植物群落对铜尾矿废弃地土壤微生物量和酶活性的影响

以铜尾矿废弃地为对象,研究了铜尾矿废弃地上植物群落发展与表层尾矿微生物量C、N和脱氢酶、过氧化氢碱性磷酸酶和脲酶活性的变化,探讨了植物群落-微生物量C、N_土壤酶活性之间的相互关系.结果表明,随着植物群落的发展,铜尾矿废弃地表层尾矿微生物量和酶活性在不断增加;铜官山老尾矿废弃地白茅群落下表层尾矿(TBM)微生物量和酶活性与杨山冲尾矿废弃地及铜官山新尾矿废弃地表层尾矿微生物量和酶活性存在显著差异性(p<0.05).相关分析表明铜尾矿废弃地表层尾矿微生物量C、N与土壤有机质、总氮之间呈显著正相关(P<0.01);脱氧酶、碱性磷酸酶及脲酶与微生物量C、微生物量N、土壤有机质、总氮之问呈显著正相关(P<0.01),但过氧化氢酶与微生物量C、微生物量N、土壤有机质、总氮之间呈显著负相关(P<0.01).     

Effects of cotton straw amendment on soil fertility and microbial communities

Maintaining soil fertility, while controlling pollution from excessive chemical fertilizer application is important for keeping soil productivity of sustainable agriculture. Variety of straws have been used and proven to be good soil amendments for increasing soil organic matter (OM) and a range of additional soil nutrients. However, little is known about the utilization of cotton straw for soil amendment. To better understand the mechanism behind cotton straw soil amendments, investigations were performed upon cucumber seedlings, where changes to soil nutrients and microbial communities were investigated. The results revealed that the cotton straw application promoted the cucumber seedling growth by significantly increasing the soil OM, available nitrogen, available phosphorus, and available potassium. The concentration of cotton straw was positively correlated to both the number of the culturable microorganisms and also the total microbial biomass within soil. Furthermore, assessment of cotton straw application using Biolog metabolic profiling and phospholipid fatty acid analysis revealed that such application increased the microbial community metabolic activity, and markedly changed the structure of microbial community. 16S rRNA gene clone library construction and phylogenetic analysis of soil bacteria revealed γ- Proteobacteria sequences dominated the cotton straw amendment soil, comprising 27.8% of the total number of analyzed sequences, while they were less represented in control soil (13.4%). On the contrary, the Sphingobacteria (7.8%) and Verrucomicrobia (2.4%) in the cotton straw amendment soil decreased after application when compared to the control soil 15.2% and 15.2%.     

镉污染土壤对潜在能源植物生长的影响

利用重金属污染土壤种植能源植物是一种同时解决环境问题和能源问题的新理念,但目前相关研究成果并不多。通过盆栽试验研究人工镉污染土壤中象草Pennisetumpurpureum和亚香茅Cymbopogonnardus两种植物植株的生长状况和两种植物对土壤镉的吸收和富集能力。结果表明,当外源可溶性镉加入到土壤后,其主要是以生物有效性较高的状态存在。土壤镉对象草和亚香茅生长的影响作用有很大的不同,亚香茅比象草具有更强的镉耐受力,其生物量受镉污染影响小。两种植物植株镉含量均随土壤镉添加量的增加而增加。除高镉处理象草外,植物地下部分含镉量比地上部分高很多。高镉处理象草地下部分含镉量比地上部分低的现象可能反映出根系已积累了太多的镉,因而加速了向地上部的转移,从而加剧了植物中毒的程度。赤泥添加剂具有降低土壤酸度,减少植物对镉的吸收和增加象草和亚香茅生物量的作用。     

Effects of sepiolite on stabilization remediation of heavy metal-contaminated soil and its ecological evaluation

Stabilization in the remediation of heavy metal contaminated soils has been gaining prominence because of its cost-effectiveness and rapid implementation. In this study, microbial properties such as microbial community and enzyme activities, chemical properties such as soil pH and metal fraction, and heavy metal accumulation in spinach (Spinacia oleracea) were considered in assessing stabilization remediation effectiveness using sepiolite. Results showed that soil pH values increased with rising sepiolite concentration. Sequential extraction results indicated that the addition of sepiolite converted significant amounts of exchangeable fraction of Cd and Pb into residual form. Treatments of sepiolite were observed to reduce Cd and Pb translocation from the soil to the roots and shoots of spinach. Concentrations of Cd and Pb exhibited 12.6%–51.0% and 11.5%–46.0% reduction for the roots, respectively, and 0.9%–46.2% and 43.0%–65.8% reduction for the shoots, respectively, compared with the control group. Increase in fungi and actinomycete counts, as well as in catalase activities, indicated that soil metabolic recovery occurred after sepiolite treatments.     

农田土壤抗生素抗性基因与微生物群落的关系

抗生素抗性基因(Antibiotic resistance genes,ARGs)作为一种新型环境污染物,近20年来在农田土壤中广泛富集,促进了耐药性的传播.土壤微生物群落在农业种植下也发生了极大的变化,由于ARGs的传播扩散与微生物息息相关,因此关于两者之间关系及相互作用的研究急速增加.本文通过综述近几年的国内外研究成果,概述了农田土壤ARGs的分布现状和优势微生物群落的变化情况,从农业种植模式、有机肥施用情况、施用有机肥的种类、土壤理化性质和土壤污染影响等角度总结ARGs富集与优势微生物群落、微生物多样性变化的关系,指出耐药菌的变化情况,基于当下研究的不足展望了继续深入探索的方向,为今后进一步深入探索两者间的科学规律提出了设想.     

High Cd and Pb in Chinese cabbage: how to safely eat vegetables from metal-contaminated agricultural soil

Trace-element contamination poses a serious threat to China's ecology, environment, food safety, and human health. Human exposure to potentially toxic trace elements is predominantly attributed to the consumption of vegetables, especially leafy vegetables, grown on metal-contaminated soil. In the present study, the concentrations of Cd in Chinese cabbage were found to decrease at an exponential rate from the outermost layer to the inner core, while there was a small change in Pb content from the 1st to the 16th layer of the plant, suddenly decreasing at the 17th layer. Although there was a little difference between the maximum permissible concentration (MPC) and the mean Cd content in the plant, from the 1st layer to the 10th layer in the edible part of Chinese cabbage, Cd concentrations were 1.1–2.5 times higher than the MPC. The Pb concentration in the whole plant was 1.9 times higher than the MPC, while the 17th layer to the 25th layer of Chinese cabbage was safe for consumption. Health risk assessment indicated that the surface layer of Chinese cabbage might cause harm to human health, especially to children, in view of cancer risk and non-cancer risk.     

Effects of two root-secreted phenolic compounds from a subalpine coniferous species on soil enzyme activity and microbial biomass

In order to evaluate the ecological consequences and potential mechanisms of specific C compounds on soil microbial processes under climate warming, we injected solutions of two modelled root exudates, 2,6-di-tert-butyl-4-methylphenol (BHT) and 1,2-benzenedicarboxylic acid, dibutyl ester (DBP), respectively, into soil at two concentrations (20 and 1000?µg?g^?1 soil). For all treatments, soils amended with the two phenolic compounds were incubated at two temperatures (20°C and 30°C) for 30 days. The responses of soil enzyme activity and microbial property to modelled root exudates to some extent depended on temperature regime, exudation component, and addition concentration. For example, the addition of BHT tended to decrease the soil enzyme activities. However, DBP addition generally increased the two metabolic enzyme activities at 30°C, and tended to decrease the two enzyme activities at 20°C, but a significant reduction was observed only at a high concentration at 20°C. The microbial biomass and enzyme activity were generally lower at 30°C compared to those at 20°C, when averaged across all treatment combinations. Taken together, our results indicated that the amounts and quality of liable root-derived C can differentially affect microbial processes, and various environmental changes will greatly complicate root–microbe–soil interactions in forests.     

Responses of soil microbial communities to water stress: results from a meta-analysis

Soil heterotrophic respiration and nutrient mineralization are strongly affected by environmental conditions, in particular by moisture fluctuations triggered by rainfall events. When soil moisture decreases, so does decomposers' activity, with microfauna generally undergoing stress sooner than bacteria and fungi. Despite differences in the responses of individual decomposer groups to moisture availability (e.g., bacteria are typically more sensitive than fungi to water stress), we show that responses of decomposers at the community level are different in soils and surface litter, but similar across biomes and climates. This results in a nearly constant soil-moisture threshold corresponding to the point when biological activity ceases, at a water potential of about -14 MPa in mineral soils and -36 MPa in surface litter. This threshold is shown to be comparable to the soil moisture value where solute diffusion becomes strongly inhibited in soil, while in litter it is dehydration rather than diffusion that likely limits biological activity around the stress point. Because of these intrinsic constraints and lack of adaptation to different hydro-climatic regimes, changes in rainfall patterns (primary drivers of the soil moisture balance) may have dramatic impacts on soil carbon and nutrient cycling.     

枯草芽孢杆菌Bs-15对板栗土壤微生物种群数量及功能多样性的影响

土壤微生物是维持土壤质量的重要组成部分,是土壤中生物活性的具体体现。土壤微生物多样性的变异可反映其对环境的响应与适应,能敏感反映生态系统的功能演变和生态环境的变化。本研究采用固体平板法研究了枯草芽孢杆菌（Bacillus subtilis）Bs-15对板栗（Castanea mollissimaBL）土壤微生物种群数量的影响,并通过BIOLOG ECO微孔板法分析Bs-15对板栗土壤功能多样性的影响。结果表明,接种Bs-15后,土壤中细菌数量比对照略有增加,但差异不显著;接种后放线菌的数量与对照相比有所减少,第7天达到极显著（p〈0.01）差异,之后差异变小,第14 d开始,处理与对照之间放线菌数量基本持平;真菌数量则先增加后减少,第7天开始接种后的真菌数量与对照相比达极显著（p〈0.01）差异。BIOLOG ECO微孔板分析显示,Bs-15使得土壤中微生物的AWCD值变大,72小时以后,AWCD值与对照相比差异达到极显著（p〈0.01）水平;接种Bs-15后增大了土壤微生物多样性指数,其中Shannon多样性指数、Simpson多样性指数和McIntosh多样性指数分别增加了4.09%、6.01%和7.20%,对对照相比差异均达到极显著水平（p〈0.01）,Simpson均匀度和McIntosh均匀度分别增加了2.07%和2.53%,与对照相比差异均达到显著水平（p〈0.05）。本研究结果表明,Bs-15不但提高了板栗土壤微生物的整体活性,丰富了土壤微生物种群,有利于保持和促进土壤肥力和健康状况;还提高了板栗土壤微生物功能多样性,使板栗土壤微生态系统功能更加稳定。     

Effects of the herbicide Roundup on freshwater microbial communities: a mesocosm study

The impact of the widely used herbicide glyphosate has been mainly studied in terrestrial weed control, laboratory bioassays, and field studies focusing on invertebrates, amphibians, and fishes. Despite the importance of phytoplankton and periphyton communities at the base of the aquatic food webs, fewer studies have investigated the effects of glyphosate on freshwater microbial assemblages. We assessed the effect of the commercial formulation Roundup using artificial earthen mesocosms. The herbicide was added at three doses: a control (without Roundup) and two treatments of 6 and 12 mg/L of the active ingredient (glyphosate). Estimates of the dissipation rate (k) were similar in the two treatments (half-lives of 5.77 and 7.37 d, respectively). The only two physicochemical parameters showing statistically significant differences between treatments and controls were the downward vertical spectral attenuation coefficient kd(lambda), where lambda is wavelength, and total phosphorus concentration (TP). At the end of the experiment, the treated mesocosms showed a significant increase in the ratio kd(490 nm)/k(d)(550 nm) and an eightfold increase in TP. Roundup affected the structure of phytoplankton and periphyton assemblages. Total micro- and nano-phytoplankton decreased in abundance in treated mesocosms. In contrast, the abundance of picocyanobacteria increased by a factor of about 40. Primary production also increased in treated mesocosms (roughly by a factor of two). Similar patterns were observed in the periphytic assemblages, which showed an increased proportion of dead: live individuals and increased abundances of cyanobacteria (about 4.5-fold). Interestingly, the observed changes in the microbial assemblages were captured by the analysis of the pigment composition of the phytoplankton, the phytoplankton absorption spectra, and the analysis of the optical properties of the water. The observed changes in the structure of the microbial assemblages are more consistent with a direct toxicological effect of glyphosate rather than an indirect effect mediated by phosphorus enrichment.     

The effect of two different biochars on remediation of Cd-contaminated soil and Cd uptake by Lolium perenne

Biochar can be widely used to reduce the bioavailability of heavy metals in contaminated soil because of its adsorption capacity. But there are few studies about the effects of biochar on cadmium uptake by plants in soil contaminated with cadmium (Cd). Therefore, an incubation experiment was used to investigate the effects of rice straw biochar (RSBC) and coconut shell biochar (CSBC) on Cd immobilization in contaminated soil and, subsequently, Cd uptake by Lolium perenne. The results showed that the microbial counts and soil enzyme activities were significantly increased by biochar in Cd-contaminated soil, which were consistent with the decrease of the bioavailability of Cd by biochar. HOAc-extractable Cd in soil decreased by 11.3–22.6% in treatments with 5% RSBC and by 7.2–17.1% in treatments with 5% CSBC, respectively, compared to controls. The content of available Cd in biochar treatments was significantly lower than in controls, and these differences were more obvious in treatment groups with 5% biochar. The Cd concentration in L. perenne reduced by 4.47–26.13% with biochar. However, the biomass of L. perenne increased by 1.35–2.38 times after adding biochar amendments. So, Cd uptake by whole L. perenne was augmented by RSBC and CSBC. Accordingly, this work suggests that RSBC and CSBC have the potential to be used as a useful aided phytoremediation technology in Cd-contaminated soil.

     

农业生产措施对土壤碳库的影响

在陆地碳平衡日益成为全球变化科学和生态科学中最为前沿与热点问题的前提下,农业碳平衡问题也受到了强烈的关注,从而促进了农业生产措施对土壤碳库影响的研究。文章综述了农业生产措施对土壤碳库的影响及其效率。从全球不同地区的研究得出,农业措施决定了现阶段农业生态系统是C源还是C汇。目前,影响农田土壤碳库的措施主要有:农业用地面积的扩张;耕地的休耕与利用;农业施肥;耕作方式;作物类型与轮作;秸秆还田。平均不同地区的研究结果,各种措施提高土壤碳积累的效率(CMg·hm-2·a-1)分别为:施用动物肥料0.6(肥料用量10Mg·hm-2·a-1)、施化肥-0.71、耕地转换为草场0.825、改善轮作0.21、实施免耕0.315、秸秆还田0.3。目前研究存在的问题及将来的研究重点应主要集中在:通过改善农业措施提高土壤碳库的可行性;土壤有机碳积累与农业措施间的关系的地区差异性;农业措施提高土壤碳库所产生的环境效益与经济效益。     

Influence of invasive plant Coreopsis grandiflora on functional diversity of soil microbial communities

Biological invasions are increasingly attracting the ecologists' attention. Invasive plants threaten the natural ecosystems not only by competing with the native plants, but also by altering the structure and function of soil microbial communities belowground. In this study, we studied the effects of the invasive plant Coreopsis grandiflora (C. grandiflora) on the functional diversity of soil microbial communities in Laoshan mountain in the province of Shandong, North of China. We sampled soil from plots that were invaded or not invaded by C. grandiflora. The functional diversity of microbial communities in the sampled soils was assessed by the Biolog procedure test. By the ANOVA analysis of average well color development (AWCD), Shannon index (H'), Shannon evenness (E), principle components analysis of the level physiological profiles (CLPP) and correlation analysis between the studied parameters, we found that the invasive species C. grandiflora enhanced the functional diversity of soil microbial communities where the habitat was invaded by the C. grandiflora. The study indicated thatthe successful invasive plants have profound effects on the function of soil microbial communities.     

免耕覆盖对土壤微生物量碳的影响

通过设置在甘肃省定西县李家堡镇甘肃农业大学旱农实验站的用间定位试验,研究连续3年春小麦(Triticum aestivum)-豌豆(Pisum sativum Linn.)双序列轮作后6种不同处理土壤微生物量碳的变化情况,结果表明:免耕条件下表土层土壤微生物量碳总是显著地高于翻耕土壤;秸秆覆盖表土层和亚表层土壤微生物量碳明显高于不覆盖;不同处理对表土层和亚表层土壤微生物量碳的影响差异达极显著;表土层土壤微生物量碳有明显的季节动态变化;土壤微生物量碳随土层加深而递减.     

丁草胺污染对高产水稻土微生物区系的影响

土壤微生物多样性是表征土壤质量最有潜力的指标,与农田生态系统的稳定性和生产力密切相关。云南永胜涛源乡是保持我国水稻小面积超高产纪录的特殊生态区,常年施用丁草胺作为选择性芽前除草剂,因此,了解丁草胺对其土壤微生物物种多样性的影响意义重大。采用平板菌落计数法,研究了模拟条件下不同丁草胺剂量（有效成分质量分数0.15、0.30和1.5 mg·kg^-1）对高产水稻土中好氧细菌（aerobic bacteria）、放线菌（actinobacteria）和真菌（fungi）,以及功能微生物自生固氮菌（nitrogen fixing bacteria）、磷酸盐溶解菌（phosphate solubilizing bacteria）和硅酸盐细菌（silicate dissolving bacteria）数量的影响。结果表明：施药7 d,中、高质量分数（0.30和1.50 mg·kg^-1）丁草胺处理好氧细菌数量比CK分别高出78.6%和153.8%,而后数量逐渐下降,表现出先刺激生长、后抑制活性的作用,低质量分数（0.15 mg·kg^-1）丁草胺对好氧细菌的生长和增殖影响不明显;施药7 d,高质量分数处理放线菌数量超过CK 75.1%,表现出明显的刺激作用;施药15 d,中等质量分数处理放线菌数量比 CK 高出125.0%,丁草胺浓度越高,刺激作用越迅速,低浓度丁草胺对放线菌则主要表现为抑制作用。低浓度丁草胺对真菌的生长和增殖基本没有影响,中等浓度有先抑制后刺激的作用,施药30 d后其真菌数量超过CK 56.9%,高浓度丁草胺则表现为抑制作用,施药7、30和45 d其真菌数量始终显著低于CK;不同浓度处理丁草胺均能刺激自生固氮菌的数量显著增加,施药7 d,低、中、高质量分数处理自生固氮菌数量分别高出CK 237.1%,179.9%和138.1%,刺激作用显著,但随培养时间延长,高浓度开始表现出抑制作用;不同浓度丁草胺均能抑制磷酸盐溶解菌的生长和增殖,低浓度处理抑制作用微弱,中、高浓度处     

Pesticide effects on microbial population and soil enzyme activities during vermicomposting of agricultural waste

The effects of different pesticides (propiconazole, profenofos, pretilachlor) on vermicomposting were evaluated for the adverse effects on soil enzyme activities (dehydrogenase, phosphatase, urease) and total microbial counts (TMC). There were remarkable increase in enzyme activities and TMC in presence of earthworm compared to control (earthworm absent). In comparison to control, the activities of phosphatase, dehydrogenase and urease in presence of vermicompost increased upto 30, 128 and 31.3% respectively; whereas increase of TMC was 71.9%. But, in presence of each of the pesticide, said activities decreased. Maximum inhibition of soil phosphatase activity (46.6%) was observed in presence of propiconazole (100 mg kg(-1)) after 120 days. Profenofos affected the soil dehydrogenase activity in the tune of 47% at 1000 mg kg(-1) concentration after 80 days and thereafter, the extent of toxicity decreased little. Soil urease activity was affected markedly in presence of profenofos and was 62% at 1000 mg kg(-1) level after 80 days. TMC also declined in presence of profenofos and pretilachlor. Increase in TMC was about 71.9% compared to control and the inhibition was more or less 60% when profenofos (1000 mg kg(-1)) was present even after 120 days of treatment.     

Effects of copper and zinc on two planktonic ciliates

The interactive effects of copper and zinc on two estuarine planktonic ciliates, Favella sp. and Balanion sp., were determined in seawater media in which the free metal ion activities were controlled by nitrilotriacetic acid (NTA) trace metal ion buffer systems. Cupric ion activities of 10^-10 M caused abnormal motility in both ciliates in shortterm (5 h) tests, and cupric ion activities as low as 10^-12.8 M decreased the growth rates of both species in longer-term experiments. In the short-term tests, zinc ion activity by itself did not affect the motility of the ciliates, but there were significant interactions between copper and zinc. In the longer-term experiments, the growth of Favella sp. was optimal at the lowest cupric ion activity (10^-13 M) and the two lowest zinc ion activities (10^-12 and 10^-13 M) and the two lowest zinc ion activities (10^-12 and 10^-11 M), and copper and zinc inhibited growth at activities above these values. By contrast, optimal growth rate of Balanion sp. occurred at the highest zinc ion activity (10^-10 M) and the lowest cupric ion activities (10^-13 to 10^-12 M) and growth rate was reduced at zinc ion activities 10^-11 M. There was an antagonism between copper and zinc which was particularly pronounced in Balanion sp.Contribution No. 5871 from the Woods Hole Oceanographic Institution     

两种生长在铜矿渣上的菊科植物的铜含量

对生长于云南鸡冠山铜矿渣上的艾蒿(Artemisiaargyi)和湖北铜绿山铜矿渣上的滨蒿(Artemisiascoparia)进行调查和铜含量测定,结果表明,2种菊科植物具有比较高的生物量,均为铜矿区的优势植物,其根周围土壤的铜含量高。艾蒿根和叶的铜含量都较高,其根部铜含量为41～156mg·kg-1,平均83±29mg·kg-1;叶部铜含量为58～464mg·kg-1,平均216±96mg·kg-1。滨蒿根部铜含量较高,其变化范围为58～513mg·kg-1,平均183±101mg·kg-1,而茎叶部铜含量相对于根部较低,为42～259mg·kg-1,平均97±52mg·kg-1(含铜量均以干重计)。研究还发现,2种植物对铜的耐受机制不同,艾蒿表现出较强的蓄积铜的潜力,而滨蒿表现出对铜污染土壤的植物固定潜能,因此2者均可作为植物修复铜污染土壤的先锋物种。     

除草剂对土壤微生物生物量碳、氮及呼吸的影响

通过室内培养试验,分别在不同时间取样分析,采用熏蒸-提取法测定土壤微生物生物量碳,提取液中的有机碳采用总有机碳分析仪测定,提取液中的氮采用凯氏消煮法测定;采用直接吸收法滴定测定土壤呼吸作用.研究了阿特拉津、甲磺隆、丁草胺3种除草剂对土壤微生物生物量碳、氮及呼吸强度的影响,揭示了3种除草剂污染的土壤中微生物生物量碳、氮的消长过程及土壤呼吸的动态变化.研究结果显示在较高使用浓度胁迫条件下,培养前20 d 3种除草剂都明显减少土壤微生物生物量碳、氮及抑制土壤呼吸.但这种抑制效应是随着时间而变化的,20 d以后,它们对这些能表征土壤环境生态效应的生物学指标的影响随之降低.甲磺隆对微生物生物量碳、氮及呼吸作用等生物学指标的影响大于阿特拉津和丁草胺也可能与它们在土壤中的降解速率有关.     

安普霉素对不同土壤中微生物活动的影响

研究了兽药抗生素安普霉素对不同土壤中微生物呼吸活动和对土壤中微生物种群生长的影响，了解该药物对土壤生态系统生态毒理学效应，以便为药物的环境安全性评价提供依据。利用直接吸收法(密闭法)测定安普霉素对土壤微生物呼吸活动的影响，结果表明：安普霉素对不同土壤中微生物呼吸活动的影响有所差异。在污染的中后期，长春土中加入一定量的安普霉素能刺激土壤的呼吸作用。在染毒的前期，安普霉素对成都土中CO2的释放量均有抑制作用。采用稀释平板法测定了药物对不同土壤中细菌、真菌生长的影响。实验结果显示：安普霉素对土壤中的细菌的生长具有明显的抑制作用，成都土和长春土的抑菌作用最为明显；同时安普霉素的这种抑制作用还表现出时间差异，24h的抑制率高于48h。安普霉素对土壤中真菌生长的影响表现出地域差异，低质量分数的安普霉素对成都土和武汉土中的真菌没有抑制作用。在所测的四种土壤中，南京土中药物对真菌的平均抑制率最高。这可能与土壤中微生物的种类和种群结构有关。安普霉素对不同土壤中对真菌的抑制作用，随药物质量分数的降低和作用时间的延长而降低。