Average Nutrient Concentrations Research Articles

Estimating nutrient concentrations and uptake in rice grain in sub-Saharan Africa using linear mixed-effects regression.

Quantification of nutrient concentrations in rice grain is essential for evaluating nutrient uptake, use efficiency, and balance to develop fertilizer recommendation guidelines. Accurate estimation of nutrient concentrations without relying on plant laboratory analysis is needed in sub-Saharan Africa (SSA), where farmers do not generally have access to laboratories. The objectives are to 1) examine if the concentrations of macro- (N, P, K, Ca, Mg, S) and micronutrients (Fe, Mn, B, Cu) in rice grain can be estimated using agro-ecological zones (AEZ), production systems, soil properties, and mineral fertilizer application (N, P, and K) rates as predictor variables, and 2) to identify if nutrient uptakes estimated by best-fitted models with above variables provide improved prediction of actual nutrient uptakes (predicted nutrient concentrations x grain yield) compared to average-based uptakes (average nutrient concentrations in SSA x grain yield). Cross-sectional data from 998 farmers' fields across 20 countries across 4 AEZs (arid/semi-arid, humid, sub-humid, and highlands) in SSA and 3 different production systems: irrigated lowland, rainfed lowland, and rainfed upland were used to test hypotheses of nutrient concentration being estimable with a set of predictor variables among above-cited factors using linear mixed-effects regression models. All 10 nutrients were reasonably predicted [Nakagawa's R2 ranging from 0.27 (Ca) to 0.79 (B), and modeling efficiency ranging from 0.178 (Ca) to 0.584 (B)]. However, only the estimation of K and B concentrations was satisfactory with a modeling efficiency superior to0.5. The country variable contributed more to the variation of concentrations of these nutrients than AEZ and production systems in our best predictive models. There were greater positive relationships (up to 0.18 of difference in correlation coefficient R) between actual nutrient uptakes and model estimation-based uptakes than those between actual nutrient uptakes and average-based uptakes. Nevertheless, only the estimation of B uptake had significant improvement among all nutrients investigated. Our findings suggest that with the exception of B associated with high model EF and an improved uptake over the average-based uptake, estimates of the macronutrient and micronutrient uptakes in rice grain can be obtained simply by using average concentrations of each nutrient at the regional scale for SSA. Further investigation of other factors such as the timing of fertilizer applications, rice variety, occurrence of drought periods, and atmospheric CO2 concentration is warranted for improved prediction accuracy of nutrient concentrations.

Clockwise hysteresis of diatoms in response to nutrient dynamics during eutrophication and recovery

AbstractMany lake ecosystems that have been severely disturbed by eutrophication, have also experienced large human efforts to restore “natural” conditions. However, the trajectories and the extent of recovery of these lake ecosystems are still poorly understood. In many shallow lakes, recovery was often delayed and counter‐clockwise hysteretic. Here, we study recovery and ecosystem trajectories in a large and deep lake using diatom remains in sediment cores and time series of phosphorus concentrations. We identified four periods of diatom community change: slow change during early eutrophication, thereafter a short period of rapid change after the 1950s, followed by community stability from the 1960s to the mid‐1980s, and finally a recovery phase until 2010. Diatom community structure responded quickly and in a saturating way to increasing phosphorus concentrations, but also fast to phosphorus decline. Hence, diatom community dynamics did not show counter‐clockwise hysteresis but was characterized by a high degree of recovery and clock‐wise hysteresis (CWH). We suggest that CWH in response to eutrophication and recovery is a typical and previously overlooked feature of deep lakes, which results from a more rapid change of average nutrient concentrations and thus productivity in the epilimnion compared to average nutrient concentrations across the entire water column. Such nonlinear and hysteretic responses to changing nutrients need to be considered when analyzing the effects of other stressors such as climate warming on ecosystem dynamics to prevent erroneous attribution of ecosystem change to other stressors instead of nutrient change.

Impacts of harvesting methods on nutrient removal in Dutch forests exposed to high-nitrogen deposition

ContextForest harvest removal may cause nutrient depletion of soils, when removal of essential nutrients, including nitrogen (N), phosphorus (P), sulphur (S), calcium (Ca), potassium (K) and magnesium (Mg) exceeds their net input by deposition and weImpacts of acid atmospheric deposition on woodland athering minus leaching. Nutrient removal by harvest depends on tree species and the harvesting method, i.e. whole-tree harvesting (removal of stems and branches) versus stem wood removal only.AimThe aim of this study was to assess the impacts of these two harvesting methods on nutrient removal in Dutch forests exposed to high-nitrogen deposition.MethodsTo assess those impacts, we measured nutrient concentrations in stem wood and branch wood of seven major tree species in the Netherlands, i.e. Japanese larch (Larix kaempferi Lamb.), Norway spruce (Picea abies L. Karst.), Douglas fir (Pseudotsuga menziesii Mirb.), Scots pine (Pinus sylvestris L.), silver birch (Betula pendula Roth), beech (Fagus sylvatica L.) and common oak (Quercus robur L.). Average nutrient concentrations in stems were based on measured concentrations in heartwood, sapwood and bark and estimated volumes and densities of these compartments. Similarly, average nutrient concentrations in branches were based on measured concentrations in coarse branches, fine branches and the bark of coarse branches and estimated volumes and densities of these compartments. Removal was assessed by using the average growth rates of these tree species on nutrient poor sandy soils in the Netherlands.ResultsCompared to other countries, N concentrations in the Netherlands were higher in stems, while phosphorus, Ca, K and Mg concentrations in both stems and branches were nearly always lower. The elevated long-term N deposition levels in the Netherlands most likely contribute to this finding, since N deposition causes soil acidification reducing the availability of Ca, K, Mg and P, that could become limiting to growth. Limits for sustainable harvest, above which outputs exceed inputs of nutrients, depend on nutrient, soil type and tree species and are mostly determined by K and P and sometimes Ca, which may already be depleted at relatively low harvest levels on poor sandy soils, in particular for broadleaved species, while depletion of Mg is not likely. Nevertheless, the average growth of forests in the Netherlands appears to be slightly higher than in most other countries in Europe.ConclusionOverall, we thus conclude that limited P, Ca, Mg and K availability in response to elevated N deposition is reflected in reduced contents of these nutrients in stem wood and branch wood but not in growth.Key messageNutrient concentrations in tree compartments were assessed for seven major tree species in the Netherlands. Concentrations of phosphorus, calcium, potassium and magnesium (base cations) in stems and branches are mostly lower compared to those in other countries, while nitrogen concentrations are higher. A long-term nitrogen deposition has likely contributed to these differences. The average growth has not declined, despite the low availability of phosphorus and base cations. Limiting the harvest of branch wood is suggested on nutrient poor soils to avoid depletion of phosphorus and base cations.

Nutrient Partitioning and Dynamics in Coriaria nepalensis Wall Dominated Shrublands of Degraded Hills of Kumaun Himalaya

Coriaria nepalensis is one of the shrubs which have the ability to mitigate the frequency of perilous natural events or natural calamities. This paper elucidates the nutrient dynamics of C. nepalensis shrublands in degraded hills of Kumaun Himalaya. The average nutrient concentration (N, P, and K) in aboveground components of C. nepalensis was in the following order: Foliage > Twigs > Branches > Bole wood, whereas in belowground components the order was: Fine roots > Lateral roots > Stump root. The order of contribution to total nutrient storage in vegetation was: Tree > Herbs > Shrubs. The proportion of nutrients stored in the shrub layer was in the order: N > K > P. The soil stored a maximum proportion of nutrients at each site (79.48–87.54% N, 70.47–87.88% P, 74.33–88.27% K). Maximum nutrient storage in soil and vegetation was recorded for site 3 (Barapatthar) and minimum for site 1 (Pines). The uptake of N, P, and K by vegetation ranged from 428 to 1,353 kg ha–1 yr–1, 32–102 kg ha–1 yr–1, and 109–479 kg ha–1 yr–1, respectively. In the present study, the turnover time was 1.06–1.33 years for N, 1.03–1.15 years for P, and 1.02–1.13 years for K. Compartment models reflect the distribution of nutrients and net annual flux that will help to develop the management plan to maintain the fertility and productiveness of the degraded sites.

Harmful algal bloom dynamics in a tidal river influenced by hydraulic control structures

The Singok weir, an instream structure in the Han River estuary constructed in the 1980s for multiple purposes, has interfered with natural river flow. Removal of this structure has been considered to restore water quality, including reducing algal blooms. Spatiotemporal changes in water quality, hydrodynamics, hydrology, and algal growth resulting from the removal of the Singok weir were analyzed using 3-D hydrodynamic, water quality, and sediment transport modules in the Environmental Fluid Dynamics Code model for a five-year period (2013 ∼ 2017) with field data. Weir removal decreased water depth and thus water volume by >10%, which increased average nutrient concentrations given fixed pollutant inputs. With the weir removal, average cyanobacteria decreased in the upper region during summer but increased in the lower region. However, differences in cyanobacteria biomass were less than 1.0 mg Chl-a/m3 except during 2015, the driest summer, where peak cyanobacteria increased by 20% (11.8 mg/m3). Factors limiting summer algal growth tended to increase modestly during normal flow (<3.1%), which suggests the weir removal can potentially enhance algal growth. The role of hydrology stood out as the major factor determining algal growth, with greater relative importance than nutrients, light, and temperature. Simulations showed minimum discharge of 150 m3/s from the Paldang dam was required to avoid excessive cyanobacteria growth downstream. Hydraulic residence time during summer determined the growth potential of algae; low discharge provided sufficient residence time for algae to proliferate, and conversely. This result also emphasizes the importance of seasonal and hydrodynamic assessments when analyzing cyanobacteria in response to external changes, which can be masked in annual average values by numerous factors.

Within-Field Variability in Nutrients for Site-Specific Agricultural Management in Irrigated Cornfield

HighlightsPhosphorus and nitrogen in soil and plants varied during the growing season across the cornfield.Spatial variability in nutrients caused spatial variability in plant growth and crop yield across the cornfield.Hydrological characteristics and soil hydraulic properties were responsible for spatial variability in nutrients.Need to consider spatial variability in nutrients in delineating management zones before adopting management practices.Abstract. The adoption of precision agricultural practices in Alabama has been increasing in recent years. Although challenging, understanding nutrient variability in agricultural fields is important for site-specific management. This study investigated phosphorus (P) and nitrogen (N) variability in an irrigated cornfield located in the Town Creek Watershed of Tennessee Valley Region of Alabama, USA during the 2019 growing season. Three different irrigation management zones (high yield-HY, moderate yield-MY, and low yield-LY) were delineated based on ten years of historical records of crop yield, soil texture, and measured topography using the Management Zone Analyst (MZA) software. The soil samples at 0 to 15 cm, 15 to 30 cm, and 30 to 60 cm depths were collected five different times during the 2019 growing season. Both manure and inorganic fertilizer were uniformly applied during the growing season. At all soil depths, HY and MY zones had higher soil nutrient concentrations than the field average nutrient concentration. However, the LY zone had below field average soil nutrient concentration in the entire soil profile. The plants (above-ground) in HY and MY zones had higher than average nutrient concentrations and the plants in the LY zone had lower than average nutrient concentrations throughout the cornfield. This site-specific nutrient variation in these zones was due to within-field terrain attributes, differences in soil properties, and surface runoff losses. A significant difference was recorded in the corn yield in the HY and LY zones of the field. Two extreme groups of nutrients were found in the cornfield similar to irrigation management zones (HY and LY). A zone with a higher yield also had higher soil and plant nutrients in the zone (HY), and a zone with a lower yield also had lower soil and plant nutrients in the zone (LY). Incorporating nutrient variability for site-specific management in management zone delineation can help with reducing nutrient application, nutrient loss, and improving yield. This study supports the adopting of precision agricultural management practices based on in-field nutrient variability. Keywords: Corn, Crop yield variability, Irrigation, Management zones, Nitrogen, Nutrient variability, Phosphorus, Site-specific management, Topographical wetness index (TWI).

Nutrient export from largely pristine catchments (Serranía de Cuenca, Central Spain)

We report here the summer nutrient (organic carbon, nitrogen and phosphorus) export from pristine catchments of the Serranía de Cuenca (Central Spain). These mountains are mostly encompassed by forested and rangeland landscapes and appear to have important groundwater outputs. On the basis of instantaneous sampling for nutrient chemistry, including in situ records of discharge in these largely non-gauged areas, nutrient fluxes downstream were estimated. Long-term (1982-2010) annual yields of total nitrogen and phosphorus downstream were also estimated from official data using discharge and concentrations at three larger sub-catchments, with the aim of relating them to the effects of global warming. Average nutrient concentrations in these streams were rather low. The fraction of organic nitrogen content was relatively high, as in other forested catchments. Variability of concentrations changed from one catchment to another, but was wide. Organic carbon, total nitrogen and total phosphorus export downstream ranged from one- for organic carbon and nitrogen to three orders of magnitude for phosphorus, but these values lie within the lower quartile of reported export worldwide. There were no statistically significant relationships between discharge and nutrient concentrations. Water retention by lakes and reservoirs upstream decreased the variability of nutrients, particulate organic carbon and total nitrogen, but total phosphorus retention was unaffected. The catchment surface area and land use were unrelated with the phosphorus export. In-stream biological processes appeared to be negligible for nutrient export. Contrary to the N export the annual P flux export was partly explained by discharge (and hence rainfall) in the long-term, which seemingly suggests a global warming effect for P. Our results suggest that pristine catchments experience a complex behaviour of nutrient export that deserves further research, and should be more detailed to see if groundwater input plays a significant role.

Linkages between catchment characteristics and river water chemistry at the locality scale in the Ikpoba River, Southern Nigeria

This study explored the linkages between catchment characteristics (topography, land cover, soil and geology), average water chemistry (pH, calcium, magnesium, sulphate, nitrate, ammonium, orthophosphate, iron, zinc and lead) and rainfall in the Ikpoba River catchment, southern Nigeria, using statistical and locality-based GIS analyses. The results show that sites with high rainfall and percentage cover of arable and sand-gravel-clay lithologies were characterized by high acidity. There were strong links between average nutrient (𝑃𝑂43−-P, 𝑁𝐻4+-N and 𝑁𝑂3−-N) concentrations and diffuse agricultural sources in the catchment. Rainfall was strongly related to 𝑆𝑂42−, 𝑃𝑂43−-P and 𝑁𝐻4+-N suggesting that atmospheric deposition may influence their riverine concentrations. Results also suggest that decomposition of organic matter from forest stands was a significant driver of nutrient concentrations. Although metals (Fe2+ and Zn2+) were positively related to bedrock geology of sand-gravel-clay, there was no clear link between Pb2+ and the catchment characteristics investigated. Wetlands was found to be attenuating river water chemistry especially 𝑆𝑂42−, 𝑃𝑂43−-P and 𝑁𝐻4+-N concentrations. To underpin current environmental protection strategies, there is need to integrate a GIS-based analysis approach with monitoring data to fully identify the variability patterns in river water chemistry dynamics at local and multiple scales of water resource management in Nigeria.&#x0D; Key words: river catchment, water quality, metals, nutrients, GIS.

Evaluation of the Seasonal Variability of Nutrient in Water of Kuibyshev Reservoir

On the basis of generalization and analysis of long-term data, the peculiarities of the processes of pollution by nutrients of the waters of the Kuibyshev reservoir were studied and the specificity of the seasonal variability of nutrients was revealed. It was revealed that all the nutrients in the water of the Kuibyshev reservoir are characterized by seasonal variability, which is most pronounced in nitrate ions. The results of the study show that in 2009-2015 yrs perennial average monthly concentrations of nutrients did not exceed the fishery standards in the water of the Kuibyshev reservoir.

The change of nutrient situation in the Prydz Bay waters along longitude 73°E, Antarctica, in the context of global environmental change

The spatial and temporal characteristics of nutrient concentrations and their influencing factors along longitude 73°E in Prydz Bay were explored. Nutrient concentrations gradually increased from the continental shelf to the open ocean in summer surface water, and the stable environment in the bay, the chlorophyll a and the ice melting were responsible for this distribution characteristic. There was also clear annual variation of nutrients in the surface water. Average concentrations of nutrients showed the highest values in 2010, while they were the lowest in 2009, which may be influenced by El Nino. In the vertical distribution, there were close relationships between chlorophyll a PO4-P, SiO3-Si, S, and NO3-N depths respectively. Moreover, the variation of water masses also influenced the distribution of nutrients. Overall, the spatial and temporal characteristics of nutrients were closely related to environmental change, and especially to the ice melting in the Prydz Bay.

Nutrient loss from three small-size watersheds in the southern Baltic Sea in relation to agricultural practices and policy

Agriculture is the major contributor of waterborne nutrient fluxes into the Baltic Sea, one of the world's most eutrophication-sensitive areas. Poland, as a large, densely populated state ohf the Baltic Region, with dominating agricultural land use, largely contributes to riverborne loads of N and P. The aim of our study was to examine the input of nutrients from three small first-order agricultural watersheds (Bladzikowski Stream, Gizdepka river and Mrzezino canal) in the Pomerania region, into the Bay of Puck, inner part of the Gulf of Gdansk. This study attempts to give a partial answer as to the question if inputs of nutrients from the 3 analysed watersheds comply with the targets of the Baltic Sea Action Plan (BSAP) and Country Allocated Reduction Targets (CART). The impact of agricultural practices was assessed on the basis of farm questionnaires and calculations of nutrient balances for the examined farms. The nutrient concentrations in the soil and drainage ditches were examined, followed by an assessment of nutrient concentrations in the watercourses at the sampling points located close to the estuaries. The average mineral N fertiliser consumption (109 kg N/ha) in the analysed watersheds was higher than Poland's average. The average N and P surpluses for surveyed farms (96.4 kg/ha and 4.4 kg/ha, respectively) were higher than the EU mean in case of N and markedly lower in case of P. We used Principal Component Analysis which confirmed that there were correlations between nutrient surpluses and nutrient concentrations in streams and/or drainage ditches. The N–NO3 and Pmin concentrations were also correlated to precipitation. The average N concentrations in the analysed watercourses were equal to 1.53 mg/L for Gizdepka, 1.88 mg/L for Mrzezino canal and 3.52 mg/L for Bładzikowski Stream. The mean P concentrations observed in the investigated watercourses were markedly higher than 0.1 mg/L. With regard to BSAP objectives, as well as CART set for Poland, the average nutrient concentrations in rivers should be approximately at the level of 2.5 mg N/L and 0.07 mg P/L.

Future Carbon Emission From Boreal and Permafrost Lakes Are Sensitive to Catchment Organic Carbon Loads

AbstractCarbon storage, processing, and transport in freshwater systems are important components of the global carbon cycle and sensitive to global change. However, in large‐scale modeling this part of the boundless carbon cycle is often lacking or represented in a very simplified way. A new process‐oriented lake biogeochemical model is used for investigating impacts of changes in atmospheric CO2 concentrations and organic carbon loading from the catchment on future greenhouse gas emissions from lakes across two boreal to subarctic regions (Northern Sweden and Alaska). Aquatic processes represented include carbon, oxygen, phytoplankton, and nutrient dynamics leading to CO2 and CH4 exchanges with the atmosphere. The model is running inside a macroscale hydrological model and may be easily implemented into a land surface scheme. Model evaluation demonstrates the validity in terms of average concentration of nutrients, algal biomass, and organic and inorganic carbon. Cumulative annual emissions of CH4 and CO2, as well as pathways of CH4 emissions, also compare well to observations. Model calculations imply that lake emissions of CH4 may increase by up to 45% under the Representative Concentration Pathway 8.5 scenario until 2100, and CO2 emissions may increase by up to 80% in Alaska. Increasing organic carbon loading to the lakes resulted in a linear response in CO2 and CH4 emissions across both regions, but increases in CO2 emissions from subarctic lakes in Sweden were lower than for southern boreal lakes, probably due to the higher importance of imported vegetation‐“generated” inorganic carbon for CO2 emission from subarctic lakes.

ĐẶC ĐIỂM PHÂN BỐ CÁC MUỐI DINH DƯỠNG TRONG NƯỚC ĐẦM Ô LOAN, TỈNH PHÚ YÊN (2012-2014)

The results of three surveys in the O Loan lagoon in the dry season (April 2013) and the rainy season (December 2012 and December 2014) showed that in the rainy season the average concentrations of nutrients in waters (ammonium: 76.8 μgN/l, nitrite: 13.9 μgN/l, nitrate: 55 μgN/l and silicate: 4021 μgSi/l) tended to be higher than those in the dry season (ammonium: 6.0 μgN/l, nitrite: 2.6 μgN/L, nitrate: 35 μgN/l and silicate: 1973 μgSi/l) while phosphate concentraiton did not differ between the two seasons with an average concentration of 66.8 μgP/l in rainy season and 60 μgP/L in dry season. By space, the concentrations of nutrients except nitrate in the lagoon, especially in the southern part, were usually higher than those in the canal connected to the sea. At O Loan lagoon waters, only ammonium (mainly in the southern part of the lagoon) and nitrate (mainly in the canal and southern part of the lagoon) concentrations were higher than the criteria values in the rainy season (December 2014) with pollution coefficient of about 1.2. However, the water quality of O Loan lagoon regarding nutrients always still needs to be monitored because from 1992 to the surveyed time, the concentrations of nutrients containing nitrogen and phosphate had the increasing trend in both seasons.

DNA BARCODING APPLICATION OF MITOCHONDRIAL COI GENE TO IDENTIFY SOME FISH SPECIES OF FAMILY GOBIIDAE IN VIETNAM

The Red river system is a typical example of Southeast Asian rivers that is strongly impacted by human and climatic conditions, especially in the recent period. In this paper, we aim to investigate the longitudinal variation of the water quality of the Red river, in the section from Hanoi city to the Ba Lat estuary. The sampling campaigns were conducted in the dry seasons in 2017 and 2018. The monitoring results showed that the average concentrations of nutrients (NO2-, NO3-, NH4+, PO43-) were still lower than the allowed values of the Vietnamese standard limits for surface water quality (QCVN 08:2015/BTNMT, column A1) whereas the average concentrations of Cl- and TSS exceeded the allowed values of the QCVN 08:2015/BTNMT, column A1 4.6 and 2.3 times, respectively. NO3- and dissolved silica (DSi) concentrations showed a significant variation from the Hanoi site to the Ba Lat site (6.62 mg/l to 1.19 mg/l for NO3- and 5.21 mg/l to 2.14 mg/l for DSi) whereas SO42-, NO2- and Cl- increased markedly in this longitudinal section, especially from the point SH6 where the salinity started to increase. Based on the three different methods for classification of trophic levels and on the different variables observed during the dry seasons in 2017–2018, the nutrient concentrations of the Red river water tended to slightly increase from the site Hanoi (SH1) to the site SH5 at Nam Dinh, indicating the increase of nutrient external input along the river whereas it tended to decrease from the site SH6 (at mesotrophic/eutrophic level) to the last observed site SH9 (at oligotrophic/mesotrophic level) at the sea due to the dilution of seawater. Seawater in dry season could affect directly the river downstream about 35 km far from the sea. The results may be a guide for planning of water use including agricultural irrigation in the Red river estuary.

Hydrodynamic Interaction Enhances Colonization of Sinking Nutrient Sources by Motile Microorganisms.

In this study, we document hydrodynamics-mediated trapping of microorganisms around a moving spherical nutrient source such as a settling marine snow aggregate. There exists a range of size and excess density of the nutrient source, and motility and morphology of the microorganism under which hydrodynamic interactions enable the passive capture of approaching microorganisms onto a moving nutrient source. We simulate trajectories of chemotactic and non-chemotactic bacteria encountering a sinking marine snow particle effusing soluble nutrients. We calculate the average nutrient concentration to which the bacteria are exposed, under regimes of strong and weak hydrodynamic trapping. We find that hydrodynamic trapping can significantly amplify (by ≈40%) the nutrient exposure of bacteria, both chemotactic and non-chemotactic. The subtle interactions between hydrodynamic and chemotactic effects reveal non-trivial variations in this “hydrodynamic amplification,” as a function of relevant biophysical parameters. Our study provides a consistent description of how microorganism motility, fluid flow and nutrient distribution affect foraging by marine microbes, and the formation of biofilms on spherical nutrient sources under the influence of fluid flow.

Research of Biogenic Substances Concentrations and their Connection with Runoff of the Siverskiy Donets River in the Borders of the Kharkiv Area

Purpose. To investigate the spatial-temporal change in the runoff of water, concentration of nutrients in water and establishment of communication between them, on the river Seversky Donets. Methods. Statistical analysis. Results. For the study of water flow and changes in average annual concentrations of nutrients in the Seversky Donets River, selected posts are located: on the border with the Russian Federation (Ogurtsovo village); Pechenezh reservoir; Chuguev city; city of Zmiev. To identify cyclical patterns in runoff fluctuations, chronological and smoothed, using a linear filter, time series for the periods 1923-2016 are used. To identify cyclical patterns in runoff fluctuations, chronological and smoothed, using a linear filter, time series for the periods 1923-2016 are used. The frequency of phases of water content is on average 3-5 years. The average perennial phosphate concentrations in posts are in the range of 0.65-1.96 mg/dm3, and the coefficient of variation is 0.2, that is, the variability of phosphates is negligible. The average concentration of nitrites by posts, for the entire observation period, varies in the range of 0.046-0.26 mg/dm3, and the coefficient of variation of nitrites varies in the range of 0.6-0.9, which indicates a significant variability of the indicator over time. The average annual concentrations of nitrates in the posts vary in the range of 0.71–4.96 mg/dm3, and the coefficient of variation of nitrates is 0.9. Conclusions. The average annual concentration of biogenic substances at the indicated positions has no relation to the cyclicity of the water content of the river, except for the Pechenezh reservoir, where the concentration of nitrites and phosphates changes in synchrony with the average annual water consumption.

Use of Oil Palm Bunch and Plantain Peel Extracts as Alternative Stimulants in Crude Oil Bioutilization by Species of &amp;lt;i&amp;gt;Bacillus&amp;lt;/i&amp;gt; and &amp;lt;i&amp;gt;Pseudomonas&amp;lt;/i&amp;gt;

The potentials of oil palm bunch and plantain peels extracts in the enhancement of crude oil utilization by Bacillus and Pseudomonas species were evaluated. The average concentration of nutrients obtained from the extracts was: Mg = 20.4mg, N2 = 20.7mg, K =63.5mg, Ca = 480.5mg, P =276.5mg and Na = 106.5mg, at pH 6.6 to 8.1 oil palm bunch extract was a better stimulant than plantain peel in the order; MSM > OPB > PP at a correlation of r = 0.55. After 24 hours of incubation, bacillus-LSI utilized the crude oil for carbon and energy better in MSM (91.4%), OPB (52.9%) and PP (50.5%) than Pseudomonas-LSI with 82.6%, 49.4% and 41.5% respectively. The difference in utilization between these test organisms is significantly positive at p > 0.05. Generally, the result imply that organic extract of oil palm bunch and plantain peel are excellent stimulants to crude oil hydrocarbon degrades relative to MSM as control and can be deployed in a cleanup campaign of oil involving less than 10% pollution level in soil and aquatic ecosystems.

Seasonality of Nutrient Flux and Biogeochemistry in an Intertidal Aquifer

AbstractBiogeochemical reactions in coastal aquifers highly affect the nutrient flux associated with submarine groundwater discharge (SGD) to the ocean, which subsequently influences the oceanic environment and ecology. This study investigates a seasonal variation of SGD‐derived nutrient flux to the ocean and nutrient biogeochemistry in an intertidal aquifer of Tolo Harbor, Hong Kong. The results show that the inventory of NOx− and PO43− in the intertidal aquifer has a clear seasonality with a large inventory in summer, a small inventory in spring, and a median inventory in autumn and winter, respectively. Differently, the inventory of NH4+ is large in winter and summer and small in spring and autumn, which results from the coupled effects of seasonal change of both production and removal of NH4+ in the aquifer. The SGD‐derived nutrient (NH4+, NOx−, and PO43−) flux is the highest in summer (271.71, 24.86, and 116.66 mmol·day−1·(m coastline)−1) and is the lowest in spring (114.83, 1.70, and 20.26 mmol·day−1·(m coastline)−1). The majority of SGD‐derived nutrient flux is supported by the local remineralization of organic matter along with seawater infiltration. In autumn, the recharge of seawater induced by tidal pumping significantly shifts the biogeochemical balance of nutrients and is the major source of groundwater nutrients in the intertidal aquifer. Among the various nutrient fluxes (SGD, river discharge, atmospheric deposition, and benthic sediment diffusion) to Tolo Harbor, SGD‐derived PO43− flux is the second major source of seawater PO43− in addition to benthic sediment diffusion. The PO43− loading via SGD is of significance to the primary production in the phosphorus‐limited environment in Tolo Harbor. After considering the natural attenuation of nutrients in a sandy/silty beach aquifer, this study suggests the overestimation of SGD‐derived nutrient loading estimated previously that simply use average nutrient concentration of fresh SGD endmember and saline SGD endmember as the nutrient concentration of total SGD endmember.

A mathematical model of reservoir sediment quality prediction based on land-use and erosion processes in watershed

The aim of this paper is to propose a mathematical model for determining of total nitrogen (N) and phosphorus (P) content in eroded soil particles with emphasis on prediction of bottom sediment quality in reservoirs. The adsorbed nutrient concentrations are calculated using the Universal Soil Loss Equation (USLE) extended by the determination of the average soil nutrient concentration in top soils. The average annual vegetation and management factor is divided into five periods of the cropping cycle. For selected plants, the average plant nutrient uptake divided into five cropping periods is also proposed. The average nutrient concentrations in eroded soil particles in adsorbed form are modified by sediment enrichment ratio to obtain the total nutrient content in transported soil particles. The model was designed for the conditions of north-eastern Slovakia. The study was carried out in the agricultural basin of the small water reservoir Klusov.

Short-term variations in surface water properties in the Sundarban Estuarine System, India

High resolution measurements were carried out to understand the short-term (<1 h) variability of surface water quality parameters in mangrove-dominated Sundarban Estuarine System of West Bengal, India during flood phases of spring-neap tidal cycle in a peak monsoon season August 2014. We observed that tidal propagation of both phases strongly influenced the water quality properties. During spring tide salinity, DO, pH, nitrate, phosphate, silicate, chlorophyll a and phaeopigments concentration exhibited increasing trends; whereas at neap tide nitrate, ammonia and chlorophyll a showed decreasing trends. Average nutrient concentrations were much higher during neap tide than spring tide. All the measured water quality parameters varied in every 15-min interval influenced by the tidal current, mangrove litter fall, re-suspension of bottom sediment and river runoff. The effect of tidal amplitude was observed to be the important factor in determining the variability in most of the water quality parameters.