Sediment Total Nitrogen Research Articles

Reduction of aquaculture wastewater eutrophication by phytotreatment ponds system: II. Nitrogen and phosphorus content in macroalgae and sediment

The presence of intensive fish farms in the Orbetello Lagoon (Italian West Coast) has produced a heavy impact on the environment and has led to a large-scale cyclic development of opportunistic macroalgae. The farms are equipped with phytotreatment basins to treat the effluent. Although it is possible to find reports in the literature of phytotreatment techniques suitable for fish-farming effluents, they refer solely to pilot scale. The flooded areas used for phytotreatment permit the growth of huge quantities of macroalgae, which remove nitrogen (N) and phosphorus (P) from the effluent. These ponds are unmanaged, and N and P are released when this vegetation dies during the Summer. Between June 1999 and May 2000 research was carried out on an intensive fish-farming facility that produces about 100 tonnes per year of European sea bass ( Dicentrarchus labrax L.) and gilt head sea bream ( Sparus aurata L.), occupying a volume of 9000 m 3. The wastewater from the plant is discharged to four phytotreatment ponds, arranged in series, and, ultimately, released into the nearby sea-lagoon canal. The research aims were: (a) to quantify the N and P in the effluent from an intensive fish farm facility which are retained by the macroalgae and sediments as the effluent passes through the phytotreatment system; (b) to detect any seasonal variations in nutrient distribution; (c) to determine spatial distribution of the nutrients between input and output of the phytotreatment system. During the test period the physico-chemical parameters of the water were recorded; sediment total organic carbon (STOC), sediment total nitrogen (STN), sediment total phosphorus (STP), macroalgal total carbon (MTC), macroalgal total nitrogen (MTN) and macroalgal total phosphorus (MTP) were determined. Also the micro- and macroalgal biomasses were determined and a floristic list was made. The data collected over the test period were subjected to discriminant type multivariate analysis. The results indicate that: (1) the system size and water residence time are not sufficient to produce adequate abatement; (2) the quantity of nutrients involved in this system is too high for the system itself to be controlled by macroalgal growth alone; (3) the Ulva rigida biomass develops over too short a period of the year (February–June) and is accompanied by rapid decomposition that produces extreme environmental conditions.

Organic matter diagenesis in sediments on the continental shelf and slope of the Eastern Tropical and temperate North Pacific

Carbon and nitrogen mineralization were determined in sediments from about 100 to 1000 m depth on the continental shelf and slope off the Pacific coast of Mexico and Washington State. Vertical down core profiles of carbon mineralization were measured both as sulfate reduction using short-term 35 S incubations and as net TCO 2 production using long-term anaerobic incubations (`jar’ technique). Nitrogen mineralization was measured as net NH + 4 production using only the latter technique. The down core attenuation of jar rates was described adequately by a double exponential decay model. By subtraction of 35 S rates from jar rates in the upper 3 cm of the sediment, oxic plus suboxic respiration were roughly estimated to account for at least 5–28% (Mexico) and 10–19% (Washington) of the 0–30 cm integrated carbon mineralization. The agreement between measured porewater profiles of TCO 2 and NH + 4 and those estimated by diagenetic modelling using rates obtained from jar incubations in the oxygen deficient zone off Mexico indicated no infaunal irrigation. At all other stations the benthic fauna appeared responsible for considerably lower measured porewater concentrations than predicted by a simple diffusion-based diagenetic model. Total carbon mineralization in sediments off Mexico was reduced 40% with water depth from 100–200 m to 1000 m, while the reduction in the same depth interval off Washington was about 80%. Water depth attenuation of total sediment nitrogen mineralization at the two locations, on the other hand, was almost similar with a reduction of 70–80%. The overall molar C : N ratio of mineralization products was generally higher off Washington than in the oxygen deficient zone off Mexico. It is suggested that the difference in sediment mineralization patterns are associated with changes in water column processes related to the different strength of the oxygen minimum at the two locations.

Macrophyte production in a shallow coastal lagoon. Part II: Coupling with sediment, SPM and tissue carbon, nitrogen and phosphorus concentrations

The spring-summer concentrations of total nitrogen (TN) and total phosphorus (TP) in the top 0–5 cm of sediment in two areas of the Venice lagoon covered by seagrasses and seaweeds, respectively, showed opposite trends. During biomass build up and decomposition, the sediment TN concentration increased by ca. 45% in an area covered by Ulva, whereas, after an early spring increase, TN progressively decreased to a concentration close to the winter values in an area populated by Zostera. A similar trend was recorded for TP, increasing by ca. 18% in the area Ulva-dominated and decreasing by ca. 14% in that populated by Zostera. The concentration of organic carbon (OC), over the same period, increased in the surface sediments of both areas, more in that populated by Zostera (ca. 100%) than in that covered by Ulva (ca. 30%). Winter values were then re-established after October. A similar trend was found at 10–15 cm sediment depth although lower nutrient concentrations were present. The mean concentrations of TN and TP in the particulate matter collected by sediment traps were ca. 3–6 times higher than in the surface sediments in both areas but showed less marked seasonal changes. The spring-summer concentrations of TN and TP in both Ulva and Zostera tissues decreased by a factor of 2–4, with nitrogen possibly acting as a limiting factor. Based on the gross primary production and the tissue nutrient content, the estimated amounts of C, N, P annually recycled by rhizophyte in the lagoon are 200,000–300,000; 11,700–17,500 and 1150–1730 tonnes, respectively. In contrast, the actual nutrient recycling by Ulva is at least one order of magnitude lower. These amounts are much higher than the nutrient availability via point or diffuse sources as well as by surface sediment fluxes; thus the sea is thought to be a major nutrient supplier for macrophyte growth in the lagoon of Venice.

Analysis of total and organic carbon and total nitrogen in settling oceanic particles and a marine sediment: an interlaboratory comparison

Abstract 10 laboratories, using their routine methods, collaborated in a comparison of analyses of total carbon, nitrogen and organic carbon in a single sample of marine sediment and a pooled sample of settling particulate material collected by sediment trap. The standard error of the means from all individual laboratories was ±3% of the mean for all total carbon results, and for total nitrogen in the marine sediment, but was ±7% of the mean for total nitrogen in the sediment trap material. Larger errors (±8% of the mean) were found for organic carbon results from both the marine sediment and the sediment trap material, with a range of results (expressed as a percentage of the untreated dry weight) for the sediment trap sample analyzed here of 5.60–8.03%. When this range is compared with that of particulate organic carbon concentration in sediment trap material obtained by different workers at various deep ocean sites (2.4–10.2%) [Wefer, G., 1989. Particle flux in the ocean: Effects of episodic production, in: W.H. Berger, V.S. Smetacek, G. Wefer (Eds.), Productivity of the Ocean: Present and Past, John Wiley & Sons, pp. 139–154.] it is apparent that a large proportion of the observed oceanic variability could be accounted for by difference in analytical technique. We suggest that the problem stems from the difficulty of accurate separation of the organic and inorganic phases and discuss the inaccuracies involved in the separation. We present evidence that the range of results is partly due to either volatilisation of organic carbon during acid treatment, or incomplete removal of organic matter during thermal treatment. If results from different laboratories are to be compared, as is presently required for basin scale and global studies of ocean carbon cycling and budgets, there is clearly a need for suitable reference materials, rigorous intercalibration and technique development.

Rainfall induced nitrogen and phosphorus losses from Manitoba soils

Losses of total sediment phosphorus, total sediment nitrogen and dissolved nitrite, nitrate and ammonium resulting from natural rainfall erosion were studied in southern Manitoba during the summers of 1988–1990. Soils used were a Gretna clay, Leary sandy loam, Ryerson sandy clay and a Carroll clay loam. "Standard" erosion plots, i.e 22.13 m slope length, 4.6 m wide on a 9% slope were used. Crop management systems were 1) alfalfa, 2) corn, 3) wheat – minimum tillage, 4) wheat – conventional tillage, and 5) fallow. Nutrient losses averaged over the study period were greatest from the corn and fallow treatments, as high as 160 kg ha−1 yr−1 for nitrogen and 70 kg ha−1 yr−1 for phosphorus. Losses from wheat were intermediate. Losses from alfalfa were negligible. Most of the nutrient losses occurred with the sediment fraction, a result consistent with previous studies. Thus, nutrient loss can be estimated from a knowledge of soil loss. The amount of nutrient loss per unit soil varied with soil, and was a function of the inherent nutrient status of the soil. Key words: Nitrogen, phosphorus, rainfall erosion, nutrients

Factors influencing biomass and nutrient content of the submersed macrophyte Egeria densa Planch. in a pampasic stream

We identified factors influencing biomass and nutrient content in E. densa in an enriched pampean stream of Argentina. Physical (current velocity, temperature), chemical (pH, conductivity, dissolved oxygen, nutrient content in water and sediments), and biological variables (biomass and nutrient content of E. densa, biomass of periphyton and other macrophytes) were estimated at each sampling occasion, and mean monthly values estimated. Biomass and nutrient content in E. densa were correlated with these physical-chemical and biological variables. Biomass was positively correlated with ammonium in stream water (P<0.05) and sediment total nitrogen (P<0.01). Nitrogen showed a positive relationship with ammonium (P<0.01), and a negative one with nitrate and periphyton biomass (P<0.05). Phosphorus was positively correlated with soluble reactive phosphorus (P<0.01). The growth of other macrophyte species in the stream seemed to influence E. densa biomass, probably through competition for light. Current velocity was low and not significantly related with E. densa biomass; however, a flood at the beginning of the study washed the macrophyte stand downstream.

Determination of total nitrogen in sediments by using high-pressure bombs and ion chromatography

The standard method for the determination of organic nitrogen in water samples has in the past been based on Kjeldahl's digestion technique which determines nitrogen in the triply negative state. In the presence of sulfuric acid, potassium sulfate, mercuric sulfate and a catalyst, amino nitrogen is converted to ammonium sulfate. Free ammonia and ammoniacal nitrogen are also converted to ammonium sulfate which can be determined spectrophotometrically, or by titration with a standard mineral acid. However, this method is time consuming and the accuracy is variable. An alternative method for the determination of organic nitrogen is the alkaline persulfate digestion technique which oxidizes all the nitrogen in the sample to nitrate as the sole product using potassium persulfate in a strongly alkaline environment under high pressure and temperature. In this paper, a methodology for total nitrogen determination in sediments is developed using 23 ml high-pressure bombs with potassium persulfate and sodium hydroxide. The determination of nitrogen as nitrate was made by using ion chromatography. Urea was used as the nitrogenous compound to calibrate the methodology, which was checked using the Kjeldahl method and showed good agreement.

Macrobenthic Crustacean Characterization of an Estuarine Area

Crustacean species from 48 stations sampled in the soft-bottoms of Ria de Ares-Betanzos (N. W. Spain) have been analysed from the point of view of their composition, distribution, feeding types and their correlations with the environmental factors. Fifty nine species have been identified belonging to the following orders: Amphipods 53%, Decapods 37%, Cumaceans 5%, Isopods 3%, Nebaliids, Mysids and Tanaids (these three included in the group Others) 2%. The trophic groups considered consist of surface deposit-feeders 27%, carnivores 37%, suspension feeders / surface deposit feeders 22.5%, omnivores 6.8% and subsurface deposit-feeders 6%. Highest numbers, diversity and species richness have been found at the outer zone where bottoms were composed of coarse, not sorted sediments in contrast to the minimal values accounted for the muddy bottoms of the inner zones. Ordination and classification analysis show a spatial distribution model principally determined by the sediment types. Other environmental factors as organic carbon and total nitrogen in sediments were found not to be correlated with species, probably due to their moderate values all along the study area.

Nutrients in the sediments of a tropical north-eastern Australian estuary, catchment and nearshore coastal zone

The distribution, transport, accumulation, modification and seasonal variability of sediment nutrients was studied in the Moresby River Estuary, catchment and nearshore zone. Phosphorus was examined by using a quick and analytically simple three-stage sequential extraction scheme that allows for natural environmental processes and differences in bio- availability. Elevated sediment phosphorus concentrations in the catchment during the wet season reflect the application of phosphate fertilizers to the agricultural lands that dominate the catchment. It is suggested that the dispersion and seasonal variability in concentration and distribution of phosphorus are controlled by sedimentary processes (e.g. erosion and transport of sediment) that are intimately linked to hydrological conditions. The physical processes that operate on a time-scale of hours (e.g, tidal currents) dominate sediment phosphorus concentration in the estuary and preclude chemical and biological equilibrium from becoming established in the sediment phosphorus along the length of the estuary. Elevated sediment total Kjeldahl nitrogen concentrations in the catchment reflect the application of nitrogenous fertilizers (mainly urea). The nitrogen distribution patterns differ from those of phosphorus, suggesting that different processes operate to control sediment nitrogen and sediment phosphorus. Low phosphorus concentrations in the sediments suggest that agricultural practices in the catchment and associated anthropogenic inputs are having little, if any, impact on the catchment, river and estuary.

Carbon and nitrogen determinations of carbonate‐containing solids1

Two methods are described for determination of organic carbon, inorganic carbon, and total nitrogen in sediments, sediment trap materials, and plankton. Both methods discriminate organic and inorganic carbon by acidification, avoid losses of acid‐soluble organic and inorganic matter, and utilize an automated CHN analyzer for all elemental determinations. Short‐term precisions for organic carbon and total nitrogen are about ± 1% of the measured value with blank levels &lt; 1.5 µg for each element.

Determination of total nitrogen in sediments and plants using persulfate digestion. An evaluation and comparison with the Kjeldahl procedure

Accuracy and precision of the persulfate and Kjeldahl determinations of total nitrogen in solid samples were assessed with certified standards, plant material and river sediments. Accuracy determined with the certified reference materials was within an acceptable range to assure quality control for routine laboratory analyses. In addition, results obtained by examining plant samples indicated that TPN and TKN were not significantly different. Precision for analyses of all samples was high; however a direct comparison of plant material indicated that TPN (RSD = 5.3%) was more precise than TKN (RSD = 8.4%). TPN is a reasonable alternative to the standard TKN procedure for analysis of sediment and plant materials. The TPN method would increase the feasibility of conducting replicate analyses and would result in increased quality control.