肠道微生物对土壤中铜、锌、锰生物可给性的影响

为了更全面、准确地评价土壤中金属元素对人体的健康风险,研究土壤中金属元素在结肠阶段的生物可给性具有重要意义。通过采集我国一些地区的6种土壤,利用in vitro方法(PBET和SHIME联用)研究土壤中Cu、Zn、Mn在胃、小肠、结肠阶段的生物可给性。研究显示,土壤中Cu、Zn、Mn在胃阶段的生物可给性分别为23.8%~63.0%、21.2%~64.4%、11.7%~35.6%;从胃阶段到小肠阶段,土壤中Cu的生物可给性提高了0.4%~14.4%,而土壤中Zn在小肠阶段的生物可给性降低了6.7%~38.7%。结肠阶段,土壤中Cu、Zn、Mn的生物可给性分别为2.4%~12.9%、5.7%~18.7%、6.2%~18.9%,与小肠阶段相比,分别降低了21.7%~56.9%、0.4%~36.8%、4.5%~19.1%。结果表明,在肠道微生物存在的情况下,土壤中Cu、Zn、Mn在结肠阶段有较低的人体健康风险。     

Trace element content in soils of the King George and Elephant islands,maritime Antarctica

Trace element concentrations were studied in soils of the King George and Elephant islands in the maritime part of West Antarctica. The lowest concentrations of Cu, Pb, Cd, Zn, Ni and Mn were typical for the pristine soil of Elephant Island. The highest concentrations of these elements were found in the Fildes Peninsula and revealed the influence of human activities in the area of the Bellingshausen station and adjacent waste disposal sites. Ornithogenic soils of the Fildes Peninsula have shown low concentrations of Cd and As. Using geoaccumulation indexes, all the pristine soils of King George and Elephant islands and ornithogenic soils of the Fildes Peninsula were classified as unpolluted; the human-affected soils were mainly identified as moderately polluted. Obtained data can be used as background concentration levels for further researches.     

禾草灵对水稻生长和典型土壤酶活性的影响

禾草灵是一种广泛使用的除草剂,在土壤中大量残留,对非靶标生物产生危害。为探究除草剂对环境生物的毒性作用,本研究模拟水稻自然生长的环境,评估禾草灵对水稻及土壤微生物的影响。研究结果表明,低浓度禾草灵(200 μg L^-1)处理4 d对土壤微生物量没有显著影响(P>0.05);8 d时,水稻生长没有明显变化,但土壤微生物量较对照组显著升高(P<0.05)。高浓度禾草灵(1 000 μg L^-1)处理4天后,土壤脲酶、酸性磷酸酶和过氧化氢酶的活性显著下降(P<0.05),下降幅度分别为8.9%,16.6%和10.2%;处理8 d后,水稻幼苗鲜重显著降低(P>0.05),叶绿素a和叶绿素b含量分别下降了13.5%和13.3%。本研究证实高浓度的禾草灵残留会对植物和土壤微生物产生不良的影响。     

基于高通量测序的工业园区地下水和土壤细菌群落结构比较研究

为探究工业园区地下水和土壤细菌群落结构、多样性变化特征,采用高通量测序技术对地下水和土壤细菌16S r RNA基因高变区域进行序列测定。通过对Alpha多样性、物种组成、丰度和群落结构的分析,比较地下水和土壤细菌群落结构的异同。Alpha多样性的比较结果表明,土壤细菌群落多样性和丰富度明显高于地下水,地下水细菌群落多样性指数反映出地下水已受到周边污染源的影响。物种注释结果表明,地下水样品共检出48个细菌门,土壤样品共检出50个细菌门。变形菌门(Proteobacteria)、拟杆菌门(Bacteroidetes)和厚壁菌门(Firmicutes)是地下水细菌群落的优势类群,共占93.54%,且该工业园区地下水细菌群落呈现出典型的淡水种群特征;土壤中优势细菌门为Proteobacteria、放线菌门(Actinobacteria)、酸杆菌门(Acidobacteria)、Firmicutes和芽单胞菌门(Gemmatimonadetes),共占85.21%。由于地下水和土壤两者的生态系统和理化环境的差异,致使Actinobacteria、Acidobacteria、绿弯菌门(Chloroflexi)、硝化螺旋菌门(Nitrospirae)、α-变形菌纲(Alphaproteobacteria)、δ-变形菌纲(Deltaproteobacteria)和Gemmatimonadetes占比在地下水和土壤细菌群落间差异显著,同时使地下水和土壤细菌群落各含有一些特有的优势细菌属(地下水2个,土壤4个)。基于高通量测序技术对工业园区样品的测序结果可以为地下水和土壤环境的生态评价提供方法依据。     

Occurrence and distribution of trifluralin,ethalfluralin, and pendimethalin in soils used for long-term intensive cotton cultivation in central Greece

In the present study, a soil monitoring program was undertaken in Greek cotton cultivated areas in 2012. Twenty-seven soil samples were collected from the entire Thessaly plain in early summer of 2012, corresponding to approximately three months (current use of pendimethalin), up to one year (for the banned ethalfluralin), and three years (for the also banned trifluralin), after the last dinitroaniline application. Low but not negligible levels of dinitroanilines were detected, ranging from 0.01 to 0.21 μg g^?1 d.w. for trifluralin and 0.01–0.048 μg g^?1 d.w. for pendimethalin, respectively. Trifluralin was the herbicide most frequently detected (44.4%). The high historic application of trifluralin and its high persistence and accumulation potential is in line with the abundance of the detected residues. The present data indicate that soil samples contain extractable residues of banned trifluralin, but based on the comparison of the theoretical PECplateau for trifluralin (0.277 µg g^?1) and the maximum Measured Environmental Concentration, it was concluded that the detected residues should be attributed to previous years’ application. The latter suggested the need for continual monitoring of the dinitroaniline family of pesticides, including the banned substances, aiming thus to an improved environmental profile for agricultural areas.     

Nutritional evaluation,bioaccumulation and toxicological assessment of heavy metals in edible fruits of FicussurForssk (Moraceae)

Ficussur (Moraceae) is an indigenous medicinal plant with a wide distribution in Africa. In this study, the nutritional potential fruit of this indigenous plant to meet domestic food demands and reduce food insecurity in KwaZulu-Natal. South Africa, was investigated. The proximate composition and concentrations of metals in the edible fruits collected from eight different sites in KwaZulu-Natal were determined to assess for nutritional value and the concentrations of metals in the growth soil was determined to evaluate the impact of soil quality on elemental uptake. The fruits contained high levels of moisture (88.8%) and carbohydrates (65.6%). The concentrations of elements in the fruits were found to be in decreasing order of Ca>Mg >Fe >Zn>Cu >Mn> Se with low levels of toxic metals (As, Cd, Co and Pb). This study shows that the consumption of the fruits of F. sur can contribute positively to the nutritional needs of rural communities in South Africa for most essential nutrients without posing the risk of adverse health effects.     

Persistence,degradation and leaching of coumaphos in soil

Abstract

Dissipation, degradation and leaching of fresh ¹⁴C coumaphos, alkylated ¹⁴C coumaphos and aged residues of ¹⁴C coumaphos from vats were studied in alkaline sandy loam soil in soil columns in the field under subtropical conditions in Delhi for a year. Dissipation, degradation and bound residue formation was more in case of alkali treated coumaphos than fresh coumaphos. After 365 days total residues of fresh coumaphos accounted for 33.25% while that of alkali treated coumaphos was 19.12%. Bound residue formation was almost double in case of alkali treated coumaphos (18.95%) than fresh coumaphos (9.53%) after 150 days followed by release of bound residue in both the cases. The proportion of metabolites 4 ‐ methylumbelliferone, chlorferon and potasan collectively was 86.05% in fresh coumaphos extractable residues while the same was 91.74% in alkali treated coumaphos after 365 days. Aged residues from vats containing copper sulphate and buffer were found to be more persistent in soil as total residues remained were 95.58% in comparison with 83.09% total residues of aged residues from vats containing only buffer after 150 days of treatment. Copper sulphate seems to inhibit the degradatiion of coumaphos in soil by microorganisms. Chlorferon was the major metabolite in generally all the samples. Coumaphos did not leach below 10 cm in all the cases.     

Variations of Bacterial Community Structure in Flooded Paddy Soil Contaminated with Herbicide Quinclorac

The denaturing gradient gel electrophoresis (DGGE) method was applied to determine the relative genetic complexity of microbial communities in flooded paddy soil treated with herbicide quinclorac (3,7-dichloro-8-quinoline-carboylic acid). The results obtained showed a significant effect of quinclorac on the development of bacterial populations in soils contaminated with different concentrations of the herbicide at the early time after application. In general, however, the number of populations of the same soil sample treated with the same concentration of the quinclorac differed obviously with increasing incubation time within the early 8 weeks. The scale of differences in banding patterns-showed that the microbial community structures of the quinclorac-treated and non-quinclorac-treated soils were not significantly different after 21 weeks of incubation. Quantification, as demonstrated in this paper, was studied by establishing dose-response relationships. Significant pattern variations were quantified. Prominent DGGE bands were excised, cloned and sequenced to gain insight into the identities of predominant bacterial populations. The majority of DGGE band sequences were related to bacterial genera Clostridium, Sphingobacterium, Xanthomonas and Rhodococcus.     

Phytoavailability and extractability of potassium,magnesium and manganese in calcareous soil amended with olive oil wastewater

Abstract

Land disposal of olive oil wastewater using it as a soil amendment requires a knowledge of the effects that its application may produce on the status of the mineral nutrients in the plant‐soil system. A pot experiment using calcareous soil was performed in a growth chamber to examine the effects of olive oil wastewater on the availability and postharvest soil extractability of K, Mg and Mn. The experiment included 6 treatments: two rates of olive oil wastewater, two mineral fertilizer treatments containing K (which supplied K in amounts equivalent to the K supplied by the olive oil wastewater treatments), a K‐free mineral fertilizer treatment, and a control. The pots were sown with ryegrass as the test plant, harvesting 3 times at intervals of one month. Olive oil wastewater has demonstrated a considerable capacity for supplying K that can be assimilated by the plant, tending in fact to surpass the mineral potassium fertilizer tested. The application of olive oil wastewater tends to reduce the concentration of Mg in the plant, similarly to the effect of adding mineral potassium fertilizer. An enhancement of Mn availability takes place in the soil amended with olive oil wastewater, which on occasion has produced Mn concentrations in plant that could be considered phytotoxic or at least excessive. After harvesting, we observed an increase in the amount of exchangeable K in soil with added industrial wastewater. However, these increases are lower than those in soil treated with mineral potassium fertilizer. The levels of exchangeable, carbonate‐bound, organic‐bound and residual Mg in soil were higher in treatments incorporating olive oil wastewater than in those with added mineral K, with the opposite tendency occurring in the amount of Fe‐Mn oxides‐bound Mg in soil. Treatments based on olive oil wastewater, especially in high doses, increased the amount of exchangeable and carbonate‐bound Mn in soil, in comparison with treatments adding mineral fertilizers with or without K. In contrast, the addition of industrial wastewater caused a drop in the amount of Fe‐Mn oxides‐bound and organic‐bound Mn in soil.     

2,4-D mineralization in unsaturated and near-saturated surface soils of an undulating,cultivated Canadian prairie landscape

The herbicide 2,4-D [2,4-(dichlorophenoxy) acetic acid] is one of the most widely used pesticides in the Canadian prairies and is frequently detected as a ground and surface water contaminant. The objective of this paper was to determine the magnitude and extent of variation of 2,4-D mineralization in a cultivated undulating prairie landscape. Microcosm incubation experiments, using a 4 × 3 × 2 factorial experimental design (soil moisture, 4 levels: 60, 85, 110, 135% of field capacity; slope position, 3 levels: upper-, mid- and lower-slopes; soil depth, 2 levels: 0–5 and 5–15 cm), were used to assess 2,4-D mineralization. The first-order mineralization rate constant (k₁) varied from 0.03 to 0.22 day^{? 1}, while total 2,4-D mineralization varied from 31 to 52%. At near-saturated conditions (110 and 135% of field capacity), the onset of 2,4-D degradation was delayed in soil obtained from the upper- and mid-slopes but not in soils obtained from the lower-slope position. The k₁ and total 2,4-D mineralizationwas significantly influenced by all three factors and their interactions. The Freundlich sorption coefficient of 2,4-D ranged from 0.83 to 2.46 ug ^1–1/ng^{? 1} mL^1/n and was significantly influenced by variations in soil organic carbon content across slope positions. The infield variability of 2,4-D sorption and mineralization observed across slope positions in this undulating field was comparable in magnitude and extent to the regional variability of 2,4-D sorption and mineralization observed in surface soils across Manitoba. The large variability of 2,4-D mineralization and sorption at different slope positions in this cultivated undulating field suggests that landform segmentation models, which are used to delineate slope positions, are important considerations in pesticide fate studies.