Ecotoxicity of soils contaminated with industrial and domestic wastewater in western Shenyang, China

Soil samples were collected from 7 sites in the up-, mid- and down-reach along and nearby the wastewater irrigation channel, western Shenyang of China. The concentrations of selected pollutants (mineral oil, PAHs - polycycle aromatic hydrocarbons and Cd) were determined by UV spectrometer, HPLC and AAS (atomic adsorption spectrometer) spectrometer, respectively. Toxicity effects of soils were evaluated by seedling emergence test with root length of wheat as the end-point and by earthworms test with the mortality rate and inhibition rates of body weight as endpoints. Results showed accumulation of pollutants for most soils with concentration of 200.2 mg.kg-1 ～1600 mg.kg-1 for mineral oil, 0.33 mg.kg-1～1.81 mg.kg-1 for Cd and 900.16 mg.kg-1～ 2737.91 mg.kg-1 for PAHs. The inhibition rates of root elongation were from -20% up to 40 %, and mortality rates of earthworms ranged from 0%～40% from the exposure period of two weeks to eight weeks by sampling interval of two weeks, the inhibition rates of earthworm growth were from -19.36% to 34.53%, showing effects of stimulation at 2 weeks to an increasing effects of inhibition at 4, 6 and 8 weeks, respectively. Mortality rates correlated with the loss of body weight of earthworms.This study indicated the potential risk of pollutants of environmental low content in soil by the determination of selected chemicals combined with toxicity indexes.     

Ecotoxicity of soils contaminated with industrial and domestic wastewater in western shenyang,China

Soil samples were collected from 7 sites in the up-, mid-and down-reach along and nearby the wastewater irrigation channel, western Shenyang of China. The concentrations of selected pollutants (mineral oil, PAHs - polycycle aromatic hydrocarbons and Cd) were determined by UV spectrometer, HPLC and AAS (atomic adsorption spectrometer) spectrometer, respectively. Toxicity effects of soils were evaluated by seedling emergence test with root length of wheat as the end-point and by earthworms test with the mortality rate and inhibition rates of body weight as endpoints. Results showed accumulation of pollutants for most soils with concentration of 200.2 mg.kg⁻¹∼1600 mg.kg⁻¹ for mineral oil, 0.33 mg.kg⁻¹∼1.81 mg.kg⁻¹ for Cd and 900.16 mg.kg⁻¹ ∼ 2737.91 mg.kg⁻¹ for PAHs. The inhibition rates of root elongation were from −20% up to 40 %, and mortality rates of earthworms ranged from 0%∼40% from the exposure period of two weeks to eight weeks by sampling interval of two weeks, the inhibition rates of earthworm growth were from −19.36% to 34.53%, showing effects of stimulation at 2 weeks to an increasing effects of inhibition at 4, 6 and 8 weeks, respectively. Mortality rates correlated with the loss of body weight of earthworms.

This study indicated the potential risk of pollutants of environmental low content in soil by the determination of selected chemicals combined with toxicity indexes.

     

Ecotoxicity of soils contaminated with industrial and domestic wastewater in western shenyang,China

Soil samples were collected from 7 sites in the up-, mid-and down-reach along and nearby the wastewater irrigation channel, western Shenyang of China. The concentrations of selected pollutants (mineral oil, PAHs - polycycle aromatic hydrocarbons and Cd) were determined by UV spectrometer, HPLC and AAS (atomic adsorption spectrometer) spectrometer, respectively. Toxicity effects of soils were evaluated by seedling emergence test with root length of wheat as the end-point and by earthworms test with the mortality rate and inhibition rates of body weight as endpoints. Results showed accumulation of pollutants for most soils with concentration of 200.2 mg.kg^?1～1600 mg.kg^?1 for mineral oil, 0.33 mg.kg^?1～1.81 mg.kg^?1 for Cd and 900.16 mg.kg^?1 ～ 2737.91 mg.kg^?1 for PAHs. The inhibition rates of root elongation were from ?20% up to 40 %, and mortality rates of earthworms ranged from 0%～40% from the exposure period of two weeks to eight weeks by sampling interval of two weeks, the inhibition rates of earthworm growth were from ?19.36% to 34.53%, showing effects of stimulation at 2 weeks to an increasing effects of inhibition at 4, 6 and 8 weeks, respectively. Mortality rates correlated with the loss of body weight of earthworms.This study indicated the potential risk of pollutants of environmental low content in soil by the determination of selected chemicals combined with toxicity indexes.     

Biodegradation of pentachorophenol by tropical basidiomycetes in soils contaminated with industrial residues

Summary The ability of tropical Brazilian basidiomycetes to degrade pentachlorophenol (PCP) in soils from areas contaminated with organochlorine industrial residues was studied. Thirty-six basidiomycetes isolated from different tropical ecosystems were tested for tolerance to high PCP concentrations in soil. Peniophoracinereaand Psilocybecastanella, two strains of Trametes villosa,Agrocybe perfecta, Trichaptum bisogenumand Lentinus villosuswere able to colonize soil columns containing up to 4600 mg pentachlorophenol kg⁻¹soil. The first four species were inoculated into soil containing 1278 mg pentachlorophenol kg⁻¹ soil supplemented with gypsum and sugar cane bagasse. P. cinerea,P.castanella, T. villosaCCB176 and CCB213 and Agrocybe perfectareduced the PCP present in the contaminated soil by 78, 64, 58, 36 and 43%, respectively, after 90 days of incubation. All fungi mineralized [¹⁴C] pentachlorophenol, mainlyP. cinereaandT. villosawith the production of 7.11 and 8.15% ¹⁴CO₂, respectively, during 120 days of incubation. All fungi produced chloride ions during growth on soil containing PCP, indicating dehalogenation of the molecule. Conversion of PCP to pentachloroanisole was observed only after 90 days of incubation in soils inoculated with A. perfecta, P.cinereaand one of T. villosastrain. The present study shows the potential of Brazilian fungi for the biodegradation of toxic and persistent pollutants and it is the first to report fungal growth and PCP depletion in soils with high pentachlorophenol concentrations.     

不同类型污染土壤中赤子爱胜蚓对伴矿景天重金属吸收的影响初报

伴矿景天Sedum plumbizincicola是我国发现和报道的镉/锌(Cd/Zn)超积累植物,在土壤Cd污染修复方面已开展实际应用。由于超积累植物伴矿景天在不同类型土壤下的生长能力以及对镉锌的去除效果存在较大差异,因此需引入强化修复技术为植物修复提供辅助作用。作为大型土壤动物,蚯蚓对植物生长的促进作用已有较多研究,但其对伴矿景天生长和重金属吸取效率的影响则鲜有报道,为探究赤子爱胜蚓对不同类型土壤种植下的伴矿景天是否具有强化修复效应,以及不同类型土壤下的强化修复效应差异,设计以下盆栽试验。通过在常湿淋溶土(Perudic Luvisols)、水耕人为土(Stagnic Anthrosols)、湿润雏形土(Udic Cambisols)3种土壤上种植伴矿景天、引入赤子爱胜蚓Eisenia foetida,探究赤子爱胜蚓对伴矿景天生长及Cd/Zn吸收性的影响。选取Cd有效性较高、修复潜力较大的水耕人为土(Stagnic Anthrosols)进行第二季盆栽修复试验。第一季修复结果显示,在酸性的常湿淋溶土中,添加赤子爱胜蚓使伴矿景天地上部生物量较对照处理增加了106%,Cd和Zn吸收量分别提高了72.0%和36.0%,且蚯蚓结合伴矿景天的处理修复后土壤Cd有效性进一步降低,其余两种土壤仅添加蚯蚓无强化修复效应;第二季结果显示,同时添加秸秆和蚯蚓,可强化中性的水耕人为土上种植的伴矿景天生长,增大植物地上部生物量和Cd/Zn吸收量。结果表明,添加蚯蚓可增强伴矿景天在常湿淋溶土中的养分吸收,提高生物量,以此强化其修复效应。在水耕人为土中,外加秸秆可作为蚯蚓强化伴矿景天修复的配套技术。     

沈阳西部污灌渠沉积物中污染物积累与生态毒性研究

沉积物样品采自沈阳西部污水灌渠的上、中、下游．进行了污染物(重金属和矿物油)含量分析和生态毒性试验．结果表明,所有沉积物中均有污染物的积累,矿物油含量在400～12500mg·kg^-1,重金属Cd为1．6～27．2mg·kg^-1．沉积物对植物和蚯蚓都有明显的毒性效应．种子发芽根伸长抑制率为10％～60％．蚯蚓试验14d和28d死亡率分别为0%～70％和0%～85％．体重增长抑制率为-21．9%～17．7％和-18．6%～37．0%．研究表明,长期污灌导致河道沉积物中污染物积累和较强生态毒性．沉积物作为重要的污染源,其污染物迁移与释放对地下水和土壤具有潜在危害．     

农村混合污水灌溉对土壤养分含量、酶活性及微生物多样性的影响

通过土柱模拟试验,研究了农村混合污水灌溉(WG)对农田土壤pH、养分含量、酶活性及微生物多样性等土壤肥力指标的影响.结果表明:与清水灌溉(CK)相比,经过WG处理,土壤全钾、全磷、速效钾和碱解氮含量增加(4.54%~46.84%),而土壤pH、有机质、全氮和速效磷含量降低(2.02%~32.61%),且土壤pH极显著降低(P<0.01),土壤速效钾含量显著增加(P<0.05);土壤过氧化氢酶和土壤酸性磷酸酶活性低于CK处理(P<0.01),而土壤脲酶和土壤转化酶活性显著高于CK处理(P<0.05);土壤中细菌和真菌的Shannon指数、Ace指数、Chao指数、Coverage指数等均有所提高,但降低了Simpson指数,改变了细菌和真菌在属水平上各优势物种的相对丰度.内梅罗综合指数法评价结果表明,农村混合污水灌溉提高了供试土壤的综合肥力水平.本研究为示范区农村混合污水灌溉模式的田间试验提供了重要依据.     

A novel membrane bioreactor for detoxifying industrial wastewater: II. Biodegradation of 3-chloronitrobenzene in an industrially produced wastewater

A novel membrane bioreactor has been used for the treatment of an industrially produced wastewater arising in the manufacture of 3-chloronitrobenzene. This wastewater is not amenable to direct biological treatment without some form pretreatment or dilution, due to the inorganic composition (pH <1, salt concentration 4% w/w) of the wastewater. In the membrane bioreactor, the organic pollutants are first separated from the wastewater by selective membrane permeation, and then biodegraded in the biological growth compartment of the bioreactor. At a wastewater flow rate of 64 mL h(-1) (corresponding to a contact time of approximately 1.7 hours) over 99% of the 3-chloronitrobenzene and over 99% of the nitrobenzene in the wastewater were degraded. Degradation of 3-chloronitrobenzene was accompanied by evolution of chloride ions in a stoichiometric ratio. Both 3-chloronitrobenzene and nitrobenzene degradation were accompanied by the evolution of carbon dioxide; approximately 80% of the carbon entering the system was oxidized to CO(2) carbon. Analysis of mass transport across the membrane revealed that 3-chloronitrobenzene and nitrobenzene are transported more rapidly than phenol. This is explained in terms of a resistances-in-series model, which shows phenol transfer to be rate limited by the membrane diffusion step, whereas the chloronitrobenzene and nitrobenzene transfer are rate limited by the liquid film mass transfer. (c) 1993 Wiley & Sons, Inc.     

Biodegradation of hexachlorobenzene by basidiomycetes in soil contaminated with industrial residues

Hexachlorobenzene (HCB), one of twelve compounds classified as persistent organic pollutants (POP), is a byproduct of the manufacture of organochlorine compounds, and is a cause of environmental contamination in several parts of the world. Its degradation by Brazilian basidiomycetes was studied through chromatographic analyses and monitoring of the production of ¹⁴CO₂ from [¹⁴C]HCB in the soil. Nineteen strains of basidiomycetes were found to be capable of tolerating concentrations of 5000 to 50,000 mg of HCB kg^–1 of soil. In spite of the low rates of production of ¹⁴CO₂, Psilocybe cf. castanella CCB444 and Lentinus cf. zeyheri CCB274 were capable of removing nearly 3150 and 1400 mg of HCB kg^–1 from respective soil samples, during a 65-day study period.     

Effect of wastewater discharge on nutrient contamination of mangrove soils and plants

The ecological impact of sewage discharges to a mangrove wetland in Futian National Nature Reserve, the People's Republic of China was assessed by comparing the plant community, plant growth and nutrient status of soils and vegetation of a site treated with settled municipal wastewater (Site A) with those of a control adjacent site (Site B) which did not receive sewage. During the one year study, the total and available N and P, and organic carbon concentrations of mangrove soils in Site A did not significantly differ from those of Site B. In both sites, the soil organic C, total N, NH₄ ^}-N and total P content exhibited a descending trend from landward to seaward regions, with the lowest measurements obtained from the most foreshore location. Seasonal variation in N content of soil samples was more obvious than any difference between wastewater treated and the control sites. The soil N content was lower in spring and summer. This was attributed to the higher temperature in these seasons which facilitated degradation of organic matter and absorption of nitrogen by the plants for growth. No significant difference in plant community structure, plant growth (in terms of tree height and diameter) and biomass was found between Sites A and B. Leaf samples of the two dominant plant species, Kandelia candel and Aegiceras corniculatum collected from Site A had comparable content of organic carbon, N, P and K to those Site B. These preliminary results indicated that the discharge of a total volume of 2600 m³ municipal wastewater to an area of 1800 m² mangrove plants over the period of a year did not produce any apparent impact on growth of the plants. The soils and plant leaves of Site A were not contaminated, in terms of nutrient content, by the discharged sewage.     

Evaluation of industrial, hospital and domestic wastewater genotoxicity with the Salmonella fluctuation test and the SOS chromotest

An evaluation of the genotoxic potential of different wastewaters collected in the Rouen area was performed with the SOS chromotest (on Escherichia coli PQ37) and the Salmonella fluctuation test on Salmonella typhimurium strains TA98, TA100 and TA102 with or without metabolic activation. The samples were taken during two 1-week periods, one in January and one in April 2003. Six sites were selected for wastewater sampling in order to allow a comparative study between an area of mixed discharge (industrial, hospital and domestic) and an area of primarily domestic discharge.Out of a total of 71 daytime samples tested, 46 (65%) were positive in at least one assay: 22 samples out of 33 in January (67%), and 24 samples out of 38 in April (63%). The two genotoxicity tests have different sensitivities. Indeed, the Salmonella fluctuation test allowed the detection of 56% of the samples as genotoxic in January (18 out of 33), and 63% in April (24 out of 38) while the SOS chromotest allowed the detection of 18% of the samples as genotoxic, whatever the sampling period. The samples collected in domestic wastewater are at least as genotoxic as the samples collected in mixed wastewater. The possible source of the detected genotoxicity (industrial, hospital or domestic) is discussed.The results of this study show that the different types of wastewaters present a genotoxic risk. Additional studies should be undertaken in the analytical field in order to try to identify and quantify the compounds responsible for the genotoxicity. This difficult task will be necessary in order to identify the sources of toxicants and thus to take preventive and/or curative measures to limit the toxicity of the wastewater.     

蚯蚓对不同厚度复垦土壤中重金属生物有效性的影响

煤矸石充填复垦土壤理化状态和重金属水平能显著影响后续生态利用.为查明蚯蚓对矸石上不同厚度覆土中重金属(Cr、Cu、Pb和Zn)总量和有效态的影响,采用土柱实验,将蚯蚓接种到矸石上覆土,设置10、20、30、50、70 cm五种覆土厚度,通过测定不同厚度覆土pH、有机质(OM)、总氮(TN)、总磷(TP)、总钾(TK)和...     

沈阳市铁西区老工业搬迁区土壤多环芳烃的健康风险评价

采用美国能源部风险评估信息系统的暴露量化方法和美国环保局健康风险评估手册的风险表征方法,评估了沈阳市铁西区老工业搬迁区土壤中15种多环芳烃对户外劳作者的健康风险.沈阳市铁西区老工业搬迁区土壤中多环芳烃含量为290.9～8492.37μg·kg-1,搬迁区户外劳作者由于土壤中多环芳烃引起的非致癌危害指数范围为6.39×10-6 ～ 3.04×10-4,致癌风险范围为2.08×10-7 ～7.52×10-6,可判定对人体健康的危害较小.沈阳市铁西区老工业搬迁区致癌多环芳烃含量最高暴露点致癌风险值为7.52×10-6,未超过致癌风险水平上限(10-4),致癌风险尚在可接受范围内.多环芳烃中苯并(a)芘对综合致癌风险贡献最大,贡献率高达61.0％,应注意防范土壤中该污染物引起的健康危害.沈阳市铁西区老工业搬迁区户外劳作者受到的非致癌危害和致癌风险主要由经口摄入途径和皮肤接触途径贡献,两种途径对非致癌危害和致癌风险贡献率分别达到99％和100％,呼吸摄入引起的非致癌危害和致癌风险则相对较小.     

Simultaneous nitrification, denitrification, and phosphorus removal from nutrient-rich industrial wastewater using granular sludge

The biological removal of nitrogen and phosphorus from nutrient-rich abattoir wastewater using granular sludge has been investigated. A lab-scale sequencing batch reactor, seeded with granular sludge developed using synthetic wastewater, was operated for 13 months under alternating anaerobic and aerobic conditions. It is demonstrated that the granules could be sustained and indeed further developed with the use of abattoir wastewater. The organic, nitrogen, and phosphorus loading rates applied were 2.7 gCOD L(-1) day(-1), 0.43 gN L(-1) day(-1), and 0.06 gP L(-1) day(-1), respectively. The removal efficiency of soluble COD, soluble nitrogen and soluble phosphorus were 85%, 93%, and 89%, respectively. However, the high suspended solids in the effluent limited the overall removal efficiency to 68%, 86%, and 74% for total COD, TN, and TP, respectively. This good nutrient removal was achieved through the process known as simultaneous nitrification, denitrification, and phosphorus removal, likely facilitated by the presence of large anoxic zones in the center of the granules. The removal of nitrogen was likely via nitrite optimizing the use of the limited COD available in the wastewater. Accumulibacter spp. were found to be responsible for most of the denitrification, further reducing the COD requirement for nitrogen and phosphorus removal. Mineral precipitation was evaluated and was not found to significantly contribute to the overall nutrient removal. It is also shown that the minimum HRT in a granular sludge system is not governed by the sludge settleability, as is the case with floccular sludge systems, but likely by the limitations associated with the transfer of substrates in granules.     

Effects of bleaching wastewater irrigation on soil quality of constructed reed wetlands

Constructed reed wetland microcosms (CRWs) in a lab of east China have been irrigated with bleaching wastewater per month for a reed growth season. The soil physicochemical properties, enzyme activities (i.e. urease, invertase, polyphenol oxidase, alkaline phosphatase and cellulase) and soil microbial diversity were assayed before and after the exposure experiment. Compared to the river water irrigated controls (CKs), bleaching wastewater application has no marked influence on soil pH, but significantly increased soil Na⁺, total halogen and absorbable organic halogen (AOX) contents, which induced the increasing of soil electrical conductivity. Furthermore, soil enzyme activities displayed significant variation (except for polyphenol oxidase). Bleaching wastewater irrigation decreased Sorenson’s pairwise similarity coefficient (C_s), which indicated the changes of the structure of bacterial and fungal communities. However, only the diversity of bacterial community was inhibited and has no effect on the diversity of fungal community, as evidenced by the calculated Shannon–Wiener index (H).     

Ecology of cycloheximide-resistant fungi in field soils receiving raw city wastewater or normal irrigation water

The effect of raw city wastewater irrigation on biodiversity and population densities of a cycloheximide-resistant (CH) fungal community was studied in 13 field soils receiving either raw city wastewater or normal irrigation, and in raw city wastewater in the Nablus area, using the hair baiting technique (HBT) and a surface soil dilution plating (SSDP) technique. Three of these fields [one had been receiving raw city wastewater for more than ten years and was designated a heavily polluted field, and the other 2 were cultivated for the first time and were either irrigated with raw city wastewater (newly polluted field) or normal irrigation water (nonpolluted)], were sampled 4–7 times over a 9-month period. The other ten fields, which had been under raw city wastewater irrigation for more than 10 years, were sampled only once. Fifty-seven CH-resistant species belonging to 18 genera were recovered, of which 49 species were recovered from soil habitats and 28 species from raw city wastewater. The HBT had shown to be more efficient in the isolation of pathogenic and potentially pathogenic fungi including dermatophytes. A higher percentage of this group of fungi was recovered from the three main field soils studied using HBT (70% of all isolates), than the SSDP (35.5%); no dermatophytes were recovered by the SSDP method. Two dermatophytes (Microsporum gypseum, and Trichophyton ajelloi), and five more fungi (Arthroderma cuniculi, A. curreyi, Chrysosporium keratinophilum, C. tropicum, and C. pannorum), were recovered from these habitats. Wastewater irrigation seemed to have affected the fungal population densities, with the highest population densities being found in the heavily polluted field soil, while lower population densities were found in the nonpolluted field soil. Increases in organic matter were also observed as a result of sewage effluent irrigation. However, basic similarities in the biodiversity of CH-resistant fungal communities existed in nonpolluted and polluted field soils, and raw city wastewater. Comparable numbers of fungal species were recovered from the three main field soils. The species most commonly found in those habitats included: Alternaria alternata, Aspergillus candidus, Geotrichum candidum, and Paecilomyces lilacinus. Field soils receiving either raw city wastewater or normal irrigation water, were found to be rich in pathogenic and potentially pathogenic CH-resistant fungi, including dermatophytes, with raw city wastewater yielding the highest percentage (81%), followed by the newly wastewater irrigated field (77.7%), the nonpolluted field (67%), and the heavily polluted field (63.4%). Hygienic measures should therefore be taken to control the spread of these fungi in the environment of human communities, and to avoid mycotic infections among farmers. This revised version was published online in August 2006 with corrections to the Cover Date.     

Water-holding capacity of ground covers and soils in alpine and sub-alpine shrubs in western Sichuan, China

The water-holding functions of soils and ground covers in terms of moss and litters in the three major shrubs at different altitude gradients were studied using field investigation. The water-holding functions were measured and expressed with Biomass (t/hm²) of moss and litters, along with their maximal water holding capacity (MWHC, t/hm²) and maximal water holding rate (MWHR, %). The physical characteristics of the soils included bulk density, MWHC, capillary water holding capacity (CWHC), and least water holding capacity (LWHC). The result showed that Rhododendron przewalskii shrub exhibited the highest water-holding capacity among the three types. The average MWHC of the moss, litters, and at a depth of 0–40cm in R. przewalskii at different elevation gradients was 46.73,139.98 t/hm², and 2216.92 t/hm², respectively, whereas the average MWHC of the moss, litters, and soils in Quercus aquifolioides was 1.64, 72.08 t/hm² and 2114.88 t/hm², respectively. There was no moss in Quercus cocciferoides, and the average MWHC of litters and soils at a depth of 0–40 cm at different elevation gradients was 84.55 t/hm² and 2062.83 t/hm², respectively. The biomass and MWHC of the moss layer in R. przewalskii shrub significantly decreased with increasing elevation, whereas the reverse occurred in Q. aquifolioides before the maximum was reached at 3400 m, and then the SCM and MWHC decreased. MWHR of the moss layer in R. przewalskii was higher than that in Q. aquifolioides. The biomass and MWHC of the litters in R. przewalskii and Q. aquifolioides decreased with increasing elevation, whereas the reverse occurred in Q. cocciferoide. Regardless of shrub types, soil bulk density increased significantly with increasing soil depth, whereas MWHC decreased significantly with increasing soil depth. Significant decrease in CWHC and LWHC were found only in certain shrub communities. The MWHC with respect to the 0–40cm soil depth significantly decreased with increasing elevation only in R. przewalskii shrub, whereas there was no significant difference in MWHCs among the different elevation gradients for the other two types.     

Water-holding capacity of ground covers and soils in alpine and sub-alpine shrubs in western Sichuan, China

The water-holding functions of soils and ground covers in terms of moss and litters in the three major shrubs at different altitude gradients were studied using field investigation. The water-holding functions were measured and expressed with Biomass (t/hm²) of moss and litters, along with their maximal water holding capacity (MWHC, t/hm²) and maximal water holding rate (MWHR, %). The physical characteristics of the soils included bulk density, MWHC, capillary water holding capacity (CWHC), and least water holding capacity (LWHC). The result showed that Rhododendron przewalskii shrub exhibited the highest water-holding capacity among the three types. The average MWHC of the moss, litters, and at a depth of 0–40cm in R. przewalskii at different elevation gradients was 46.73,139.98 t/hm², and 2216.92 t/hm², respectively, whereas the average MWHC of the moss, litters, and soils in Quercus aquifolioides was 1.64, 72.08 t/hm² and 2114.88 t/hm², respectively. There was no moss in Quercus cocciferoides, and the average MWHC of litters and soils at a depth of 0–40 cm at different elevation gradients was 84.55 t/hm² and 2062.83 t/hm², respectively. The biomass and MWHC of the moss layer in R. przewalskii shrub significantly decreased with increasing elevation, whereas the reverse occurred in Q. aquifolioides before the maximum was reached at 3400 m, and then the SCM and MWHC decreased. MWHR of the moss layer in R. przewalskii was higher than that in Q. aquifolioides. The biomass and MWHC of the litters in R. przewalskii and Q. aquifolioides decreased with increasing elevation, whereas the reverse occurred in Q. cocciferoide. Regardless of shrub types, soil bulk density increased significantly with increasing soil depth, whereas MWHC decreased significantly with increasing soil depth. Significant decrease in CWHC and LWHC were found only in certain shrub communities. The MWHC with respect to the 0–40cm soil depth significantly decreased with increasing elevation only in R. przewalskii shrub, whereas there was no significant difference in MWHCs among the different elevation gradients for the other two types.     

Lead fractionation and bioaccessibility in contaminated soils with variable chemical properties

Abstract

The hazard imposed by trace elements within soils is dependent on soil properties and the relative distribution of metal species. Hence, a greenhouse column study was conducted to investigate the geochemical speciation and bioaccessibility of lead (Pb) as a function of soil properties. Four different soil types (Immokalee, Belle Glade, Tobosa and Millhopper series) varying in physico-chemical properties were selected and amended with Pb as Pb(NO₃) at 400, 800, and 1,200 mg kg^?1. A sequential extraction was employed to define the reactive metal pool, which was correlated with Pb bio-accessibility as determined by the physiologically based extraction test. Results show that Pb was mainly distributed in soluble+exchangeable phase in Immokallee (82%) and Millhopper (45%) series, and carbonate and Fe+Mn oxide fractions in Belle Glade (14–74%) and Tobosa (31–64%) series at time zero. With soil aging, Pb underwent chemical transformations in the soils and the majority of added Pb was associated with Fe+Mn oxide fraction (64–81%). Also, Pb bioaccessibility varied widely as a function of soil type and soil aging. Gastric phase (IVG-S) extracted 34–81% and 29–75% and the absorbed intestinal phase (IVG-AI) extracted 12–79% and 12–45% of amended Pb in all the soils at time zero and 6 months, respectively. Among soil types, Tobosa and Belle Glade showed reduced bioaccessibility relative to Immokalee and Millhopper. Statistical analysis revealed that the IVG-S Pb decreases as soil organic matter and cation exchange capacity (CEC) increases and total P decreases. While the Mehlich extractable P and Ca+Mg, total Fe+Al and organic matter predicted the Pb in an intestinal system.     

Effect of domestic sewage wastewater irrigation on nutritional and nutraceutical perspectives of Eleusine coracana and Zea mays (raw and processed) from selected semi-urban and rural areas of Coimbatore,Tamil Nadu

Abstract

Rapid growth of the urban population, particularly in developing countries, places an enormous pressure on water. Sewage farming is common in all urban areas in India. This study is an attempt to evaluate the effect of diluted sewage wastewater irrigation on cultivation of Eleusine coracana and Zea mays from selected semi-urban and rural areas of Coimbatore, Tamil Nadu. For this, parameters analyzed were water/soil quality, crop quality, and mineral analysis including heavy metal composition and in vitro antioxidant potential. From the results, the physicochemical parameters of both rural and semi-urban wastewater samples are within the permissible limits according to the WHO. In mineral analysis, the heavy metals such as Pb, Fe, and Zn are high in all samples and Ni, Cr, and Cu are within the permissible limits in rural samples but slightly high in semi-urban samples. The proximate composition provides general overview of the nutritional value of a food. E. coracana and Z. mays samples collected from rural area show adequate mineral profile required for growth and nutrition. Both the samples show significant antioxidant values significant at p < 0.05. The results demonstrated that the diluted sewage wastewater has physicochemical properties for safe irrigation. Micronutrient and heavy metal contents in the plant samples were not extremely high and were within the range of FAO/WHO standards.