氧化节杆菌生物降解苯并芘

A pot experiment was conducted with multi-metal (Pb, Cd, Cu, and Zn) contaminated acidic soil to investigate changes in available metal burden resulting from the application of industrial wastes (fly ash and steel slag). The efficiency of amendments-induced metal stabilization was evaluated by diffusive gradients in thin films (DGT), sequential extraction, and plant uptake. The stability of remediation was assessed by an acidification test and by chemical equilibrium modeling. Addition of fly ash (20 g kg-1 ) and steel slag (3 g kg-1 ) resulted in similar increase in soil pH. Both amendments significantly decreased the concentrations of metals measured with DGT (C DGT) and the metal uptake by Oryza sativa L. Significant correlations were found between C DGT and the concentration of a combination of metal fractions (exchangeable, bound to carbonates, and bound to Fe/Mn oxides), unraveling the labile species that participate in the flux of metal resupply. The capability of metal resupply, as reflected by the R (ratio of C DGT to pore water metal concentration) values, significantly decreased in the amended soils. The C DGT correlated well with the plant uptake, suggesting that DGT is a good indicator for bioavailability. Acidification raised the extractable metal concentration in amended soil but the concentration did not return to the pre-amendment level. Equilibrium modeling indicated that the soil amendments induced the precipitation of several Fe, Al and Ca minerals, which may play a positive role in metal stabilization. Chemical stabilization with alkaline amendments could be an effective and stable soil remediation strategy for attenuating metal bioavailability and reducing plant metal uptake.     

潮褐土上蔬菜产量和土壤各形态磷变化对长期过量施磷的响应

【目的】研究长期连续过量施用磷肥下蔬菜的产量响应、磷肥去向及土壤各形态磷库的动态变化。 【方法】在太行山山前平原典型潮褐土上,连续进行11年21茬露地蔬菜的长期定位肥料试验,P₂O₅年施用量设0 (P0)、360 (P1)、720 (P2)、1080 (P3)、1440 (P4) kg/hm2共5个处理,分别测定每茬蔬菜产量及各年土壤不同形态磷素含量。 【结果】与不施磷肥处理比较,单季P₂O₅用量180、360、540、720 kg/hm2均显著增加大白菜、菜豆产量,不同磷肥用量间蔬菜产量均无显著差异。P₂O₅年用量为360、720、1080、1440 kg/hm2,土壤年盈余磷为41.2～478.7 kg/hm2,积累率为26.2%～76.1%。与基础土比较,随着磷肥用量的增加,土壤有效磷、全磷、无机磷总量及无机磷中的Ca₂-P、Ca₈-P、Al-P、Fe-P含量均呈显著增加趋势,无机磷中的O-P、Ca₁₀-P含量无显著变化。P₂O₅年用量为720、1080、1440 kg/hm2处理土壤的有效磷年均增加量为2.3、4.2、5.0 mg/kg;土壤有效磷增加量与磷盈余量呈显著直线正相关关系,土壤磷素每盈余100 kg/hm2,有效磷、Ca₂-P、Ca₈-P、Al-P、Fe-P 含量分别增加1.13、2.41、15.27、4.14、1.37 mg/kg。随着土壤磷盈余量和施肥年限的增加,有效磷占全磷比重、Ca₂-P、Ca₈-P、Al-P占无机磷比重逐渐增加。 【结论】施用磷肥显著增加大白菜和菜豆产量,过量施用磷肥蔬菜产量无显著变化;土壤磷素处于盈余状态下,随着磷肥用量的增加或种植年限的增加,土壤积累磷的有效性随之增加。基于蔬菜对磷肥产量响应和土壤磷素收支表观平衡状况,露地大白菜P₂O₅推荐用量180 kg/hm2,菜豆270 kg/hm2。     

利用薄膜扩散梯度技术研究不同土壤性质影响下镉对黑麦草的生物有效性

A generally accepted method for predicting the bioavailability and transfer of cadmium (Cd) from soil to plants has not yet been established. In this study, the diffusive gradients in thin films (DGT) and conventional extraction methods for metal fractions were used to investigate how effective these methods were at predicting Cd bioavailability to ryegrass (Lolium perenne) and to assess whether these holistic variables were independent of the soil property variables. The influences of soil properties on the predictive capabilities of the different methods were evaluated using multivariate statistics. The Cd concentrations in the shoots and roots of ryegrass correlated more closely with the effective Cd concentration measured by DGT (C_E), compared with those with soil total Cd, pore water Cd, and ethylenediaminetetraacetic acid disodium salt (Na₂EDTA)- and acetic acid (HOAc)-extractable Cd. When soil properties were included in a stepwise multiple linear regression, Cd transfer to L. perenne was negatively influenced by pH and positively influenced by organic matter (OM). The multivariate statistics showed that the adjusted correlation coefficients for the plots involving soil total Cd, pore water Cd, and Na₂EDTA- and HOAc-extractable Cd had been significantly improved after considering the influences of soil properties, which suggested that these methods were pH and OM dependent. For C_E, the relationship was pH independent or only dependent in strongly acidic soils. These results suggested that the main soil factors affecting bioavailability had the lowest impact on the DGT technique. Therefore, the DGT technique provided significant advantages over conventional methods when assessing Cd bioavailability.     

梯度扩散薄膜技术（DGT）的理论及其在环境中的应用I：工作原理、特性与在土壤中的应用

根据文献资料,详细阐述了梯度扩散薄膜技术（DGT）的原理、影响DGT技术测量的因素和它的应用特性,同时回顾了DGT技术问世以来在土壤中的应用实例,并认为DGT技术为研究土壤重金属的生物可利用性提供了可行可靠而又有效的方法。     

Effect of phosphate fertilization on crop yield and soil phosphorus status

To evaluate the effect of three phosphorus (P) fertilization regimes (no P, P input equivalent to P off‐take by crops, P input higher than P off‐take) on crop yield, P uptake, and soil P availability, seven field experiments (six in crop rotations, one under permanent grassland) were conducted in Switzerland during nine years (six trials) or 27 years (one trial). Soil total P (Pt), inorganic P (Pi), organic P (Po), and the amount of isotopically exchangeable soil P were measured in the 0–20 cm and 30–50 cm layers of the arable soils and in the 0–10 cm layer of the permanent grassland soil. Omitting P fertilization resulted in significant yield decreases only in one field crop trial as the amount of P isotopically exchangeable within one minute (E_1min) reached values lower than 5 mg P (kg soil)^–1. In the absence of P fertilization Pi decreased on average from 470 to 410 mg P (kg soil)^–1 in the upper horizon of 6 sites while Po decreased only at two sites (from 510 to 466 mg P (kg soil)^–1 on average). In all the treatments of the trials started in 1989 the E_1min values of the upper horizon decreased on average from 15.6 to 7.4 mg P (kg soil)^–1 between 1989 and 1998. These decreases were also observed when P inputs were higher than crops needs, showing that in these soils the highest P inputs were not sufficient to maintain the high initial available P levels. Finally for the six arable trials the values of the isotopic exchange kinetics parameters (R/r₁, n, C_P) and P exchangeable within 1 minute (E_1min) at the end of the experiment could be estimated from the values measured at the beginning of trial and the cumulated P balance.     

不同水分条件下分层施磷对冬小麦根系分布及产量的影响

研究不同水分条件下分层施磷对冬小麦根长分布、水分利用效率(water use efficiency,WUE)及产量的影响,旨在找出旱地农业最佳水肥处理方式。试验设不施磷(CK)、表施磷(surface P,SP)、深施磷(deep P,DP)和侧深施磷(deep-band P,DBP)4种处理,每个施磷水平下设补充灌溉(W1)和干旱(整个生育期无补充灌溉)(W2)2种水分处理。结果表明,施磷位置及补充灌溉显著(P0.05)影响冬小麦孕穗期根长分布、WUE及产量,同时会改变根系空间分布。干旱胁迫使冬小麦0~30 cm土层根长密度下降,降低17.5%,却促进了30 cm以下土层根长发育,增加13.3%,促进对土壤水分和磷素的吸收,从而提高产量。无论灌溉与否,施磷处理0~30 cm土层根长密度、吸磷量、WUE及产量均显著高于CK(P0.05)。施磷位置对冬小麦WUE和产量的影响随土壤水分而异,无补充灌溉时,与磷肥表施相比,磷肥深施显著增加WUE和产量(P0.05),分别平均增加28.5%和16.0%,且深层根长(30~100 cm)与吸磷量、WUE和产量的变化趋势一致;而在补充灌溉时,与磷肥表施相比,磷肥深施却显著降低WUE(P0.05),平均降低13.3%,且深层根长与WUE、产量的关系缺乏规律性。该试验结果表明,土壤水分供应不足时,磷肥深施有利于促进冬小麦深层土壤根系生长发育,提高对土壤水分吸收利用能力,从而利于形成高产。该研究可为理解作物生长及产量对水分养分空间耦合的响应提供理论依据。