Total Nitrogen Input Research Articles

WHOLE FARM NITROGEN BALANCE ON POULTRY FARMS IN CENTRAL BOSNIA REGION

UDK 636.2:66.074.32(497.6)
 At livestock farms most part of nitrogen arrives as purchased products (fertilizer, animal feed and purchased animals). Within the boundaries of the farm, nitrogen recycles between the livestock and crop components. Finally, nitrogen exit a livestock operation unit preferably as managed outputs (meat, crops and manure) sold off the farm. Difference between the inputs and the managed outputs represents an itrogen balance that can be an indicator of environmentally sustainable production. Nitrogen (im)balance consider only amount of the nutrient that cross the border of the farm. In ideal conditions the nitrogen input/output ratio should be 1:1. Some nitrogen exits the farm as losses to the environment (nitrates in groundwater, ammonia volatilized into the atmosphere, and nitrogen into groundwater and surface water).
 A study was conducted on five small poultry farm in order to determine whole farm nitrogen balance as difference between total nitrogen inputs (one day chickens, litter, animal feed) and outputs (meat, dead animals and manure). Selected farms differ according to capacity (ranging from 5,000 to 40,000 birds), producers of poultry feed, type and length of manure storage as well as other sensible farming practice which could influence on nitrogen balance.
 Collection of data on all farms is done using a questionnaire. Nitrogen content in all substrates (feed, manure, litter) was determinate by Kjeldahl procedure. The results of the whole farm nitrogen balance with the recommendations of its balancing in order to reduce the negative environmental implications are presented in the paper.

Nitrogen and phosphorus transformations and balance in a pond-ditch circulation system for rural polluted water treatment

A pond-ditch circulation system (PDCS), which located along the bank of Donghu Lake (Wuchang District, Wuhan, China) and can effectively remove nitrogen and phosphorus, was proved to be a promising solution for the restoration of a degraded rural water environment. However, little is known about the removal process of nitrogen and phosphorus in the PDCS and the contribution of various pathways to nitrogen and phosphorus removal. This study aims to investigate the mechanisms of nitrogen and phosphorus removal for the PDCS. The results showed that (1) for nitrogen removal in the PDCS, it effectively reduced the total nitrogen level within the first 20days, where dissolved oxygen (DO) played a pivotal role in the process. Based on the mass balance approach, the plant uptake and sediment storage removal contributed to 20.5% of the total nitrogen input removal, whereas other pathways such as N2 emission accounted for 79.5% of the nitrogen removal. These results indicated that nitrogen removal mainly depended on nitrification and denitrification. Meanwhile, in addition to microbial mechanisms, plant uptake and sediment storage were the major N transformation and removal pathways; in the static system, the pathways for nitrogen removal were similar with those observed in the PDCS system. (2) For phosphorus removal, microorganism processes coupled with plant uptake might be the major methods for phosphorus removal in the PDCS. In the static system, however, the phosphorus removal was mainly attributed to plant uptake.

International food trade reduces environmental effects of nitrogen pollution in China.

The globalization of agricultural trade has dramatically altered global nitrogen flows by changing the spatial pattern of nitrogen utilization and emissions at a global scale. As a major trading country, China uses a large amount of nitrogen, which has a profound impact on global nitrogen flows. Using data on food production and trade between China and 26 other countries and regions, we calculated nitrogen inputs and outputs in food production ecosystem in each country. We estimated nitrogen flows in international food trade and analyzed their impact on nitrogen pollution in China. We divided nitrogen flows into embodied and virtual nitrogen flows. Embodied nitrogen is taken up by the plant and incorporated into the final food product, whereas virtual nitrogen is lost to the environment throughout the food production process and is not contained in the final food product. Our results show that China mainly imports food products from America and Asia, accounting for 95% of all imported food. Asia (mainly Japan) and Europe are the main exporters of food from China, with Japan and the EU accounting for 17 and 10% of all exported food, respectively. Total nitrogen inputs and outputs in food production in China were 55,400 and 61,000Gg respectively, which were much higher than in other countries. About 1440 and 950Gg of embodied and virtual nitrogen respectively flow into China through the food trade, mainly from food-exporting countries such as the USA, Argentina, and Brazil. Meanwhile, 177 and 160Gg of embodied and virtual nitrogen respectively flow out of China from the export of food products, mainly to Japan. China's net food imports have reduced 720 and 458Gg for nitrogen utilization and outputs, respectively, which accounted for 1.3 and 0.78% of total nitrogen inputs and outputs in China. These results suggest that food trade in China has a profound effect on nitrogen flows and has greatly reduced environmental impacts on nitrogen pollution in China.

Measures required to reach the nitrate objectives in groundwater based on a long-term nitrate model for large river basins (Júcar, Spain)

Nitrate pollution, primarily in groundwater (GW), has been one of major water pollution problems in Europe over the last 30years. Specially, Mediterranean areas (semi-arid zones) are more vulnerable to nitrate pollution, as in these areas a small excess of nitrogen produce higher nitrate concentrations than in more humid countries because the aquifer recharge is minor. A large number of GW bodies in the Júcar River Basin District (RBD) (43.000km2), located in Spain, has nitrate concentrations above 50mg/L. The Water Framework Directive (WFD) sets out the goal of good status for the water bodies of the European Union, which also implies compliance with the Nitrates Directive.The River Basin Authorities (RBAs) must define the measures needed to reach the environmental objectives in the River Basin Management Plans (RBMPs), considering the long time-lag of aquifers is decisive in the measures effectiveness. By means of nitrogen cycle simulation in the river basin district and with the help of the monthly distributed PATRICAL model, the Júcar RBA has defined the measures to be applied and the exemptions to reach the objectives in GW in relation to nitrate pollution. Both, model and methodology are useful for other river basins to define measures.The total nitrogen inputs in the Júcar RBD amounts to 180,000tN/year, which represents a nitrogen surplus of 80,000tN/year and a pressure of 58.5kgN/year/ha-crop. Around 3/4 of GW bodies have currently the good status while the remaining of GW bodies could reach the good status during following hydrological planning cycles through the implementation of modernized irrigation systems that include fertigation -the use of fertilizers in the water for irrigation. The implementation of this scenario involves increasing efficiency in fertilizer application, in order to reduce nitrogen losses from slightly under a half to <1/3.

Input and Output Budgets for Nitrogen of Paddy Field in South Korea

The main objective of this research was to estimate the total mass of nitrogen discharged from various sources in paddy field area of South Korea in 2010 and 2013. Input and output budgets for nitrogen were estimated by mass balance approach. The mass balance approach reduces the effect of flow variations, and the large scale approach minimizes local effects, resulting in easier and faster establishment of strategy for nonpoint pollution problems. Nitrogen inputs were chemical fertilizer, compost, atmospheric deposition, biological fixation, and agricultural water, while crop uptake, denitrification, volatilization, and infiltration were nitrogen outputs. The estimated total nitrogen inputs for paddy field in South Korea were 266,211 ton yr -1 , 260,729 ton yr -1 , while those of total nitrogen outputs were 168,463 ton yr -1 , 164,994 ton yr -1 in 2010 and 2013, respectively. Annual amounts of potential nitrogen outflow from paddy field were 97,748 ton yr -1 , 95,735 ton yr -1 in 2010 and 2013. Also, annual rate of potential nitrogen outflow were 36.7%, 36.7% in 2010 and 2013, respectively.

Nutrient removal efficiency of lake wetlands:A case study of Sanshan Wetland in Lake Taihu, eastern China

To understand the function of lake wetlands in nutrient removal efficiency,Sanshan Wetland in Lake Taihu was selected as the study region. Remote sensing,GIS techniques,field investigation,chemical analysis and hydro-dynamical simulation were integrated to analyze the effects of nitrogen and phosphorus nutrient retention of wetland in this study. Various forms of nitrogen and phosphorus in the Sanshan Wetland were analyzed. In 2014,the input of total nitrogen( TN) and total phosphorus( TP) were 549.45 t and 19. 4 t,respectively. About 20. 99 t TN and 4. 52 t TP were removed by emerged plants harvest and floating plants salvages. Changes of TN and TP in Sanshan Wetland were 528. 46 and 14. 88 t during the year,respectively. Ways of the nutrients output included several processes of phosphorus sunking,depositing,degradating and exchanging between the Sanshan Wetland and Lake Taihu. The wetland captures of TN and TP were 2723. 56 and 102. 48 kg /( ha·a),respectively. The sediment dredging and plant harvesting and refloating are good ways to improve the water quality in Sanshan Wetland. Hydrodynamic simulation results show that due to the construction of Sanshan Wetland,the flow directions have changed and the velocity currents reduced.

Total Nitrogen Sources of the Three Gorges Reservoir--A Spatio-Temporal Approach.

Understanding the spatial and temporal variation of nutrient concentrations, loads, and their distribution from upstream tributaries is important for the management of large lakes and reservoirs. The Three Gorges Dam was built on the Yangtze River in China, the world’s third longest river, and impounded the famous Three Gorges Reservoir (TGR). In this study, we analyzed total nitrogen (TN) concentrations and inflow data from 2003 till 2010 for the main upstream tributaries of the TGR that contribute about 82% of the TGR’s total inflow. We used time series analysis for seasonal decomposition of TN concentrations and used non-parametric statistical tests (Kruskal-Walli H, Mann-Whitney U) as well as base flow segmentation to analyze significant spatial and temporal patterns of TN pollution input into the TGR. Our results show that TN concentrations had significant spatial heterogeneity across the study area (Tuo River> Yangtze River> Wu River> Min River> Jialing River>Jinsha River). Furthermore, we derived apparent seasonal changes in three out of five upstream tributaries of the TGR rivers (Kruskal-Walli H ρ = 0.009, 0.030 and 0.029 for Tuo River, Jinsha River and Min River in sequence). TN pollution from non-point sources in the upstream tributaries accounted for 68.9% of the total TN input into the TGR. Non-point source pollution of TN revealed increasing trends for 4 out of five upstream tributaries of the TGR. Land use/cover and soil type were identified as the dominant driving factors for the spatial distribution of TN. Intensifying agriculture and increasing urbanization in the upstream catchments of the TGR were the main driving factors for non-point source pollution of TN increase from 2003 till 2010. Land use and land cover management as well as chemical fertilizer use restriction were needed to overcome the threats of increasing TN pollution.

Nutritional-metabolic factors affecting nitrogen balance and substrate utilization in the critically ill.

To determine clinical, anthropometric, metabolic, and nutritional factors affecting nitrogen balance somatic protein status and substrate utilization in critically ill children measured energy expenditure (MEE) was measured by indirect calorimetry within 24 hr of an acute illness, solid organ transplantation, or cardiovascular surgery. Predicted basal metabolic rate was calculated using the Schofield equation. Somatic protein was estimated by the creatinine-height index. Nitrogen balance (NB) was calculated by subtracting the total nitrogen input from output. The net substrate (fat, carbohydrate, and protein) oxidation rates were calculated using the Weir formula modified by Frayn. Sixty-eight NB studies, indirect calorimetric and anthropometric measurements performed in 37 patients. Nitrogen balance was worse when the MEE/Predicted basal metabolic rate ratio was < 0.9 or > 1.1. The incidence of negative NB was 91% when the caloric intake was less than MEE and 9% when it was equal to or greater than MEE (P < 0.05). On day 1, 27% had mild to moderate somatic protein depletion and 5.4% had severe somatic protein depletion. Only the persistence of stress and co-morbidity were associated with the creatinine-height index (P < 0.001). Without Multiple Organ System Failure (MOSF), there was a trend toward positive nitrogen balance by day 7 while with MOSF, negative nitrogen balance persisted even by day 7 (P < 0.05). When caloric intake was less than MEE, mean substrate utilization was 48.6% from lipid, 37.1% from carbohydrate, and 14.3% from proteins. But, when caloric intake was greater than MEE, mean substrate utilization was 83.3% from carbohydrate and 16.7% from protein. Significant negative nitrogen balance and somatic protein depletion develops in critically ill pediatric patients, especially when they are inadequately fed, develop MOSF, or have previous chronic illness. Caloric intake and MOSF independently affect substrate utilization.

Effects of grass species and grass growth on atmospheric nitrogen deposition to a bog ecosystem surrounded by intensive agricultural land use.

We applied a 15N dilution technique called “Integrated Total Nitrogen Input” (ITNI) to quantify annual atmospheric N input into a peatland surrounded by intensive agricultural practices over a 2-year period. Grass species and grass growth effects on atmospheric N deposition were investigated using Lolium multiflorum and Eriophorum vaginatum and different levels of added N resulting in increased biomass production. Plant biomass production was positively correlated with atmospheric N uptake (up to 102.7 mg N pot−1) when using Lolium multiflorum. In contrast, atmospheric N deposition to Eriophorum vaginatum did not show a clear dependency to produced biomass and ranged from 81.9 to 138.2 mg N pot−1. Both species revealed a relationship between atmospheric N input and total biomass N contents. Airborne N deposition varied from about 24 to 55 kg N ha−1 yr−1. Partitioning of airborne N within the monitor system differed such that most of the deposited N was found in roots of Eriophorum vaginatum while the highest share was allocated in aboveground biomass of Lolium multiflorum. Compared to other approaches determining atmospheric N deposition, ITNI showed highest airborne N input and an up to fivefold exceedance of the ecosystem-specific critical load of 5–10 kg N ha−1 yr−1.

Evaluation of the simultaneous biogas upgrading and treatment of centrates in a high-rate algal pond through C, N and P mass balances

The simultaneous capture of CO2 from biogas and removal of carbon and nutrients from diluted centrates in a 180 L high-rate algal pond (HRAP) interconnected to a 2.5 L absorption column were evaluated using a C, N and P mass balance approach. The experimental set-up was operated indoors at 75 μE/m(2)·s for 24 h/d at 20 days of hydraulic retention time for 2 months of steady state, and supported a C-CO2 removal in the absorption column of 55 ± 6%. Carbon fixation into biomass only accounted for 9 ± 2% of the total C input, which explains the low biomass productivity recorded in the HRAP. In this context, the low impinging light intensity along with the high turbulence in the culture broth entailed a C stripping as CO2 of 49 ± 5% of the total carbon input. Nitrification was the main NH4(+) removal mechanism and accounted for 47 ± 2% of the inlet N-NH4(+), while N removal as biomass represented 14 ± 2% of the total nitrogen input. A luxury P uptake was recorded, which resulted in a P-PO4(-3) biomass content over structural requirements (2.5 ± 0.1%). Phosphorus assimilation corresponded to a 77 ± 2% of the inlet dissolved P-PO4(-3) removed.

Indirect nitrogen losses of managed soils contributing to greenhouse emissions of agricultural areas in Austria: results from lysimeter studies

A considerable share of greenhouse gas emissions, especially N2O, is caused by agriculture, part of which can be attributed to indirect soil emissions via leaching and runoff. Countries have to report their annual emissions, which are usually calculated by using the default value of 0.3 for FracLEACH, a factor that represents the fraction of nitrogen losses compared to total nitrogen inputs and sources. In our study we used 22 lysimeters, covering a wide range of soils, climatic conditions and management practices in Austria, to evaluate nitrogen losses through leaching and to calculate FracLEACH. The terms of the nitrogen mass balance of the lysimeters were directly measured for several years. Both grassland and arable land plots gave significantly smaller values of FracLEACH than the default value. For grassland, FracLEACH values of only 0.02 were found which varied very little over the entire observation period. For arable sites, FracLEACH values were higher (around 0.25) and showed significant variability between years due to variations in crop rotation, fertilization rates, and yields.

Quantification and contribution of nitrogen inputs in the soil on groundwater contamination by nitrates: Valley of High-Cheliff (North Algerian)

Nitrogen (N2) is an essential nutrient for plants. However, when the application of nitrogen exceeds the needs of the plant and the denitrification capacity, nitrogen can migrate to groundwater, usually in the form of nitrates. The transfer of nitrates in soil results from a large number of interdependent factors: climatic, agrological, and agronomic. The Conditions of interaction of these factors can lead to situations more or less favorable to leaching of nitrates. Thus, according to some studies in agronomy, high levels of nitrate pollution observed result from an increase in the mineralization capacity of soils under the cumulative effect of intensive farming practices. Many European countries and some U.S. states are already based on the nitrate test for establishing the optimum nitrogen doses. In agricultural areas, the use of large amounts of mineral fertilizers and the increased volume of animal waste as a result of development of breeding cause nitrogen excess surplus capacity utilization by the vegetation, it is driven into groundwater and causes an increase in nitrate concentrations. With a total annual volume of agricultural production of around 1.5 million tons, agriculture is certainly the pole par excellence of the Hight-Cheliff. The main crops are arboriculture and gardening. Potatoes covered nearly half (48%) of the total volume of agricultural production, it is a major consumer of Nitrogen fertilizers. For the purpose of estimate the amount of leachable nitrogen, nitrogen balance was drawn up , see all the inputs and outputs of nitrogen were almost estimated. This study associate groundwater nitrate pollution with agricultural activity in the high-Cheliff intensive farming regions in Algeria. The spatial probability distribution of nitrate contents, based on nonlinear methods of indicatory kriging, shows the spatial evolution of nitrate through a map established for the year 2011 during high waters. The obtained results show that the areas exceeding nitrate concentrations of 50ppm, occupy more than 80% of the aquifer area, it appears, from this map, the most affected areas are those for with the level of intensification of nitrogen fertilization is strongest specially in the zone of potatoes crops. These results are coherent with the experimental data, which show an average nitrate concentration value of 75ppm, significantly higher than the WHO'S maximum contaminant level. In this study the estimate of the total nitrogen inputs to soils of the valley was 247Kg.ha-1 for this year and compared it with the results of Computer models such as PILOTEN used to analyze alternative management practices together with soil, plant, and climate characteristics to determine nitrogen leached under the potatoes crops ( hot spot areas ).The result show that 60% of nitrogen input is leaching under potato crops which coherent with the spatial evolution of nitrate.

Net ecosystem production and organic carbon balance of U.S. East Coast estuaries: A synthesis approach

AbstractNet ecosystem production (NEP) and the overall organic carbon budget for the estuaries along the East Coast of the United States are estimated. We focus on the open estuarine waters, excluding the fringing wetlands. We developed empirical models relating NEP to loading ratios of dissolved inorganic nitrogen to total organic carbon, and carbon burial in the sediment to estuarine water residence time and total nitrogen input across the landward boundary. Output from a data‐constrained water quality model was used to estimate inputs of total nitrogen and organic carbon to the estuaries across the landward boundary, including fluvial and tidal‐wetland sources. Organic carbon export from the estuaries to the continental shelf was computed by difference, assuming steady state. Uncertainties in the budget were estimated by allowing uncertainties in the supporting model relations. Collectively, U.S. East Coast estuaries are net heterotrophic, with the area‐integrated NEP of −1.5 (−2.8, −1.0) Tg C yr−1 (best estimate and 95% confidence interval) and area‐normalized NEP of −3.2 (−6.1, −2.3) mol C m−2 yr−1. East Coast estuaries serve as a source of organic carbon to the shelf, exporting 3.4 (2.0, 4.3) Tg C yr−1 or 7.6 (4.4, 9.5) mol C m−2 yr−1. Organic carbon inputs from fluvial and tidal‐wetland sources for the region are estimated at 5.4 (4.6, 6.5) Tg C yr−1 or 12 (10, 14) mol C m−2 yr−1 and carbon burial in the open estuarine waters at 0.50 (0.33, 0.78) Tg C yr−1 or 1.1 (0.73, 1.7) mol C m−2 yr−1. Our results highlight the importance of estuarine systems in the overall coastal budget of organic carbon, suggesting that in the aggregate, U.S. East Coast estuaries assimilate (via respiration and burial) ~40% of organic carbon inputs from fluvial and tidal‐wetland sources and allow ~60% to be exported to the shelf.

Estimation of nutrient sources and transport using Spatially Referenced Regressions on Watershed Attributes: a case study in Songhuajiang River Basin, China.

We report here the first application of the Spatially Referenced Regressions on Watershed Attributes (SPARROW) model to China, a country naturally and culturally distinct from previous SPARROW applications. The Songhuajiang River Basin (556,700 km(2)) empties into the Tongjiang monitoring section, a shared water resource of great import for both Chinese and Russian citizens. The model was calibrated to annual loads of total nitrogen (TN) at 102 sites and total phosphorus (TP) at 65 sites. We assessed the rates of delivery and loss of nutrients from diffuse sources and also provided reach-level predictions of the percentage of nutrient loads delivered from upstream subbasins to Tongjiang monitoring section. The results indicated that farmland and pasture land were responsible for about 70 % of nutrient inputs to the Tongjiang monitoring section. Point source inputs were not statistically significant sources of TN or TP. We presented evidence that rice paddies delivered less TN to streams per area than other types of cropland. The locations responsible for the highest TN and TP inputs to the Tongjiang monitoring section tended to be located near the mainstream, though the areas of highest TN delivered yield did not correspond to the areas of highest TP delivered yield. This suggests that different management priorities may be needed in different parts of the Songhuajiang River Basin.

Reproduction of Mm.106 Rootstocks Propagated by Stooling as Affected by Organic Sources

Six organic sources of nutrients including commercial organic fertilizer (CF), poultry litter (PL), green compost (GC), wood chips (WC), shredded paper (SP), grass clippings (GR), and extracts from water (NF, as a control) were investigated under controlled conditions. One-year-old MM.106 apple (Malus × domestica Borkh.) trees grown under greenhouse conditions in 10 L pots were treated with nutrient solutions. All treatments were applied proportionally based on the volume ratio of material recommended for organic apple orchard field production. A nutrient solution from GC provided the greatest total nitrogen (N) input over the 12-week experimental period, followed in order by the GR, PL, WC, CF, SP, and NF treatments. The PL- and GR-treated plants had the largest stem diameter, largest leaf area, longest stem extension, and fastest dry matter production rate, as well as greater carbon dioxide (CO2) assimilation, SPAD readings, N accumulation, and N use efficiency.

Long-term patterns in 50 years of scyphomedusae catches in the western Dutch Wadden Sea in relation to climate change and eutrophication

Using a unique 50-year high-resolution time series of daily kom-fyke catches, long-term patterns of scyphomedusae in the western Dutch Wadden Sea were analysed and related to changes in environmental conditions [eutrophication in the 1980s–1990s and recent climate change (increased water temperature)] in the area. Over the years, species composition and general pattern of appearance has remained the same: the first species that occurred in spring was Aurelia aurita, followed by Cyanea lamarckii/C. capillata. Chrysaora hysoscella and Rhizostoma octopus occurred from June to July onwards. All species appeared earlier in recent decades and first appearance and peak occurrence of A. aurita was in part inversely related to previous winter seawater temperature. Last occurrence of C. hysoscella was related to summer seawater temperature and the species is present longer in recent decades. Phenological relationships might have been decoupled since the seasonality of the phytoplankton bloom did not change. All species showed large inter-annual abundance fluctuations, with prolific years followed by sparse years. Peak catches of the coastal species A. aurita occurred in the late 1970s−early 1990s when eutrophication peaked, however, without a significant relationship with total nitrogen input into the area. Unlike for phenology, the patterns of mean abundance of any species did not show a relationship to climate change in the area. This might imply that population regulating mechanisms do not operate during the planktonic phase but during the sessile demersal polyp stages.

50 year trends in nitrogen use efficiency of world cropping systems: the relationship between yield and nitrogen input to cropland

Nitrogen (N) is crucial for crop productivity. However, nowadays more than half of the N added to cropland is lost to the environment, wasting the resource, producing threats to air, water, soil and biodiversity, and generating greenhouse gas emissions. Based on FAO data, we have reconstructed the trajectory followed, in the past 50 years, by 124 countries in terms of crop yield and total nitrogen inputs to cropland (manure, synthetic fertilizer, symbiotic fixation and atmospheric deposition). During the last five decades, the response of agricultural systems to increased nitrogen fertilization has evolved differently in the different world countries. While some countries have improved their agro-environmental performances, in others the increased fertilization has produced low agronomical benefits and higher environmental losses. Our data also suggest that, in general, those countries using a higher proportion of N inputs from symbiotic N fixation rather than from synthetic fertilizer have a better N use efficiency.

Quantitative identification of riverine nitrogen from point, direct runoff and base flow sources.

We present a methodological example for quantifying the contributions of riverine total nitrogen (TN) from point, direct runoff and base flow sources by combining a recursive digital filter technique and statistical methods. First, we separated daily riverine flow into direct runoff and base flow using a recursive digital filter technique; then, a statistical model was established using daily simultaneous data for TN load, direct runoff rate, base flow rate, and temperature; and finally, the TN loading from direct runoff and base flow sources could be inversely estimated. As a case study, this approach was adopted to identify the TN source contributions in Changle River, eastern China. Results showed that, during 2005-2009, the total annual TN input to the river was 1,700.4±250.2 ton, and the contributions of point, direct runoff and base flow sources were 17.8±2.8%, 45.0±3.6%, and 37.2±3.9%, respectively. The innovation of the approach is that the nitrogen from direct runoff and base flow sources could be separately quantified. The approach is simple but detailed enough to take the major factors into account, providing an effective and reliable method for riverine nitrogen loading estimation and source apportionment.

Investigation on Nutrient Loads of Lake Taihu in China

Based on measured data and laboratory experiments, the spatial and temporal distribution of nutrient loads of Lake Taihu from the sources of river runoff, atmospheric bulk deposition and internal release was quantitatively analyzed. Results showed that: (1) In 2011, annual river inputs of total phosphorus (TP) and total nitrogen (TN) respectively were 2382.4 tons and 50245.0 tons, and annual river outputs of TP and TN respectively were 849.1 tons and 24236.7 tons, Huxi area was the major transverse source of nutrients as a large proportion of TP(71.6%) and TN(66.2%). (2) Annual nutrient loads of Lake Taihu were 3306.6 tons TP and 48007.0 tons TN, of which the contribution of river runoff, atmospheric bulk deposition and internal release to TP accounted for 46.3%, 38.3% and 15.4%, and that to TN accounted for 54.2%, 43.7% and 2.1%, respectively. (3) Inputs of nutrients to Lake Taihu were higher in summer (June to August), of which 983.9 tons TP and 8874.9 tons TN in June, 1420.9 tons TP and 7463.3 tons TN in July, 1347.1 tons TP and 7181.3 tons TN in August. The results have great significance for eutrophication control and water environment protection in Lake Taihu.

Response of bacterial pdo1, nah, and C12O genes to aged soil PAH pollution in a coke factory area.

Soil pollution caused by polycyclic aromatic hydrocarbons (PAHs) is threatening human health and environmental safety. Investigating the relative prevalence of different PAH-degrading genes in PAH-polluted soils and searching for potential bioindicators reflecting the impact of PAH pollution on microbial communities are useful for microbial monitoring, risk evaluation, and potential bioremediation of soils polluted by PAHs. In this study, three functional genes, pdo1, nah, and C12O, which might be involved in the degradation of PAHs from a coke factory, were investigated by real-time quantitative PCR (qPCR) and clone library approaches. The results showed that the pdo1 and C12O genes were more abundant than the nah gene in the soils. There was a significantly positive relationship between the nah or pdo1 gene abundances and PAH content, while there was no correlation between C12O gene abundance and PAH content. Analyses of clone libraries showed that all the pdo1 sequences were grouped into Mycobacterium, while all the nah sequences were classified into three groups: Pseudomonas, Comamonas, and Polaromonas. These results indicated that the abundances of nah and pdo1 genes were positively influenced by levels of PAHs in soil and could be potential microbial indicators reflecting the impact of soil PAH pollution and that Mycobacteria were one of the most prevalent PAHs degraders in these PAH-polluted soils. Principal component analysis (PCA) and correlation analyses between microbial parameters and environmental factors revealed that total carbon (TC), total nitrogen (TN), and dissolved organic carbon (DOC) had positive effects on the abundances of all PAH-degrading genes. It suggests that increasing TC, TN, and DOC inputs could be a useful way to remediate PAH-polluted soils.