Form Of Inorganic Nitrogen Research Articles

Sravneniye assimilyatsionnoy yemkosti i indeksa trofnosti razlichnykh chastey akvatorii Sevastopol'skoy bukhty

The ecological state of the marine shallow water ecosystem (the case of the Sevastopol Bay) is analyzed by the ratio of assimilative capacity and E-TRIX index depending on the anthropogenic load level for the whole bay ecosystem. As part of analysis, the eastern, central, western parts of the bay were distinguished as well as the Yuzhnaya Bay (southern part). Calculations of the assimilative capacity and E-TRIX index for ecosystems of different parts of the Sevastopol Bay were performed using the in situ data of inorganic nitrogen for the period 1998–2012 obtained from the MHI RAS oceanographic data bank. The paper compares values of ecosystem assimilative capacity calculated for inorganic nitrogen as a prevailing pollutant in municipal and storm wastewaters and E-TRIX trophic index of the sea ecosystem, with the technogenic load and biological process seasonality (warm and cold periods) of nutrient income taken into account. This allowed to properly distinguish water areas, which are most vulnerable in terms of formation of negative ecological events, up to disasters. According to the obtained data, such an area is that of the Yuzhnaya Bay. The second vulnerable water area is the eastern apex part of the Sevastopol bay exposed to the Chernaya River discharge. As the results showed, the situation worsens during winter and spring freshets due to increase in content of inorganic nitrogen forms in the Chernaya River runoff. The ecosystem of the western bay part adjoining the open sea is the safest in terms of nitrate nitrogen assimilative capacity, whereas the central part ecosystem appears to be the cleanest in terms of E-TRIX. The ecosystem most exposed to ecological risks in terms of both indices (assimilative capacity and E-TRIX) is that of the Yuzhnaya Bay (the southern part of the Sevastopol Bay). The observed imbalance of distribution of the calculated trophic index E-TRIX and assimilative capacity in different parts of the Sevastopol Bay is due to various nature of these quantities. The assimilative capacity of an ecosystem is defined by physical, chemical and biological processes given a dynamic removal of pollutants from the ecosystem, whereas E-TRIX is determined, in general, by seasonal variability of nutrient income into the ecosystem.

Development and testing of a 3D-printable polylactic acid device to optimize a water bioremediation process

In the present work, a remediation bioprocess based on the use of a native isolate of Chlorella vulgaris immobilized in an alginate matrix inside a polylactic acid (PLA) device is proposed. This microalga immobilized in alginate beads was previously shown to be useful for the reduction of several chemical and microbial contaminants present in the highly polluted water from the Matanza–Riachuelo watershed. However, these beads had a relatively short shelf life in the natural environment. To overcome this limitation, a 3D-printed PLA device was designed. PLA is a biocompatible and biodegradable material suitable for biotechnological applications. We used Erlenmeyers and stirred-tank bioreactors fed batch with Murashige Skoog (MS) culture medium or water from the Cildáñez stream (one of the water bodies of the aforementioned watershed) to estimate the growth kinetics parameters and the bioremediation capacity of immobilized-microalgal cells as an unconfined system (UcS) or a confined system (CfS) inside PLA devices on Cildáñez water. Although alga’s growth parameters were maximum in the UcS fed with MS medium as substrate, successful bioremediation of the target water was possible using the CfS: all inorganic nitrogen forms and total phosphorus were reduced at least by 90% after 5 days of bioprocess in an agitated bioreactor, whereas aerobic mesophilic bacteria decreased by about 85%. The number of coliforms also decreased. Standardized cytotoxicity tests using Allium cepa seeds carried out to prove the effectiveness of the bioremediation process, confirmed the high degree of decontamination achieved by the use of immobilized microalga confined in a 3D-printable PLA-device.

High nitrogen to phosphorus ratio in a Texas coastal river: origins and implications for nutrient pollution sources and exports

Inorganic forms of nitrogen and phosphorus, oxygen levels, suspended solids, and planktonic primary productivity were monitored in Guadalupe River, a major waterway in southeast Texas. Our measurements have shown elevated levels of inorganic nutrients, with soluble reactive phosphorus reaching into 30 μg/L. Curiously, those elevated levels of nutrients combined with unexpectedly high nitrogen to phosphorus (N:P) ratio and low planktonic primary productivity. We attribute those phenomena to suspended solids acting as a selective sink for phosphorus while preventing effective photosynthesis in planktonic algae. At the same time, the potential for nitrogen removal is limited by abundant oxygen present in the water. This combination of low light, selective phosphorus removal, and high oxygen levels suggest that the Guadalupe River is likely to effectively export nitrogen, but not phosphorus into the estuary.

Coupling Between Carbon and Nitrogen Metabolic Processes Mediated by Coastal Microbes in Synechococcus-Derived Organic Matter Addition Incubations.

Phytoplankton are major contributors to labile organic matter in the upper ocean. Diverse heterotrophic bacteria successively metabolize these labile compounds and drive elemental biogeochemical cycling. We investigated the bioavailability of Synechococcus-derived organic matter (SOM) by estuarine and coastal microbes during 180-day dark incubations. Variations in organic carbon, inorganic nutrients, fluorescent dissolved organic matter (FDOM), and total/active microbial communities were monitored. The entire incubations could be partitioned into three phases (labeled I, II, and III) based on the total organic carbon (TOC) consumption rates of 6.38–7.01, 0.53–0.64, and 0.10–0.13 μmol C L–1 day–1, respectively. This corresponded with accumulation processes of NH4+, NO2–, and NO3–, respectively. One tryptophan-like (C1) and three humic-like (C2, C3, and C4) FDOM components were identified. The intensity variation of C1 followed bacterial growth activities, and C2, C3, and C4 displayed labile, semi-labile, and refractory DOM characteristics, respectively. Alphaproteobacteria, Gammaproteobacteria, Bacteroidetes, and Actinobacteria dominated the quickly consumed process of SOM (phase I) coupled with a substantial amount of NH4+ generation. Thaumarchaeota became an abundant population with the highest activities in phase II, especially in the free-living size-fraction, and these organisms could perform chemoautotroph processes through the ammonia oxidation. Microbial populations frequently found in the dark ocean, even the deep sea, became abundant during phase III, in which Nitrospinae/Nitrospirae obtained energy through nitrite oxidation. Our results shed light on the transformation of different biological availability of organic carbon by coastal microorganisms which coupled with the regeneration of different form of inorganic nitrogen.

Inorganic Nitrogen Form Determines Nutrient Allocation and Metabolic Responses in Maritime Pine Seedlings.

Nitrate and ammonium are the main forms of inorganic nitrogen available to plants. The present study aimed to investigate the metabolic changes caused by ammonium and nitrate nutrition in maritime pine (Pinus pinaster Ait.). Seedlings were grown with five solutions containing different proportions of nitrate and ammonium. Their nitrogen status was characterized through analyses of their biomass, different biochemical and molecular markers as well as a metabolite profile using 1H-NMR. Ammonium-fed seedlings exhibited higher biomass than nitrate-fed-seedlings. Nitrate mainly accumulated in the stem and ammonium in the roots. Needles of ammonium-fed seedlings had higher nitrogen and amino acid contents but lower levels of enzyme activities related to nitrogen metabolism. Higher amounts of soluble sugars and L-arginine were found in the roots of ammonium-fed seedlings. In contrast, L-asparagine accumulated in the roots of nitrate-fed seedlings. The differences in the allocation of nitrate and ammonium may function as metabolic buffers to prevent interference with the metabolism of photosynthetic organs. The metabolite profiles observed in the roots suggest problems with carbon and nitrogen assimilation in nitrate-supplied seedlings. Taken together, this new knowledge contributes not only to a better understanding of nitrogen metabolism but also to improving aspects of applied mineral nutrition for conifers.

Effect of Lumbricus Rubellus and Amynthas Agrestis Earthworms on Soil Biogeochemistry at the Aggregate Scale in Northern Hardwood Forests

ABSTRACT Invasive earthworms can increase both pH and the nitrate concentrations in northern hardwood forests while nitrification is an acidification source. To obtain the nitrogen deposition impact, the soil pH, Ca, greenhouse gas emissions, and inorganic nitrogen forms have been compared for NH4 +-N added and not added spodosol soils at aggregate scale inhabited by Amynthas agrestis (A) (ivasive/non-calciferous), Lumbricus rubellus (R) (non-invasive/calciferous), or no earthworm (C). Soils were classified into the three earthworm treatments by Naïve Bayes classification using all gas emissions, Ca, and pH (misclassification rate of 9.3%). There were significant differences among the earthworm treatments in pH, Ca, N2O, and CO2 emissions. pH varied among earthworm treatments (A < C < R) and reduced over time for all three treatments. Water-soluble Ca and N2O emissions were greater in R than in A soils. Both earthworm treatments had greater NO3 –N concentrations than the control. Stepwise regression identified Ca (4 out of 5 incubations, positive effect, explaining 11% to 26% of pH variance) and CO2 evolution (4 out of 5 incubations, negative effect 4% to 47% of pH variance) as the two most consistent predictors of pH. We consider the earthworm invasion may be an alternative buffering agent for the nitrogen deposition for forests.

Changes of Soil Microbes Related with Carbon and Nitrogen Cycling after Long-Term CO2 Enrichment in a Typical Chinese Maize Field

Elevated atmospheric CO2 concentration (eCO2) has been the most important driving factor and characteristic of climate change. To clarify the effects of eCO2 on the soil microbes and on the concurrent status of soil carbon and nitrogen, an experiment was conducted in a typical summer maize field based on a 10-year mini FACE (Free Air Carbon Dioxide Enrichment) system in North China. Both rhizospheric and bulk soils were collected for measurement. The soil microbial carbon (MBC), nitrogen (MBN), and soil mineral N were measured at two stages. Characteristics of microbes were assayed for both rhizospheric soil and bulk soils at the key stage. We examined the plasmid copy numbers, diversities, and community structures of bacteria (in terms of 16s rRNA), fungi (in terms of ITS-internal transcribed spacer), ammonia oxidizing bacteria (AOB) and denitrifiers including nirK, nirS, and nosZ using the Miseq sequencing technique. Results showed that under eCO2 conditions, both MBC and MBN in rhizospheric soil were increased significantly. The quantity of ITS was increased in the eCO2 treatment compared with that in the ambient CO2 (aCO2) treatment, while the quantity of 16s rRNA in rhizospheric soil showed decrease in the rhizospheric soil in the eCO2 treatment. ECO2 changed the relative abundance of microbes in terms of compositional proportion of some orders or genera particularly in the rhizospheric soil-n particular, Chaetomium increased for ITS, Subgroups 4 and 6 increased for 16s rRNA, Nitrosospira decreased for AOB, and some genera showed increase for nirS, nirK, and nosZ. Nitrate N was the main inorganic nitrogen form at the tasseling stage and both quantities of AOB and denitrifiers, as well as the nosZ/(nirS+nirK) showed an increase under eCO2 conditions particularly in the rhizospheric soil. The Nitrosospira decreased in abundance under eCO2 conditions in the rhizospheric soil and some genera of denitrifiers also showed differences in abundance. ECO2 did not change the diversities of microbes significantly. In general, results suggested that 10 years of eCO2 did affect the active component of C and N pools (such as MBC and MBN) and both the quantities and relative abundance of microbes which are involved in carbon and nitrogen cycling, possibly due to the differences in both the quantities and component of substrate for relevant microbes in the rhizospheric soils.

Soil aggregate size influences the impact of inorganic nitrogen deposition on soil nitrification in an alpine meadow of the Qinghai-Tibet Plateau.

BackgroundAmmonium (NH4+) and nitrate (NO3−) are two inorganic forms of nitrogen (N) that are deposited from the atmosphere into soil systems. As the substrate and product of soil nitrification, these two forms of inorganic nitrogen will affect or be affected by the soil net nitrification rate (Nr). Our knowledge regarding soil nitrification is mainly derived from studies with bulk soil. However, soil is composed of different aggregate fractions, which may have an important impact on Nr.MethodsIn 2017, we collected soil samples from an alpine meadow of the Qinghai–Tibet Plateau and separated them into four soil aggregates (2–4, 1–2, 0.25–1, and <0.25 mm) using the dry sieving method. The four soil aggregate sizes amended with the 2 N deposition forms (NH4+-N and NO3−-N) were then incubated at 25 °C for 28 days, and the soil aggregates for each treatment were collected on day 0, 7, 14, 21, and 28 to determine the NO3−-N concentration. The soil Nr and contribution of soil aggregates to the nitrification rate in the bulk soil were calculated.ResultsThere were differences in the physicochemical properties of the soil aggregates. The addition of N and aggregate size had strong effects on soil Nr, which were significantly increased under high levels of NH4+ addition across all soil aggregates. The Nr during the 4 week incubation period differed among aggregate sizes. Nr in the 2–4 mm aggregates was higher than in the other aggregates, which was correlated with the maximum values of the soil porosity observed in the 2–4 mm aggregates. Furthermore, almost half of the soil was composed of aggregates of <0.25 mm, indicating that the <0.25 mm aggregates made a higher contribution to the nitrification rate in the bulk soil than the other aggregates, even though these aggregates had a lower nitrification ability. Overall, our study revealed that the soil nitrification rate was influenced by both the N addition and soil aggregates, and that the 2–4 mm aggregates had a dominant effect on the response of soil N transformation processes to future nitrogen deposition in the alpine meadow.

Changes in metabolism, growth and nutrient uptake of Ulva fasciata (Chlorophyta) in response to nitrogen source

The form of inorganic nitrogen (N) determines the biofiltration performance of Ulva, particularly by inhibition of nitrate assimilation in the presence of ammonia. In the current study, Ulva fasciata from a biofilter of fishpond effluent was examined for its biomass production, photosynthetic activity, nutrient uptake and activity of nitrate reductase when supplied with either ammonia or nitrate as the sole nitrogen source. The effects of prior acclimation to either nitrogen source were also studied. Cultivation of Ulva with ammonia resulted in a rapid uptake of this nutrient, whereas photosynthesis, uptake of orthophosphate and C:N ratio were greater in cultures with nitrate. The transfer of Ulva from ammonia to nitrate nutrition increased carbohydrate content in the biomass. Longer culture in nitrate did not influence photosynthetic yields, growth, or N and P uptake rate by the algae, but increased both lipid and P content in biomass. Once transferred from ammonia-rich to nitrate-rich seawater, nitrate uptake by Ulva commenced immediately, although the activity of the enzyme nitrate reductase was first detected only 28 h later. Culture of Ulva in different nitrogen forms, ammonia and nitrate, may determine application of the resulting biomass in different industries, e.g., feeding, bioethanol, biofiltration, etc., considering the rapid production of protein-rich Ulva in the presence of ammonia, while yield is lower in the presence of nitrate but the biomass contains more carbohydrates and removes P from the effluent more rapidly.

Nutritional strategy for the preferential uptake of $${{\text{NO}}_{3}}^{ - } {\text{{-}N}}$$ by Phaeocystis globosa

The cosmopolitan alga Phaeocystis globosa forms massive colonies during blooms. In addition to producing haemolytic toxins that affect the ecosystem, centimetre-sized colonies can block nuclear power plant cooling systems. Nitrogen plays a key role in P. globosa blooms; however, the preferred form of inorganic nitrogen taken up by colonies remains unknown. Therefore, we set up four groups with different nitrogen types and levels of enrichment. The culture medium and intracolonial fluid were sampled at different times for the determination of nutrient concentrations to elucidate the nutrient uptake strategy that presumably favours colonies. Although $${{\text{NH}}_{4}}^{ + } {\text{ {-} N}}$$ and $${{\text{NO}}_{2}}^{ - } {\text{{-}N}}$$ were absorbed by the colonies, $${{\text{NO}}_{3}}^{ - } {\text{{-}N}}$$ was the favoured nitrogen, and the average uptake rate of $${{\text{NO}}_{3}}^{ - } {\text{{-}N}}$$ was significantly higher than that of $${{\text{NH}}_{4}}^{ + } {\text{{-}N}}$$ and $${{\text{NO}}_{2}}^{ - } {\text{{-}N}}$$ in each group (P < 0.05). In the enriched groups, the replenishment of $${{\text{NO}}_{3}}^{ - } {\text{{-}N}}$$ in the intracolonial fluid was faster than that of $${{\text{NH}}_{4}}^{ + } {\text{{-}N}}$$. The symbiotic bacteria and some biochemical processes may explain the differences in the nutrient concentrations inside and outside of the colonies. Considering the high consumption of $${{\text{NO}}_{3}}^{ - } {\text{{-}N}}$$ during P. globosa blooms, controlling the concentration of $${{\text{NO}}_{3}}^{ - } {\text{{-}N}}$$ is key to preventing P. globosa blooms.

Effects of nitrogen loading from domestic wastewater on groundwater quality

In this study the effects of nitrogen effluent from a permeable constructed sewage tank on groundwater quality were investigated. Sampling took place before and 1.5 years after the closure. Using a 3D hydrogeological model, the spatial distribution of dissolved inorganic nitrogen (DIN), comprising the species NH4+, NO2- and NO3-, was modelled in the saturated zone and the amounts and changes in the ratio of NH4-N, NO2-N, NO3-N were determined. The first part of our general hypothesis, that the groundwater was heavily contaminated in the area surrounding the sewage tank, was clearly verified, since every investigated nitrogen compound exceeded the contamination limit values; but the second part of our hypothesis, that the degree of contamination would significantly decrease after the sewage tank was taken out of use has not been confirmed, since the amount of nitrogen present in inorganic forms increased in the modelled zone. The increase in DIN and the relatively high concentration of NH4+ (35 mg/L) in the immediate vicinity of the tank can be explained by the fact that organic matter (OM) accumulated over the decades provided a constant supply of inorganic nitrogen forms.

Toward the improvement of total nitrogen deposition budgets in the United States.

Frameworks for limiting ecosystem exposure to excess nutrients and acidity require accurate and complete deposition budgets of reactive nitrogen (Nr). While much progress has been made in developing total Nr deposition budgets for the U.S., current budgets remain limited by key data and knowledge gaps. Analysis of National Atmospheric Deposition Program Total Deposition (NADP/TDep) data illustrates several aspects of current Nr deposition that motivate additional research. Averaged across the continental U.S., dry deposition contributes slightly more (55%) to total deposition than wet deposition and is the dominant process (>90%) over broad areas of the Southwest and other arid regions of the West. Lack of dry deposition measurements imposes a reliance on models, resulting in a much higher degree of uncertainty relative to wet deposition which is routinely measured. As nitrogen oxide (NOx) emissions continue to decline, reduced forms of inorganic nitrogen (NHx = NH3 + NH4+) now contribute >50% of total Nr deposition over large areas of the U.S. Expanded monitoring and additional process-level research are needed to better understand NHx deposition, its contribution to total Nr deposition budgets, and the processes by which reduced N deposits to ecosystems. Urban and suburban areas are hotspots where routine monitoring of oxidized and reduced Nr deposition is needed. Finally, deposition budgets have incomplete information about the speciation of atmospheric nitrogen; monitoring networks do not capture important forms of Nr such as organic nitrogen. Building on these themes, we detail the state of the science of Nr deposition budgets in the U.S. and highlight research priorities to improve deposition budgets in terms of monitoring and flux measurements, leaf- to regional-scale modeling, source apportionment, and characterization of deposition trends and patterns.

Determination and Mapping of the Relationship between Potassium and Ammonium of Calcareous Soils with Different Moisture Content

The aim of this study was to determine the conditions of potassium (K+) and the inorganic form of nitrogen (NH4+), and to map their current status using geographic information systems, in calcareous soils with different moisture content. Potassium in the soil is in exchangeable, soluble and non-changeable forms. Because the ions are fixed by the same mechanism, their release might be expected to be somewhat similar so, it has been suggested that NH4+ and K+ ions are fixed in soils. This study was carried out in the field of Horticulture Fruit Research Unit (AR-GE) in Osmanbey Campus at Harran University. Mean concentrations were evaluated which soils were extracted in dry and moisture conditions respectively. The average concentration was determined K+ 362 and NH4+ 98 ppm in dry soil while were K+ 258, NH4+ 50.26 ppm in moisture soil. Ammonium and potassium in soil were detected to be lower concentrations in moisture than dry conditions. Key words : Ammonium, potassium, CBS, moisture soil, jeostatistic. DOI : 10.7176/JSTR/5-7-03

ЗАКОНОМІРНОСТІ ФОРМУВАННЯ ФІТОПЛАНКТОНУ ЗА РІЗНИХ КОНЦЕНТРАЦІЙ БІОГЕННИХ ЕЛЕМЕНТІВ ТА ОРГАНІЧНОЇ РЕЧОВИНИ

The seasonal dynamics of the concentration of nutrients in the form of inorganic nitrogen (NH4+, NO2, NO3-, ΣN), dissolved phosphorus, organic matter and the connection with the development of phytoplankton in waters with high content of total inorganic nitrogen (from 23.31 to 102.65 mg N/dm3) and its compounds (ammonia - from 8.42 to 76.60, nitrate - from 4.94 to 15.93, nitrite - from 0.077 to 4.35 mg N/dm3) and organic matter (from 8.00 to 21.92 mg O/dm3 by permanganate oxidation values and from 58.46 to 265.2 mg O/dm3 by dichromate oxidation values) were analyzed in paper. The peculiarity of the hydrochemical regime of the reservoirs was phenomenally high relations ΣN:P (133,54-12152,86) during the growing seasons. Found that response algal plankton communities such features hydrochemical regime is a simplification of the structure due to the predominance of representatives of departments Euglenophyta, Chlorophyta and Bacillariophyta, while Chrysophyta, Dinophyta, Charophyta and presented Cryptophyta 1-3 species. The response of phytoplankton to the high content of compounds of inorganic nitrogen is the increase in the number and biomass of green algae, and organic matter - eugenic algae.THE REGULARITIES OF PHYTOPLANKTON FORMATION AT VARIOS BIOGENIC ELEMENTS AND ORGANIC MATTER CONCENTRATIONS

Decoupling Abundance and Biomass of Phytoplankton Communities Under Different Environmental Controls: A New Multi-Metric Index

Increased nutrient delivery to estuarine systems results in elevated growth of primary producers. This is evidenced by high chlorophyll concentrations and increased frequency of phytoplankton blooms. However, shifts in nutrient loads to estuarine ecosystems can also cause modifications in the structure of phytoplankton communities which can have adverse impacts right through the food web. Acknowledging these modifications is imperative if response mechanisms are to be fully understood. In this study Ireland’s current Water Framework Directive (WFD) tool for determining the status of phytoplankton communities was built upon to encompass not only biomass and bloom frequency but also community structure (diversity and evenness) and abundance. This method allows for comparison with site- and date- specific environmental data which could give an indication of cause and effect relationships. The newly developed Phytoplankton Index performed well against current methods to determine ecological status. Furthermore, it had a better agreement with other physico-chemical and biological WFD parameters. Statistical analysis captured the relationship between the Phytoplankton Index and physico-chemical parameters allowing for a more detailed look at the impact of disturbance on the system. The inclusion of community structure acknowledged the imbalances in the phytoplankton communities of some systems even when frequent blooms are not evident. In bloom conditions, the disparity between the chlorophyll and abundance metrics within the Phytoplankton Index can be linked to winter dissolved inorganic nitrogen concentration and forms, temperature and light conditions. Development of the Phytoplankton Index will allow not only for compliance with WFD requirements, but is a method for understanding and assessing ecosystem health of estuarine phytoplankton communities over spatial and temporal timelines in line with changes in physiochemical parameters.

The research of steady-state electrochemical kinetics of effective and selective conversion of total nitrogen to N2.

The electrochemical conversion of inorganic nitrogen forms (i.e., NO3--N, NO2--N, and NH4+-N) to N2 was studied using Ti as cathode and Ti/PbO2 as anode in the simulated wastewater. According to linear sweep voltammetry, nitric nitrogen was effectively converted to N2 on Ti cathode at the working potential more negative than - 1.1 V (vs. SCE). Ti/PbO2 anode had the working potential of + 0.8 V (vs. SCE) for NH4+-N converted to N2. The apparent rate constants of NO3--N to NO2--N and NO2--N to N2 were 2.46 × 10-2 min-1 and 4.03 × 10-2 min-1, respectively. The kinetic analyses revealed that the reduction of NO3--N was a two-step process, and NO2--N was an unstable intermediate, which could be easily oxidized to NO3--N or reduced to NH4+-N. The majority of NH4+-N could be effectively converted to N2 on Ti/PbO2 anode with the apparent rate constants of 5.12 × 10-2 min-1. The dual-chamber (DC) reactor with circulation was used in the batch electrolysis of simulated and actual wastewater. The results verified the pathways of NH4+-N oxidation and NO3--N reduction and achieved high conversion rate of total nitrogen (TN) to N2.

Dairy-CropSyst: Gaseous emissions and nutrient fate modeling tool

Dairy concentrated animal feeding operations (CAFO) are required to implement nutrient management plans enforced by environmental protection agencies to minimizing the risk of water resource degradation and to report gaseous emissions when they exceed certain threshold values. Although tools exist to aid in completing such tasks, few of the tools integrate the impact of on-farm manure treatment unit operations such as anaerobic digestion, solids separation, and nutrient recovery. Furthermore, existing tools do not estimate the nutrient value of recovered products and effluent leaving the dairy system or the nutrient fate after effluent is applied to crop fields.Dairy-CropSyst is a decision support tool for researchers and CAFO managers aimed at evaluating the effects of different manure treatment unit operations on gaseous emission and nutrient fate in dairy systems. The model tracks nutrients through the dairy system, including inorganic and organic forms of carbon, nitrogen, and phosphorus. This is accomplished by integrating established transformation and emission equations, performance parameters of manure treatments from industrial data and literature, and using a cropping system model for the land application evaluation. Comparison of simulated values with observed emissions indicated that model performance was reasonable. The overall correlation coefficient of observed and predicted ammonia and methane emission from dairy manure management was 0.72 and 0.58 respectively. Simulated and observed N2O emission were found in close agreement before and after the irrigation event, however, the model over estimated N2O emission after irrigation events (Coefficient of Residual Mass = −0.87). The use of Dairy-CropSyst has the potential to assist the dairy industry in decision making on manure management treatment strategies and as a tool for reporting GHG and ammonia emissions.

Migration and transformation of nitrogen in bioretention system during rainfall runoff

Bioretention systems have been extensively studied as a highly efficient technical measure to tackle the global threat of nitrogen pollution during global rainfall runoff. However, the migration and transformation of various forms nitrogen in bioretention system is unclear. So, in this paper, the bioretention systems with different flow regimes and planted configurations were designed to study the nitrogen removal performance and migration and transformation mechanism. The dynamic changes of NH4+-N and NO3−-N were continuously monitored within 60 h after rainfall, and the abundance of 15N isotopes in soil layer NH4+-N was simultaneously measured. The results indicated that NH4+-N was mainly intercepted in soil layer in four constructed bioretention systems with similar removal efficiencies (95.42–97.69%). However, NO3−-N was retained in submerged layer with significant different removal efficiencies (43.03–83.00%). After fitting calculation, the nitrification rate of NH4+-N (0.0626 mg kg−1 h−1) in soil was 5.31 times higher than that of the accumulation rate of NO3−-N (0.0118 mg kg−1 h−1). During the elimination process of residual NH4+-N in soil, 41.46% removed by denitrification and plant absorption assimilation, another 57.28% stored in the form of organic nitrogen or inorganic nitrogen, only 1.26% leaked out. Based on this, the content variation of TN, NH4+-N and NO3−-N could be analyzed by a system-wide and established the nitrogen balance model, which provides a new insight into the enhancement of nitrogen removal in the bioretention system.

Rapid change in forms of inorganic nitrogen in soil and moderate weed invasion following translocation of wet meadows to reclaimed post‐industrial land

AbstractAnthropogenic expansion and loss of natural environments calls for the more sustainable use of resources, including land. To combine the conservation of highly valuable meadow habitat with reclamation of post‐industrial land, 1.3 ha of turf were translocated from an urban area to basins constructed near an abandoned quarry. In contrast to the usual method of choosing similar habitats as salvage sites, the selected quarry possessed different environmental properties to the meadows, challenging their acclimatisation. To evaluate the project, we monitored three meadows (Molinion caeruleae alliance) for three seasons: immediately before the transfer and for 2 years afterwards. We recorded vegetation composition in tandem with 27 physico‐chemical properties of the soil. In the first year following translocation, enrichment of soil in total calcium, potassium, sodium, and sulphur was noted. The contents of available phosphorus, nitrogen, and magnesium, as well as soil pH, were lower in the second year. The domination of ammonia over nitrate, which is characteristic of wetlands, decreased markedly. Water holding capacity slowly decreased as well, suggesting humus decomposition. The plant communities maintained their high level of diversity, and the dominance of characteristic meadow species continued. However, an increase in the number of weeds was observed, along with the replacement of some meadow plant species by others. We conclude that if a receptor site does not resemble a habitat type of a donor site, the ecosystem becomes more human‐dependent and requires site‐specific aftercare. In this case, the active control of competitive and ruderal species invasion and moisture management is required.

Spatial and temporal distribution characteristics of different forms of inorganic nitrogen in three types of rivers around Lake Taihu, China

In order to control nitrogen (N) pollution of Lake Taihu, China, we studied the spatial and temporal distribution characteristics of inorganic N in inflowing rivers polluted by industry, agriculture, and domestic sewage during low, moderate, and high flow periods. The results showed that dissolved total nitrogen (DTN) was the main fraction of total nitrogen (TN) input from these rivers. Inflowing rivers had distinct impacts on TN, DTN, ammonium N (NH4+), and nitrate N (NO3-) concentrations of Lake Taihu during the low flow period. Particulate nitrogen (PN) had an impact on Lake Taihu during the three flow periods and all the three types of rivers would increase PN concentration in the lake. Rivers polluted by agriculture had the greatest impact on Lake Taihu's TN, DTN, NO3-, and dissolved inorganic N (DIN) concentrations, while rivers polluted by industry had the greatest impact on NH4+ concentration. Therefore, agriculture and industry should be key targets for nutrient reductions. The in-lake N concentrations were higher than those of inflowing rivers during moderate and high flow periods.