沟渠化对沼泽湿地土壤铁分异的影响

利用沼泽湿地中距离渠岸不同位置所形成的沼泽土壤水文植被特征的差异,通过原位采集不同深度的土壤和土壤溶液,比较了湿地土壤固相和液相中铁的空间分异,分析了沟渠化对这种分异的影响。结果表明,土壤总铁量呈距离沟渠越近其质量分数越高,总铁量从沟渠边(25.17±4.06)g/kg下降到8.8 m外的(21.81±3.47)g/kg,减少了13.35%;无论溶解性亚铁(Fe~(2+))、溶解性高铁(Fe~(3+))还是溶解性总铁,都表现为随沟渠距离增加,先增加再降低的趋势,即距离沟渠4.4 m处溶解性铁质量浓度最高((1.75±0.95)mg/L);以溶解性亚铁(Fe~(2+))与溶解性高铁(Fe~(3+))质量浓度比,表征的土壤氧化还原环境以距离沟渠6.6 m处还原性最强。沟渠对天然湿地的穿过显著影响土壤铁的分布,导致部分铁通过土壤表层(0~-10 cm)的冲刷和中上层土壤(-20~-40 cm)的侧向渗流从沟渠两侧土壤向沟渠汇集,从而导致天然湿地土壤铁的流失。土壤p H值和水势是影响土壤铁空间分异的主要因素。     

桑树修复土壤重金属污染的研究进展

重金属污染修复已成为当前国际环境科学研究的热点问题,利用桑树修复土壤重金属污染也是一种有效的植物修复技术。笔者简单介绍了土壤重金属与植物修复技术的概念,并阐述了桑树的生长特性,桑树生长与土壤中镉、铅、锌、砷等重金属元素的关系,并结合江西省土壤重金属污染的形势,探讨了桑树作为江西省土壤重金属污染修复树种的潜力。     

Fixed Ammonium Content and Maximum Capacity of Ammonium Fixation in Major Types of Tillage Soils in Hunan Province, China

In order to understand the status of fixed ammonium, fixed ammonium content, maximum capacity of ammonium fixation, and their influencing factors in major types of tillage soils of Hunan Province, China, were studied with sampling on fields, and laboratory incubation and determination. The main results are summarized as follows: (1) Content of fixed ammonium in the tested soils varies greatly with soil use pattern and the nature of parent material. For the paddy soils, it ranges from 135.4 ± 57.4 to 412.8 ± 32.4 mg kg⁻¹, with 304.7 ± 96.7 mg kg⁻¹ in average; while it ranges from 59.4 to 435.7 mg kg⁻¹, with 230.1 ± 89.2 mg kg⁻¹ in average for the upland soils. The soils developed from limnic material and slate had higher fixed ammonium content than the soils developed from granite. The percentage of fixed ammonium to total N in the upland soils is always higher than that in the paddy soils. It ranges from 6.1 ± 3.6% to 16.6 ± 4.6%, with 14.0% ± 5.1% in average for the paddy soils and it amounted to 5.8 ± 2.0% to 40.1 ± 17.8%, with 23.5 ± 14.2% in average for upland soils. (2) The maximum capacity of ammonium fixation has the same trend with the fixed ammonium content in the tested soils. For all the tested soils, the percentage of recently fixed ammonium to maximum capacity of ammonium fixation is always bellow 20% and it may be due to the fact that the soils have high fertility and high saturation of ammonium-fixing site. (3) The clay content and clay composition in the tested soils are the two important factors influencing their fixed ammonium content and maximum capacity of ammonium fixation. The results showed that hydrous mica is the main 2:1 type clay mineral in <0.02 mm clay of the paddy soils, and its content in 0.02–0.002 mm clay is much higher than that in <0.002 mm clay of the soils. The statistical analysis showed that both the fixed ammonium content and the maximum capacity of ammonium fixation of the paddy soils were positively correlated with the total 2:1 type clay mineral content and hydrous mica content in <0.02 mm clay and 0.02–0.002 mm clay at the significant level of P_0.01 or P_0.05, respectively, but not correlated with the total 2:1 type clay mineral content and hydrous mica content in <0.002 mm clay significantly. It demonstrated that the ammonium-fixing matrix of the tested soils mainly exists in the 0.02-0.002 mm clay. The above-mentioned results showed that fixed ammonium is a major form of N in the tillage soils in Hunan Province, China. It would play an important role in N nutrition of crops, especially for upland crops, and deserve to be further researched.     

湖南省双季稻田土壤无机磷形态的分级研究

为弄清湖南省双季稻田土壤无机磷的形态及其与土壤有效磷的关系,运用张氏法和蒋氏法两个分级体系对湖南省临澧、醴陵、湘乡３县（市）双季稻田土壤无机磷形态进行分级研究．结果表明,风化程度较高的第四纪红土母质发育的红黄泥田,土壤无机磷以Ｏ－Ｐ和Ｆｅ－Ｐ为主,占无机磷总量的７８．７％;而风化程度较低的紫泥田和河沙泥田,土壤无机磷以Ｃａ－Ｐ为主,分别占无机磷总量的４７．０％和４５．９％,Ｆｅ－Ｐ和Ｏ－Ｐ也占了相当大的比例,大致与Ｃａ－Ｐ的含量相当,但无机磷的总量较红黄泥田高．相关分析结果表明,Ｆｅ－Ｐ,Ｃａ２－Ｐ和Ａｌ－Ｐ与有效磷之间均呈极显著的正相关,是土壤有效磷的主要来源．蒋氏法不仅适用于北方的石灰性土壤无机磷形态的区分,同样适用于南方大面积分布的中、酸性双季稻田土壤无机磷形态的区分．     

呼和浩特周边农田土壤中多环芳烃污染特征与生态风险评价

[目的]为呼和浩特市农田土壤污染预警和农业规划用地提供科学理论依据.[方法]对呼和浩特市农田土壤60个采样点位中15种多环芳烃进行污染特征、 来源解析和生态风险评价.[结果]ΣPAHs含量范围为114~948μg/kg,平均含量为338μg/kg,参照相关研究评价标准判定,呼和浩特市农田土壤中70%以上属于轻微污染,不存在严重污染点位;研究区农田土壤中高分子量多环芳烃污染占总含量的74%,以近郊农田土壤污染最为严重;定量解析来源主要是煤、焦炭和木材的燃烧以及汽车尾气的排放.[结论]采用生态效应区间法评价和苯并(a)芘毒性等效当量法评价均证明呼和浩特市农田土壤存在一定的潜在生态风险,其中苯并[a]芘、二苯并[a,h]蒽等高分子量多环芳烃是主要潜在的污染物.     

溶磷细菌对复垦土壤有效磷及各形态无机磷含量的影响

为探索溶磷细菌在复垦土壤中对磷的作用效果,采用室内摇瓶培养的方法,研究了溶磷细菌及其组合对磷酸钙的溶解能力,从而确定最佳组合,并探讨最佳组合溶磷细菌对复垦土壤有效磷及各形态无机磷含量的影响。结果表明,拉恩式菌(W2)+荧光假单胞菌1(W3)+荧光假单胞菌2(W4)培养液的有效磷含量最高,为609.1 mg/L,其为最佳溶磷细菌组合。施用此溶磷细菌组合肥可以增加复垦土壤有效磷含量,复垦土壤有效磷含量表现为BG(溶磷细菌肥+磷酸钙)处理B(溶磷细菌肥)处理MG(基质+磷酸钙)处理M(基质)处理CK(空白),其中,B处理在苗期、拔节期、收获期分别比M处理显著增加15.7%、119.7%、54.1%,BG处理在苗期、拔节期、收获期分别比MG处理显著增加55.8%、91.8%、88.9%。在玉米苗期和收获期,施用溶磷细菌可以增加复垦土壤Ca_2-P、Ca_8-P、Fe-P、Al-P含量,其中收获期B处理比基质处理M分别显著增加86.6%、88.7%、38.6%、83.3%;复垦土壤O-P和Ca_(10)-P含量均表现为MGBGMBCK,溶磷细菌对复垦土壤O-P含量影响较小,对Ca_(10)-P含量影响较大,苗期和收获期B、BG处理Ca_(10)-P含量分别比对应的基质处理M、MG处理降低5.8%、23.1%和9.5%、24.4%,即溶磷细菌可以减少复垦土壤Ca_(10)-P的含量。土壤有效磷含量与土壤Ca_2-P、Ca_8-P、Al-P、Fe-P含量呈极显著正相关,与O-P、Ca_(10)-P含量无显著相关性。     

太原市农田土壤中多氯联苯污染特征及健康风险

[目的]研究多氯联苯(PCBs)在太原市农田土壤中的分布特征、来源以及对周围人群的健康风险.[方法]以太原市农田土壤为研究对象,分析测定土壤中7种指示性PCBs的含量,并根据太原市人群实际情况的暴露参数和USEPA的部分参数,对太原市农田土壤中PCBs的健康风险进行评价.[结果]太原市农田土壤中7种指示性PCBs的平均值为87.29μg/kg,以六氯及以上的高氯联苯为主;与国内外其他城市土壤中PCBs的残留量相比较,太原市农田土壤中PCBs残留量处于相对较高水平;且35%采样点的∑7PCBs残留量高于农业用地限定值;主成分分析结果表明,土壤中PCBs污染可能主要与大型企业电子电力设备绝缘材料、电容器浸渍剂和变压器的泄漏,以及含有Aroclor1254绝缘材料、油漆添加剂和化产车间使用Aroclor1260一类的工业产品有关;太原市农田土壤中的PCBs在敏感用地和非敏感用地方式下均不会对成人和儿童产生非致癌健康风险;在2种不同用地方式下太原市农田土壤中PCBs对成人的综合致癌风险较小,但对儿童会存在一定的致癌风险,3种暴露途径对健康风险贡献率依次为经口摄入皮肤接触呼吸吸入.[结论]该研究可为太原市土壤污染残留分布分析及其评价提供参考.     

菌根生理机能及其在污染土壤修复中的应用

伴随工农业生产的迅猛发展及人口的快速增长,环境污染日益加剧,土壤成了直接受害者,土壤污染的治理迫在眉睫.治理污染土壤的方法很多,其中菌根修复是近年来发展起来的利用真菌和植物根系形成共生体的一种生物修复方法.本文概述了菌根在生态系统中的重要性,讨论了菌根增强植物在各种胁迫环境中的耐受性及其机理,并对国内外利用菌根生物技术修复受污染土壤的研究作了介绍,旨在为菌根修复的应用提供科学依据.     

昭通植烟土壤的有机质与氮含量

在昭通市8个产烟县(区)采集605个植烟耕层土壤进行分析。结果表明,昭通植烟土壤有机质和全氮含量中偏高,平均含量分别为2.63%和0.13%,处于中上以上水平含量的土壤样本分别占76.19%和67.6%。速效氮含量平均107.28 mg/kg,处于中上以上水平含量的土壤样本占95.37%。各产烟县(区)植烟土壤有机质和全氮含量地域分布差异较大,其中镇雄县和威信县较高,巧家县和永善县较低。全市植烟土壤有机质和氮素含量从地理分布上表现出由南向北递增、自东向西递减的趋势。     

Root growth response of serradella species to aluminium in solution culture and soil

Serradella (Ornithopus) species are high‐quality pasture legumes that originate from the Mediterranean basin and have been increasingly used in southern Australian temperate grazing systems. They are generally regarded as tolerant of soils with low pH and, by inference, elemental toxicities such as aluminium (Al). No studies have examined the effect of high Al concentrations on the growth of French serradella (Ornithopus sativus Brot.) or newly developed cultivars of yellow serradella (O. compressus L.). Several cultivars/accessions of each species were grown in low ionic‐strength nutrient solutions at pH_Ca 4.5 containing a range of Al concentrations. Their susceptibility to root growth inhibition by Al was benchmarked against reference species ranging from Al‐sensitive to Al‐tolerant. Most serradella cultivars had moderate‐to‐high Al tolerance in solution culture but one yellow and two French serradella cultivars ranked alongside the Al‐sensitive reference species. A subset of cultivars and reference species were then grown in an Al‐toxic soil to test the validity of the solution culture results; these cultivars spanned the apparent range in Al sensitivity/tolerance indicated by the solution culture experiment. Variation in the relative root length achieved in Al‐toxic solution culture explained ~59% of the variation in the relative root length achieved in the acidic Al‐toxic soil. This result supports the conclusion that Al tolerance varies among serradella and that some cultivars may not thrive in soils with pH_Ca < 4.5 and elevated extractable Al concentrations.