Evaluating maize growth models “CERES-Maize” and “IXIM-Maize” under elevated temperature conditions

It would be preferable to use a reliable crop growth model for studies on climate change impact assessment. The objectives of this study was to evaluate simulation performance for two maize models, including CERES-Maize and IXIM models, included in the DSSAT model (version 4.6) in terms of phenology and yield. Two early maturing cultivars, Chalok#1 and Junda# 6, were grown under controlled environment in plastic houses at Suwon, Korea. Each cultivar, which was sown at four different date in 2013 and 2014, was subjected to four sets of temperature conditions including ambient (AT), AT+1.5°C, AT+3°C, and AT+5°C. In simulations of phenology under given conditions, the anthesis date and grain filling ratio were underestimated, especially when temperature was unusually high, e.g., in 2013. The maize models also had poor accuracy in grain yield, which resulted from the fact that these models had relatively large errors in simulation of kernel number and kernel weight under elevated temperature conditions. In addition, both models were not able to simulate the drastic decrease of kernel number due to heat stress around flowering periods. These results indicated that two maize models would need improvements in simulation of crop response to supra-optimal temperature before they would be used to assess the impact of the climate change on maize yield. This studies merits further study to improve algorithms in phenology simulation at supraoptimal temperature.     

Nitrogen availability decreases prokaryotic diversity in sandy soils

In this study, the interrelation between nitrogen availability and prokaryotic diversity are studied using a well-characterised system from a long-term field experiment on a loamy sandy soil. The prokaryotic potential functional diversity and community composition were assessed using community-level physiological profiling (CLPP), and their phylogenetic diversity was analysed using polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) in combination with sequencing analysis. Highest prokaryotic potential functional diversity was measured in the control soil receiving no N fertilisation, indicating an efficient as well as versatile utilisation of the substrates in this soil. Both substrate utilisation richness and substrate utilisation evenness, the two constituents of the functional diversity, were decreased with increasing N supply. Furthermore, distinct prokaryotic community compositions were generated in N-enriched soils compared to unfertilised control soils. These differences suggest a dominance of populations adapted to utilising readily available substrates. We demonstrated that the shift in prokaryotic functional diversity was connected to a shift in the phylogenetic structure of the bacterial and archaeal communities. Taken together, our data clearly show that, for the sandy soil system, prokaryotic diversity and N availability were interrelated.     

Tracing Pharmaceuticals in the Unsaturated Zone (10 pp)

Background, Aim and Scope   One of the first occurrences of pharmaceutically active compounds in groundwater was reported from the sewage irrigation farms south of Berlin. At these sewage irrigation farms treated sewage effluent passed the soil and unsaturated zone before reaching the aquifer. Clofibric acid was detected in pore water from soils of those sewage irrigation farms in concentrations between 65 ng/L and 1430 ng/L. The aim of this study was to investigate the transport behavior of regularly detected clofibric acid, diclofenac, ibuprofen, and propyphenazone under conditions comparable to those at the sewage irrigation farms in a multiple compound sand column laboratory experiment. Materials and Methods   Sediment column experiments were conducted to study the transport of pharmaceuticals in the unsaturated zone. The migration was measured in fine to medium grained sand and leaching solution containing 1 mg/L of pharmaceutically active compounds and 61 mg/L of the tracer lithium chloride (LiCl). For the analysis of the pharmaceutical compounds the water samples were adjusted to a pH value of 2 and then extracted by solid-phase extraction (SPE). Before extraction, the samples were spiked with a surrogate standard for analytical quality control. The sample extracts were analyzed by capillary gas chromatography-mass spectrometry (GC-MS) with selected ion monitoring (SIM). Depending on the sample volume (100 to 200 mL) and the matrix, the limits of detection were between 1 and 10 ng/L, and the limits of quantitation were between 5 and 25 ng/L. Analysis for calcium, magnesium and lithium were carried out using a 'Trace Scan' ICP-AES from Thermo Jarrel Ash. Sodium, potassium, iron and manganese were analyzed using a Philips PU 9400 flame AAS. Analysis of anions was performed on a Dionex ion chromatograph DX 120. Results   At the sewage irrigation farms the average concentrations of clofibric acid in the unsaturated zone declined from higher values near ground surface (480 ng/L) to lower values near the groundwater table (65 ng/L). From the pharmaceuticals analyzed only clofibric acid, primidone and propyphenazone could be analyzed in the first (upper) aquifer at the sewage irrigation farms. All other pharmaceuticals could neither be detected in the first aquifer nor in the deeper aquifers. Breakthrough curves from soil column experiments revealed no transformation and no retardation for clofibric acid, whereas transformation of diclofenac was so high (79%) that no retardation factor could be calculated. Ibuprofen was significantly transformed (37%), transformation of propyphenazone (17%) was quite low and retardation (Rf = 2.05) was in the range of previously conducted column experiments. Discussion   The results confirm previously conducted experiments with clofibric acid where this compound was identified as highly mobile and persistent. The results that diclofenac and ibuprofen are significantly transformed where unexpected as other studies exhibited much lower transformation under saturated conditions at least for diclofenac. However, lower pH values and higher oxygen contents in the unsaturated zone compared to the aquifer may explain this observed high transformation of these compounds at the column experiments. Conclusions   We conclude that irrigation with sewage effluent containing the compounds used in our experiments will lead to an input into groundwater of clofibric acid, whereas diclofenac and ibuprofen will most likely be transformed during the passage. Propyphenazone will be retarded but will most likely occur in groundwater. These results from the column experiments coincide very well with the occurrence of the pharmaceuticals clofibric acid, primidone, and propyphenazone in the first aquifer. Recommendations and Perspective  : The results underline the need to study the sorption of pharmaceuticals on various materials. e.g. organic matter, surfaces at pH values occurring in the unsaturated zone. Future field studies will also include the investigation of desorption behavior in the unsaturated zone.     

Selection of Tolerant Plants and Their Arrangement to Restore a Forest Ecosystem Damaged by Air Pollution

Plants tolerant to polluted environments were selected, based on several criteria, to restore a coastal forest ecosystem severely damaged by air pollutants discharged from an industrial complex. In addition, a restoration plan was prepared synthesizing these results and the diagnostic ecological indicators in the area for which restoration is required. Pollution-tolerant plants of 11 tree and subtree species, 10 herb species and one shrub species were selected from field surveys in the vicinity of two representative industrial complexes in Korea, Ulsan and Yeocheon. Nine species were selected for tolerance to SO₂ fumigation and six species were selected for tolerance to Al³⁺. Growth and photosynthetic responses of sample plants transplanted into polluted and unpolluted sites showed that 15 species out of the 26 sample plants showed a disposition for tolerance. Most of these are endemic plants and they are composed of diverse species in structure and function. This result implies that these tolerant species could play important roles in the restoration of the study area, which has several specific features. On the other hand, results from transplant tests indicate that a field survey is the most reasonable method for selection of tolerant plants to restore a pollution-damaged ecosystem, as was shown in another restoration program. Results of ecological analysis on vegetation map indicate that the spatial range within the first ridge is the sector for which restoration is required. This sector was classified into four zones on the basis of topographic conditions: lower and upper slopes of both slopes facing and opposite the pollution source. Guidelines for soil amelioration and arrangement of tolerant plants were prepared considering the degree of vegetation degradation, leaf damage of major plant species and soil pollution in each zone under the restoration plan.     

Inorganic and organic carbon dynamics in forested soils developed on contrasting geology in Slovenia—a stable isotope approach

Purpose

Soil carbon dynamics were studied at four different forest stands developed on bedrocks with contrasting geology in Slovenia: one plot on magmatic granodiorite bedrock (IG), two plots on carbonate bedrock in the karstic-dinaric area (CC and CD), and one situated on Pleistocene coalluvial terraces (FGS).

Materials and methods

Throughfall (TF) and soil water were collected monthly at each location from June to November during 2005–2007. In soil water, the following parameters were determined: T, pH, total alkalinity, concentrations of Ca²⁺ and Mg²⁺, dissolved organic carbon (DOC), and Cl^? as well as δ¹³C_DIC. On the other hand, in TF, only the Cl^? content was measured. Soil and plant samples were also collected at forest stands, and stable isotope measurements were performed in soil and plant organic carbon and total nitrogen and in carbonate rocks. The obtained data were used to calculate the dissolved inorganic carbon (DIC) and DOC fluxes. Statistic analyses were carried out to compare sites of different lithologies, at different spatial and temporal scales.

Results and discussion

Decomposition of soil organic matter (SOM) controlled by the climate can explain the ¹³C and ¹⁵?N enrichment in SOM at CC, CD, and FGS, while the soil microbial biomass makes an important contribution to the SOM at IG. The loss of DOC at a soil depth of 5 cm was estimated at 1 mol m^?2 year^?1 and shows no significant differences among the study sites. The DOC fluxes were mainly controlled by physical factors, most notably sorption dynamics, and microbial–DOC relationships. The pH and pCO₂ of the soil solution controlled the DIC fluxes according to carbonate equilibrium reactions. An increased exchange between DIC and atmospheric air was observed for samples from non-carbonate subsoils (IG and FGS). In addition, higher δ¹³C_DIC values up to ?19.4?‰ in the shallow soil water were recorded during the summer as a consequence of isotopic fractionation induced by molecular diffusion of soil CO₂. The δ¹³C_DIC values also suggest that half of the DIC derives from soil CO₂ indicating that 2 to 5 mol m^?2 year^?1 of carbon is lost in the form of dissolved inorganic carbon at CC and CD after carbonate dissolution.

Conclusions

Major difference in soil carbon dynamics between the four forest ecosystems is a result of the combined influence of bedrock geology, soil texture, and the sources of SOM. Water flux was a critical parameter in quantifying carbon depletion rates in dissolved organic and inorganic carbon forms.

     

Long-term electricity production from soil electrogenic bacteria and high-content screening of biofilm formation on the electrodes

Purpose

This study was conducted to determine the existence of soil bacteria in soil by soil microbial fuel cell (SMFC). The main objectives were (1) to differentiate the type of soil which will influence the electricity production, (2) to demonstrate the impact of different volume of soil in the MFC and feeding MFC for long-term electricity production, and (3) to conclude that electricity production is directly proportional to the biofilm formation on the anode surface.

Materials and methods

MudWatt kits were purchased from Keego Technologies USA, and 22 identical SMFCs were designed to study the electricity production from agricultural soil (S1) and vermicompost soil (S2). Ten milliliters of bioslurry is fed in SMFC to study the stability of electricity production at different stages. Microbes were isolated and characterized from the surface of the electrode. Biofilm analyses were done by high-content screening (HCS) system using 10 μl of acridine orange (100 μg/ml) at different stages of biofilm, and scanning electron microscopy is applied to confirm the matured biofilm on the surface of the anode.

Results and discussion

Application of bioslurry at different stages of electricity production conquers the normal energy recovery of the SMFCs and S2 soil with bioslurry sample produced the highest open circuit voltage (OCV) of 2.8 V (460 days) and S1 soil sample with bioslurry produced 1.7 V (364 days). The difference between SMFCs and MudWatt kits significantly confirms that increasing the volume of soil in the anode part increases the electricity production. The maximum OCV of S1 and S2 in MudWatt kits were 1.5 V (90 days) and 1.8 V (190 days), respectively. Increased volume of soil in our SMFCs produce maximum OCV of 1.8 V (S1 for 173 days) and 2.2 V (S2 for 240 days), and HCS analysis of biofilm at different stages reveals that electricity production is directly proportional to the biofilm formation.

Conclusions

Thus, it was concluded that the nature of soil and soil bacterium is important for the electricity production, and S2 soil sample produces maximum electricity than the S1 soil sample. Feeding of SMFCs with bioslurry aids the long-term and stabilized electricity production in both the soil samples.

     

Human activities modify soil properties in urban parks: a case study of Tel Aviv-Jaffa

Purpose

The aim of the present study was to investigate the effects of visitors’ activities on soil properties in parks of Tel Aviv-Jaffa city, Israel.

Materials and methods

The city was divided into three geographical regions: south, central, and north. This division reflects the course of development of the city from south to north and encompasses various socioeconomic levels of residents. In each region, 9–15 parks were randomly chosen and classified into three groups according to their size (in m²): 2?×?10³ to 10?×?10³, 11?×?10³ to 20?×?10³, and 21?×?10³ to 50?×?10³. In each park soil, 0–2 cm of depth layer was sampled in areas under various levels of visitor pressure from July to August 2011, and organic matter, electrical conductivity, and sodium and chlorine contents were determined. Lawns and path and picnic areas represented low and high visitor pressure, respectively. Observations were conducted to characterize the various land uses of the parks and to estimate the numbers of visitors. Also, questionnaires were used at selected parks to assess visitors’ motivations or reasons for visiting the parks.

Results and discussion

Socioeconomic indicators, such as the number of residents, the apartment areas, and the percentages of family households, differed among the regions. Soil properties differed between the areas of high and low visitor pressure: they were influenced by type of human activity, size of the park, and number of visitors.

Conclusions

Soil properties are affected by variations in the intensity of park use by visitors and by the type of activities enjoyed by these visitors, both of which depend on the socioeconomic status of the park area.

     

Quantitative determination of linoleic acid in infant formulas by gas chromatography

A method has been developed for the quantitative determination of linoleic acid in infant formulas by gas chromatography (GC). A known amount of triheptadecanoin was spiked into the sample. Total lipid was extracted from the product by an ethyl ether-petroleum ether-ethanol system in a Mojonnier flask. The sample was saponified by methanolic KOH after the solvents were evaporated. Methyl esters of the fatty acids were prepared by boron trifluoride (BF3) in methanol and analyzed by gas chromatography. A glass column packed with 10% SP-2340 (75% cyanopropyl silicone) was used to separate and identify the methyl linoleate and the methyl heptadecanoate. The quantity of methyl linoleate was calculated by comparing the integrated peak areas of these 2 fatty acid methyl esters. This method was satisfactory for both milk protein-based and soy protein-based matrixes. The results obtained by this method are comparable to those obtained by the AOAC spectrophotometric method 28.082-28.085.