Levels Of Organic Nitrogen Research Articles

Composição química e potencialidade do uso de resíduo de extração de pedra ametista como fertilizante agrícola

Ametista do Sul, northem RS, whose main economic activity practice amethyst stone extraction. The mining takes place in the underground system, resulting in tons of solid waste (tailings) which are mostly deposited in the hillsides without any care or discretion. This study aimed to determine the chemical composition of wastes, in order to evaluate the potential use of these as agricultural fertilizer, by incorporation into the soil. Basic determinations were performed according ROLAS, for the parameters pH, organic matter, nitrogen, potassium, phosphorus, calcium and magnesium. Samples were collected in eight different sampling points, taking into account the differences between mining wastes. The results indicated the mineral character of waste, due to low levels of organic matter and nitrogen, and for these two parameters waste is not suitable for fertilization. As for macronutrients P, K, Ca and Mg, the residue has demonstrated good yields, being in high concentration, these being suggested the use as agricultural fertilizer by soil incorporation.

Distributions, Early Diagenesis, and Spatial Characteristics of Amino Acids in Sediments of Multi-Polluted Rivers: A Case Study in the Haihe River Basin, China.

The Haihe River Basin, which is one of the most water-scarce and polluted river basins in China, has abnormally high nitrogen levels. In this study, total hydrolyzable amino acids (THAAs) were measured in surface sediment and sediment core samples in the Haihe River Basin to determine if amino acids were potential sources of ammonium, organic nitrogen, and organic carbon. The rivers were found to be in a state of hypoxia and contain abnormally high levels of ammonium and organic nitrogen. Additionally, NH3-N was the predominant form of inorganic nitrogen in the surface sediments, while organic nitrogen accounted for 92.53% of sedimentary nitrogen. THAAs-C accounted for 14.92% of the total organic carbon, while THAAs-N accounted for more than 49.59% of organic nitrogen and 45.68% of total nitrogen. The major fraction of THAAs were protein amino acids. Three sediment cores of the most heavily polluted rivers also showed high levels of THAAs. Evaluation of the degradation index (DI) of sedimentary organic matter in sediments evaluated based on the THAAs revealed that most positive DI values were found in the downstream portion of the Ziya River Watershed. Additionally, the DI of surface sediment was correlated with THAAs (r2 = 0.763, p < 0.001), as was the DI of sediment cores (r2 = 0.773, p < 0.001). Overall, amino acids in sediments were found to be an important potential source of ammonium, organic nitrogen, and organic carbon.

Formation and occurrence of new polar iodinated disinfection byproducts in drinking water.

During drinking water disinfection, iodinated disinfection byproducts (I-DBPs) can be generated through reactions between iodide, disinfectants, and natural organic matter. Drinking water I-DBPs have been increasingly attracting attention as emerging organic pollutants as a result of their significantly higher toxicity and growth inhibition than their chloro- and bromo-analogues. In this study, by adopting ultra performance liquid chromatography/electrospray ionization-triple quadrupole mass spectrometry precursor ion scan, multiple reaction monitoring, and product ion scan analyses, 11 new polar I-DBPs with confirmed structures and eight new polar I-DBPs with proposed structures were detected in simulated drinking water samples. Chloramination of simulated raw waters containing natural organic matter with higher aromaticity produced higher levels of new phenolic I-DBPs. Formation of new polar I-DBPs and total organic iodine (TOI) was most favored in chloramination, followed by chlorine dioxide treatment, and relatively minor in chlorination. Lower pH in chloramination substantially enhanced the formation of new polar I-DBPs and TOI. NH2Cl and dissolved organic nitrogen could be important nitrogen sources and precursors for formation of the two new nitrogenous phenolic I-DBPs. Notably, in tap water samples collected from nine major cities located in the Yangtze River Delta region of China, seven of the 11 new polar I-DBPs with confirmed structures were detected at levels from 0.11 to 28 ng/L, and the two new nitrogenous phenolic I-DBPs were ubiquitous with concentrations from 0.12 to 24 ng/L, likely due to the relatively high dissolved organic nitrogen levels in regional source waters.

Soil Organic Carbon, Nitrogen, and Phosphorus Levels and Stocks After Long‐Term Nitrogen Fertilization

The effects of fertilizers and tillage on soil organic carbon (SOC) storage have been tested in many field experiments worldwide. However, conflicting findings have been reported in the literature about the long‐term effects of nitrogen (N) fertilization on the profile distribution of SOC, N, and phosphorus (P) concentrations and stocks. To determine the carbon (C), N, and P changes occurring after long‐term N fertilization at different levels, SOC, soil total N (TN), soil total P (TP), and soil bulk density were measured in a long‐term N fertilization experiment (2004–2013) using two winter wheat cultivars and five N application rates. The findings showed that (i) N fertilization affected the C and N distribution at the 0–120 cm soil depth, whereas the effect on P was mainly in the 0–30 cm soil layer; additionally, C, N, and P levels were positively correlated in the 0–30 cm layer, but the relationship weakened as the soil depth increased. (ii) N fertilization had a large influence on C, N, and P stocks and these influences varied for the different wheat cultivars. Wheat cropping with an N fertilizer rate &lt;270 kg ha−1resulted in C fixation in the soil after long‐term N fertilization, but when N was applied in excess of the crop requirements for the maximum yield, the soil became a C source; moreover, after long‐term N fertilization, the stock of N was decreased, and the stock of P was increased.

Reuse of fish pond sediments as fertilizer for fodder grass production in Bangladesh: Potential for sustainable intensification and improved nutrition

Intensive aquaculture systems (e.g. pangasius farming) make important contributions to food security in developing countries, including Bangladesh, but are associated with a variety of negative environmental impacts, including the discharge of nutrient rich sediments into local ecosystems. The present study consists of laboratory based analysis of the nutrient content of pangasius pond sediments (PPS), a trial of the efficacy of reuse of PPS as fertilizer to produce para grass as a green fodder for dairy cattle, and a comparative assessment of the economic viability of para grass production in rice fields using PPS to support small-scale dairy farming operations, thereby removing a major constraint to the growth of commercial dairy production in Bangladesh. PPS had significantly higher levels of organic carbon, nitrogen, phosphorous, potassium and sulfur than rice plot soil, and was a highly effective fertilizer for para grass cultivation. Production of green fodder for dairy cows using PPS yielded a higher rate of return than rice production. The indirect integration of aquaculture with agriculture through the reuse of PPS as fertilizer for green fodder production has significant potential to contribute to sustainable intensification and nutrition security goals, by improving the efficiency of nutrient use in aquaculture, reducing local environmental impacts associated with sediment disposal, and increasing the production of micronutrient rich milk.

Crescimento de tambaqui em resposta a densidade de estocagem em tanques-rede

O tambaqui Colossoma macropomum é criado em diferentes sistemas e ambientes com boa produção em tanques-rede. O objetivo deste trabalho foi avaliar o crescimento do tambaqui em diferentes densidades de estocagem em tanques-rede em lago abastecido com água de chuva e seus efeitos sobre a qualidade ambiental. O experimento foi conduzido em fases consecutivas: recria nas densidades de 50, 100, 200 e 300 alevinos m-3 e terminação nas densidades de 20, 40, e 60 juvenis m-3. A temperatura da água, oxigênio dissolvido, pH e condutividade da água foram medidas diariamente. Amostras de sedimento e água foram coletadas para análise de nitrogênio e fósforo mensalmente. Na recria, a produção de 14,03 kg m-3 foi significativamente maior na densidade de 300 alevinos m-3. O maior peso final foi obtido na densidade de 50 alevinos m-3. A sobrevivência na recria foi superior a 97%. Na terminação, o ganho de peso e o crescimento específico foram inversamente proporcionais as densidades. A conversão alimentar e o fator de condição não foram influenciados pelas densidades testadas. A densidade de 20 juvenis m-3 é a mais adequada para a terminação de tambaquis em tanques-rede. A criação de tambaqui em tanques-rede não alterou os níveis de nitrogênio e fósforo da água do lago. Aumento dos teores de matéria orgânica, nitrogênio e fósforo foram verificados no sedimento abaixo dos tanques-rede, sem causar eventos de eutrofização. O presente estudo demonstrou que a criação de tambaquis em tanques-rede é viável em lagos abastecidos com água de chuva e pode integrar-se aos preceitos dos usos múltiplos da água.

Sewage sludge use in bioenergy production. A case study of its effects on soil properties under Cynara cardunculus L. cultivation

Energy crops cultivation is expected to further increase, which represents an opportunity to establish synergies able to enhance key environmental components (i.e. soil). To reach this benefits crop management is crucial and should be properly assessed. The aim of this work is to provide an insight on the effects of sewage sludge compost (SSC) on soil properties, when this material is applied as basal dressing for the cultivation of a Mediterranean energy crop (Cynara cardunculus L.). A 3-years trial (2008/2011) was conducted in Alicante (Southeastern Spain), testing four SSC application rates (0, 30, 50 and 70 t/ha) on a heavy textured Anthrosol. The addition of SSC enhanced soil fertility, primarily increasing organic carbon (Cox), Kjeldahl nitrogen (Nk), available P (PBurriel), CuDTPA and ZnDTPA levels. Comparatively with the control (0 t/ha), 30, 50 and 70 t/ha treatments induced a rise of 11%, 19% and 25% in Nk (Control=1.11 g/kg) and PBurriel (Control=79 mg/kg), while for Cox (Control=11.8 g/kg) was 14%, 21% and 30%. However, these variables apparently did not significantly decrease throughout the experiment, which suggests that the organic matter added was under a stabilization process, favoured by the poor physical properties of the soil. Other elements (NaNH4Ac, KNH4Ac, MnDTPA) were accumulated within the soil as time passed by, as a result of soil status, Mediterranean environmental conditions and crop management. The use of SSC as organic fertilizer represents an effective option to optimize cynara cultivation systems while improving soil quality through enhanced long-lasting organic matter pools.

Chemical Differentiation of Domestic Sewage Sludge and Cattle Manure Stabilized by Microbioreators: Study by Pyrolysis Coupled to Gas Chromatography Coupled to Mass Spectroscopy

The aim of the present study was to evaluate the chemical alterations in substrates of vermicomposts from domestic sewage sludge and from cattle manure, besides its quality as an organic fertilizer. Elemental and infrared analysis and UV-Vis spectroscopy were used for their characterizations. Chemical characteristics determined in the vermicomposts indicate that they can be used as organic fertilizers, mainly with regard to organic matter content, pH, C/N ratio, and nitrogen and phosphorus levels. The main constituents of the humic substances extracted from the vermicomposts were obtained by pyrolysis coupled to gas chromatography-mass spectrometry (GC/MS), showing that these compounds are quite similar, despite being produced by domestic sewage sludges or by cattle manure.

Reproductive ecophysiology ofRubus occidentalisin southeastern Michigan I. A survey of tolerance ranges

Research on Rubus occidentalis (black raspberry or blackcap) has recently intensified due to the health benefits of its fruits, its potential as a crop, and its aggressive growth in certain sensitive environments. However, the conditions in the wild in which stands of the species best persist and fruit are currently unknown. I measured light, soil pH, soil organic matter, soil fine particle fraction, and soil nitrogen in 49 R. occidentalis stands in southeastern Michigan and, using generalized linear and general mixed-effects models, examined whether these environmental factors were correlated with measures of reproductive success. Rubus occidentalis stands generally grew in moderate to low incident light and in neutral to mildly acidic (pH ∼5–7.5), coarsely textured soils with average to low levels of organic matter and inorganic nitrogen. Stands had a significantly higher proportion of successfully fruiting canes as light and soil pH increased and as organic matter decreased. Stands also had significantly more fruit receptacles and fruits per cane as light, ammonium, and pH increased. Significantly greater premature cane dieback during the fruiting season was observed as organic matter, nitrate, and soil pH increased and as soil texture became finer. Wild R. occidentalis appears to persist well in low-light environments with coarse, neutral, organic matter-poor soils, but it may achieve higher fruiting success in higher light environments with finer and more ammonium-rich soils. This study is the first to quantitatively assess the degree to which environmental context influences stand persistence and reproductive success for R. occidentalis in the wild.

DÉCHET URBAIN-AGRICULTURE-ENVIRONNEMENT (DUAE): USING WASTE AS A RESOURCE FOR AGRICULTURE

Increasing agricultural production sustainably implies the use of organic fertilizer. Urban wastes in developing countries are rich in recyclable organic matter and they increase as urbanization increases. A recent project carried out in Dakar analyzed the potential contribution of urban organic waste (OW) to urban horticultural production. A research project was conducted in order to 1) carry out farm surveys to understand local fertilization practices; 2) identify and characterize locally available organic wastes chemically; and 3) carry out experiments with these wastes in greenhouses and farms to evaluate their agronomic potentialities and their implementation in local farmers' practices. Horse and poultry manure are the main OW used by farmers around Dakar; however, these may become less available and/or more expensive in the future. The OW obtained after sifting through other sources of urban wastes (i.e., compost) could provide an alternative and unlimited source of organic matter. However, chemical analyses of this compost show that organic matter and nitrogen levels are weak compared to manure. Experiments were therefore conducted in greenhouses with the two representative soils of the region, a sandy-clay soil (Deck) and a sandy soil (Dior): these showed no significant effect of compost on the early growth of tomatoes compared to treatment without compost, but rather a light-positive effect at the end of the tomato-growth cycle, consistent with the analytical properties of the product. The fertilizing value of this compost is low and will require the addition of other fertilizing inputs. On-farm tests have been carried out on tomato in the same soils, where the agronomic values of treatments combining compost, manure and other local organic inputs are compared. The initial results are now under study (available December 2010).

Soil fertility, physical and chemical organic matter fractions, natural 13C and 15N abundance in biogenic and physicogenic aggregates in areas under different land use systems

The dynamics of soil aggregation, including aggregate formation by biogenic and physicogenic processes, is affected by the soil management system. The present study aimed to divide soil aggregates into biogenic and physicogenic, and to characterise the aggregates in terms of soil exchange complex, distribution of total organic carbon (TOC), nitrogen (N) levels, and natural 13C and 15N abundance, and determine C levels in the soil organic matter (SOM) fractions of the aggregates. The areas studied were under a no-till system (NTS) established 15 years before, conventional tillage system (CTS) managed with ploughing and harrowing for 56 years, and a secondary forest (Forest) and pasture grass (Axonopus compressus) (Pasture) (both ≥30 years old). Undisturbed soil samples were collected at 0–5 and 5–10 cm. CTS was unsuitable for biogenic aggregate formation, and NTS and Forest areas showed similar biogenic and physicogenic aggregate content. The Pasture area promoted the formation of biogenic aggregates. In contrast to CTS, NTS increased TOC, calcium, magnesium, nitrogen and phosphorus levels. Considering the parameters evaluated, the Forest area showed the most variation (differences) between biogenic and physicogenic aggregates. Biogenic aggregates exhibited higher TOC and nutrient levels than their physicogenic counterparts. In the CTS area, the absence of legumes and the long-term and constant use of N-fertilisers resulted in 15N soil enrichment (at 0–5 cm). In the Pasture area, the absence of legumes and the constant deposition of cattle manure also increased 15N content relative to NTS and Forest areas. The Forest area had the lowest 15N values in the two layers and aggregate types studied. The levels of 13C reflect the type of material incorporated in the soil (mostly C3 plants in Forest and NTS areas and C4 plants in Pasture and CTS areas). The Pasture area favoured the formation of stable SOM, with higher levels of C content in humin fraction (C-HUM) and mineral-associated OC (MOC). CTS compromised SOM stabilisation, producing lower levels of C-HUM, MOC, and moderately oxidisable and resistant fractions. The biogenic aggregates enhanced soil fertility and contained higher C content in SOM fractions than the physicogenic aggregates. We conclude that biogenic rather than physicogenic aggregates can be considered reliable indicators of soil quality.

Diversity and community analysis of ammonia oxidizing bacteria in a streambed surrounding an artificial dam

The degree to which small natural dams affect the native bacterial nitrogen cycling community was explored by molecular methods. The identities and relative abundances of ammonia oxidizing bacteria in the sediment surrounding an artificial dam both at the surface and in the hyporheic zone were characterized. Analyses were performed using tRFLP of the conserved amoA gene using a semi-nested degenerate PCR approach. Additionally, an amoA gene library was constructed to characterize the most dominant sediment genotypes. The results of the tRFLP analyses showed clear differences between the upstream and downstream communities at different depths in the sediment column. Non-metric multidimensional scaling ordination of the tRFLP data set produced a stable one-dimensional solution with significant correlations to oxygen, pH, nitrate, and dissolved organic nitrogen levels. The sample corresponding to the hyporheic zone downstream of the dam showed 28–50% higher amoA richness and higher diversity than the other samples. All gene fragments sequenced from the samples grouped with sequences of the Nitrosospira type. Ordination of 16S rDNA tRFLP data revealed a two dimensional data structure, one axis of which had similar chemical correlation characteristics as the amoA model axis. Taken together, the results from this study suggest that the presence of the dam creates physical and chemical heterogeneity that may foster genetic diversity and community changes amongst ammonia oxidizing bacteria.

Do bacterial and fungal communities in soils of the Bolivian Altiplano change under shorter fallow periods?

Traditional fallow periods in the Bolivian highlands are being shortened in an effort to increase short-term crop yields, with potential long-term impacts on soil microbial communities and their functions. In addition, native vegetation, such as Parasthrephia sp. or Baccharis sp. (both locally known as ‘thola’) are often removed as a fuel for cooking. We evaluated the effects of fallow period and thola on soils in 29 farmers' fields in two municipalities in the Bolivian Altiplano (Umala and Ancoraimes). Soil fungal and bacterial community responses were characterized using 454-pyrosequencing. Soils in Ancoraimes had significantly higher levels of organic matter, nitrogen and other macronutrients compared to Umala. Ancoraimes soils also supported more diverse fungal communities, whereas Umala had more diverse bacterial communities. Unexpectedly, the longer fallow periods were associated with significantly lower fungal diversity in Umala and lower bacterial diversity in Ancoraimes. Fungi assigned to genera Bionectria, Didymella, and Alternaria, and bacteria assigned to genera Paenibacillus, Segetibacter, and Modestobacter decreased in frequency with longer fallow period. The presence of thola was not associated with significantly different overall soil fungal or bacterial diversity, but was associated with higher frequency of some genera, such as Fusarium and Bradyrhizobium. Our results indicate that fallow period has a range of effects on soil communities, and that the removal of thola may impact the dynamics of these communities.

Mosquito population dynamic (diptera: culicidae) in a eutrophised dam

This study observed the mosquito population in a rural eutrophised dam. Larvae of L3 and L4 stages and pupae were dipped out during twelve month collections and the reared to the adult stage for identification. The collections were done along nine metres from the edge of the dam divided in three parts (P1, P2 and P3), each part being 3 m long. P1 did not have vegetation (grass) along its edge,which would reach or sink into the water to promote some shade on the marginal water. A total of 217 adults of four species was identified with the following constancies and frequencies: Culex quinquefasciatus (Say, 1823) (83% and 40.6%), Anopheles (Nyssorhynchus) evansae (Brèthes, 1926) (92% and 26.7%), Anopheles (Nyssorhynchus) rangeli (Gabaldon, Cova Garcia and Lopez, 1940) (83% and 14.3%) and Culex nigripalpus (Theobald, 1901) (33% and 18.4%). C. quinquefasciatus, A. evansae, A. rangeli and C. nigripalpus were more frequent in the quarters Nov./Dec./Jan. (85.7%), May/June/July (75%), Aug./Sept./Oct. (29.4%) and Aug./Sept./Oct. (23.5%) particularly in the months of December (88.4%) Sept.tember (48.94), (38.3) and August (47.62) respectively. The presence of C. quinquefasciatus and the high incidence of Daphinia sp. and also the levels of Organic Nitrogen (0.28 mg/L) and of total Phosphorus (0.02 mg/L) are indications of the eutrophication of the dam. There was a difference regarding the total of Anopheles (A. avansae + A. rangeli) and Culex species (C. quinquefasciatus + C. nigripalpis) between P1 and P2 (χ(2) = 0.0097), P1 and P3 (χ(2) = 0.0005), but not between P2 and P3 (χ(2) = 0.2045).The high C. quinquefasciatus constancy and frequency were confirmed to be a good biological indicator for a eutrophised environment and A. evansae showed a good potential for this environment. Vegetation can be an important factor for anopheline population dynamic also in eutrophic breeding sites.

Biological Nutrient Removal and Fouling Phenomena in a University of Cape Town Membrane Bioreactor Treating High Nitrogen Loads

AbstractThe behavior of a University of Cape Town (UCT) membrane bioreactor (MBR) system was investigated for use in biological nutrient removal from real wastewater. The pilot plant was in operation for a period of 165 days, during which an extensive data gathering campaign was conducted. The pilot plant was started up by inoculating it with activated sludge from a nearby wastewater treatment plant, and it was fed by real municipal wastewater characterized by high organic nitrogen concentrations attributable to discharges from industrial wastewater and sporadic landfill leachate. Carbon and biological nutrient removal processes, a sludge production process, and a membrane fouling mechanism were analyzed and discussed. The organic nitrogen levels, which were higher than typical values for municipal wastewater, caused ammonification phenomena. This led to intense nitrification and denitrification activities. The pilot plant showed satisfactory efficiency in terms of average removal efficiencies for both ca...

Environment-Dependent Distribution of the Sediment nifH -Harboring Microbiota in the Northern South China Sea

The South China Sea (SCS), the largest marginal sea in the Western Pacific Ocean, is a huge oligotrophic water body with very limited influx of nitrogenous nutrients. This suggests that sediment microbial N(2) fixation plays an important role in the production of bioavailable nitrogen. To test the molecular underpinning of this hypothesis, the diversity, abundance, biogeographical distribution, and community structure of the sediment diazotrophic microbiota were investigated at 12 sampling sites, including estuarine, coastal, offshore, deep-sea, and methane hydrate reservoirs or their prospective areas by targeting nifH and some other functional biomarker genes. Diverse and novel nifH sequences were obtained, significantly extending the evolutionary complexity of extant nifH genes. Statistical analyses indicate that sediment in situ temperature is the most significant environmental factor influencing the abundance, community structure, and spatial distribution of the sediment nifH-harboring microbial assemblages in the northern SCS (nSCS). The significantly positive correlation of the sediment pore water NH(4)(+) concentration with the nifH gene abundance suggests that the nSCS sediment nifH-harboring microbiota is active in N(2) fixation and NH(4)(+) production. Several other environmental factors, including sediment pore water PO(4)(3-) concentration, sediment organic carbon, nitrogen and phosphorus levels, etc., are also important in influencing the community structure, spatial distribution, or abundance of the nifH-harboring microbial assemblages. We also confirmed that the nifH genes encoded by archaeal diazotrophs in the ANME-2c subgroup occur exclusively in the deep-sea methane seep areas, providing for the possibility to develop ANME-2c nifH genes as a diagnostic tool for deep-sea methane hydrate reservoir discovery.

Correlation of Root Structures and Soil Properties in the Near-Surface Soil of Three Forest Types in the Southern Mountains of Henan Province, China

We investigated the physico-chemical characteristics and root structure indicators in the near-surface soil of a broadleaf forest, a coniferous forest, and a mixed forest in China. Canonical correlation analysis and a fitting model were used to analyze the relationship between the root and soil characteristics. The results showed that the soil physico- chemical characteristics that can significantly affect root structure indicators including soil organic matter and available nitrogen, and the root structure indicators that are sensitive to soil physico-chemical characteristics include specific root length, root length density and root surface area density. The levels of organic matter and available nitrogen are significantly correlated with root length density, root surface area density, and the root volume density. A cubic curve can well describe the correlation between the available nitrogen and the soil physico-chemical characteristics, while a power function and a S-shaped curve can well describe the correlation between the soil organic matter and the soil physico-chemical characteristics.

Soils development in opencast coal mine spoils reclaimed for 1–13 years in the West-Northern Loess Plateau of China

Soil development is the key process of mine spoil reclamation. To investigate the effects of different plant species and reclamation time on the soil development, 9 plots in the reclaimed spoils of Pingshuo opencast coal mine in Shanxi, China were established and the physical, chemical and microbiological properties of the soils were analyzed. The results showed that, soil bulk density and field capacity in plots with longer reclamation time were statistically different from plots with younger vegetation in both the 0–20 cm and 20–40 cm soil layers. Accordingly, values of organic matter and available nitrogen levels showed a significant increase in both 0–20 cm and 20–40 cm depth with reclamation time increasing and the top layer marked higher value except for some individual data. The organic matter in plot 8 in 0–20 cm depth with 13-year old vegetation reached 9.45 g kg−1, about 2.5-, 2.0- and 3.1-fold higher than the plots of 1-, 3- and 4-year old vegetation respectively. Total microbial amount showed a positive correlation with contents of organic matter which reached 1436.72 × 105 g−1 in plot 8 with 13-years old vegetation, about 11.3-fold greater than plot 1 of 1-yr old vegetation. Plots planted with sea buckthorn (Hippophae rhamnoides ssp. sinensis) singly or mixed with other species tend to develop better soil aggregation and microbiological properties than other plots, which may be due to its particular biological characteristics, developed root system and high growth rate in the first 4–6 year and 8–10 year, indicating that sea buckthorn may be a good species choice for activating soil development in the early stage of reclamation.

Microbial biomass and community structure changes along a soil development chronosequence near Lake Wellman, southern Victoria Land

AbstractFour pedons on each of four drift sheets in the Lake Wellman area of the Darwin Mountains were sampled for chemical and microbial analyses. The four drifts, Hatherton, Britannia, Danum, and Isca, ranged from early Holocene (10 ka) to mid-Quaternary (c. 900 ka). The soil properties of weathering stage, salt stage, and depths of staining, visible salts, ghosts, and coherence increase with drift age. The landforms contain primarily high-centred polygons with windblown snow in the troughs. The soils are dominantly complexes of Typic Haplorthels and Typic Haploturbels. The soils were dry and alkaline with low levels of organic carbon, nitrogen and phosphorus. Electrical conductivity was high accompanied by high levels of water soluble anions and cations (especially calcium and sulphate in older soils). Soil microbial biomass, measured as phospholipid fatty acids, and numbers of culturable heterotrophic microbes, were low, with highest levels detected in less developed soils from the Hatherton drift. The microbial community structure of the Hatherton soil also differed from that of the Britannia, Danum and Isca soils. Ordination revealed the soil microbial community structure was influenced by soil development and organic carbon.

Halonitroalkanes, Halonitriles, Haloamides, and N-Nitrosamines: A Critical Review of Nitrogenous Disinfection Byproduct Formation Pathways

Interest in the formation of nitrogenous disinfection byproducts (N-DBPs) has increased because toxicological research has indicated that they are often more genotoxic, cytotoxic, or carcinogenic than many of the carbonaceous disinfection byproducts (C-DBPs) that have been a focus for previous research. Moreover, population growth has forced utilities to exploit source waters impaired by wastewater effluents or algal blooms. Both waters feature higher levels of organic nitrogen, that might serve as N-DBP precursors. Utilities are exploring new disinfectant combinations to reduce the formation of regulated trihalomethanes and haloacetic acids. As some of these new combinations may promote N-DBP formation, characterization of N-DBP formation pathways is needed. Formation pathways for halonitroalkanes, halonitriles, haloamides, and N-nitrosamines associated with chlorine, ozone, chlorine dioxide, UV, and chloramine disinfection are critically reviewed. Several important themes emerge from the review. First, the formation pathways of the N-DBP families are partially linked because most of the pathways involve similar amine precursors. Second, it is unlikely that a disinfection scheme that is free of byproduct formation will be discovered. Disinfectant combinations should be optimized to reduce the overall exposure to toxic byproducts. Third, the understanding of formation pathways should be employed to devise methods of applying disinfectants that minimize byproduct formation while accomplishing pathogen reduction goals. Fourth, the well-characterized nature of the monomers constituting the biopolymers that likely dominate the organic nitrogen precursor pool should be exploited to predict the formation of byproducts likely to form at high yields.