渭河宝鸡段表层沉积物重金属污染研究

采用现场采样及室内分析方法,在对渭河宝鸡段表层沉积物基本理化性质分析的基础上,研究了沉积物中重金属的含量、赋存形态及迁移特征,并进行了污染评价。结果表明,沉积物中Zn、Co、Cd和Hg的平均含量均高于世界、中国和陕西土壤元素背景值,其中Cd（中国和陕西土壤元素背景值的4倍）和Hg（中国和世界土壤元素背景值的7~8倍、陕西土壤元素背景值的16倍）尤为突出。Cr、Ni、Zn、Cu和Co在沉积物中主要以残余态形式存在（50%以上）,Pb主要以可还原态形式存在（近55%）,Mn和Cd主要以乙酸可提取态形式存在（近50%）。重金属迁移顺序为Mn（56.70%）≈Pb（56.65%）〉Cd（53.66%）〉Co（48.82%）〉Cu（43.99%）〉Zn（21.93%）〉N（i15.49%）〉C（r11.43%）,其中Mn、Pb、Cd、Co和Cu的危害较大,有近45%~60%可以发生迁移转化。污染评价结果表明,沉积物主要受到Cd和Hg污染,具有高的潜在生态危害。     

Amount and speciation of N leached from a sandy soil fertilized with urea,liquid digestate,struvite and NH4-enriched chabazite zeolite-tuff

The large use and the bad management of fertilizers that are applied to soil for improving crop production have dramatically impaired soil, water, and air quality. To meet the requirements to reduce nitrogen (N) losses and all the related negative impacts on the environment and food production, it is mandatory to substitute or at least partially substitute the use of inefficient and unsustainable fertilizers with more efficient alternatives. The aim of this paper was to address the amount and speciation of the N released by a sandy soil fertilized with “slow-release fertilizers” and traditional fertilizers (urea and liquid digestate) by means of a series of column leaching experiments. The slow-release alternatives were represented by NH₄-enriched zeolitic tuff and struvite, both obtained by recovering the N from liquid digestate. The treatments consisted of sandy soil fertilized with (i) urea (U) (ii) liquid digestate (LD), (iii) NH₄-enriched zeolitic tuff (N-CHA) and (iv) struvite (STRV). Eight different flushing events were performed over 38 days, leachates were collected and analysed for total Kjeldahl N, organic-N, NH₄⁺-N, NO₃⁻-N, NO₂⁻-N and pH. U and LD lost the majority of N within the first 2 flushing events as organic N and NH₄⁺-N, respectively. On the other hand, STRV and N-CHA lost less N over the whole course of the experiment and with more balanced speciation. The mass balance outlined that after the experiment, native soil N was mined in U and LD treatments while in N-CHA and STRV a fraction of N from the fertilizers was still present. The results showed a slow release of N which can be used more efficiently in agricultural applications, minimizing the N losses.     

Short‐term response of the Ca cycle of a montane forest in Ecuador to low experimental CaCl2 additions

The tropical montane forests of the E Andean cordillera in Ecuador receive episodic Sahara‐dust inputs particularly increasing Ca deposition. We added CaCl₂ to isolate the effect of Ca deposition by Sahara dust to tropical montane forest from the simultaneously occurring pH effect. We examined components of the Ca cycle at four control plots and four plots with added Ca (2 × 5 kg ha^–1 Ca annually as CaCl₂) in a random arrangement. Between August 2007 and December 2009 (four applications of Ca), we determined Ca concentrations and fluxes in litter leachate, mineral soil solution (0.15 and 0.30 m depths), throughfall, and fine litterfall and Al concentrations and speciation in soil solutions. After 1 y of Ca addition, we assessed fine‐root biomass, leaf area, and tree growth. Only < 3% of the applied Ca leached below the acid organic layer (pH 3.5–4.8). The added CaCl₂ did not change electrical conductivity in the root zone after 2 y. In the second year of fertilization, Ca retention in the canopy of the Ca treatment tended to decrease relative to the control. After 2 y, 21% of the applied Ca was recycled to soil with throughfall and litterfall. One year after the first Ca addition, fine‐root biomass had decreased significantly. Decreasing fine‐root biomass might be attributed to a direct or an indirect beneficial effect of Ca on the soil decomposer community. Because of almost complete association of Al with dissolved organic matter and high free Ca²⁺ : Al³⁺ activity ratios in solution of all plots, Al toxicity was unlikely. We conclude that the added Ca was retained in the system and had beneficial effects on some plants.     

鼠李糖脂淋洗修复重金属污染土壤的工艺条件优化研究

以湖南某冶炼厂周边重金属-砷复合污染土壤为对象,应用表面活性剂鼠李糖脂为主要淋洗剂,研究了不同pH值、温度和淋洗次数等工艺条件对重金属及砷淋洗效果的影响。结果表明:Zn、Cd、As在淋洗剂pH为2时提取能力最高,分别可达397、30、21 mg·kg^-1,但Cu的洗脱能力随着pH值的升高而增加;淋洗剂对Cd、Zn、Cu、As的洗脱能力在40 ℃时达到最大值,在30 ℃时淋洗液中Pb浓度最高,为54 mg·kg^-1;多次淋洗有助于土壤中重金属及砷的洗脱,Pb、Cd、Zn、Cu、As的3次淋洗效率分别可达23.1%、53.8%、44.7%、63.2%和34.4%;淋洗后土壤中重金属的酸可提取态、氧化物结合态及有机物结合态浓度大幅降低,砷的残渣态和氧化物结合态浓度明显下降。试验研究确定的最优淋洗条件为污染土壤淋洗修复工程应用提供了可借鉴的工艺参数。     

沈阳城市土壤Pb的污染状况及其化学形态研究

研究了沈阳市城市土壤Pb的含量及其化学形态分布,结果表明:沈阳市土壤全Pb平均含量为106.41 mg/kg,变幅为5.65~279.81 mg/kg,各个土地利用类型Pb含量都超过了沈阳市土壤背景值,土壤Pb污染严重。土壤Pb各形态比例为残渣态>有机结合态>铁锰氧化物结合态>碳酸盐结合态>可交换态。各土地利用类型Pb的活性不大。     

佛山市某工业区周边蔬菜地土壤重金属含量与评价

采集并分析测试佛山市某工业区周边蔬菜地土壤.研究土壤Zn、Cu、Pb和Cd的含量和分布特征,按照国家土壤环境质量二级标准对其现状进行评价;并采用连续提取的方法分析了表层土壤Zn、Cu、Pb和Cd的化学形态分布.结果表明,研究区域20%的土壤样品受到重金属轻度污染,污染因子主要为Cd.土壤中Zn和Cu以残渣态所占比例最高,Pb和Cd分别以铁锰氧化物结合态和酸可提取态所占的比例最高,Zn、Cu、Pb和Cd非残渣态所占比例随着全量的增加而增加,Zn、Cu、Pb和Cd迁移能力依次为Cd>Zn>Cu>Pb.人类活动已导致该工业区周边农业土壤中Zn、Cu、Pb和Cd的明显积累,且土壤重金属明显向深层迁移.     

伊通河(长春市区段)沉积物重金属元素化学形态分布特征

对伊通河（长春市区段）沉积物中重金属元素的含量和形态的分布特征进行了研究。结果表明,重金属元素的总量呈现出沿河变化的趋势,且各重金属元素沿河变化程度有很大区别;沉积物中铁主要以残渣态存在,Mn、Pb、Cu、Zn元素残渣态含量很低,而有效态含量却很大（70%）,即伊通河沉积物中存在着潜在的重金属污染。沉积物中重金属在各形态的叠加也有所区别,Pb和Cu主要叠加在有机物态和残渣态中,而Zn则主要叠加在铁锰氧化物态中。     

Segregation for performance in recombinant inbred populations resulting from inter-gene pool crosses of common bean ( Phaseolus vulgaris L.)

The germplasm of cultivated common bean exhibits a lower level of genetic diversity within each geographical gene pools (Mesoamerican and Andean) compared to that of the respective wild ancestors. Crosses between these two gene pools potentially provide a source of additional genetic diversity but their progenies have been characterized by phenotypic abnormalities and reduced productivity. In order to gain additional insights into this problem, we examined the segregation for performance in two recombinant inbred populations (RIPs) resulting from Mesoamerican × Andean crosses in three contrasting environments and two years. The two RIPs – ‘California Dark Red Kidney’ (of Andean origin) × ‘Yolano’ (Mesoamerican), n = 150, and A55 (Mesoamerican) × G122 (Andean), n = 67 – were grown in replicated field tests to assess the agronomic performance of each recombinant inbred line. Both populations exhibited, on average, greater days to maturity (DTM), lower biomass growth rate (above-ground dry weight/DTM), lower economic growth rate (seed yield/DTM), and lesser harvest index. In contrast with the conclusions of earlier experiments, there was no evidence from the field trials for a genetic association (due to linkage or pleiotropy) between seed weight and economic growth rate, but there may be a genetic association between seed weight and life cycle length. We compare the results of these studies with earlier experiments on inter-gene pool recombinant populations of common beans and relate our observations of diminished performance to models of speciation mechanisms. This revised version was published online in July 2006 with corrections to the Cover Date.     

宇宙线散落核素7Be在山区表土层中的分布特征及侵蚀示踪原理

宇宙线散落核素⁷Be具稳定的物质来源和53.3天的半衰期,提供了示踪环境微粒季节性迁移的必要条件;其在土粒中主要存在于Fe-Mn氧化物及有机质结合相,适应于季节性微粒迁移示踪;它在表土层中的垂直分布特征提供了示踪微粒季节性迁移的充分条件。⁷Be在表土层中的累计值、表观比活度、最大渗透深度及相对侵蚀(或堆积)速率是土粒迁移的示踪参数。     

不同寄主上桃蛀果蛾的滞育研究

调查了桃蛀果蛾Ｃａｒｐｏｓｉｎａｓａｓａｋｉ在杏、桃、枣、苹果、海红、梨、槟子、山楂、酸枣等寄主上幼虫的滞育情况和年发生代数,研究了杏和海红上幼虫滞育对光周期的反应。结果表明,桃蛀果蛾在桃、枣和苹果上一年发生１～２代,５０％个体进入滞育时间在８月上旬;在杏、海红、梨、槟子、山楂和酸枣上一年只发生１代;滞育的临界光周期,在杏上略长于１２ｈ,海红上接近１５ｈ．讨论了滞育在桃蛀果蛾生活史趋异和物种分化中的作用。