of the flame retardant significantly increased the phosphorus-rich char yield at elevated temperature.

Trophic state changes of semi-arid reservoirs as a function of the hydro-climatic variability

In semi-arid areas, such as the Northeast Region of Brazil (NRB), droughts lead to reduction of reservoir volumes and to increase of nutrient concentrations. The goal was to evaluate the trophic state index (TSI) of semi-arid reservoirs due to interannual variations of precipitation and stored volume. The study included 65 reservoirs in 8 NRB-based watersheds for 2008–2017. From 2013, NRB faced a severe drought that induced a significant reservoir volume reduction. Although the trophic state was already high before the drought (mostly eutrophic and hypereutrophic), the TSI of 91% of the reservoirs increased in the dry period. However, differently from the other watersheds, in which 100% TSI increase was observed for all reservoirs, the groundwater-rich and the lowest-water demand watersheds presented TSI decreases in 30 and 50% of the reservoirs, respectively. Thus, the impact of droughts on these two watersheds was less pronounced, as a potential result of groundwater flow with low-phosphorus concentration into the reservoirs of the former watershed, and lower nutrient loads/higher stored reservoir volumes of the latter one. Simple empirical equations, which are capable to estimate the mean TSI based solely on precipitation and reservoir volume, showed to be potential tools for integrated water management.

Selective Flotation of Scheelite from Calcite Using a Novel Reagent Scheme

ABSTRACT Scheelite and calcite are usually intergrown calcium minerals that are separated via froth flotation. However, their selective separation remains difficult because of their similar surface properties. 2-phosphonobutane −1, 2, 4-tricarboxylic acid (PBTCA or H5L) is widely used in water treatment due to its low phosphorus content and efficient anti-scaling performance. With its excellent calcium-chelating ability, PBTCA was used as a novel depressant to selectively separate scheelite from calcite in this study. The flotation results of single mineral, binary mixed minerals, and real ore showed that PBTCA could selectively depress calcite at pH 9.0 using sodium oleate as collector. The results of zeta potential measurements, solution chemistry calculation, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and density functional theory calculation indicated that the dominant form of PBTCA was L5-. This anion had a stronger adsorption on negatively charged calcite surfaces through electrostatic interaction. Higher Ca density and stronger Ca activity on calcite promote the adsorption of L5-. Moreover, the active O atoms in L5- could better match with two Ca sites on calcite in the interatom distance. Thus, PBTCA provides a new option for calcite depressants and has great industrial application potential.

Índice do Estado Trófico (IET) em águas amazônicas: baía do Marajó e baía do Guajará

O monitoramento da qualidade da água é de fundamental importância, pois através dela podemos diminuir os problemas relacionados à poluição e contaminação dos corpos hídricos. Pode-se citar como um dos problemas relacionados à qualidade da água a eutrofização, sendo esse um fenômeno que consiste na proliferação de algas em corpos d’água. Pesquisas que visam estudar os índices de qualidade da água são oportunas por ajudarem a evitar problemas maiores, relacionados à saúde pública, bem estar humano e até mesmo a potabilidade. Nesse sentido, este trabalho visou obter o Índice do Estado Trófico (IET) em águas amazônicas e comparar os resultados de fósforo total e/ou clorofila a de acordo com o CONAMA 357/2005. Os cálculos foram realizados de acordo com a metodologia de Lamparelli (2004), sendo uma adaptação para ambientes tropicais do índice adotado por Carlson (1977). Percebe- se que o lago Bolonha e a Baía do Guajará, obtiveram valores de “Supereutrófico” e variação de “Ultraliogotrófico” a “Supereutrófico” respectivamente para IET, sendo possível associar o uso e ocupação do solo próximo aos pontos de amostragens e a interferência urbana do recurso hídrico estudado. Já o rio Pará e o rio Maratauíra apresentaram baixo risco de eutrofização, com predominância do estado “ultraoligotrófico” indicando que as áreas de estudos apresentaram um baixo grau de trofia. Obteve-se valores de fósforo total acima do limite estabelecido pela Resolução CONAMA 357/2005 nos trabalhos realizados na baía do Guajará e no lago Bolonha para águas doces classe 2. Na área portuária de Barcarena e rio Maratauíra, apresentaram concentrações baixas de fósforo total.

Effect of Intercropping on Productivity and Profitability of Sesame under Dryland Arid Conditions

An experiment on sesame intercropping system was conducted during kharif (rainy) season of 2017 on sandy loam soil (8.72 pH, 0.88 EC dS m-1), with low nitrogen (137 kg N ha-1), medium phosphorus (14.4 kg ha-1) and high potassium content (357 kg ha-1) at Agricultural Research Station, Mandor, Jodhpur in randomized block design with 3 replications. Among 7 treatments (T1 – Sole sesame, T2 – Sesame + Urdbean in 3:1, T3 – Sesame + Urdbean in 4:2, T4 – Sesame + Mungbean in 3:1, T5 – Sesame + Mungbean in 4:2, T6 – Sesame + Mothbean in 3:1, T7 – Sesame + Mothbean in 4:2 row ratio), it was found that intercropping of sesame with mungbean in ratio 3:1 resulted significantly higher total productivity and net returns (541 kg ha-1 & Rs. 18270 ha-1) over sole sesame crop (344 kg ha-1 & Rs. 6156 ha-1) followed by mungbean in 4:2 (490 kg ha-1 with net return of Rs. 15164 ha-1) being at par with urdbean in 3:1 (473 kg ha-1 with net return of Rs. 14078 ha-1). It was concluded that mungbean can be grown as a beneficial intercrop in sesame under dryland conditions of Rajasthan.