Technical note: fate and transport of jet fuel (JP-8) in soils with selected plants

Remediation of soil and groundwater contaminated by leaking fuel storage tanks may be assisted by plants, although plant effects on abiotic and biotic removal processes remain unclear. The objectives of this study were to investigate abiotic and biotic removal of JP-8, a kerosene-based jet fuel, in soils with plants, and to determine the effects of plant-induced water movement. Loss of JP-8 in a dry-soil, control column was 25% after 5 months, primarily due to volatilization and gas-phase diffusion. By comparison, managed treatments with simulated surface spills averaged 86% mass reduction at 5 months, indicating an important contribution of biodegradation. Overall JP-8 mass reduction was similar in surface and subsurface-irrigated systems, indicating water content, not mode of water application, influences bioremediation in near-surface systems. The JP-8 concentration reductions in soil columns contaminated above a simulated watertable were 36% after 3 months and 50% after 12 months for vegetated columns compared to 26% and 34% in unplanted columns. Downward movement of JP-8 in unplanted columns was double that in planted columns. Near the groundwater table, JP-8 persists longer than near the soil surface. Plants promote upward movement of water and help draw spilled JP-8 to aerobic near-surface soil.     

Selection of cold‐tolerant plants for growth in soils contaminated with organics

A mixture of organic chemicals (MOC) containing equal molar amounts of benzoic acid, hexadecane, 2,2‐dimethyl 4,n‐propyl‐benzene, phenanthrene, pyrene, and either cycloheptane or cis‐decahydronaphthalene (cis‐decalin) was applied to soil at rates of 0 to 8000 mg/kg. In a plant‐screening experiment, growth responses of four legume and five nonlegume species were determined at 10 and 25°C. The MOC applied at 2000 mg/kg reduced the growth of several species without resulting in significant seedling death. At 10°C, the growth of alpine bluegrass (Poa alpina L.) in the 1000 and 2000 mg/kg treatments of soil increased by more than 185%. In a plant growth response experiment, alpine bluegrass and alfalfa (Medicago sativa L.) were grown in soil that had been contaminated at rates of 0 and 2000 mg/kg. At 14 weeks, the shoot and root dry weights of alfalfa were 97% lower in the contaminated soil, while the shoot dry weight, root dry weight, and root length of alpine bluegrass were 135,235 and 268% higher, respectively. Except for pyrene, <23% of the compounds comprising the MOC remained in the soil after 4 weeks and <5% after 14 weeks. The disappearance of the MOC was not significantly influenced by the presence of alfalfa or alpine bluegrass.     

Suitability of Dicloster acuatus MH013435 and Kalenjinia gelatinosa MH012185 for growth in Garcinia cambogia washwater effluent with efficient nutrient removal

Abstract

The present study investigates the suitability of growing Dicloster acuatus MH013435 and Kalenjinia gelatinosa MH012185 in Garcinia cambogia washwater for biomass production and nutrient removal. In recent years, the wastewater effluent treatment with microalgae is gaining importance since it serves multiple purposes including CO₂ sequestration, production of biofuel feedstock and value-added biochemicals in addition to wastewater treatment. Contaminated washwater is generated at a significant quantity during extraction of hydroxycitric acid from G. cambogia and it represents a serious environmental concern when discharged without proper processing. However, this G. cambogia washwater can be used as a low-cost source of nutrients for microalgal growth. The two microalgal species D. acuatus MH013435 and K. gelatinosa MH012185 demonstrated robust growth in washwater and achieved maximum biomass concentration of 0.68 and 0.63?g/L dry weight. The nitrate was removed to an extent of 98.5 and 99.6% whereas chloride removal was 72 and 80.5%, sulfate concentration got reduced by 98 and 98.7% and phosphate got reduced to 95 and 92% for D. acuatus MH013435 and K. gelatinosa MH012185, respectively. The results indicate the suitability of D. acuatus MH013435 and K. gelatinosa MH012185 in treating G. cambogia washwater with efficient nutrient removal.     

SURVIVAL AND GROWTH OF THE DOMINANT SALT MARSH GRASS SPARTINA ALTERNIFLORA IN AN OIL INDUSTRY SALINE WASTEWATER

Saline oil produced water (PW) is the largest wastewater stream in the oil exploration and production processes. Although eventual disposal of PW into shallow coastal waters occurs nearby coastal wetlands, no studies regarding its toxicity to higher plants were found in our literature review. To fill this knowledge gap and evaluate the potential use of this halophyte for PW phytoremediation the salt marsh grass Spartina alterniflora was grown in five PW concentrations and no PW treatment control for seven weeks. The oil & grease, NaCl, and ammonium (N-NH4⁺) concentrations in the PW were 120 mg L^?1, 30 g L^?1, and 381 mg L^?1, respectively. Plants grown in 30% PW and 10% PW achieved survival rates (75%) significantly higher than plants grown in 100% PW (35% survival). LT50 of S. alterniflora to raw PW with 120 mg L^?1 of oil & grease (100% PW) was estimated at 30 days. Root and sprout biomass were significantly stimulated by PW; plants grown in 10% to 50% PW concentrations were 70–300% more productive than those in control, 80% PW and 100% PW, respectively. No significant inhibitory effects on survival or growth were detected for concentrations of PW less than 80% when compared to control. Our results pointed out that S. alterniflora grows in saline oil PW and its potential use to phytoremediate this effluent should be evaluated.     

PHYTOREMEDIATION OF BTEX HYDROCARBONS: POTENTIAL IMPACTS OF DIURNAL GROUNDWATER FLUCTUATION ON MICROBIAL DEGRADATION

Volatile hydrocarbons have multiple potential fates in phytoremediation. This research investigated the relationship between biodegradation and plant uptake of BTEX compounds in laboratory and field settings. At a phytoremediation site, preliminary studies revealed minimal uptake into trees and enhanced degradation potential in the rhizosphere and in the bulk soil. Increased oxygen transport to the vadose zone caused by diurnal rise and fall of the water table was hypothesized to enhance degradation in the bulk soil. A detailed greenhouse study was then conducted to investigate potential bioremediation impacts using field-site soil and DN34 hybrid poplar trees.

In rhizosphere soils, the contaminated-planted reactor had significantly higher BTEX degrader populations versus the uncontaminated-planted reactor, as was anticipated. The bulk soil in the planted-contaminated reactor had increased degrader populations than the unplanted-contaminated soil or planted-uncontaminated soil, and planting increased degradation throughout the soil profile, not just in the limited volume of rhizosphere soils. Oxygen diffusive and advective transport into reactors was modeled and calculated. Oxygen input in planted reactors was at least 3 to 5 times higher than in unplanted reactors, and increasing oxygen input lead to increased degrader populations in a linear manner. These results combined with the knowledge that high-transpiration trees draw the contaminated groundwater to the capillary fringe and the rhizosphere indicate that phytoremediation can aid microbial degradation via multiple mechanisms: increasing degrader populations, increasing oxygen input via groundwater diurnal fluctuations, and transporting contaminants to the biologically-enriched soil profile.     

Bioremediation and phytoremediation of total petroleum hydrocarbons (TPH) under various conditions

Remediation of contaminated soils is often studied using fine-textured soils rather than low-fertility sandy soils, and few studies focus on recontamination events. This study compared aerobic and anaerobic treatments for remediation of freshly introduced used motor oil on a sandy soil previously phytoremediated and bioacclimated (microorganisms already adapted in the soil environment) with some residual total petroleum hydrocarbon (TPH) contamination. Vegetated and unvegetated conditions to remediate anthropogenic fill containing residual TPH that was spiked with nonaqueous phase liquids (NAPLs) were evaluated in a 90-day greenhouse pot study. Vegetated treatments used switchgrass (Panicum virgatum). The concentration of aerobic bacteria were orders of magnitude higher in vegetated treatments compared to unvegetated. Nevertheless, final TPH concentrations were low in all saturated soil treatments, and high in the presence of switchgrass. Concentrations were also low in unvegetated pots with fertilizer. Acclimated indigenous microbial communities were shown to be more effective in breaking down hydrocarbons than introducing microbes from the addition of plant treatments in sandy soils. Remediation of fresh introduced NAPLs on pre-phytoremediated and bioacclimated soil was most efficient in saturated, anaerobic environments, probably due to the already pre-established microbial associations, easily bioavailable contaminants, and optimized soil conditions for microbial establishment and survival.     

Degradation of crude oil in the rhizosphere of Sorghum bicolor

Dissipation of petroleum contaminants in the rhizosphere is likely the result of enhanced microbial degradation. Plant roots may encourage rhizosphere microbial activity through exudation of nutrients and by providing channels for increased water flow and gas diffusion. Phytoremediation of crude oil in soil was examined in this study using carefully selected plant species monitored over specific plant growth stages. Four sorghum (Sorghum bicolor L.) genotypes with differing root characteristics and levels of exudation were established in a sandy loam soil contaminated with 2700 mg crude oil/kg soil. Soils were sampled at three stages of plant growth: five leaf, flowering, and maturity. All vegetated treatments were associated with higher remediation efficiency, resulting in significantly lower total petroleum hydrocarbon concentrations than unvegetated controls. A relationship between root exudation and bioremediation efficiency was not apparent for these genotypes, although the presence of all sorghum genotypes resulted in significant removal of crude oil from the impacted soil.     

石油污染土壤植物-微生物修复研究进展

依据国内外近10年来有关石油污染土壤生物修复研究的成果,综合阐述了石油污染土壤的植物修复、微生物修复及植物-微生物联合修复方法研究,重点讨论植物-微生物联合作用,主要包括植物根际微生物、根分泌物以及菌根对石油污染物降解的影响,提出了污染土壤原位修复中需要重视的问题.     

Restoration of Petroleum-Contaminated Soil Using Phased Bioremediation

A conceptual approach is presented for the restoration of petroleum-contaminated sites by combining bioremediation with revegetation using native plants. Phased bioremediation includes active and passive treatment options for soil containing greater than 1% total petroleum hydrocarbons (TPHs). Phase I is used when initial soil TPH exceeds 1%. Phase I utilizes either active land treatment, with regular soil tillage, or passive bioremediation to attain a treatment endpoint of 1% soil TPH. Passive treatment utilizes static soil and TPH-tolerant plants. Phase II is utilized when soil contains 1% TPH or less. It combines passive bioremediation with revegetation using native plants to complete the site restoration process. The phased approach to bioremediation was developed from results of full-scale field bioremediation and laboratory treatability studies. This approach assumes that the kinetics of TPH biodegradation are initially rapid, followed by a much slower second stage. It provides active initial treatment, followed by lower-cost passive treatment. The selection of either active or passive treatment in Phase I depends on whether total cost or time of treatment is more important. Passive treatment, although less costly than active treatment, generally requires more time. Phased bioremediation may provide a flexible, cost-effective, and technically sound approach for restoration of petroleum-contaminated sites.

Vegetation used with passive bioremediation has several benefits. Plants stabilize soil, preventing erosion and thereby minimizing exposure to soil contaminants. Phytoremediation may also occur within the rhizosphere. The use of native plants has a strong ecological basis. They provide ecological diversity, are aesthetically pleasing and beneficial to wildlife, while requiring little maintenance. Phased bioremediation can provide a flexible, cost-effective, and technically sound approach for the restoration of petroleum-contaminated sites.     

Effect of Cyclic Phytoremediation with Different Wetland Plants on Municipal Wastewater

Phytoremediation is a promising cleanup technology for contaminated soils, groundwater, and wastewater that is both low-tech and low-cost. The objective of this study was to investigate the ameliorative effect of phytoremediation on municipal wastewater (MWW). For this purpose, a phytoremediation garden was established using different aquatic plants species [Pistia stratiotes, Eichhornia crassipess, Hydrocotyle umbellatta, Lemna minor, Tyhpa latifolia, and Scirpus acutus ] in seven earthen pond systems (P1-P7) for the cyclic treatment of MWW. The physico-chemical analysis of MWW was carried out before and after the cyclic phytoremediation. Results showed that pH, EC and turbidity of MWW were reduced by 5.5%, 33.7%, and 93.1%, respectively after treatment (from P1 to P7). Treatment system also reduced total dissolved solids (TDS) by 35.2%, Cl by 61%, HCO₃ by 29.2%, hardness by 45.7%, Ca by 32.3% and Mg by 55.9%. Nitrate concentration was reduced by 77.6% but SO₄ was enhanced slightly. An ameliorative combined effect of wetland plants namely L. minor, T. latifolia, and S. acutus on MWW was noticed. Sequential phytoremediation with a mixture of plants was more effective than that relying only on a single plant species.     

锰毒及植物耐性机理研究进展

综述了近些年国内外关于锰毒及植物耐锰机理的研究成果,并指出了存在的问题和发展前景。锰毒是酸性土壤上限制作物产量的重要因子,国内外针对锰毒及植物耐受机制进行了相关研究,但进展较为缓慢。锰对植物的毒害效应体现在不同的细胞组织及生理生化水平上,不同植物耐受锰的机理也存在差异性,但大都集中在有机酸的螯合解毒、内部积累、外部排斥及氧化等方面。某些锰胁迫所诱导的基因也被筛选出来,并且部分生物学功能得以鉴定。此外,锰与其他营养元素间的协同或拮抗作用也得以阐述,伴随锰超富积植物-商陆在中国的发现,对锰毒及植物耐性机理的深入研究和探讨,将会对植物修复技术的开展产生理论和实践意义。     

Influence of Phenol and Phenanthrene on the Growth of Phalaris arundinacea and Phragmites australis

In constructed wetlands for the treatment of industrial effluents and in contaminated waterlogged soils, wetland plants (helophytes) are exposed to toxic chemicals. Hence, the plants' resistance to contaminants is an important prerequisite for applying phytoremediation to solve these environmental problems. For toxicity tests on the germination and growth of various helophytes (Phalaris arundinaceae and Phragmites australis), phenol, phenanthrene, and a mixture of both were used as examples of chemicals from the petrol- and coal-processing industries. The germination rate, shoot length, root length, and influence on leaves, young shoots, and dry weight were studied. Although an increase in contaminant concentration decreased plant growth (dry weight, shoot length); interestingly, the number of young shoots rose. Low contaminant concentration (about 50 mg/l in case of phenol) stimulated the plant growth. The cress seed germination test was less susceptible compared with plantlet exposure in the case of phenol and phenanthrene. Due to its low bioavailability, solid phenanthrene (without solutizer) did not significantly affect plant growth.     

Degradation of Polycyclic Aromatic Hydrocarbons in the Rhizosphere of Festuca arundinacea and Associated Microbial Community Changes

A phytoremediation growth chamber study was conducted to evaluate the contribution of soil microbial diversity to the contaminant degradation. Target contaminant removal from soil was assessed by monitoring concentrations of polycyclic aromatic hydrocarbons (PAHs), along with changes in the bacterial community structure over a time period of 10 months in the presence of tall fescue (Festuca arundinacea). Enhanced degradation of PAHs was observed in rhizosphere soil, with a maximum reduction in pyrene at a rate 36% higher than that noted for the unvegetated control. The dissipation of < 4-ring PAHs, 4-ring PAHs, and > 4-ring PAHs in unvegetated soil was 70%, 54%, and 49% respectively, whereas a higher dissipation rate was observed in tall fescue treated soil of 78%, 68%, and 61% at the end of the study. Microbial enumeration results showed greater total bacterial numbers and PAH-degrading bacteria in rhizosphere soil when compared to unvegetated soil. The results from the terminal restriction fragment length polymorphism (T-RFLP) analysis indicated that there was a shift in the rhizosphere bacterial community during the phytoremediation process.     

A two-year field study of phytoremediation using Solanum nigrum L. in China

A two-year in-situ phytoremediation trial was launched in Shenyang Zhangshi (Sewage) Irrigation Area (SZIA). The phytoremediation efficiency of Solanum nigrum L. was determined, by both monitoring the change of soil Cadmium level in the upper 20 cm of soil, and calculating the plant uptake of soil Cd. After two years experimental, by monitoring the soil Cd concentrations, The Cd concentrations decreased on average from 2.75 mg kg^?1to 2.45 mg kg^?1 in the first year and from 2.33 mg kg^?1 to 1.53 mg kg^?1 in the second year, amounting to a decrease by a factor of 10.6% in the first year and 12% in the second year. After two years phytoremediation by S. nigrum, Cd concentrations of the seven experimental plots with S. nigrum growth decreased from 2.75 mg kg^?1 to 1.53 mg kg^?1, a decrease by a factor of 24.9%. And the soil Cd concentration decreased only 2.1% and 1.7% in the bared experimental plot. And the calculating of Cd uptake by S. nigrum shown that, the plants uptake 4.46% and 5.18% of the total soil Cd in 2008 and 2009, while the soil Cd concentrations decreased by a factor of 10.6% in 2008 and 12.1% in 2009.     

Screening perennial rye-grass from New Zealand for aluminium tolerance

Approximately 11,500 seedlings from 510 lines of perennial rye-grass (Lolium perenne L.) were screened for tolerance to aluminium (Al) using a low ionic strength still solution culture technique. Although none of the individual lines were consistently more tolerant than any other line, 23 individual plants were selected from 13 lines for superior vigour and colour in the presence of Al.The growth of three of these elite plants was examined on a reconstructed acid soil profile protected from prevailing weather conditions allowing control of the moisture status of the soil. The plants selected for Al tolerance in solution culture had significantly higher yields before drought and after recovery from drought than the rye-grass cultivars Ariki, Ellett and Droughtmaster and 4 other hill country lines which were previously selected for high yields in the presence and absence of nitrogen, and for drought and grassgrub resistance. Of the total number of plants tested from all cultivars and lines, <2% had yields that were greater than one third of the yields of the 3 Al tolerant plants. The better performance of the Al tolerant plants is attributed to better root growth in the acid soil.Three polycrosses were made from the 23 Al tolerant plants selected in solution culture. When tested in solution culture, the yields of the half-sib families in the presence of Al averaged approximately twice that of Grasslands Nui in one experiment, but were similar to Grasslands Nui in another. Heritability of total yield and relative yield in the presence of Al, calculated from half-sib measurements on a single replicate basis, averaged 0.33 and 0.24 respectively. Individual plants from the half-sib families from two polycrosses were grown in a nursery and heading date and vigour recorded. There were no significant differences in heading data between the polycross lines and either of the cultivars Grasslands Nui or Yatsyn. Although there were significant differences in spring vigour between lines, they were not significantly different from either Grasslands Nui or Yatsyn. Twelve of the polycross lines showed decreased vigour in summer and autumn. This decline in vigour was attributed to damage from Argentine stem weevil (Listronotus bonariensis) as a consequence of low levels of lolium endophyte (Acremonoim lolii).     

Constructed Wetlands for Tannery Wastewater Treatment in Portugal: Ten Years of Experience

Wastewaters from tannery industry are complex in composition and providing adequate treatment can be difficult. Constructed wetlands (CW) are regarded as an alternative treatment to the conventional biological systems, as a developing cost-effective and environmentally friendly phytoremediation technology. The present review compiles and integrates information on CWs technology for the needs of the tannery sector. The following issues arise as crucial for the implementation of such systems, namely i) an accurate wastewater characterization and an effective pretreatment before reaching the CW, ii) choosing the plants species better adapted to the imposed conditions, iii) substrate selection and iv) range of organic loadings applied. The examples practiced in Portugal give indication that horizontal subsurface flow systems, with expanded clay media, are a suitable option to be considered when dealing with high organic loading tannery wastewater (up to c.a. 3800 kgCODha^?1d^?1), being resilient to a wide range of hydraulic variations. Plants such as Phragmites and Typha have shown to be adequate for tannery wastewater depuration, with Arundo donax proving resilient to high salinity wastewaters. The flexibility of implementation allows the CW to be adapted to different sites with different configurations, being suitable as main secondary or tertiary treatment stage.     

Reduction index of the upper M2 in marmosets

Marmosets have reduced second molars of which size and shape are varied in different species. Mesiodistal and buccolingual diameter of the first and second upper molars in 16 species were measured, and molar area (molar rectangle) and M2 reduction index were calculated by the equation,R=(M2 area/M1 area) × 100. This index ranged from 36.1 inSaguinus oedipus geoffroyi to 70.6 which was the largest found inCebuella pygmaea. Species ofSaguinus showed relatively wide variation as well as a consistantly smaller index. The index forCallithrix registered around 60 andLeontopithecus rosalia was positioned within this genus. There was no relationship between this index and body size of each form. The sizes of the first molar and second molar may not significantly correlate either with body size across species, becauseLeontopithecus rosalia had exceptionally large molars for its body size and contrarily genusSaguinus had relatively small molars. When the shape of the mandible was expressed as length/width ratio, the reduction index significantly correlate with this ratio in genusSaguinus andCallithrix, indicating that longer jaw in shape had relatively large M2. The reduction indices of two possible subspecies,S. oedipus geoffroyi andS. o. oedipus, were 36.1 and 47.3, respectively. This difference suggested that there was a difference in diet or function of jaw apparatus beyond subspecies level.