复合改良剂对Cd污染稻田早晚稻产地修复效果

选取湖南省长沙市北山镇某中重度Cd污染稻田,连续种植早晚两季水稻,研究复合改良剂(石灰石+硅藻土+硫酸铁)对稻田土壤重金属Cd的生物有效性和水稻各部位累积Cd的影响.结果表明,施用复合改良剂提高了早、晚稻土壤pH值、CEC值,降低了早稻土壤中有机质含量(OM值).Cd的TCLP提取态与交换态Cd含量分别降低了18.0%~33.0%、5.4%~57.9%,但对晚稻土壤中Cd的2种提取态含量与OM值影响不显著.施用复合改良剂显著降低早稻糙米、谷壳、茎叶、根系中的Cd含量,分别降低了29.6%~56.1%、52.1%~54.0%、18.1%~80.7%、24.4%~41.6%.早稻与晚稻之间对Cd的转运能力呈现明显差异,Cd在晚稻植株体内的转运过程更为通畅.晚稻除谷壳中的Cd含量在2 g·kg~(-1)的添加量下有所上升外,复合改良剂对水稻各部位Cd含量影响不显著(P0.05).糙米中Cd含量与土壤中TCLP可提取态含量和Cd的交换态含量存在显著正相关关系.复合改良剂有效地抑制了早稻植株对土壤中Cd的吸收,糙米中的Cd含量显著降低;晚稻期间复合改良剂随水分流失,不能持续地固化土壤中的Cd,建议在各季稻之间补加一次.     

磁性锆铁改性膨润土添加对河道底泥磷迁移与形态转化的影响

首先采用Fe~(3+)、Fe~(2+)、溶解性锆盐、膨润土和碱液作为原料制备得到了一种磁性锆铁改性膨润土,再通过底泥培养实验考察了磁性锆铁改性膨润土添加对底泥中磷迁移与形态转化的影响.结果表明,在缺氧条件下,河道底泥中磷会被释放进入间隙水中,继而会被释放进入上覆水中,而磁性锆铁改性膨润土添加可以极大地降低底泥中磷向间隙水的迁移通量,最终导致了上覆水中磷数量的显著下降.此外,添加磁性锆铁改性膨润土不仅促使底泥中弱吸附态磷(Liable-P)和氧化还原敏感态磷(BD-P)这2种容易释放态磷向较为稳定的金属氧化物结合态磷(NaOH-rP)和非常稳定的残渣态磷(Res-P)转变,而且降低了底泥中水溶性磷(WSP)、易解吸磷(RDP)、NaHCO_3可提取磷(Olsen-P)、藻类可利用磷(AAP)和铁氧化物-滤纸提取磷(FeO-P)这5种不同类型生物有效态磷(BAP)含量,从而降低了底泥中磷的释放风险.从底泥中分离出来的磁性锆铁改性膨润土中潜在活性磷(NH4Cl-P+BD-P)占总磷的26%左右,且含一定数量的FeO-P和Olsen-P(含量分别为161 mg·kg~(-1)和127mg·kg~(-1)).因此,及时采用磁分离的方式从底泥中将吸附磷后的磁性锆铁改性膨润土回收是非常必要的.磁性锆铁改性膨润土添加控制河道底泥中磷释放的机制是:改良剂通过对底泥中潜在活性磷和生物有效态磷的钝化作用,以及通过对间隙水中磷的吸附作用,降低了底泥中磷向间隙水的释放风险,导致间隙水中磷浓度的下降,进而降低了底泥-上覆水界面磷的扩散通量,最终导致上覆水中磷浓度的下降.以上结果说明,磁性锆铁改性膨润土是一种非常有希望的用于控制河道底泥中磷释放的改良剂.     

一种新型土壤改良剂的制备及性能研究

以废弃蔗渣为原料提取纤维微晶,结合筛选的高效菌株制备成一种新型的土壤改良剂.通过土壤改良剂的红外光谱分析和电子扫描显微镜(SEM)微观形貌分析,土壤改良剂是由各单体在交联剂作用下形成的交联网状大分子,具有众多亲水基团的共聚体,纤维微晶呈白色条状分布,被共聚体所包裹.土壤改良剂吸水持续时间及吸水性能较蔗渣有明显提升,在去...     

A multi-criteria evaluation of organic amendments used to transform an unproductive shrubland into a Mediterranean dehesa

Environmental and health problems associated with the use of digested sewage sludge hinder its application and encourage the introduction of additional treatments such as composting and thermal drying. The aim of this paper is to assess the possibility of using three different types of sewage sludge (digested, composted and thermally dried) to improve soil fertility and enhance the transformation of an unproductive shrub land into a Mediterranean dehesa for grazing purposes and also to reduce wildfire risk. In total, 10t ha(-1) of dry matter of three types of sewage sludge were spread on the soil surface of 4x5m field plots, and then seeded with a mixture of grasses. Effects on soil fertility and plant growth were monitored over 2 years. The results show that all three types of sludge application had a significant effect on vegetation cover, herbaceous biomass (2767.7+/-716.1 and 1735.0+/-299.7kgha(-1) for digested sludge amended and control plots, respectively) and tree growth (0.41+/-0.108cmyear(-1) on amended trees, 14.6% more than control trees). This study proposes the use of multi-criteria analysis to identify the most suitable fertilization alternatives and to assist in the decision-making process of sludge recycling. Because of the high degree of uncertainty and conflicting objectives associated with these decisions, multi-criteria evaluation tools make a valuable contribution to decision-making processes concerning sewage sludge applications. According to multi-criteria results, the composted sludge alternative is the most suitable. This is because all the objectives are achieved: an improvement in the properties and functions of the soil with a positive vegetation response as well as minimal economic cost and risk of toxicity.     

组配改良剂对污染稻田中Pb、Cd、Cu和Zn钝化效果持续性比较

为研究组配改良剂碳酸钙+海泡石(LS)对稻田土壤重金属Pb、Cd、Cu、Zn钝化效果的持久性,通过一次性施用0、2、4、8 g·kg-1的LS,并分别于2012年(第一季)、2013年(第二季)和2014年(第三季)连续种植水稻,在湘南某矿区附近污染稻田进行了一个3 a的大田修复试验.结果表明:1LS能显著提高三季土壤p H值,且LS对土壤p H值提高效果为:第一季第二季第三季.2LS能显著降低三季水稻土壤中Pb、Cd、Zn的交换态含量,且第三季水稻土壤中Pb、Cd、Zn的交换态含量分别降低32.6%~97.7%、8.3%~71.4%和10.9%~83.5%,但对降低三季土壤中Cu的交换态含量无显著影响;LS降低三季土壤中Pb、Cd、Cu、Zn交换态含量的效果均为:PbZnCdCu.3LS使第三季水稻糙米中Pb和Cd含量分别降低26.7%~66.7%、59.1%~80.3%,这种降低效果均随着改良剂LS添加量的增加而增大,但对糙米中Cu和Zn含量无明显影响.LS降低糙米中Pb、Cd、Cu、Zn含量的效果为:第一季,PbCdCuZn;第二季,PbCdCuZn;第三季,CdPbZnCu.LS降低三季水稻糙米中重金属含量的整体效果为PbCdCuZn.4随着时间的延长,LS对土壤中Pb和Cd具有更稳定的钝化效果.因此,LS对治理Pb和Cd污染的土壤具有良好的持久性.     

三元土壤调理剂对田间水稻镉砷累积转运的影响

通过镉砷复合污染稻田的土壤调理剂原位治理,研究了三元土壤调理剂QFJ（羟基磷灰石+沸石+改性秸秆炭）对稻田土壤基本理化性质和水稻各部位镉砷累积转运的影响.结果表明,在土壤Cd总量3.58 mg·kg^-1,As总量124.79 mg·kg^-1污染程度下,施用QFJ后,水稻根际土壤pH值、阳离子交换量及有机质含量有增大的趋势;土壤交换态Cd和As含量可分别从0.37 mg·kg^-1、0.07 mg·kg^-1下降到0.12 mg·kg^-1、0.04 mg·kg^-1.QFJ的施用,可有效降低水稻各部位中Cd和As含量,在9.00 t·hm^-2施用量水平,可将糙米中Cd含量从0.46 mg·kg^-1下降到0.18 mg·kg^-1,无机As含量从0.25 mg·kg^-1降低到0.16 mg·kg^-1,同时低于国家食品污染物限量标准0.2 mg·kg^-1的要求,实现水稻安全生产.施用QFJ减少了水稻根系对Cd和As的富集,降低了水稻植株将Cd从地下部转运到地上部的能力,降低了根系转运Cd的能力以及茎叶、谷壳转运As的能力.     

组配改良剂对土壤-蔬菜系统铅镉转运调控的场地研究

以组配改良剂LS(石灰石∶海泡石=2∶1)为试验材料,通过对湘南某矿区附近铅镉复合污染旱地土壤进行现场改良钝化,研究施加不同量的LS(0、2、4、8 g·kg-1)对茄子和苋菜植株吸收累积Pb和Cd的影响以及对Pb和Cd在2种蔬菜植株各部位间转运的调控.结果表明:1施加LS能够显著提高土壤p H,降低土壤中交换态Pb和Cd的含量.2施加LS能显著降低2种蔬菜植株各部位中Pb和Cd的含量.LS施加量为2~8 g·kg-1时,茄子果实中Pb和Cd的含量分别降低44.7%~78.6%和36.0%~78.7%;苋菜植株茎叶中Pb和Cd的含量分别降低45.8%~59.1%和40.0%~87.2%.3LS的施加降低了2种蔬菜植株各部位间Pb和Cd的转运系数.2种蔬菜植株在根-茎-果实间或根-茎叶间转运Cd的能力大于Pb,且施加LS各处理下,同种蔬菜相同部位对Pb和Cd的转运能力大小关系保持不变.     

Impact of biofumigation with solarization on degradation of pesticides and heavy metal accumulation

A greenhouse study was conducted to evaluate the effect of biofumigation (with sheep and chicken manure) combined with solarization on the dissipation of pesticides (pyrifenox, DDT and dieldrin), and on soil metals accumulation. The treatments consisted of a control, and soil disinfestations by biofumigation combined with solarization (B+S) for two, four, five, six consecutive years. B+S enhanced the dissipation of pyrifenox with regard to control treatment. Significant differences were not detected among plots disinfected with B+S for consecutive years. On the other hand, B+S had no effect on the dissipation of DDT and dieldrin, probably due to the resistance of these pesticides to microbial degradation and/or high temperatures. Biofumigation is considered to be an environmentally safe practice, since no accumulation of heavy metals such as Cd, Co, Cu, Cr, Pb, Ni, or Zn was observed after the subsequent application of organic matter through the treatments.     

方解石/氯磷灰石混合物添加对水体内源磷迁移转化的调控效应和机制

阐明方解石/氯磷灰石混合物添加对内源磷迁移转化的调控效应与机制,对于其实际应用至关重要.为此,本文采用氯化钙和磷酸钠制备得到氯磷灰石,再与天然方解石进行混合,形成氯磷灰石和方解石的混合物,然后通过批量吸附实验考察了该混合物对水中磷酸盐的去除作用,再通过底泥培养实验考察了该混合物添加对底泥中磷迁移转化的影响.结果表明,该混合物对水中磷酸盐的去除能力明显强于单纯的方解石和氯磷灰石;该混合物对水中磷酸盐的去除动力学过程较好地符合准二级和Elovich动力学模型;增加方解石和氯磷灰石的投加量均有利于该混合物对水中磷酸盐的去除;溶液共存钙离子促进了该混合物对水中磷酸盐的去除.该混合物的添加可以有效控制底泥中磷向上覆水体的释放,导致上覆水中的溶解性活性磷(SRP)浓度处于相对较低的水平.此外,该混合物添加还可以降低间隙水中SRP的浓度,其对间隙水中SRP的削减作用对其调控底泥中磷向上覆水体的迁移转化起到重要的作用.该混合物添加虽然会增加底泥中磷的含量,但所增加的磷主要是以稳定的钙磷形式存在,发生二次污染的风险低.结果显示,方解石/氯磷灰石混合物可以作为底泥改良材料用于水体内源磷释放的控制.     

Species Listing under Canada's Species at Risk Act

Abstract: In a preliminary analysis of listing decisions under Canada's Species at Risk Act (SARA), Mooers et al. (2007) demonstrated an apparent bias against marine and northern species. As a follow‐up, we expanded the set of potential explanatory variables, including information on jurisdictional and administrative elements of the listing process, and considered an additional 16 species recommended for listing by SARA's scientific advisory committee as of 15 August 2006. Logistic model selection based on Akaike differences suggested that species were less likely to be listed if they were harvested or had commercial or subsistence harvesting as an explicitly identified threat; had Department of Fisheries and Oceans (DFO) as a responsible authority (RA); were located in Canada's north generally, and especially in Nunavut; or were found mostly or entirely within Canada. Subsequent model validation with an independent set of 50 species for which a listing decision was handed down in December 2007 showed an overall misclassification rate of <0.10, indicating reasonable predictive power. In light of these results, we recommend that RAs under SARA adopt a two‐track listing approach to address problems of delays arising from extended consultations and the inconsistent use by the RAs of socioeconomic analysis; consider revising SARA so that socioeconomic analysis occurs during decisions about protecting species and their habitats rather than at the listing stage; and maintain an integrated database with information on species’ biology, threats, and agency actions to enable future evaluation of SARA's impact.