SOURCES OF TRACE METALS IN STREAMS AND HEADWATER LAKES IN FINLAND

Distributions of Mn, Zn, Cu, Ni, Cr, Pb, As, and Cd in Finnish surface waters were studied by comparing two data sets: samples from 154 headwater lakes collected by the Water and Environment Administration in 1992 and samples from 1165 headwater streams collected during the environmental geochemical mapping program of the Geological Survey of Finland in 1990. It was expected that headwater lakes with catchments smaller than 1 km² and high lake percentage (ratio of lake area to catchment size) would be more influenced by atmospheric trace metal deposition than the streams, with average catchment size of 30 km². The lakes with highest arsenic concentrations lie in an area with greenstones and arsenic-rich black schists. The same lakes have high copper concentrations, which evidently are derived from the Cu-rich greenstones of the catchment. The high copper concentrations of streams and lakes in the industrialized region of the southwest coast are due to several anthropogenic sources. The highest concentrations of chromium occur in brown stream and lake waters rich in humic matter, while manganese and zinc concentrations, which are controlled by acidity, tend to be elevated in low-pH waters. The high nickel concentrations in lakes in southwestern Finland probably are due to anthropogenic input, while Ni anomalies in stream and lake water in eastern Finland are correlated with high Ni contents of glacial till. The lead concentrations in lakes are mainly of airborne anthropogenic origin. The pattern of atmospheric deposition is reflected in the concentrations of Cd, As, Cu, Zn, and Ni in headwater lakes, but land-use, the natural distribution of metals in the overburden, water acidity, and the amount of humic substances influence the distribution of trace metals in both lakes and streams. Thus the trace metal distribution in headwater lakes cannot be used alone to estimate the contribution of anthropogenic atmospheric deposition to metal anomalies in Finnish surface waters.     

INCREASING ROLE OF NITROGEN IN THE ACIDIFICATION OF SURFACE WATERS IN THE ADIRONDACK MOUNTAINS,NEW YORK

Assessments of the aquatic effects of acidic deposition have focused on sulfur, as have recent efforts to control the emissions of acidifying compounds. Nitrogen dynamics were excluded from most acidic deposition modeling studies because it was believed that terrestrial ecosystems strongly retain N and because modeling N is a more formidable task than modeling S due to the influence of complex biological processes on N cycling. Re-examination of available data for the Adirondack Mountains of New York suggests that N deposition may be contributing to both chronic and episodic acidification of freshwaters to a greater extent than is generally believed. Previous research concluded that N has played a limited role in acidification processes in these lakes, based on regional averages of chronic chemistry. However, it is now known that historic acidification responses have been spatially variable within the Adirondack Mountains and that the declines in lakewater pH have been less than previously believed. Lakewater NO₃ ^- concentrations are commonly in the range of 5 to 25 μeq L^-1 on a chronic basis in portions of the Adirondack region that have experienced significant chronic acidification. These NO₃ ^- concentrations correspond in magnitude to inferred historical acidification. Furthermore, the relative importance of NO₃ ^- as an agent of acidification increases dramatically during snowmelt when conditions are most toxic to fish. The consequence of not addressing N in formulating acidification recovery strategies for the Adirondacks includes the likelihood that we will overestimate the response of surface water to the mandated sulfur emissions reductions.     

EVIDENCE OF DICALCIUM PHOSPHATE PRECIPITATION IN A CALCAREOUS SOIL

The‘precipitated-calcium/precipitated-phosphorus’ mole ratio approached a limiting value of 1 as the amount of phosphate, added to a suspension of calcareous soil in 0·01m CaC1₂, was increased, indicating the precipitation of dicalcium phosphate. The phosphate and lime potentials provided further evidence that dicalcium phosphate was present at high rates of phosphate addition.     

果园土壤酸化及铝毒矫治的研究

模拟酸雨使得土壤pH下降,土壤酸化加重,土壤pH值分别比CK下降了0.23、0.54、1.22、1.79,活性Al含量分别比CK增加了0.22%、14.33%、41.41%、66.38%,交换性K含量下降了0.01~0.08cmol/kg,交换性Na含量下降了0~0.08cmol/kg、交换性Ca含量下降了0.14~0.31cmol/kg、交换性Mg含量下降了0~0.10cmol/kg,盐基总量下降了6.1%~23.1%。MgSO4、CaCl2、KH2PO4、柠檬酸处理减少了土壤活性Al的溶出和盐基离子的流失,也明显抑制了龙眼幼苗对Al的吸收,当Al胁迫浓度为0.185mmol/L时,2mmol/L.Mg2 、Ca2 、PO43-和柠檬酸根处理下,根、茎、叶的含Al量下降了13.9%~39.2%、16.9%~39.7%、30.1%~41.0%;当Al胁迫浓度为1.850mmol/L时,根、茎、叶的含Al量下降了29.3%~51.3%、15.3%~39.7%、16.5%~42.5%。     

MINERALIZATION AND CORN RECOVERY OF 15NITROGEN FROM BLACK OATS RESIDUES TREATED WITH HERBICIDES

Nitrogen (N) mineralization from black oat residues (Avena strigosa), with or without previous application of herbicides, and its utilization by corn crop were investigated. The experiments were performed in a completely randomized setup, with three treatments and ten replicates. The treatments were: A) control - corn grown in soil with residues of black oats harvested without herbicide application; B) glyphosate - corn grown in soil with residues of glyphosate-desiccated black oat; and C) glufosinate - corn grown in soil with residues of black oat previously desiccated with glufosinate-ammonium. The remaining black oat residues on the soil surface were smaller in the control treatment than in glyphosate and glufosinate treatments. Black oat residues from the control treatment released 30% and 20% more carbon (C) and nitrogen (N), respectively, than from herbicide treatments. Microbial biomass carbon, total and mineral soil N arising from black oat residues were reduced by herbicide management. Black oat residues treated with glyphosate reduced corn total-N by 16%; however, dry mass yield was not affected by the treatments. Herbicide application on black oat reduced the total amount of residue-released nitrogen in the corn kernels, leaves and the whole plant. Net nitrogen mineralization from black oat residues is affected by the application of glyphosate or glufosinate-ammonium.     

太湖地区高产稻田氮肥施用与作物吸收利用的研究

本讨论长期高量偏施氮素化肥的高产稻田氮肥施用与作物产量、作物对养分吸收利用之间的关系。研究结果表明：化学氮肥施用量（养分量，下同）３００ｋｇ／ｈａ·ｙｒ．，作物增产显，每公斤氮增产１３．５ｋｇ粮食，氮素利用率达４０．３％，省肥、经济、合理；施用量达４５０ｋｇ／ｈａ·ｙｒ．，作物产量增长甚微；施用量达６００ｋｇ／ｈａ·ｙｒ．，每公斤氮只增产７．２９ｋｇ粮食，氮肥利用率降至１７．２％，水稻茎秆中含     

茶园—土壤系统铝和氟的生物地球化学循环及其对土壤酸化的影响

黄棕壤植茶以后,土壤pH下降,土壤酸度随植茶年限的增长而增大,且上层土壤pH的减幅大于下层土壤。茶园土壤的酸化是与茶树对铝和氟的生物积聚、土壤交换性铝与铝络合物的增加以及土壤盐基的淋溶有关。茶树落叶中铝和氟的含量分别高达5836—6136 ppm和469—520ppm;茶树透冠水和土壤渗漏液中均有相当多的Al和F,茶园土壤系统中铝和氟的循环,不仅导致土壤Al³⁺及F^-的增多,还使表土的有机络合态铝以及土壤交换性复合体和土壤溶液中的氟铝络合物积聚。因此,土壤中铝和氟的积累、转化及其生物地球化学循环是茶园土壤酸化的主要原因。     

EVALUATION OF DIFFERENT IRON SOURCES FOR IRON CHLOROSIS RECOVERY IN LOW-CHILL PEACH CULTIVARS

An experiment was conducted with iron chlorosis affected low-chill peach cultivars such as ‘Shaharanpur Prabhat’, ‘Shan-e-Punjab’, and ‘Pratap’ to examine the recovery upon foliar application of three iron sources namely iron (Fe)-sulfate, Fe-citrate and Fe ethylenediaminetetraacetic acid (EDTA). All the iron sources significantly increased the SPAD meter value, physiologically active (Fe²⁺) iron and total iron content of the leaves over control. However, highest values were noted with foliar spray of 1.0% Fe-sulfate. The low-chill peach cultivar ‘Saharanpur Prabhat’ responded best with iron resupply treatment. Significant correlations (at P ≤ 0.01) were obtained between SPAD meter readings with both physiologically active iron (Fe²⁺) and total iron content of leaves in all peach cultivars. Among the sources, the correlations between SPAD meter readings, physiologically active iron (Fe²⁺) and total iron contents were significant at P ≤ 0.01 for only Fe-sulfate and Fe-citrate. The regression analysis showed that the SPAD meter reading accounted 78.2 to 88.0% variation in physiologically active iron (Fe²⁺) and 65.0 to 73.7% variation in the total iron content in the low-chill peach cultivars. The SPAD readings could be used for management of iron chlorosis in peach orchard.     

植物离体培养筛选耐盐突变体的研究

本文总结了利用离体培养系统筛选耐盐突变体的研究进展 ,分别从材料选择、变异来源、突变体的筛选等方面进行了讨论 ,概括了人工诱变离体培养材料的常用诱变剂及诱变剂量的选择 ;从生理生化及分子生物学等角度分析和归纳了耐盐突变体鉴定的研究进展 ,并指出了筛选耐盐突变体应考虑的问题     

用15N研究吉林黑土春玉米对氮肥的吸收利用

用1 5N示踪技术在吉林省中部黑土地区进行田间微区试验 ,研究不同氮肥追施深度与次数对氮肥利用率的影响。结果表明 ,两次深追肥处理 ( 1 0～ 1 5cm)比当地传统的垄上一次浅追肥处理 ,肥料氮的利用率从 2 4 5 %提高到 39 0 % ,氮肥深施并增加追肥次数能有效地提高利用率 ;肥料氮的总损失为 1 6%～ 2 7% ,土壤残留率为 34%～ 5 4 % ;吸收的标记肥料氮中有 1 /2是在 8月 1日以后籽粒形成期被玉米吸收利用的 ;氮肥损失的 70 %～ 90 %是在追肥以后 35天期间发生的 ;施肥的激发效应较弱     

牛体外胚胎质量检测与评价

来源于体外成熟和体外受精的牛早期胚胎与不同细胞的单层细胞共同培养，以检测不同阶段胚胎的细胞数。本研究共检测了３１５３枚桑椹胚和囊胚。通过体外培养４～１０ｄ，不同阶段的胚胎，早期桑椹胚、紧凑型桑椹胚、早期囊胚、囊胚、待扩展囊胚、扩展囊胚、待孵化囊胚和孵化囊胚，经检测其细胞数分别为：４５，６９，７０，８８，１０３，１２７，１３９和１５１。第９ｄ的囊胚细胞数比第７ｄ或第８ｄ的囊胚细胞数无显著差异，然而，不同等级的囊胚的细胞数差异显著（Ｐ＜０．０５）；同时，细胞数少的胚胎发育也慢。通过囊胚免疫法检测，第７ｄ、第８ｄ和第９ｄ回收的扩展囊胚的细胞数分别为６６，６０和５２。此外，虽然在子宫内膜细胞或输卵管细胞－子宫内膜细胞的单层细胞上的囊胚发育慢，且发育率低，但其细胞数与在其它单层细胞上发育的囊胚相比无显著差异。试验结果表明，通过体外化培养出来的囊胚细胞数也能达到体内囊胚的水平。     

盆栽-自然土生长试验研究小麦对土壤中137Cs的吸收

利用环境放射性示踪剂盆栽模拟试验研究了2种小麦对不同活度水平的纯自然江西红壤中137Cs的吸收规律。结果表明,除林地土壤基本不含137Cs外,小麦植株中137Cs均有一定程度的积累,且小麦对137Cs的浓集能力(用转移系数TF表示)随土壤活度水平的提高而增强,大致为扬麦12号:草地(116.36)>水稻旱(47.22)>旱耕(27.33)>林地(几乎没有);扬麦158号:草地(194.92)>水稻旱(16.54)>旱耕(13.41)>林地(几乎没有)。小麦植株各组成部分137Cs积累量大致为:根>茎秆和籽粒外壳>籽粒。小麦吸收的137Cs对估算土壤侵蚀量有很大影响,可为今后示踪模型的修正提供依据。     

白莲二次航天搭载的选育研究

经二次航天搭载后 ,白莲种子SP1代产生广谱分离 ,其生物习性、形态特征及经济生状等出现较大变异 ,其中花型由单瓣变为重瓣或半重瓣 ,并出现部分种子只长立叶 ,不开花 ,部分种子只开花不结蓬、部分种子结蓬后不能正常成熟的现象 ,也出现种子单缸现蕾 9朵 ,花期始蕾期提前 7～ 2 2d ,种子最大单粒重达 1 85g的优良变异 ,这是采用常规育种很少出现的情况     

URANIUM ACCUMULATION IN SOILS FROM LONG-CONTINUED APPLICATIONS OF SUPERPHOSPHATE

This paper describes the accumulation of uranium in soils from superphosphate applied annually to arable and grassland soils. Rates of application of superphosphate were equivalent to about 33kg P and 15 gU ha^?1 year^?1 in three experiments at Rothamsted and to about 37 kg P and 16g U ha ^?1 year ^?1 in one experiment in New Zealand. Most of the uranium (about 1300 g U ha ^?1) applied in superphosphate to the clay loam soil at Rothamsted since 1889 was retained, like P, in the plough layer of arable soils or was adsorbed by the organic surface layers of soils under permanent grassland. Uranium applied in superphosphate to grassland in New Zealand since 1954 (about 330 g U ha^?1) was also concentrated in the surface layers of the soil.     

THRESHOLD MODEL IN STUDIES OF ECOLOGICAL RECOVERY IN BERMUDAGRASS (CYNODON DACTYLON L.) UNDER NUTRIENT STRESS CONDITIONS

Bermudagrass (Cynodon dactylon L.), an important turfgrass as well as a grazing species, was used as a case study for the threshold model in this paper. The growth of this grass in terms of root and shoot lengths and general quality (i.e., color) were evaluated under various levels (full, 1/4, 1/8, and 1/16 N) of nutrients in the culture medium. The concept of a simplified threshold model was described and applied and the conclusions were drawn on the bases of the results of this study. Bermudagrass shoot length and the grass general quality (i.e., color) significantly decreased at lower (1/8 and 1/16 N) nutrient levels. However, root length was stimulated at lower (1/4, 1/8, and 1/16 N) nutrient levels. The values of 1/8 and 1/16 N are significant, because the shoot length at the 1/8 N is reversible and this can be considered the conservation zone in the threshold model. However, the 1/16 N is irreversible or as an indicator of unrecoverable period of life span for bermudagrass which is equal to the critical threshold value. This can be a management guide for bermudagrass production for grazing purposes. Root length was stimulated at lower (1/4, 1/8, and 1/16 N) nutrient levels. Since the bermudagrass roots were not adversely affected by the stress and were somehow stimulated, this grass can be used for reclamation purposes. The grass general quality followed the same pattern as the shoot length, decreased only at the lower levels of nutrients (1/8, and 1/16 N). These three features of bermudagrass are important indicators for the life cycle of this species. These indicators would help the manager for an early warning phase between “healthy” and “unhealthy” states of this grass for production or grazing purposes.     

NITROGEN UPTAKE AND RECOVERY FROM N FERTILIZER AND LEGUME CROPS IN WETLAND RICE MEASURED BY 15N AND NON-ISOTOPE TECHNIQUES

Intensive rice-based cropping systems rely on nitrogenous fertilizer for optimum grain production and legume crops could be used as an alternative nitrogen (N) source for rice. We investigated the fate of N applied to dual cropping wetland rice in the form of legume residue and ¹⁵N labeled fertilizer. In 2001–2002, hairy vetch and broad bean accumulated 131 and 352 kg N ha^?1 of which 41 and 78% was derived from N₂ fixation. In 2002–2003, hairy vetch accumulated 64 kg N ha^?1 and broad bean accumulated 320 kg N ha^?1 of which 21 to 24% was derived from hairy vetch and 31 to 82% N was derived from broad bean by N difference and ¹⁵N-natural abundance method. Our results reveal that hairy vetch and broad bean can supply 50–100% of N required for intensive wetland rice and can be a viable alternative N source to enhance soil fertility.     

酸沉降影响下近20年来衡山土壤酸化研究

对不同时期采自衡山东坡垂直带谱上6个典型土壤剖面Ah层和AB层的样品分析,土壤酸化指标研究结果表明,近2 0年来,由于酸沉降的影响,由花岗岩风化物发育的各类土壤,都有不同程度的酸化,表现在pH值下降,交换性酸,尤其是交换性Al3 增加,交换性盐基总量减少,盐基饱和度下降,特别是土壤酸缓冲性能和土壤酸害容量降低。相比之下,山顶的常湿淋溶土和山麓的湿润富铁土酸化更明显,而山体中部的常湿富铁土酸化进程较慢,山体上部的常湿雏形土酸化进程更慢,表明土壤酸化除了与土壤酸沉降量有关外,还与土壤类型有关     

EXCLOSURE EFFECTS ON RECOVERY OF SELECTED SOIL PROPERTIES IN A MIXED BROADLEAF FOREST RECREATION SITE

Human‐caused trampling that results from excessive recreational use has caused damage to soil and vegetation in forest ecosystems in the Belgrad Forest of Istanbul. The objectives of this study were to examine effects of exclosure on selected soil properties and to determine the recovery time required for soil characteristics in a broadleaf forest recreation site. Litter biomass and topsoil (0–15 cm) were sampled in the forest, exclosure and recreational sites, and soil samples were analysed for saturation capacity, permeability, bulk density, total porosity, organic matter, root biomass, electrical conductivity and soil pH. Results showed that saturation capacity, permeability, total porosity and organic matter increased whereas bulk density decreased significantly in the topsoil under the exclosure, and all these soil properties in the topsoil of the exclosure were greater than those of recreational site. When effects of main factors were compared, averaging over sampling year and soil sampling depth, soils from the exclosure had significantly greater saturation capacity, permeability, total porosity, organic matter and litter biomass and lower bulk density values than the soils from recreational site. Six years of exclosure was effective in improving most of the soil properties in the topsoil. When topsoil and subsoil are considered together, it is obvious that a longer time period is needed for soil recovery in the forest recreational sites. Copyright © 2011 John Wiley & Sons, Ltd.