Ionic composition of rainwater and atmospheric aerosols in Sardinia,southern Mediterranean

The ionic composition of 55 aerosol samples and 31 precipitation events collected in a coastal site in southern Sardinia (Capo Carbonara, 39°06 N; 09°31 E) were compared. The samples were collected during one year period (Oct'90/Oct'91) and showed high variability in composition according to meteorological conditions. Rain and soluble part of aerosol showed a strikingly similar ionic composition: most significant anions were chlorine and sulphate, and sodium is the principal cations, followed by magnesium and calcium. The acid events are associated with N-NW trajectories (anthropogenic influxes from N. Europe) with avg. pH=4.65, non sea salt (nss) Ca=60 eq/l and NO₃/_nssSO₄=0.6. Southern precipitations are influenced by Saharan dust alkaline effects, with avg. pH=6.75,_nssCa=271 eq/l and NO₃/_nssSO₄=0.4. Na/Cl ratio in rain is similar to sea water (0.87), whilst in aerosols there is a Cl loss (Na/Cl=1.10), probably due to reaction with nitric acid. Total fluxes of Ca, Mg, NO₃ and SO₄ were 104, 9, 64 and 113 g/cm², and wet deposition exceeded (65–90%) dry deposition. Scavenging ratios (SR) as defined by the equation:SR=[(Ci)rain/(Ci)air] ^*d, (d=1200g/m³) were calculated, using geometric means (Ci) of precipitation and aerosols collected concurrently during the period (a total of 23 samples). The SR values are Ca=3400, Cl=2400, Na, K, SO₄=1700, Mg=1000 and NO₃=750. These numbers could be useful to infer total fluxes by using simply rainwater ionic composition in Mediterranean semi-arid sites like Sardinia.     

ECOWAT—A model for ecosystem evapotranspiration estimation

In recent years, the availability of near real-time and forecast standardized reference evapotranspiration (E₀) has increased dramatically. Use of the E₀ information in conjunction with calibration coefficients that adjust for differences between the vegetation and the reference surface provides a method to greatly improve the estimates of actual evapotranspiration (E_a) from landscapes (or ecosystems). Difficulties in estimating evapotranspiration (ET) of well-watered vegetation in an ecosystem depend on local advection and edge effects, wide variations in radiation resulting from undulating terrain, wind blockage or funnelling, and differences in temperature due to spatial variation in radiation, wind, etc. Estimating the ET of an ecosystem that is water stressed is even further complicated because of stomatal closure and reduced transpiration. The Ecosystem Water Program (ECOWAT) was developed to help improve estimates of E_a of ecosystems by accounting for microclimate, vegetation type, plant density, and water stress. The first step in estimating E_a is to calculate E₀ using monthly climate data from one representative weather station in the study area. Then, local microclimate data are used to determine a standardized reference evapotranspiration for the local microclimate (E_m). The ratio K_m = E_m/E₀ is calculated and applied as a microclimate correction factor to estimate E_m. The product of E_m and a vegetation coefficient (K_v = E_v/E_m) is used to estimate the evapotranspiration of the ecosystem vegetation (E_v) under well-watered conditions with a full-canopy cover within the same microclimate. Next, a coefficient for plant density (K_d), which is based on the percentage ground cover, is used to adjust the full-canopy E_v to the evapotranspiration of a sparse canopy from a well-watered ecosystem (E_w). A stress (K_s) coefficient, which varies between 1.0 with no stress to 0.0 with full stress, is determined as a function of available water in the root zone. The predicted actual ecosystem evapotranspiration (E_p) is estimated as E_p = E_w × K_s. In this paper, we present how the ECOWAT model works and how it performs when the predicted actual evapotranspiration (E_p) is compared with measured actual evapotranspiration (E_a) collected in several Mediterranean ecosystems (three in Italy and two in California) over a number of years. The potential use of ECOWAT in integrated fire danger systems is discussed.     

质子束诱变大豆的能量和剂量效应

用3个能量（3.0、5.0和7.0 MeV）和4个注量（1×108、1×109、1×1010和1×1011 H+/cm2）的质子束处理大豆品种绥农14的风干种子,以期确定质子束诱变大豆的效果和辐照参数。结果表明：质子束辐照可以导致大豆产生丰富的变异。在本试验条件下,经质子束辐照的大豆种子发芽率未受影响,但M₁代株高显著增加;M₂代出现早熟、黄化和不育等变异类型,总变异频率为6.81%。总变异频率有随注量增加而增加的趋势,但随能量变化的规律不明显。在M₂代,3.0 MeV、1×1011 H+/cm2处理的变异频率最高,为8.26%;在不同能量和注量水平下得到的突变类型不同,其中质子注量为1×1010和1×1011 H+/cm2的处理产生了较多的早熟突变,注量为1×109和1×1010 H+/cm2的处理产生了较多的黄化和不育的突变;质子能量为3.0 MeV时产生了较多的不育突变,5.0 MeV时产生了较多的早熟突变,7.0 MeV时产生了较多的黄化突变。结果表明质子束辐照可以作为一种新的育种手段在大豆上应用。     

Simulation of hydrology following various volumes of irrigation to soil with different depths to the water table

Vertical water fluxes at the water table and in the subsoil need to be quantified because of their significance for the supply of water to crops and the control of soil salinization in areas with shallow groundwater. A soil–water–atmosphere–plant (SWAP) model was calibrated using measured values of soil water content and the water fluxes at the water table. The measurements were taken in a field experiment where the depth to groundwater and the volume of irrigation water applied were controlled. The calibrated SWAP model was then used to simulate the soil water content and fluxes at the water table and in the subsoil under different irrigation and groundwater conditions. The predicted values provided a quantitative insight into specific terms in the water balance equation together with soil water fluxes in the subsoil that cannot be measured directly by field instruments. Crops utilized significant amounts of water from deeper soil layers and directly from groundwater, when the volume of irrigation decreased and the depth to the water table was <3.0 m. Depth to the water table significantly influenced water fluxes occurring in the soil profile over the period when evaporation dominated the hydrological cycle. Shallow groundwater is a very significant water resource for meeting the water requirement of crops. In practice, the frequency and quantity of irrigation need to be varied according to groundwater conditions.     

Water availability and abundance of microbial groups are key determinants of greenhouse gas fluxes in a dryland forest ecosystem

Forests are considered key biomes that could contribute to minimising global warming as they sequester carbon (C) and contribute to mitigate emissions of the potent greenhouse gases (GHG) including nitrous oxide (N₂O), methane (CH₄) and carbon dioxide (CO₂). Management practices are prevalent in forestry, particularly in dryland ecosystems, known to be water and nitrogen (N) limited. Irrigation and fertilisation are thus routinely applied to increase the yield of forest products. However, the contribution of forest management practices to current GHG budgets and consequently to soil net global warming potential (GWP) is still largely unaccounted for, particularly in dryland ecosystems. We quantified the long-term effect (six years) of irrigation and fertilisation and the impact of land-use change, from grassland to a Eucalyptus plantation on N₂O, CH₄ and CO₂ emissions and soil net GWP, within a dryland ecosystem. To identify biotic and abiotic drivers of GHG emissions, we explored the relationship of N₂O, CH₄ and CO₂ fluxes with soil abiotic characteristics and abundance of ammonia-oxidizers, N₂O-reducing bacteria, methanotrophs and total soil bacteria. Our results show that GHG emissions, particularly N₂O and CO₂ are constrained by water availability and both N₂O and CH₄ are constrained by N availability in the soil. We also provide evidence of functional microbial groups being key players in driving GHG emissions. Our findings illustrate that GHG emission budgets can be affected by forest management practices and provide a better mechanistic understanding for future mitigation options.     

The effect of nitrogen fertilization and no‐till duration on soil nitrogen supply power and post–spring thaw greenhouse‐gas emissions

With a world population now > 7 billion, it is imperative to conserve the arable land base, which is increasingly being leveraged by global demands for producing food, feed, fiber, fuel, and facilities (i.e., infra‐structure needs). The objective of this study was to determine the effect of varying fertilizer‐N rates on soil N availability, mineralization, and CO₂ and N₂O emissions of soils collected at adjacent locations with contrasting management histories: native prairie, short‐term (10 y), and long‐term (32 y) no‐till continuous‐cropping systems receiving five fertilizer‐N rates (0, 30, 60, 90, and 120 kg N ha^–1) for the previous 9 y on the same plots. Intact soil cores were collected from each site after snowmelt, maintained at field capacity, and incubated at 20°C for 6 weeks. Weekly assessments of soil nutrient availability along with CO₂ and N₂O emissions were completed. There was no difference in cumulative soil N supply between the unfertilized long‐term no‐till and native prairie soils, while annual fertilizer‐N additions of 120 kg N ha^–1 were required to restore the N‐supplying power of the short‐term no‐till soil to that of the undisturbed native prairie soil. The estimated cumulative CO₂‐C and N₂O‐N emissions among soils ranged from 231.8–474.7 g m^–2 to 183.9–862.5 mg m^–2, respectively. Highest CO₂ fluxes from the native prairie soil are consistent with its high organic matter content, elevated microbial activity, and contributions from root respiration. Repeated applications of ≥ 60 kg N ha^–1 resulted in greater residual inorganic‐N levels in the long‐term no‐till soil, which supported larger N₂O fluxes compared to the unfertilized control. The native prairie soil N₂O emissions were equal to those from both short‐ and long‐term no‐till soils receiving repeated fertilizer‐N applications at typical agronomic rates (e.g., 90 kg N ha^–1). Eighty‐eight percent of the native soil N₂O flux was emitted during the first 2 weeks and is probably characteristic of rapid denitrification rates during the dormant vegetative period after snowmelt within temperate native grasslands. There was a strong correlation (R² 0.64; p < 0.03) between measured soil Fe‐supply rate and N₂O flux, presumably due to anoxic microsites within soil aggregates resulting from increased microbial activity. The use of modern no‐till continuous diversified cropping systems, along with application of fertilizer N, enhances the soil N‐supplying power over the long‐term through the build‐up of mineralizable N and appears to be an effective management strategy for improving degraded soils, thus enhancing the productive capacity of agricultural ecosystems. However, accounting for N₂O emissions concomitant with repeated fertilizer‐N applications is imperative for properly assessing the net global warming potential of any land‐management system.     

Study on the Dearsenization of Hot Metal Using CaO Basis Fluxes

There is plenty of iron ore with arsenic in China. Because a proven dearsenization technique does not come into existence in now iron making and steel making processes and it is necessary for developing the dearsenization of hot metal technologics. A serial of dearsenization experiments are carried out on electric resistance heated furnace, it's found that arsenic in hot metal can be removed by CaO basis fluxes. X ray qualitative analysis of CaO basis slag after dearsenization revealed that the product of hot metal dearsenization with CaO slag is Ca 3As 2 and the dearsenization reaction is a reducing one. The thermodynamic conditions of dearsenization of hot metal using CaO basis fluxes are that the lower of oxygen fraction pressure of the system and [s] in hot metal, the higher of temperature of the system and basically of the slag, the dearsenization efficiency is better.     

Modelling of nitrogen loads from the farming of yellowtail kingfish Seriola lalandi (Valenciennes, 1833)

Farming of yellowtail kingfish ( Seriola lalandi , Valenciennes, 1833) in the coastal waters of Australia is a relatively new aquaculture industry, and little is known about the magnitude of nutrient discharges from individual pens. In this work, we modelled the flow of nitrogen for each of two commercial pens in Fitzgerald Bay, upper Spencer Gulf, South Australia. The fish were fed commercial pellets with feed conversion ratios (FCRs) between 3.0 and 3.2 (dry weight feed/wet weight growth). These high values of FCR were reflected in the high nitrogen loads to the environment (176–195 kg N tonne⁻¹ growth) and a small retention of nitrogen in fish growth (14–16% of feed inputs). Considering an annual production of 2000 tonnes, total loads to the environment can reach 391 tonnes N year⁻¹. Eighty-two per cent of these loads are expected to be lost to the water column as dissolved wastes. The high nutrient loads and the importance of dissolved wastes compared with other aquaculture species, such as salmon and trout, reflect the distinctly higher metabolic rates of this pelagic predatory species. The nature of the wastes suggests low localized impacts at current production levels, but regional effects remain unknown.     

常用减排政策在肉牛养殖业中的有效性分析

为分析常用减排政策在肉牛养殖业中的有效性,探讨了肉牛饲喂过程中的温室气体减排问题。首先利用联合国政府间气候变化委员会(IPCC)提供的饲料成分排放因子测算方法,估算肉牛个体在育肥过程中的温室气体排放量;在此基础3种减排手段,建立了考虑温室气体排放的饲喂决策模型。数值试验表明,价格补贴最具可行性,且有助于降低养殖场运营成本;碳排放限额约束具有最优的单位减排成本,但需要制定完善的政策以避免权力寻租等不端行为;碳税的减排效果最为明显,但将极大地增加养殖场运营成本,可行性最差。     

Development of mold fluxes for welding rod steel at the Shuicheng Iron and Steel (Group) Co., Ltd.

The solidification characteristics of steel are analyzed with the aim of explaining the appearance of serious surface depressions and frequent breakouts when casting billet H08 steel at the Shuicheng Iron and Steel (Group) Co., Ltd., P.R. China