五华河流域景观格局演变对径流泥沙的影响

根据五华河流域1981—2011年逐月的气温、降水、径流量和输沙量数据,以及1991年、2000年和2011年的Landsat TM遥感影像,运用景观格局指数分析方法和统计学方法,从景观水平和斑块类型水平两方面探讨了景观格局演变对径流泥沙的影响。结果表明:景观水平上,景观多样性指数（SEI）和景观边缘密度（ED）与年径流量和年输沙量呈正相关,而景观形状指数（PSCV,AWMSI,AWMPFD）与年径流量、年输沙量、输沙量变差系数呈负相关。类型水平上,林地景观破碎度（PD）和边缘密度（ED）、草地形状指数和边缘密度,建筑用地的斑块破碎度与年径流量、输沙量有明显的正相关关系,而林地斑块形状指数,草地和耕地斑块破碎度,建筑用地边缘密度和形状指数则与年径流量和输沙量呈负相关关系。同时,林地斑块形状指数、草地和耕地斑块破碎度、建筑用地边缘密度和形状指数均与输沙量变差系数存在明显的正相关关系。     

南方红壤丘陵区流域植被景观格局变化及水沙响应关系

以南方红壤丘陵区典型流域濂江河流域为研究对象,依托GIS和Fragstats平台与长时间系列水沙数据,运用景观格局指数分析和统计学方法,分析流域景观格局和水沙变化特征及其相关性。结果表明:流域内径流呈减少趋势,泥沙呈增加趋势。流域内以有林地为主,面积增加最显著的是经果林。景观水平上,斑块面积均方差(PSCV)、香浓多样性指数(SHDI)与径流呈现正相关,蔓延度指数(CONTAG)与径流呈现负相关;斑块数(NP)、斑块密度(PD)、景观边缘密度(ED)、面积加权的平均形状指数(AWMSI)、香浓多样性指数与径流呈现负相关。类型水平上,耕地的斑块面积(CA)、ED与径流呈负相关,与泥沙呈现正相关;有林地的形状指数(PSCV、AWMSI)与径流呈正相关,CA与泥沙呈现正相关,NP、PD与泥沙呈现负相关;灌木林的CA、ED与径流呈负相关;经果林的所有的指数与径流均呈现正相关,与泥沙呈现负相关性;同时,草地的NP、PD与径流呈现负相关。     

旬河流域景观格局变化对泥沙输出的影响

为探究河流输沙量对景观格局变化的响应,以旬河流域为研究区,选取旬河上、中、下游12个典型流域,借助SWAT模型对各支流泥沙进行了模拟分析;在此基础上,通过1995年和2015年遥感影像解译及景观指数分析,探究流域内部景观格局变化及其与河流输沙量的关系。结果表明:SWAT在径流、泥沙模拟过程中,率定期和验证期的决定系数(R~2)均大于0.75,Nash-Sutteliffe系数(Ens)为0.74～0.85,模型的适用性良好。通过遥感影像解译,旬河流域土地利用类型主要以林地和农用地为主。受"退耕还林还草"和"植树造林"等植被恢复措施的影响,2015年流域景观的优势化程度比1995年显著加深,景观类型之间的连通性趋于优良,斑块分布更加集中,景观格局朝着单一化方向发展,导致河流输沙量显著降低。其中,景观水平上的景观分离度指数(DIVISION)和类型水平上水体的斑块密度指数(PD_5)对输沙量解释度最大。此外,相较于景观水平,以类型水平指数表征对输沙量的解释度,拟合效果优良。该研究可为旬河流域水土流失治理及减缓土壤侵蚀等方面提供一定的科学依据。     

基于径流侵蚀功率的长江典型流域能沙关系模型及改进

基于径流侵蚀功率概念建立流域能沙关系模型,可为长江流域泥沙变化精准模拟与水土保持规划提供技术支撑。该研究以长江典型流域及其典型小流域为研究对象,通过收集1965—2018年金沙江流域、嘉陵江流域和湘江流域3个典型流域逐日水沙数据以及万安和李子口2个典型小流域2014—2020年场次降水径流泥沙数据,采用径流侵蚀功率、径流量和降雨侵蚀力对比分析不同时空尺度水沙(径流量和输沙量)、雨沙(降雨侵蚀力和输沙量)和能沙(径流侵蚀功率和输沙量)关系的优劣性,解析能沙关系优越性,并识别能沙关系非一致性变化,从而改进能沙关系模型提高流域输沙量模拟精度。结果表明：1)长江流域3个典型流域及2个典型小流域,在绝大部分情况下能沙关系的表现总是优于水沙关系和雨沙关系,在场次、月和年尺度修正的决定系数最大值分别可达到0.94、0.87和0.54。2)对于不同时间尺度,其流量序列中任意2个流量乘积与输沙量的相关性较高时,第一个流量Q₁分位点总是接近1且第二个流量Q₂分位点在0.5附近或者高于0.5。基于径流侵蚀功率可以较为准确地计算不同时空尺度流域输沙量,具有明显适用性...     

泾河流域植被景观格局对流域径流的调节作用

对黄土高原腹地泾河流域12个子流域植被景观格局和流域径流动态的关系进行了探讨。结果表明景观层次上植被的整体空间格局对流域径流动态有着如下调节作用:(1)泾河流域4种植被景观类型中,森林灌丛植被景观流域年径流量最大,径流年内分配比较均匀,但年际变化很大;其次为复合植被景观,农业植被景观流域径流量较小,且主要集中在汛期;草地植被景观流域径流极小,主要发生在汛期的7~8月份,年际变化比较小。(2)在主要植被景观指数中,景观破碎度、景观多样性与流域径流正相关,景观聚集度、景观优势度与流域径流负相关,景观形状与流域径流相关不显著。(3)结构复杂的植被景观对流域径流具有较好的调洪补枯作用。随着景观破碎度和景观多样性的增大,流域径流年内分配趋于均衡;而随景观聚集度的增大,流域径流年内分配则趋向集中,景观形状对流域径流调节作用不明显。(4)多样性高的植被景观可降低极端径流出现,维持流域生态系统的稳定性。     

气候变化及人为活动对湘江流域径流和输沙的影响

湘江是洞庭湖流域最大的支流,在全球气候变化以及高强度人为活动影响的背景下,明确湘江流域水沙关系及其影响因素,对洞庭湖流域水资源安全以及洞庭湖湿地生态环境保护具有重要意义。以湘江控制站湘潭水文站1982—2011年水沙数据为基础,综合考虑气候和人为活动变化等因素,结合趋势分析、突变分析、相关分析等方法,分析了湘江流域年径流量、输沙量、植被覆盖和气候(降雨量(R)、降雨强度(R_i)、最大日降雨量(R_(x1))、最大5d降雨量(R_(x5))、干旱情势(Palmer Drought Severity Index(PDSI)和Standardized Precipitation Evapotranspiration Index(SPEI)的变化规律,并分三个阶段气候突变前(1981—1990年)、气候突变后至退耕还林前(1991—2002年)和退耕还林后(2003—2011年)探讨了湘江流域水沙变化的影响因素。结果表明,在1982—2011年期间,总体上湘江流域降雨呈下降趋势,但降雨强度、干旱情势和植被覆盖上升。流域径流与气候因子(降雨、PDSI,SPEI)波动步调基本一致,但输沙量呈持续下降趋势。径流和输沙量与气候和植被因子有良好的相关性。进一步分析表明,气候变化是径流变化的主要原因;对于输沙量而言,1995—2002年泥沙降低的主要原因是水利工程建设,而2003—2011年之间输沙量降低则主要因为退耕还林等生态保护措施的综合效应。     

黄土高原粗泥沙集中来源区水沙变化特征及趋势性分析

黄土高原粗泥沙集中来源区为治理黄河泥沙的重点核心地区.根据1960-1999年黄土高原粗泥沙集中来源区皇甫川、孤山川I、窟野河,秃尾河和佳芦河径流及输沙资料,以流域为单元,分析了区内各流域径流量、输沙量的年内、年际变化特征及变化趋势.结果表明,区内径流量及输沙量的年际、年内变化较大.在季节上,除秃尾河径流量集中期为6月份外,其余4条流域径流量的集中期均为8月份;5条流域输沙量的集中期均为8月份.各流域径流量、输沙量的突变时间均在20世纪70年代,说明各流域水沙量呈现减少的趋势,尤以20世纪90年代减少最明显.人类活动和气候变化是影响该区内各流域水沙变化的主要因素.     

北京山区典型小流域景观格局变化对径流的影响

根据北京市密云县红门川小流域1990—2006年的水文资料,在统计分析降水、径流、蒸发年际变化特征的基础上,利用1990年、1995年、2000年和2005年4期遥感影像,采用ArcMAP及Fragstats等景观分析软件,从斑块和景观两个尺度上,分析红门川流域的景观空间格局变化及其与径流的关系。结果表明:（1）红门川小流域的降水、径流多集中在汛期（6—9月）,且年降水量、径流量逐年减少,气候变化是径流减少的主要原因;（2）红门川流域土地利用类型以林地为主,林地约占流域总面积的75%,其中以针叶林最多,阔叶林、混交林次之,灌木林最少,另外水域面积逐年减少,从另一个方面反映了径流量逐年减少;（3）红门川流域景观斑块个数增加,整体景观格局破碎化程度减小,斑块分布趋于均匀,其中斑块平均面积（AREA）、斑块周长（PERIM）、景观形状指数（LSI）、景观聚集度（CONTAG）均呈波动减小的趋势,斑块形状指数（SHAPE）、斑块分维度（FRAC）、Shannon-Wienner多样性指数（SHDI）则是逐年减小;（4）平均斑块周长、景观聚集度与径流变化相关性较强,平均斑块面积、平均分维度与径流变化相关性一般,平均斑块形状指数、景观形状指数、Shannon-Wienner多样性指数与径流变化基本不相关。     

窟野河水沙变化及驱动力分析

利用窟野河入黄控制站——温家川水文站1956-2012年降雨、径流、洪水、泥沙实测资料,采用线性趋势分析、滑动平均、累积距平、R/S分析、双累积曲线法等多种方法,分析了窟野河水沙变化特征,降水和人类活动对径流及输沙的影响。结果表明:1总体上,窟野河径流量和输沙量呈持续下降趋势。21世纪初,年径流量和输沙量下降显著,其值分别为多年均值的34.4%和5%;2受降水和人类活动影响,径流量和输沙量年际变化过程经历了3个阶段,其转折点分别是1979年和1997年;3降水对径流量和输沙量的影响越来越弱,而人类活动对其两者的影响日益增强,成为影响径流和输沙的主导因素;4温家川站径流和泥沙的Hurst指数分别为0.876 7和0.803 9,表明未来一段时间内窟野河径流量和输沙量变化趋势将与过去保持同一势态,有持续递减的特征。正确认识水沙变化特性及产生的原因可为流域水资源合理开发和综合治理提供科学依据。     

昕水河流域综合治理及水沙变化分析

<正> 昕水河流域是山西省临汾地区西山最大的入黄一级支流,面积4326km~2,占临汾西山地区总面积的42％。统计该流域葛口水文站1955～1989年径流泥沙资料,可知1973～1989年的17年,水沙变化较大,年平均径流量、输沙量分别比1955～1972年减少了39.6％和54.8％。特别是1981～1989年,年平均径流量减少了47.8％,输沙量减少70.8％。本文拟对该流域的水沙变化原因作一初步分析。     

Bioavailability of As,Cd, Co,Cr, Cu,Hg, Mo,Ni, Pb,Se, and Zn from Biosolids Amended Compost

Appropriate compost standards are being considered in Canada. Five aspects of compost safety and quality are being evaluated; probably the most controversial aspect is the standards for metals in compost. In order to assist in the development of appropriate standards, the authors began an extensive research project in October, 1993 to determine the bioavailability of metals from compost and compost-metal mixtures. Swiss chard was grown in compost-amended soils or compost in a growth room using five treatments of increasing percentages of compost in the media (0, 25 percent, 50 percent, 75 percent, 100 percent compost (v/v)). A Truro loamy sand and a race-track manure-biosolids compost (RTM-biosolids) supplemented with a high metal biosolids were used in a completely randomized design with five replicates. Dry matter yield, metal content in plant tissue, and total metal uptake were evaluated as well as the total and DTPA-extractable metal content in the compost-soil mixes. The results of this and five other experiments conducted by the authors will help determine whether the suggested limits for As, Cd, Co, Cr, Cu, Hg, Mo, Ni, Pb, Se and Zn in composts are appropriate.     

Variation of N,P, K,Ca, Mg,Mn, Zn,and al in slash pine foliage

Abstract

The seasonal patterns of foliage nutrient concentrations and contents were monitored for two growing seasons in an 11‐year—old Pinus el1iottii stand. In the first growing season after needle initiation, N, P, K, Mg, and Zn concentrations decreased, but this was followed by an increase in the fall and winter months. Another drop in concentration of all elements, except P, occurred in the second growing season. Decreases in total contents indicated that this drop was a result of translocation to other tissues. In contrast to the mobile elements, the concentration and fascicle contents of Ca, Mn, and Al increased with aging of the needles.

Between‐tree variability was least for N, P, and Zn and the N, K, Mg, Mn, and Zn in the current foliage had consistently lower variation than that in the 1‐year‐old foliage. Between‐tree variation for K was lower in the winter than the spring.

For pine foliage, recommended sampling period for N, P, Mg, and Zn is mid to late summer and for the other elements it is late fall to late winter.

There are several sources of variation that influence the level of nutrients in tree foliage. The most important of these, apart from the tree nutrient status, are seasonal fluctuations, variation between trees, and age of needles . Smaller sources of variation are associated with position of the needles within the crown, diurnal changes, year to year variation, and analytical errors^1,2. These variables must be studied in order to develop suitable sampling techniques and in Pinus this has been undertaken for P. banksiana ¹, P. taeda ³, P. strobus ⁴, P. resinosa ⁴, P. sylvestris ⁵, and P. radiata ^6,7. However, foliage sampling has not been studied in detail for slash pine (Pinus elliottii Englem var. elliottii) and earlier studies with other pines have been largely confined to temperate or cool climates.

This study reports the variation in elemental concentrations with season, age of foliage, and between slash pine trees growing in a subtropical climate in Florida.     

Phytotoxicity of cobalt,vanadium, titanium,silver, and chromium

Abstract

The phytotoxicity of five nonessential elements (Co, V, Ti, Ag, Cr) to higher plants was studied in solution culture experiments with bush beans (Phaseolus vulgaris L. C.V. Improved Tendergreen). All, but in varying degrees, tended to concentrate in roots with a decreasing gradient to stems and leaves. Cobalt was one of the more mobile of the five trace metals. Its toxicity was expressed as severe chlorosis; 43 (with 10^‐5 M) and 142 (with 10^‐4 M) μg Co/g dry weight in leaves resulted in severe chlorosis. Vanadium as 10^‐4 M vanadate resulted in smaller plants but not in chlorosis. Leaf, stem, and root V, respectively, were 13, 8, and 881 μg/g dry weight. Titanium was somewhat mobile with considerable yield decrease at 10^‐4 M; leaf, stem, and root Ti concentrations, respectively, were 202, 48, and 2420 μg/g. Symptoms were chlorosis, necrotic spots on leaves, and stunting. Silver was very lethal at 10^‐4 M AgNO₃; at 10^‐5 M yields were greatly decreased, but plants were grown without symptoms. Leaf, stem, and root concentrations of Ag for this treatment, respectively, were 5.8, 5.1, and 1760 μg/g dry weight. Plants grown with 10^‐5 N Cr₂O₇ were decreased in yield by about 25% with or without EDTA (ethylenediamine tetraacetic acid) while the same level of Cr₂(SO₄)₃ was essentially without effect. For the two salts, the leaf, stem, root concentrations for Cr, respectively were 2.2 and 1.3, 0.7 and 0. 7, and 140 and 104 μg/g. Most of the trace metals studied here had interactions in the uptake and/or distribution of other elements.     

Thin layer chromatographic determination of aflatoxins, ochratoxins, sterigmatocystin, zearalenone, citrinin, T-2 toxin, diacetoxyscirpenol, penicillic acid, patulin, and penitrem A.

A general method is described for determining 16 mycotoxins in mixed feeds and other food products used in the manufacture of these feedstuffs. The mycotoxins are extracted and cleaned up by extracting with solvents of different pH. Thin layer chromatography is used to separate the toxins; toxins are then quantitated by the limit detection method. The minimum detectable concentration of mycotoxins in various products is: aflatoxin B1 or G1, 4--5 micrograms/kg; ochratoxin A or ethyl ester A 140--145 micrograms/kg; citrinin 600--750 micrograms/kg; zearalenone, 410--500 micrograms/kg; sterigmatocystin, 140--145 micrograms/kg; diacetoxyscirpenol, 2400--2600 micrograms/kg; T-2 toxin, 800--950 micrograms/kg; patulin, 750--800 micrograms/kg; penitrem A 14,000--14,500 micrograms/kg; penicillic acid 3400--3650 micrograms/kg.     

Organochlorine pesticide residues in different Indian cereals, pulses, spices, vegetables, fruits, milk, butter, Deshi ghee, and edible oils.

A total of 244 samples of cereals (wheat flour, rice, and maize), pulses (arhar, moong, gram, lentil, and black gram), spices (turmeric, chili, coriander, and black pepper), vegetables (potato, onion, spinach, cabbage, brinjal, and tomato), fruits (mango, guava, apple, and grape), milk, butter, Deshi ghee, and edible oils (vegetable, mustard, groundnut, and sesame) collected from different cities of Northern Province (Utter Pradesh) were analyzed by gas liquid chromatography for the presence of organochlorine pesticide residues. Residues of hexachlorocyclohexane (HCH) and 2,2-bis(p-chlorophenyl)-1,1,1-trichloroethane (DDT) were detected in about 85% of the total samples of cereals, spices, milk, butter, Deshi ghee, and edible oils analyzed in the present study. However, the residue levels were either very small (less than 0.06 ppm) or not detected at all in pulses, vegetables, and fruits as compared with very high concentrations in wheat flour (4.42 and 0.12 ppm), butter (1.19 and 4.85 ppm), mustard oil (1.26 and 2.42 ppm), Deshi ghee (1.10 and 3.84 ppm), vegetable oil (1.02 and 0.59 ppm), groundnut oil (0.51 and 1.49 ppm), and chili (0.48 and 1.92 ppm). The levels of HCH and DDT residues detected in rice, maize, turmeric, corlander, black pepper, and all the vegetables and fruits were also lower than those found in wheat flour, oil, and fat samples analyzed in the present study. These findings suggest that a restricted and controlled use of such persistent pesticides may be useful for decreasing their contamination levels in different food items.     

Evaluation of Decomposition Procedure to Determine Ba,Co, Cr,Cu, Ni,Mn, V,and Zn Total Content in Soil Samples

Different procedures have been proposed to decompose soil samples. Most of them regard determination with fertility aims. In this case, the contents available to the plants are considered. On the other hand, there are procedures to determine total content. The objective of this work was to propose a new decomposition procedure to determine barium (Ba), cobalt (Co), chromium (Cr), copper (Cu), manganese (Mn), nickel (Ni), vanadium (V), and zinc (Zn) total content in tropical soils with high content of oxides and silicate. According to the results, the digestion procedure proposed in this study provided satisfactory results for the contents recovery for the elements Ba, Co, Cr, Cu, Mn, Ni, V, and Zn, above 90%, and the use of inverted aqua regia, hydrogen peroxide (H₂O₂), hydrofluoric acid (HF), pre-digestions and agitation was shown as a new alternative for the high silicate content soil sample total digestion, such as the oxisols.     

Estimation of Reference Values for Cadmium,Cobalt, Chromium,Copper, Nickel,Lead, and Zinc in Brazilian Soils

Abstract

The objectives of this study were 1) to recommend reference values (RVs) and tolerance limits (TLs) for representative Brazilian soils and 2) to propose a model to calculate natural contents of cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn) in a soil from the silt, clay, manganese (Mn), iron (Fe), and cation exchange capacity (CEC) values. A set of 256 soil samples was classified by similarity in seven groups, and the concentrations corresponding to the upper quarter of data collected were then calculated. These concentrations are proposed as RVs for Brazilian soils. Additionally, TLs were obtained for each group from the antilog expression (m+2s), where m=mean value and s=standard deviation of data transformed in log₁₀. The classification functions of discriminant analysis proved to be suitable to allocate new samples in the established groups. Thus, it is possible to evaluate soils under anthropic activity and, by comparison with reference values, to be aware of pollution risks in a given area.     

Caimans,Capybaras, otters,manatees, and man in amazonia

Amazonia, the world's largest tropical rain forest, is often assumed to be a virtually untouched wilderness. The region is often referred to as a demographic void; there is on average only about one person per sq. km. Yet in response to international market forces, the hand of man has penetrated deep into the imposing forests. Since colonial times, wildlife, particularly along rivers, has been exploited on a large-scale basis for commercial purposes. This paper focuses on the effects of the trade on some aquatic animals.     

Total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone

The total phenolics and antioxidant activities of fenugreek, green tea, black tea, grape seed, ginger, rosemary, gotu kola, and ginkgo extracts, vitamin E, and tert-butylhydroquinone, were determined. Grape seed and green tea were analyzed for their phenolic constituents using high-performance liquid chromatography. The total phenolics of the plant extracts, determined by the Folin-Ciocalteu method, ranged from 24.8 to 92.5 mg of chlorogenic acid equivalent/g dry material. The antioxidant activities of methanolic extracts determined by conjugated diene measurement of methyl linoleate were 3.4-86.3%. The antioxidant activity of the extracts using chicken fat by an oxidative stability instrument (4.6-10.2 h of induction time) followed a similar trend in antioxidant activity as determined by the Folin-Ciocalteu method. Seven phenolics in grape seed and green tea extracts were identified that ranged from 15.38 to 1158.49 and 18.3 to 1087.02 mg/100 g of extract, respectively. Plant extracts such as green tea and grape seed extracts can be used to retard lipid oxidation in a variety of food products.