我国的麻类质量安全问题

本文概述了我国麻类生产的现状,针对麻类生产存在的质量问题,提出了提高麻类质量安全的对策及建议。     

Have you checked for charcoal? Assessment of soil condition using soil organic carbon

Soil condition is commonly assessed by using soil organic carbon (SOC) as an indicator; however, a large proportion of the world's soils can contain charcoal, a biologically‐inert form of organic carbon. We investigated whether the presence of charcoal in soil could lead to an inaccurate assessment of soil condition when using SOC as an indicator. We sampled topsoil in a south‐east Australian catchment affected by severe fires in 2003. Samples (n = 100) were analysed for two SOC fractions: (i) total SOC (t‐SOC, loss on ignition), which included charcoal, and (ii) biologically‐active SOC (a‐SOC, persulphate‐oxidation), which did not contain charcoal. Using novel (boosted regression trees) and traditional (linear regression) modelling methods we compared the relative importance of abiotic (slope, aspect, elevation and soil texture) and biotic (land use and vegetation structure) factors as predictors of t‐SOC and a‐SOC concentration. A major difference between the two response variables was less relative importance of land use as a predictor when using t‐SOC as a response variable. Therefore, ignoring the presence of charcoal would have led to an under‐estimation of the effect of land‐use conversion on the biologically‐available SOC fraction. The presence of charcoal has important ramifications for routine assessments of soil condition given that (i) SOC is a commonly used indicator and charcoal and biologically‐active SOC differ in their effects on soil properties, (ii) fires historically occur on a large area of land, (iii) charcoal is a long‐lasting consequence of fires and (iv) charcoal can account for a large proportion of SOC and yet be unnoticed during sample preparation.     

Anthropogenic environmental impact in the Mediterranean coastal area of Koper/Capodistria,Slovenia

Purpose

Heavy metal content in soils could be a consequence of geogenic and different anthropogenic sources. In ancient times, soils in the Mediterranean region were affected by agriculture and viticulture, whereas more recently, industry and traffic might contribute more to their pollution. The aim of the study is to determine the extent of multisource heavy metal pollution in soils within the Koper area.

Materials and methods

Along the northern Adriatic Sea coast, around the port city of Koper/Capodistria, 24 topsoil samples were collected; sets of six samples representing four possible pollution sources: intensive agriculture, viticulture, port activities and industry. The parent material of the soil is mainly derived from the Eocene flysch weathered marls and calcarenites and the soil types are eutric. The chemical composition of the samples was determined by ICP-ES for oxides and several minor elements and by ICP-MS for heavy metals. The mineral composition of the selected samples was checked using X-ray powder diffraction. Different statistical analyses were performed on the normally distributed data.

Results and discussion

The mean concentrations of all samples are: Cr 215 mg kg^?1, Ni 81 mg kg^?1, Zn 67 mg kg^?1, Cu 44 mg kg^?1 and Pb and Co 18 mg kg^?1. The ANOVA showed significant differences only in CaO, C/TOT, P₂O₅, Co and Pb between those locations within reach of the different contamination sources. The observed average values of heavy metals are well below Slovenia’s Directive limit for Cu, Pb and Zn, close to but not above it for Co and above the action value for Cr and Ni. According to Igeo, soils from all the sampling locations are uncontaminated with Co, Ni and Pb, and uncontaminated to moderately contaminated with Cu and Zn at one port location, and with Cr at all locations.

Conclusions

The very high Cr and Ni levels could still be geogenic because soils developed on Eocene flysch rocks are enriched in both metals. Cr and Ni are not correlated because of their different levels of sorption and retention in carbonate soils. Cr was retained and concentrated in the sand fraction but Ni has been mobilised in solution. The only serious threat to the environment seems to be an illegal waste dumping area near the port.     

Origin of Wine Lignans

Plant Foods for Human Nutrition - Plant lignans possess several properties beneficial for human health and therefore, increasing their contents in foods and beverages is desirable. One of the...     

Humus accumulation, humification, and humic acid composition in soils of two post-mining chronosequences after coal mining

Purpose

To assess how the rates of humus formation and humification are affected by land use and age of ecosystems, this study investigated soil development in two post-mining chronosequences (spoil heaps formed from open-cast coal mining near Sokolov, Czech Republic). The following characteristics were measured: content, composition, and properties of humic acids; organic carbon (C) and total nitrogen (N) contents; pH; and amorphous iron content.

Materials and methods

Two chronosequences were studied. One consisted of unreclaimed spontaneously revegetated spoils (3, 12, 20, and 40 years old). The other consisted of heaps that were reclaimed by planting alder in graded heaps (7, 15, 20, 30, and 40 years old). Humus and iron contents as well as pH were determined, and humic acids were extracted for detailed chemical analyses (C, H, N, ¹³C-NMR, and pyrolysis mass-spectrometry).

Results and discussion

C and N accumulated faster in the reclaimed sites than in the unreclaimed sites; organic matter accumulation results in the decrease of pH in all soils and in spontaneous sites also increase of amorphous iron content. Humic acids (HA) and fulvic acids (FA) increased with the site age in both chronosequences. The CHA/CFA was higher in the reclaimed soils than in the unreclaimed soils, and the CHA/CFA ratio increased with age in the unreclaimed soils. Humic acid aromaticity was higher in the reclaimed site than in the unreclaimed sites but increased with the age of unreclaimed sites. H and O content decreased with age of reclaimed soils. Humification led to an increase in HA caloricity in the reclaimed sites but not in unreclaimed sites because of the influence of residual wax-type substances in the unreclaimed sites. Degree of HA oxidation (ω) for the reclaimed plots was similar to that in typical zonal soils but was highly variable in unreclaimed soils.

Conclusions

Relative to spontaneous revegetation in the unreclaimed sites, reclamation increased the rates of humus accumulation, humification, and humus acid transformations. The differences between reclaimed and unreclaimed sites, however, decreased with site age and were very small in 40-year-old sites. These differences correspond to the rapid colonization of the reclaimed sites and the slow colonization of the unreclaimed sites by soil biota.     

Effects of soil solarization on nematodes in Croatia

For the first time soil solarization was investigated in Croatia both in the field and in the greenhouse in 1991, 1992, 1993 and 1994. For two months (July and August), the soil was mulched with transparent polyethylene (PE) sheets of 0.015 or 0.050mm thickness. Soil temperatures at depths of 5, 10 and 20cm were recorded daily. In order to assess nematode population densities, soil samples were analysed before mulching and at the end of the mulching treatment. The results of these experiments showed that soil solarization drastically reduced the population of plant-parasitic nematodes (Meloidogyne, Pratylenchus, Paratylenchus, Tylenchus, Tylenchorhynchus spp.) by about 97–100% at a depth of 10cm and 92–97% at a depth of 20cm in the field, while in the greenhouse, the population of plant-parasitic nematodes was reduced by about 89–100% at a depth of 10cm and 98–100% at a depth of 20cm.In the same experiments, the population of saprophytic nematodes in the field was reduced by about 86–90% at a depth of 10cm and 72–89% at a depth of 20cm. In the greenhouse, the population of saprophytic nematodes was reduced by about 87–97% at a depth of 10cm and 87–93% at a depth of 20cm. This data shows that soil solarization was less effective in the control of saprophytic nematodes, which is considered to be an advantage.