Exogenous succinate increases resistance of maize plants to copper stress

The effect of copper (Cu) excess (1.5, 4.7, 31, 78, 156 μM) and exogenously supplied succinate on plant growth, chlorophyll content, chlorophyll fluorescence, and isoenzym profiles of some antioxidant enzymes in maize plants was studied. Excessive Cu supply led to a reduction in the relative growth rate (RGR), tolerance index (TI), chlorophyll a and chlorophyll b contents, and the quantum yield of PSII electron transport in the light‐adapted state (ΦPSII). Copper treatment induced several changes in the anionic and cationic peroxidases (PODs), as well as superoxide dismutase (SOD) isoenzyme profiles. After 8 d of 78 μM–Cu treatment, two new anionic and two new cationic peroxidase isoenzymes in the roots were registered. Copper applied at concentrations above 31 μM resulted in higher levels of manganese superoxide dismutase (Mn‐SOD) in the roots and Cu,Zn‐superoxide dismutase (Cu,Zn‐SOD) in the leaves. However, the addition of Na‐succinate (200 μM) to the root medium prior to Cu treatment increased the capacity of the plants to partially overcome Cu toxicity.     

Fate of heavy metals in a strongly acidic shooting‐range soil: small‐scale metal distribution and its relation to preferential water flow

To assess the mobility of Pb and associated metals in a highly contaminated shooting range soil (Losone, Ticino, Switzerland), we investigated the spatial distribution of the metals and their relation to preferential water flow paths. A 2.2 m² plot located 40 m behind the stop butt was irrigated with a solution containing bromide and Brilliant Blue, a slightly sorbing dye. A soil profile 50 cm in width was sampled down to 80 cm with a spatial resolution of 2.5 cm, resulting in 626 samples. Concentrations of elements (12 ≤ Z ≤ 92) were determined by energy‐dispersive Xray fluorescence spectrometry, and Brilliant Blue concentrations were determined with a chromameter. In the acidic (pH 3), organic matter‐rich, well drained Dystric Cambisol, maximum concentrations of 80.9 g kg^‐1 Pb, 4.0 g kg^‐1 Sb, and 0.55 g kg^‐1 Cu were measured in the topsoil. Within 40 cm soil depth, however, Pb, Sb, and Cu approached background concentrations of 23 mg kg^‐1, 0.4 mg kg^‐1, and 9.4 mg kg^‐1, respectively. The even horizontal distribution and the steep gradient along soil depth indicate tight metal binding in the topsoil, and a fairly homogeneous transport front. In contrast, water flow through the profile was highly heterogeneous. In the uppermost 20 cm, preferential flow was initiated by heterogeneous infiltration at the soil surface, but had no influence on metal distribution. Below 20 cm, however, preferential flow originated from larger tree roots, and metal concentrations were significantly elevated along these macropores. Spatial distributions of Pb, Sb, and Cu were similar, suggesting that all three metals are strongly retained in the topsoil and transported along preferential water flow paths in the subsoil.     

铜盐毒害对紫鸭跖草养分吸收和生长的影响

通过含有不同浓度CuSO4的Hoagland营养液培养紫鸭跖草枝条,研究了紫鸭跖草对铜的耐性和超积累以及铜胁迫下紫鸭跖草生长和营养状况.结果表明:紫鸭跖草根部铜的积累量低浓度Cu2 供应时增加幅度不大,高浓度Cu2 供应时增加幅度较大;茎部的情况与根部相似;但叶部在低浓度Cu2 供应时铜的积累量几乎没有变化,高浓度Cu2 供应时铜的积累量增幅较大.在500 μmol · L-1和1 000 μmol · L-1铜处理下,紫鸭跖草整株铜积累量分别为866 mg · kg-1(DW)和1 130 mg · kg-1(DW).紫鸭跖草对铜的吸收和转运效率与铜的供给量呈正相关性.100～250 μmol · L-1铜的供应能明显促进紫鸭跖草生长.高浓度铜促进了钾、钙的吸收而阻碍了锌的吸收及镁向地上部分的运输,尽管如此,氮、磷、钾、镁、钙的浓度均在满足常规植物正常生长的浓度范围内.铜胁迫下对根部蛋白质表达活跃,氨基酸含量增加.研究结果表明紫鸭跖草对铜有很大耐性和富集能力.     

Soil Test to Predict the Copper Availability in Pasture Soils

Abstract

The proportion of copper (Cu) that can be extracted by soil test extractants varied with the soil matrix. The plant‐available forms of Cu and the efficiency of various soil test extractants [(0.01 M Ca(NO₃)₂, 0.1 M NaNO₃, 0.01 M CaCl₂, 1.0 M NH₄NO₃, 0.1 M HCl, 0.02 M SrCl₂, Mehlich‐1 (M1), Mehlich‐3 (M3), and TEA‐DTPA.)] to predict the availability of Cu for two contrasting pasture soils were treated with two sources of Cu fertilizers (CuSO₄ and CuO). The efficiency of various chemical reagents in extracting the Cu from the soil followed this order: TEA‐DTPA>Mehlich‐3>Mehlich‐1>0.02 M SrCl₂>0.1 M HCl>1.0 M NH₄NO₃>0.01 M CaCl₂>0.1 M NaNO₃>0.01 M Ca(NO₃)₂. The ratios of exchangeable: organic: oxide bound: residual forms of Cu in M1, M3, and TEA‐DTPA for the Manawatu soil are 1:20:25:4, 1:14:8:2, and 1:56:35:8, respectively, and for the Ngamoka soil are 1:14:6:4, 1:9:5:2, and 1:55:26:17, respectively. The ratios of different forms of Cu suggest that the Cu is residing mainly in the organic form, and it decreases in the order: organic>oxide>residual>exchangeable. There was a highly significant relationship between the concentrations of Cu extracted by the three soil test extractants. The determination of the coefficients obtained from the regression relationship between the amounts of Cu extracted by M1, M3, and TEA‐DTPA reagents suggests that the behavior of extractants was similar. But M3 demonstrated a greater increase of Cu from the exchangeable form and organic complexes due to the dual activity of EDTA and acids for the different fractions and is best suited for predicting the available Cu in pasture soils.     

紫花苜蓿、黑麦草和狼尾草对Cu、Pb复合污染土壤修复能力的研究

随着经济和社会的发展,土壤重金属污染对粮食安全及人类的身体健康构成了巨大的威胁,而目前对于土壤重金属污染的治理主要以植物修复为主。为了寻找适宜修复Cu、Pb复合污染土壤的牧草,采用盆栽试验法,将试验的植物设置9组处理:1组对照组(CK),不添加任何重金属盐;4组单一污染,即单一Cu低(Cu1,200 mg×kg-1)、高浓度(Cu2 400 mg×kg-1),单一Pb低(Pb1 300 mg×kg-1)、高浓度(Pb2 800 mg×kg-1);4组Cu、Pb复合污染(Cu1Pb1、Cu1Pb2、Cu2Pb1、Cu_2Pb_2)。通过比较紫花苜蓿(Medicago sativa)、黑麦草(Lolium perenne)、狼尾草(Pennisetum alopecuroides)的适应能力和富集特征,研究了这3种常见牧草植物对受Cu、Pb复合污染土壤的修复效果。结果表明:1)紫花苜蓿地上部和根部生物量均在Pb1处理组时最大,显著高于其他处理组;黑麦草地上部生物量在Cu1Pb1处理组最大,根部生物量在Pb1处理组最大;狼尾草地上部生物量在Cu_2Pb_2处理组最大,根部生物量在Cu2处理组最大。2)Cu单一污染下,狼尾草抗性系数最大;Pb单一污染下,紫花苜蓿抗性系数最大;Cu-Pb复合污染下,狼尾草的抗性系数较大。高浓度Cu处理组3种牧草植物的地上部生物量、根部生物量和抗性系数均呈现:狼尾草黑麦草紫花苜蓿,且狼尾草显著大于黑麦草和紫花苜蓿。3)种植3种牧草植物后,土壤重金属Cu、Pb含量均有所降低。在一定浓度下,土壤Cu-Pb重金属间会相互促进对方在牧草植物中的吸收。4)3种牧草中紫花苜蓿地上部对Cu的富集系数在Cu_2Pb_2处理组最大,达1.61;黑麦草根部对Cu的富集系数在Cu_2Pb_2处理组最大,达3.80;3种牧草地上部和根部对Pb的富集系数只在黑麦草根部的Cu1Pb1处理组时大于1,达1.46。5)黑麦草对Pb的吸收能力较强,且主要积累在根系;紫花苜蓿对Cu-Pb复合污染综合修复效果最好。紫花苜蓿和黑麦草分别在Cu-Pb复合污染和Pb单一污染土壤中对Pb的转运系数大于1,分别为2.72和2.06,反映其对土壤中的Pb具有富集潜力。综合表明,黑麦草对重金属Pb具有较强的耐性,在Pb单一污染土壤的植物修复及尾矿废弃地的植被重建中,可优先作为选择的材料;紫花苜蓿对重金属Cu、Pb均具有较强的耐性,在重金属Cu单一或Cu-Pb复合污染土壤的植物修复及尾矿废弃地的植被重建中,可优先作为选择的材料。     

磷灰石等改良剂对铜污染土壤的修复效果研究——对铜形态分布、土壤酶活性和微生物数量的影响

通过田间小区试验,研究了磷灰石、石灰、木炭、猪粪、铁粉对Cu污染土壤中Cu形态分布、土壤酶活性和微生物数量的影响。结果表明:改良剂的处理减少了离子交换态Cu的百分含量,增加了碳酸盐、铁锰氧化物、有机结合态Cu的百分含量,但对残留态Cu百分含量影响不大。磷灰石、石灰、木炭显著提高了土壤过氧化氢酶、酸性磷酸酶活性和土壤pH,但对脲酶活性影响较小。改良剂不同程度地增加了土壤细菌和真菌数量,且细菌和真菌数量均与土壤pH呈正相关关系,特别是真菌,与pH的相关系数达0.90。pH是影响Cu化学形态、土壤酶活性和微生物数量的主要因素,磷灰石、石灰和木炭显著提高了土壤pH,降低Cu的活性,增加了土壤酶活性和微生物数量,对Cu污染土壤具有较好的修复效果。     

Bacterial pollution induced community tolerance (PICT) to Cu and interactions with pH in long-term polluted vineyard soils

Pollution induced community tolerance (PICT) has been suggested as an end-point measurement less affected by confounding environmental factors compared to standard methods of microbial growth, activity and community composition. We evaluated the use of PICT to determine Cu toxicity in vineyard soils polluted with Cu based fungicides (25-1120 mg Cu kg⁻¹). These soils also varied in pH (4.3-7.3), organic C (0.31-6.91%) and texture (14-56% silt). PICT was estimated as bacterial community tolerance to Cu measured by the [³H]leucine incorporation method. Bacterial tolerance to Cu increased 9 times in the most polluted compared to the unpolluted soils. Cu tolerance was also affected to a minor degree by pH, organic C and soil texture. Lower bacterial tolerance was found in soils with high pH and organic C, probably due to Cu becoming less bioavailable in soils with high pH and organic C content. The silt content appeared to increase bacterial tolerance, probably due to fine soil particles decreasing Cu bioavailability during the PICT detection phase. Despite the effects of other environmental factors, the main determinant of increased bacterial community tolerance to Cu was the pollution level. PICT measured with the leucine incorporation technique thus appears to be a sensitive and stable concept to evaluate toxic impacts, unless soils with very different pH, organic C or texture are studied.     

Cu对猪粪堆肥过程中堆料性质和氧化还原类酶活性的影响

以猪粪和秸秆为主要试验材料, 添加不同浓度重金属Cu, 采取发酵罐处理方法, 在好氧高温条件下研究了重金属Cu对猪粪堆肥过程中多酚氧化酶、脱氢酶活性的变化, 以及堆腐过程堆体温度、堆料pH、胡敏酸E4/E6值变化的影响。结果表明: 不添加外源重金属Cu的CK处理在降温期堆温高于Cu含量为100 mg·kg^-1、500 mg·kg^-1的堆料; CK堆料pH最低点为5.94, E4/E6平均值为3.88。Cu含量为500 mg·kg^-1的堆料pH最高点为8.85, E4/E6平均值为3.68。Cu含量为100 mg·kg^-1的堆料升温快, 高温期持续时间长, 最高温度高于CK和Cu含量为500 mg·kg^-1的堆料, 能有效杀灭病原微生物, 达到无害化处理要求; 堆料pH控制在7~8之间, E4/E6大多情况低于CK和Cu含量为500 mg·kg^-1的堆料, 多酚氧化酶平均活性、脱氢酶平均活性均最高, 但在脱氢酶活性测定中表现出“抗性酶活性现象”。     

不同铜水平下海洲香薷的生理特性和铜积累研究

本文研究了Cu对耐性植物海洲香薷(Elsholtzia splendens)的生长、Cu积累、叶绿素含量和根系活力的影响,探讨了后2项生理指标与海洲香薷Cu积累之间的关系。研究结果表明:1) 低浓度Cu可促进海洲香薷生长(0.31～50 mmol/L),但随着其浓度的增加出现抑制现象(75～100 mmol/L)。2)叶绿素a及叶绿素b受Cu的影响规律一致。100 mmol/L的高Cu处理可显著降低这两者含量,其余Cu处理水平没有产生显著影响。3)随着Cu浓度的增加根系活力呈现不断下降的趋势。与其余处理相比,Cu浓度高于75 mmol/L时影响达显著水平。4) 地上部和根系Cu浓度、积累量均随着Cu处理浓度的增加而增加,但地上部分Cu积累水平未达到超积累植物的要求。     

绿化植物废弃物对重金属迁移的影响

采用土柱模拟实验,比较研究了覆盖绿化植物废弃物与土壤之上和绿化植物废弃物与土壤混合处理对城市绿地土壤中重金属淋溶的影响。结果表明,Zn、Pb和Cd均在80天后淋溶完全,而Cu有所不同,在80天后又有增加的趋势,原因可能跟重金属与有机质的结合能力有关。此外,绿化植物废弃物与土壤相混合能抑制Cu、Zn、Pb和Cd向下淋溶,而绿化植物废弃物覆盖于土壤之上则有促进Cu、Zn、Pb和Cd淋溶的趋势,且不论是混合处理还是覆盖处理,20cm厚绿化植物废弃物的处理均比10cm厚绿化植物废弃物处理对Cu、Zn、Pb和Cd的促进或抑制作用大。研究还得知,Cu、Zn、Pb和Cd的迁移还与土壤pH有关,低pH土壤有利于重金属的淋溶。