Factors and Predictions for Cadmium Transfer from Soils into Tomato Plants

Soil-plant transfer models are needed to predict levels of cadmium (Cd) in vegetables when evaluating the food chain risks of Cd contamination in agricultural soils. In the present study, the transfer of Cd from a wide range of soils into tomato plants was investigated in order to identify the major factors and to develop predictive models. It was found that soil pH was the main factor controlling Cd uptake and lower pH was more favorable for Cd bioaccumulation. Furthermore, the hydrogen ion activity, other than pH, was correlated linearly with the ratio of plant Cd to soil Cd. Combining soil Cd, and the interaction between soil Cd and hydrogen ion activity greatly improved the model to predict the transfer of Cd from soil to plant. Compared with the previous log transformation model, the predicted model improved the regression coefficient from 0.799 to 0.973 and has important significance in practice.     

Transfer of Cd, Pb, Ra and U from Phosphogypsum Amended Soils to Tomato Plants

About 170 million tons of phosphogypsum (PG) are annually generated worldwide as a by-product of phosphoric acid factories. Agricultural uses of PG could become the main sink for this waste, which usually contains significant radionuclide (from the ²³⁸U-series) and toxic metals concentrations. To study PG effects on pollutant uptake by crops, a completely randomised greenhouse experiment was carried out growing Lycopersicum esculentum Mill L. on a reclaimed marsh soil amended with three PG rates (treatments), corresponding to zero (control without PG application), one, three and ten times the typical PG rates used in SW Spain (20 Mg ha^?1). The concentrations of Cd, Pb, U (by inductively coupled plasma mass spectroscopy) and ²²⁶Ra and ²¹⁰Po (by γ-spectrometry and α-counting, respectively) were determined in soil, vegetal tissue and draining water. Cadmium concentrations in fruit increased with PG rates, reaching 44?±?7 μg kg^?1 formula weight with ten PG rates (being 50 μg kg^?1 the maximum allowed concentration by EC 1881/2006 regulation). Cd transfer factors in non-edible parts were as high as 4.8?±?0.5 (dry weight (d.w.)), two orders of magnitude higher than values found for lead, lead, uranium and radium concentrations in fruit remained below the corresponding detection limits—0.5 and 0.25 mg kg^?1 and 0.6 mBq kg^?1, respectively (in a d.w. basis). ²³⁸U (up to 7 μg kg^?1 d.w.) and ²¹⁰Po (up to 0.74 Bq kg^?1 d.w.) could be measured in some fruit samples by α-spectrometry. Overall, the concentrations of these metals and radionuclides in the draining water accounted for less than 1% of the amount applied with PG.     

黄土丘陵沟壑区小流域治沟骨干工程淤积量预报模型探讨

黄土丘陵沟壑区治沟骨干工程泥沙淤积来源于坡面侵蚀，沟 道侵蚀和库区岸坡坍塌，控制面积的坡面侵蚀量可以根据同一地区的径流试验小区资料进行计算；库区岸坡坍塌量可以通过实测现库岸地形，并与建库初期库岸地形比较计算而得，通过实测已建骨干工程的淤积量，并减去相应的坡面侵蚀量和库区岸坡坍塌量，便可求得沟道侵蚀量，在先期建立坡面侵蚀量，沟道侵蚀量分别与降雨，土地利用状况和流域特征等相应预测因子相关关系的基础上，建立了治沟骨干工程淤积量的预测模型，实际检验结果表明，模型的最低精度为79％。     

Cesium-137 Concentrations in Sediments and Aquatic Plants from the Pinios River, Thessalia (Central Greece)

The levels of radioactive contamination by artificial radiocesium (¹³⁷Cs) were evaluated in sediments and the commonest species of water plants. Specimens were collected from a range of biotopes along the Pinios River and its tributaries, during the years 1998 and 2010. The ¹³⁷Cs concentrations within the above period clearly indicate that this radionuclide still decrease in the River Pinios. A marked decrease is also observed in comparison to our previous results in 1993. ¹³⁷Cs concentration activities in the sediment are higher than in the plant material. In general, roots showed greater ¹³⁷Cs concentration than leaves, while stems showed the lowest concentration. Significant differences in ¹³⁷Cs concentrations were found among different species growing under similar environmental conditions. ¹³⁷Cs content in collected aquatic plants was in the descending order: Ceratophyllum demersum L. > Myriophyllum spicatum L. > Paspalum pasalodes Scribner > Cladophora glomerata L. > Cyperus longus L. > Potamogeton nodosus Poiret. A comparison of the studied stations indicated that the southwest side of Thessalia plain, where the first two initial sampling stations of the Pinios River and the tributaries Enipeas and Kalentzis are situated, was highly contaminated. Low ¹³⁷Cs concentrations were observed in the Titarisios tributary, originated from the northeast part of Thessalia plain, behind Mt. Olympus and the last sampling stations of the Pinios River.     

沉水植物对沉积物中铜锌铅的富集

选用4种南方常见水生植物(狐尾藻、轮叶黑藻、金鱼藻和水绵),以郴州重金属污染土样作为底泥,通过4种藻类单独及两两组合的水培方式,在室内模拟条件下培养1周,培养结束,比较各藻类的生长情况;经过浓盐酸+浓硝酸+高氯酸消化处理后,利用原子吸收光谱法测定藻体内铜锌铅3种重金属的含量。结果表明,单独培养和组合培养,藻体均有不同程度的增长,以狐尾藻的长势最好,狐尾藻+轮叶黑藻的培养中狐尾藻的生长百分比达到最大值65.7%。轮叶黑藻+水绵的组合方式可用于治理铜污染严重的区域,轮叶黑藻和水绵体内的铜含量可分别达到4.69mg/kg和20.13mg/kg,富集系数分别为0.041和0.178;金鱼藻+轮叶黑藻的组合方式可用于治理锌污染严重的区域,金鱼藻和轮叶黑藻体内的锌含量可分别达到139.96mg/kg和117.93mg/kg,富集系数分别为0.301和0.253;金鱼藻+狐尾藻的组合方式可用于治理铅污染严重的区域,金鱼藻和狐尾藻体内的铅含量可分别达到302.01 mg/kg和290.33mg/kg,富集系数分别为0.337和0.324;     

蔷薇科模式植物林丛野草莓的基因组测序完成

野草莓(Fragaroa vesaca),俗称林丛或高山草莓,是蔷薇科的一员,蔷薇科是由超过100个属,3000个种组成的大家庭.这个庞大的家族包含许多重要经济和受欢迎的水果、坚果、观赏植物、木本作物,如杏仁,苹果,桃子,樱桃,覆盆子,草莓,玫瑰.这个被视为蔷薇科模式植物的林丛野草莓的基因组序列在国际研究财团的支持下,与在2010年1月在美国圣迭戈召开的动植物基因组大会上宣布完成.     

石佛寺人工湿地不同营养特征淤积物对水生植物生长的影响

为研究淤积物营养特征对不同生长时期内水生植物生物量的影响,在石佛寺水库人工湿地采集对比了芦苇（Phragmites communis）和蒲草（Typha angustifolia）两种不同水生植物区域内的淤积物和生物植株,研究了不同营养特征淤积物对水生植物生物量的影响。结果表明:淤积物内营养特征与各时期内水生植物的生物量具有一定的相关关系。生长初期,芦苇和蒲草的生物量与淤积物中氮元素（N）和磷元素（P）呈负相关,其中与TP含量的相关性达到显著水平（p<0.05）,即较高的淤积物中营养元素含量会对水生植物的生长产生抑制作用;随着水生植物的进一步生长,这种抑制作用逐渐变小,并逐渐转变为促进作用,淤积物中营养元素含量与水生植物生物量的相关关系由负相关转为正相关;水生植物进入成熟期后,芦苇和蒲草的生物量达到最大值,淤积物内TN及TP含量均与水生植物的生物量呈显著正相关关系;之后随水生植物死亡腐解,这种关系逐渐消失。淤积物营养水平会对水生植物生长产生影响,主要表现在生物量的累积上。不同水生植物生长所受影响有所差异,蒲草的生物量与淤积物中营养元素含量的相关性更高。     

Sediment Records of Fallout Radionuclides and their Application to Studies of Sediment-Water Interactions

The fallout radionuclides 210Pb and 137Cs are widely used to date environmental records contained in lake sediments. Since the radionuclide records are themselves the outcome of the transformation of atmospheric fallout by mediating transport processes from the catchment, through the water column and post-depositional migration via pore waters, reliable models of these processes are crucial to accurate dating. The large quantities of data on 210Pb and 137Cs in lake sediments accumulated through their widespread dating applications may be used to study transport models. Their advantages as tracers of transport processes include widespread dispersal through the environment, relatively simple and well known input functions, and ease of measurement. One of the principle factors controlling the transport of any species through the water column is its distribution between aqueous and particulate phases. The relatively solubility of 137Cs in the water column is demonstrated by the reduced 137Cs/210Pb inventory ratios in sediments compared to values expected from direct fallout. Using sediment records from a wide range of Cumbrian lakes, calculations based on simple models indicate that the particulate fraction of weapons fallout 137Cs in the water column ranged from 5-22%, and was proportional to the square root of the sedimentation rate (determined by 210Pb). The KD value for weapons 137Cs in the water column is estimated to be in the range 1-2×105 L kg-1. This is comparable with KD values for Chernobyl 137Cs in these lakes (Smith et al. in press) obtained from direct measurements in the water column.     

Transfer of zinc from xylem to phloem in the peduncle of wheat

Maturing wheat grains represent major sinks for solutes in the phloem, while the xylem sap entering the ear is mainly delivered to the glumes. Nutrients and assimilates transported in the phloem may either be exported from source organs or loaded into the sieve tubes by a xylem‐to‐phloem transfer in the stem. The transfer of zinc from xylem to phloem in the peduncle of wheat was investigated by feeding radiolabelled zinc into the cut xylem of detached shoots. The label accumulated in grains of shoots with an intact phloem but not in those steam‐girdled below the ear. These findings indicate that zinc fed in low concentrations (0.1 ‐ 10 μM) entered the ear mainly via the phloem. After feeding high zinc concentrations (100 ‐1000 μM), the label was mainly retained in the stem and steam‐girding below the ear was rather ineffective. These results led to the conclusion that at these high concentrations zinc was still eliminated from the xylem sap, but loaded only in a minor percentage into the phloem. The interactions between the two long distance transport systems may play an important role in the regulation of zinc transport to the maturing grains of cereals.     

Wetland Simulation Model for Nitrogen, Phosphorus, and Sediments Retention in Constructed Wetlands

Steamboat Creek, Washoe County, Nevada, is considered the most polluted tributary of the Truckee River, therefore the reduction of nutrients from the creek is an important factor in reducing eutrophication in the lower Truckee River. Restoration of the wetlands along the creek has been proposed as one method to improve water quality by reducing nutrient and sediments from non-point sources. This study was aimed to design a simulation model wetlands water quality model (WWQM) that evaluates nitrogen, phosphorus, and sediments retention from a constructed wetland system. WWQM is divided into four submodels: hydrological, nitrogen, phosphorus, and sediment. WWQM is virtual Visual Basic 6.0 program that calculates hydrologic parameters, nutrients, and sediments based on available data, simple assumptions, knowledge of the wetland system, and literature data. WWQM calibration and performance was evaluated using data sets obtained from the pilot-scale constructed wetland over a period of four and half years. The pilot-scale wetland was constructed to quantify the ability of the proposed wetland system for nutrient and sediment removal. WWQM simulates nutrient and sediments retention reasonably well and agrees with the observed values from the pilot-scale wetland system. The model predicts that wetlands along the creek will remove nitrogen, phosphorus, and sediments by 62, 38, and 84 %, respectively, which would help to reduce eutrophication in the lower Truckee River.     

经高赖氨酸基因导入玉米自交系的研究

通过对18个玉米自交系的组织培养,筛选到8个可以正常分化的自交系.用基因枪的方法对其中的4个自交系进行了遗传转化,将高赖氨酸基因导入玉米的胚性愈伤组织.以减少潮霉素筛选次数和筛选浓度的方法,得到分化再生植株.经分子检测,证明外源基因已成功整合到玉米基因组中.部分T0代植株正常结实,通过对T1代植株的分子检测,表明外源基因可以稳定遗传.对其中的转化植株所结的种子进行了赖氨酸含量的检测,发现赖氨酸含量最高提高了16%.     

Availability in Soil and Acquisition by Plants as the Basis for Phosphorus and Potassium supply to Plants

This report summarizes research aimed at describing the processes and quantifying the factors affecting transfer of P and K from soil into plants. Soil properties related to availability and plant properties reflecting nutrient acquisition were determined. Their interactions in the rhizosphere and their importance for nutrient supply of plants were studied by a combination of measurements and calculations using a simulation model. Phosphorus and potassium uptake by roots decreased P and K concentration at the root surface and caused characteristic depletion profiles in the adjacent soil. The shape of the profiles depended on the effective diffusion coefficient, the concentration of the nutrient in soil, morphological properties of the roots and on influx into roots. The degree of depletion at the root surface indicated the proportion of the nutrient potentially available in the soil. The shape of the depletion profiles reflected the amount of the nutrient taken up by a root section. The parameters found to describe nutrient acquisition are (i) influx per unit root length, (ii) root length per unit shoot weight (root/shoot ratio), and (iii) the period of time a root section absorbs nutrients. Plant species differed considerably in these properties. In order to integrate the processes involved and to evaluate the importance of individual factors, the Claassen-Barber model was used. Depletion profiles and nutrient uptake calculated with this model were in good agreement with measured values in a number of cases. However, at low P supply, plants absorbed substantially more P than the model predicted. This indicates that influx in this case is supported by mechanisms not properly taken into account yet. Influx per unit root length depends on morphological properties of and nutrient mobilization by roots. Root hairs increase root surface area per unit root length. In addition, because of their small diameter and geometric arrangement in soil, root hairs are specially apt to gain from diffusion when concentration gradients are small. This applies even more to VA-mycorrhizae. Their hyphae are longer and thinner than root hairs and can thus deplete larger volumes of soil per unit root length. Root-induced changes of soil pH increased the size of P depletion profiles, indicating that roots can mobilize soil P by this mechanism. Both acid and alkaline phosphatase enzyme activities were found to be markedly increased at the soil-root interface suggesting that soil organic P may contribute to the P supply of plants.     

园林植物模型在Quest3D中的应用研究

随着计算机软硬件水平的提高和可视化技术的不断发展更新,虚拟现实技术在园林中应用的领域越来越广,对园林设计的影响也越来越大。作为主流的虚拟现实软件,Quest3D在园林表现中越来越多地被应用,而园林植物对园林设计效果的表现起着重要的作用。对园林植物模型在Quest3D中的应用提出了优化的方法,以改进和完善基于Quest3D的园林虚拟漫游系统的表现效果。     

成都经济区放射性环境评价分析研究

运用区域1/25万土壤化探数据中铀、钍、钾的含量数据,对成都经济区的放射性水平进行了评价。介绍了放射性核素含量分布情况和环境放射性水平,通过成都经济区地质情况和成都经济区放射性环境分布情况,分析了地质条件对成都经济区环境放射性的影响,并初步研究了地质条件影响放射性水平的原因。最后总结了成都经济区地质环境对天然放射性水平分布情况的影响规律:除龙门山褶皱带和峨眉山-瓦山断块少部分地区外,绝大部分地区γ射线内外照射指数都在国家建筑材料放射性核素限量标准控制式的范围内;地质构造、地表出露岩层和地表水对放射性水平有较大的影响。     

Transport Characteristics of Tile-Drain Sediments from an Agricultural Watershed

The use of tile drains for subsurface drainage in agricultural watersheds It as created concern for the delivery of sediment to receiving waters and potential undesirable effects on surface and subsurface water quality. In this study, transport characteristics of sediment from the drains in an agricultural watershed of the Thames River, near Kintore, Ontario, Canada were tested in a 5 m diameter. rotating circular flume located at the National Water Research Institute in Burlington. Ontario. Tile drain sediments were collected and mixed with river water at different speeds in the flume to study transport processes such as deposition, erosion and flocculation as a function of bed shear stress. During deposition and erosion experiments. water samples were collected to detennine changes in the concentrations of rations, anions and dissolved organic carbon. The results show that tile drain sediments have a tendency to flocculate when subjected to a range of shear stresses. The median diameter (D₅₀) of the floc size distribution reached a maximum value at a shear stress of 0.169 Nn² which can be considered an optimum shear stress for flocculation for this sediment. The critical shear stress at which all of the initially suspended sediment deposited to the flume bed was measured as 0.056 Nm². The pH and cation concentrations remained relatively constant during erosion and deposition experiments. Anion concentrations were more variable, most likely due to the presence of bacteria which could have also played a role in the flocculation mechanism oftile drain sediment.     

Variations of Phosphorus Release from Sediments in Stratified Lakes

The aim of this investigation was to study the temporal variation in phosphorus release from the sediments and its influence on water quality of stratified lakes. The concentrations of soluble reactive phosphorus (SRP), calcium and sulfate in the interstitial water and the pH in the wet sediments of dimictic lakes were investigated during the spring circulation and at the end of summer stratification. Multiple regression analysis using the calculated diffusive fluxes of SRP out of the sediments and the morphometric characteristics of the lakes (reduced water depth), explained 73 % of the variance of the SRP-accumulation in the hypolimnia during summer stagnation. At the end of surnmer stratification diffusive fluxes of SRP out of the sediments increased and pH-values and sulfate-concentrations decreased at the sediment surface (0–2 em) and in the hypolimnia. The maximum diffusive flux of SRP was calculated to be 5.8 mg/m²/d at the end of summer stagnation. Prob able reasons for these higher diffusive fluxes of SRP at the end of summer stagnation are higher supply of labile organic matter and thereby higher mineralization rates. lower redox potential and thus higher dissolution of redox sensitive P-binding forms and/or dissolution of phosphorus being bound to Ca-phases at lower pH.     

Environmental Impacts in the Jianghan Plain: Evidence from Lake Sediments

There is growing concern about the environmental impact of rapid economic growth in China. The problem is compounded by the scarcity of baseline data on the state of China's natural environment. As a step towards solving this problem, palaeolimnological methods have been applied to seven lakes in the Jianghan Plain, China, to evaluate recent changes in human impact. Lake sediment cores show enhanced concentrations of fossil fuel derived spheroidal carbonaceous particles (SCP) and Pb at all sites across the Jianghan Plain. The distribution of these industrial contaminants shows the overwhelming influence of the industrial cities. Wuhan dominates the fossil fuel derived pollution, while the copper smelter at Daye dominates the heavy metal pollution. Analysis of sediment diatom assemblages indicates mean total phosphorus concentrations of greater than 40 μg L-1 P in the lakes of the more intensely agricultural western part of the Jianghan Plain. The sediment concentration profiles for biogenic elements at these sites indicates a post-1960 eutrophication. Evidence for eutrophication in the eastern lakes is much weaker, though some evidence is present at all sites. The tracers of industrial pollution (Pb and SCP) correlate with Mn in the many of the lake sediments. This is compatible with both soil acidification, and soil gleyification due to intensified rice production.     

Picric Acid Degradation in Sediments from the Louisiana Army Ammunition Plant

Picric acid is an explosive historically produced and disposed at the Louisiana Army Ammunition Plant (LAAP) in northern Louisiana. The potential for natural degradation of picric acid was investigated by creating picric-acid slurries with four LAAP sediments of variable composition and monitoring for up to 98 days. The concentrations of picric acid decreased rapidly in all slurries during the first day, attributed to adsorption, followed by slower decreases in some samples due to degradation. Degradation in unsterilized slurries was nearly complete within 80 days for two of the four sediments. Increases in nitrite and nitrate concentration over time were proportional to the loss of picric acid and indicate that at least two of the three nitrite groups were removed from the picric acid molecule. The absence of significant concentrations of compounds with a mass greater than 100 amu in the final solutions suggests that all three nitrite groups were removed. No correlation was found between the degree of degradation and grain size, clay content, organic content, carbonate content, or a suite of element concentrations in the sediment. Degradation in sterilized samples was minimal for all sediment slurries, indicating microbial activity as the primary mechanism of degradation.     

Correcting the Effect of the Sorbent to Solution Ratio on Sorption Isotherms from Batch Tests with Soils and Sediments

There is evidence in the literature that the ratio of mass of sorbent (M) to volume of solution (V) affects the results of batch tests with soils and sediments. This restricts the use of such data to conditions with the same M/V ratio they were derived with, unless its influence is corrected. To find a correction, we conducted batch tests with soil and zinc solution using four M/V ratios. For each ratio, the experiments produced a different relationship between the mass of zinc sorbed per unit mass of soil (a _s) and the zinc concentration in the solution after shaking and removal of the solid phase (C _det), which is usually taken as the equilibrium concentration (C _eq). A theoretical analysis revealed that the M/V effect can be accounted for by dividing C _det by the M/V ratio, if it is caused by the presence of a “third phase”. The relationship between a _s and C _det×V/M is the same for all ratios then.