Escherichia coli O157 survival following the surface and sub-surface application of human pathogen contaminated organic waste to soil

Escherichia coli O157:H7 contaminated wastes such as animal manures and abattoir wastes, may be applied directly onto vegetation, the soil surface, or injected deep into the soil. Our aim was to determine the influence of method of waste application to land on E. coli O157:H7 survival. Bovine slurry and ovine stomach contents containing E. coli O157:H7 were applied to the surface vegetation or sub-surface injected at 25 cm below the soil surface. E. coli O157 survived but did not proliferate on grassland vegetation for up to 6 weeks and in the underlying soil for 8 weeks. Our results suggest that sub-surface injection of organic wastes into soil may reduce the risk of pathogen persistence in the environment.     

Heat Inactivation of E. coli During Manure Composting

Contamination of food and water by microorganisms from animal manure has become an important issue in public health. Escherichia coli O157:H7 is one of several emerging pathogens of concern. In this research, we studied how the self-heating, thermophilic phase of composting influenced laboratory-grown vs. bovine-derived E. coli O157:H7 mortality, specifically the relationship between temperature, time at temperature, and pathogen survival. Composting experiments were conducted in laboratory-scale bioreactors operated in three temperature ranges: 40°C to 50°C, 50°C to 60°C, and greater than 60°C. We measured the effects of temperature and composting time on E. coli O157:H7 mortality. Laboratory-grown E. coli O157:H7, inoculated into the initial compost material, were not detected after approximately 300 degree days of heating. In several experiments where compost temperatures did not rise above 50°C, an initial decline of E. coli O157:H7 with subsequent regrowth was observed. E. coli O157:H7 in compost materials from infected cattle were not detected after approximately 180 degree days of heating. Numbers of total coliform bacteria declined with temperature similarly to those of E. coli O157: H7. The results of this research provide information for reducing or eliminating E. coli O157:H7 in animal wastes.     

Glycopeptide derived from hen egg ovomucin has the ability to bind enterohemorrhagic Escherichia coli O157:H7

Ovomucin glycopeptide (OGP) was prepared by size exclusion chromatography after Pronase digestion of hen egg ovomucin, and the binding of OGP to foodborne pathogens (Bacillus cereus,Clostridium perfringens, Escherichia coli O157:H7, Listeria monocytogenes, Salmonella enteritidis, Salmonella typhimurium, and Staphylococcus aureus) was investigaed. Binding assays with biotinylated bacteria as probes in microtiter plates showed that OGP bound to only E. coli O157:H7 among these foodborne pathogens. Periodate treatment markedly reduced the binding ability, indicating that E. coli O157:H7 bound to carbohydrate moieties of OGP. Lectin blot analysis with Maackia amurensis (MAA) and Sambucus nigra (SNA), which are specific for oligosaccharides containing sialic acid, revealed their binding sites in OGP were similar to the E. coli O157:H7 binding sites that were probed with biotinylated E. coli O157:H7 after Western blotting of OGP. Sialydase treatment of OGP abolished its ability to bind E. coli O157:H7, demonstrating that sialic acid played an important role in the binding. These results suggest that OGP has E. coli O157:H7-specific binding sites that consist of sialic acid. On the basis of these properties, OGP has the potential to be an ingredient with a protective effect against E. coli O157:H7 infection and to be a novel probe for the detection of E. coli O157:H7 in the food hygiene field.     

Fate of Escherichia coli and Escherichia coli O157 in soils and drainage water following cattle slurry application at 3 sites in southern Scotland

Abstract. Slurry from farm animals may contaminate water supplies, rivers and bathing waters with faecal coliforms, such as Escherichia coli . Where animals harbour the O157 strain the hazard to human health is particularly high, but both the hazard level, and the low incidence and sporadic nature of the excretion of E. coli O157 make it difficult to study this strain under field conditions. The survival of total E. coli and of E. coli O157 were compared in the laboratory for two soils under controlled temperature and moisture. E. coli O157 die-off rate was the same as or quicker than for total E. coli . This result meant that field experiments studying the fate of total E. coli should give a satisfactory evaluation of the risk of water contamination by the O157 strain. In four field experiments at three sites, slurry containing total E. coli numbers of 2.2 × 10⁴ to 5.7 × 10⁵ colony forming units per mL (c.f.u. mL^–1) was applied to drained field plots. Field die-off was faster than expected from laboratory experiments, especially in one experiment where two weeks dry weather followed application. In all but this experiment, the first drain flow events after slurry application led to very high E. coli concentrations in the drains (10³ to 10⁴ c.f.u. mL^–1). E. coli O157 was present in the slurry used for two of the experiments (33 c.f.u. per 100 mL in each case). However the proportion of E.coli O157 was very low (about 1 in 10⁵) and it was not detected in the drainage water. After the first week E. coli drainage water numbers decreased rapidly but they were 1–10 c.f.u. mL^–1 for much of the sampling period after slurry application (1–3 months).     

Survival of <Emphasis Type="Italic">Escherichia coli</Emphasis> O157:H7 in various soil particles: importance of the attached bacterial phenotype

The risk of enteropathogens to food and water is highly dependent on their survival in soil environments. Here, the effects of soil type, particle size, the presence of natural organic matter (NOM) or Fe/Al (hydro)oxides on pathogenic Escherichia coli O157:H7 survival in sterilized soil particles were assessed through survival, attachment, metabolic activity, and qRT-PCR analyses. The abundance of inoculated E. coli O157:H7 in Brown soil (Alfisol) particles increased 0.6–1.4 log₁₀ CFU/g within 3 days (except for NOM-stripped clay), while that in Red soil (Ultisol) particles decreased rapidly in 8 days post-inoculation. Additionally, survival of bacteria was significantly enhanced when Fe/Al (hydro)oxides had been removed from Red soil particles. For the two soils, E. coli O157:H7 survived the longest in NOM-present clays and the bacterial adenosine 5′-triphosphate (ATP) levels were 0.7–2.0 times greater in clays than in sands and silts on day 8. Moreover, clays were more effective than silts and sands in binding cells and changing the expressions of acetate pathway-associated genes (pta and ackA). For silts and sands, E. coli O157:H7 decayed more rapidly in the presence of NOM and similar trends of bacterial ATP levels were observed between NOM-stripped and NOM-present soil particles, indicating that the primary role of NOM was not as a nutrient supply. These findings indicate that soil particles function mainly through attachment to change the metabolic pathway of E. coli O157:H7 and ultimately impact the survival of bacterial pathogens in soils.     

Inactivation of Escherichia coli O157:H7 and Salmonella Typhimurium in manure-amended soils studied in outdoor lysimeters

The inactivation of Escherichia coli O157:H7 (CCUG 44857) and Salmonella enterica serovar Typhimurium was investigated in two agricultural soils (sandy loam and silty clay) amended with poultry manure, cattle manure slurry or human urine. The study was performed in soil lysimeters placed outdoors, and was repeated over two consecutive years. The amendments, inoculated with E. coli O157:H7 and Salmonella Typhimurium, were mixed with soil on the top of the lysimeters. Samples were collected from the top 5-cm layer of each lysimeter at regular intervals, and the inactivation was monitored over 6 months, by the plate spread method and by enrichment. The inactivation was modelled by fitting a non-linear model to the data, and pathogen reduction times were calculated (90 and 99% reduction). The results showed that the inactivation of E. coli O157:H7 and Salmonella Typhimurium varied depending on the manure type used and its carbon content. The longest inactivation time occurred in samples amended with poultry manure, in which both E. coli O157:H7 and Salmonella Typhimurium were detected up to day 90 with the spread plate method. The most rapid inactivation for both pathogens occurred in soil amended with urine. However, low amounts of culturable E. coli O157:H7 and Salmonella Typhimurium were detected by enrichment throughout the study period (180 days), regardless of manure type.     

Fate of chlorate present in cattle wastes and its impact on Salmonella Typhimurium and Escherichia coli O157:H7

Chlorate salts are being developed as a feed additive to reduce the numbers of pathogens in feedlot cattle. A series of studies was conducted to determine whether chlorate, at concentrations expected to be excreted in urine of dosed cattle, would also reduce the populations of pathogens in cattle wastes (a mixture of urine and feces) and to determine the fate of chlorate in cattle wastes. Chlorate salts present in a urine-manure-soil mixture at 0, 17, 33, and 67 ppm had no significant effect on the rates of Escherichia coli O157:H7 or Salmonella Typhimurium inactivation from batch cultures. Chlorate was rapidly degraded when incubated at 20 and 30 degrees C with half-lives of 0.1 to 4 days. Chlorate degradation in batch cultures was slowest at 5 degrees C with half-lives of 2.9 to 30 days. The half-life of 100 ppm chlorate in an artificial lagoon system charged with slurry from a feedlot lagoon was 88 h. From an environmental standpoint, chlorate use in feedlot cattle would likely have minimal impacts because any chlorate that escaped degradation on the feedlot floor would be degraded in lagoon systems. Collectively, these results suggest that chlorate administered to cattle and excreted in wastes would have no significant secondary effects on pathogens present in mixed wastes on pen floors. Lack of chlorate efficacy was likely due to low chlorate concentrations in mixed wastes relative to chlorate levels shown to be active in live animals, and the rapid degradation of chlorate to chloride at temperatures of 20 degrees C and above.     

Translocation of bacteria from animal excrements to soil and associated habitats

The population dynamics of Salmonella enterica var. Typhimurium MAE 110 gfp, Escherichia coli O157:H7 gfp, and Pseudomonas fluorescens 32 gfp were investigated in their introduction to cattle excrements and subsequent entering the soil, plants of cress (Lepidium sativum L.), and migration through the gastroenteric tract of French snails (Helix pomatia L.). The survival of these bacteria in the excrements and soil was investigated at cyclically changing (day-night, 25–15 °C) and constant (18 °C) temperatures. The cyclically changing temperature adversely affected the survival of E. coli O157:H7 gfp, and P. fluorescens but did not influence S. enterica var. Typhimurium. All the bacteria and, especially, the analogues of enteropathogens showed high survival in the cattle and snail excrements, soil, and on the plants under the gradual decrease in their population. On the cress plants grown in a mixture of cattle excrements and soil, an increase in the number of the introduced bacteria was observed.     

Response of Escherichia coli O157:H7 survival to pH of cultivated soils

Purpose

The Escherichia coli (E. coli) O157:H7 survival dynamics in original and pH-modified agricultural soils were investigated to determinate how E. coli O157:H7 survival responded to the pH values of different soils, identify the relationships between E. coli O157:H7 survival time (t _d ) and soil properties, and assess the potential pathogen contamination after soil pH changed.

Materials and methods

The six soil samples were collected from different provinces of China, and 18 pH-modified soil samples were obtained from original soils by treating the original soils with direct electric current. The E. coli O157:H7 cells were inoculated into 24 soils and incubated at soil moisture of ?33 kPa and 25 °C. The soils were sampled for determining the numbers of E. coli O157:H7 at given time intervals over the incubation. The effects of soil pH change and other properties on the t _d values were analyzed.

Results and discussion

The t _d values in the test soils were between 7.1—24.7 days. Results indicate that soil pH, texture, and free Fe₂O₃ (Fe_d) were the most important factors impacting the t _d values in the test soils. Further, the response of E. coli O157:H7 survival to pH change varied with different soils. In the acidic soils (shorter t _d values), the t _d values decreased as the pH decreased and Fe_d increased, while in the neutral or alkaline soils (pH?≥?6.45, longer t _d values), the t _d values did not change significantly with pH.

Conclusions

The changes of amorphous and free sesquioxides induced by pH change might strengthen the response of E. coli O157:H7 survival to soil pH. Closer attention should be paid to E. coli O157:H7 long survival in soils and its potential environmental contamination risk.     

Plant extracts, spices, and essential oils inactivate Escherichia coli O157:H7 and reduce formation of potentially carcinogenic heterocyclic amines in cooked beef patties

Meats need to be heated to inactivate foodborne pathogens such as Escherichia coli O157:H7. High-temperature treatment used to prepare well-done meats increases the formation of carcinogenic heterocyclic amines (HCAs). We evaluated the ability of plant extracts, spices, and essential oils to simultaneously inactivate E. coli O157:H7 and suppress HCA formation in heated hamburger patties. Ground beef with added antimicrobials was inoculated with E. coli O157:H7 (10(7) CFU/g). Patties were cooked to reach 45 °C at the geometric center, flipped, and cooked for 5 min. Samples were then taken for microbiological and mass spectrometry analysis of HCAs. Some compounds were inhibitory only against E. coli or HCA formation, while some others inhibited both. Addition of 5% olive or apple skin extracts reduced E. coli O157:H7 populations to below the detection limit and by 1.6 log CFU/g, respectively. Similarly, 1% lemongrass oil reduced E. coli O157:H7 to below detection limits, while clove bud oil reduced the pathogen by 1.6 log CFU/g. The major heterocyclic amines 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) were concurrently reduced with the addition of olive extract by 79.5% and 84.3% and with apple extract by 76.1% and 82.1%, respectively. Similar results were observed with clove bud oil: MeIQx and PhIP were reduced by 35% and 52.1%, respectively. Addition of onion powder decreased formation of PhIP by 94.3%. These results suggest that edible natural plant compounds have the potential to prevent foodborne infections as well as carcinogenesis in humans consuming heat-processed meat products.     

中性电解水对鸡蛋表面的清洗灭菌效果

为寻求一种高效、安全、无污染的禽蛋清洗消毒剂,采用无隔膜电解装置电解稀盐酸溶液制备中性电解水（pH值6.0～7.5）考查不同有效氯浓度、处理时间和温度条件下中性电解水对鸡蛋人工接种鸡白痢沙门氏菌（Salmonella pullorum,鸡蛋表面的初始菌落数对数为6.19～6.26 log10 (cfu/g)）和大肠杆菌O157:H7（鸡蛋表面的初始菌落数对数为6.12～6.19 log10 (cfu/g)）的杀灭效果。结果表明,中性电解水对2种病菌均具有较强的杀灭效果,其杀菌效果随着有效氯浓度和处理时间的增加而增强,但温度对中性电解水的杀菌效果影响不显著。对菌悬液的杀菌试验表明：当中性电解水有效氯质量浓度为1.5 mg/L时,可以在20℃下3 min内完全杀灭鸡白痢沙门氏菌（初始含菌数的对数为 8.12 log10 (cfu/mL)）;质量浓度为2 mg/L时,可以100%杀灭大肠杆菌O157:H7（初始含菌数的对数为7.78 log10 (cfu/mL)）。当中性电解水清洗消毒被人工污染的鸡蛋表面时,有效氯质量浓度为12 mg/L、处理3 min可将鸡蛋表面的鸡白痢沙门氏菌全部杀灭,大肠杆菌O157:H7菌落数对数降低到1.0 log10 (cfu/g) 以下,且处理废液中没有残存菌,无二次污染问题。因此,中性电解水可以代替化学杀菌剂应用于鸡蛋清洗消毒。     

我国商品有机肥和有机废弃物中重金属、养分和盐分状况

【目的】 分析我国主要菜区商品有机肥和有机废弃物的重金属、养分和盐分状况,为蔬菜高效安全施肥和菜田土壤质量改善提供一定的理论依据。【方法】 针对全国主要菜区包括北方6省（市）和南方12省（市）典型商品有机肥和有机废弃物展开调查,取样时间是2014年1月上旬,共采取商品有机肥样品126个和有机废弃物样品255个,对3类商品有机肥和5类有机废弃物中重金属、养分和盐分状况进行了研究。【结果】 1）按照我国现有的NY525-2012有机肥料中重金属限量标准,商品鸡粪中Cd、Pb和Cr超标率分别为10.3%、17.2%和17.2%,商品猪粪中Cd和As超标率分别为20.0%和6.7%,其它商品有机肥中Cr、Cd、As和Hg超标率分别为13.4%、2.4%、2.4%和2.4%;鸡粪中Cd、As和Hg超标率分别为2.4%、7.1%和2.4%,猪粪中Cd、Pb、As和Hg超标率分别为1.5%、3.1%、15.4%和1.5%,牛粪中Cd和Hg超标率分别为1.7%和1.7%,羊粪中Cd超标率为12.5%,其它有机废弃物中Cr和As超标率分别为4.5%和13.6%。现在的畜禽粪便与传统有机肥已经大不相同,尤其是鸡粪和猪粪中Cu、Zn含量远高于上个世纪90年代初,分别增加1.5~16.2倍和1.3~4.7倍。2）商品有机肥中全氮含量、全钾含量和氮磷钾总含量较有机废弃物平均分别高出51.2%、32.0%和15.0%,有机废弃物中全磷含量、有机质含量、C/N比值和C/P比值较商品有机肥平均分别高出23.7%、41.5%、22.7%和15.2%。商品有机肥中,商品猪粪的全磷含量、有机质含量和C/N比值均相对较高,其它商品有机肥的全氮含量、全钾含量、氮磷钾总含量和C/P比值均相对较高;有机废弃物中,鸡粪和猪粪的全氮含量、全磷含量和氮磷钾总含量均相对较高,鸡粪、羊粪和其它有机废弃物的全钾含量相对较高,猪粪、牛粪和羊粪的有机质含量相对较高,牛粪的C/N比值相对较高,牛粪和羊粪的C/P比值相对较高。3）商品有机肥的EC值（平均23.5 mS/cm,n=126）较有机废弃物（平均7.7 mS/cm,n=255）高出2.1倍。商品有机肥中其它商品有机肥的EC值很高,其次是商品猪粪,商品鸡粪的EC值相对较低;有机废弃物中鸡粪和其它有机废弃物的EC值相对较高,其次是羊粪,猪粪和牛粪的EC值相对较低。【结论】 商品鸡粪以Cd、Pb和Cr超标为主,商品猪粪以Cd和As超标为主,其它商品有机肥以Cr超标为主;猪粪、鸡粪和其它有机废弃物以As超标为主,羊粪以Cd超标为主。商品有机肥中全氮含量、全钾含量和氮磷钾总含量均高于有机废弃物,有机废弃物中全磷含量、有机质含量、C/N比值和C/P比值均高于商品有机肥。商品有机肥的EC值远高于有机废弃物。     

植物–微生物联合修复镍污染土壤研究进展

土壤健康是粮食安全的保障,人类活动给土壤造成的污染亟待治理。镍是人体必需微量元素,但过量的镍具有较大的毒性。目前我国土壤中镍污染比较严峻,应尽快响应《土壤污染防治行动计划》来改善土壤中镍污染状况。本文综述了植物–微生物联合修复技术的基本原理,微生物在镍污染土壤中对植物生长状况、有效态镍含量以及植物吸收镍的影响,对寻找合适的植物和微生物修复镍污染土壤具有重要意义;最后,提出将有机酸运用到植物–微生物联合修复镍污染土壤中、建立PGPB库和寻找我国超富集植物等下一步研究的重点。     

Water properties in cream cheeses with variations in pH, fat, and salt content and correlation to microbial survival

Water mobility and distribution in cream cheeses with variations in fat (4, 15, and 26%), added salt (0, 0.625, and 1.25%), and pH (4.2, 4.7, and 5.2) were studied using (1)H NMR relaxometry. The cheese samples were inoculated with a mixture of Listeria innocua, Escherichia coli O157 and Staphylococcus aureus, and partial least-squares regression revealed that (1)H T(2) relaxation decay data were able to explain a large part of the variation in the survival of E. coli O157 (64-83%). However, the predictions of L. innocua and S. aureus survival were strongly dependent on the fat/water content of the samples. Consequently, the present results indicate that NMR relaxometry is a promising technique for predicting the survival of these bacteria; however, the characteristics of the sample matrix are substantial.     

S. typhimurium and E. coli O157:H7 retention and transport in agricultural soil during irrigation practices

During animal waste agricultural applications, the major concern is pathogen spreading, which may contaminate surface water and groundwater. Among the pathogenic microorganisms found in animal waste, Salmonella typhimurium and Escherichia coli O157:H7 are of particular concern. When transported in sub‐surface agricultural soil, S. typhimurium and E. coli O157:H7 are captured at the air–water–sediment interfaces through physical interactions. Because in situ colloids contribute to the formation of air–water–sediment, their mobilization affects the transport of S. typhimurium and E. coli O157:H7. The impact of irrigation rates on in situ colloid mobilization and S. typhimurium and E. coli O157:H7 transport was investigated in intact soil columns collected from an agricultural site in Gadsden County of Florida, USA. The columns were irrigated with sterilized nano‐pure deionized water to mobilize the colloids in the soil by stepwise increases in flow rate. For each flow rate, after colloids were mobilized and steady state was reached, S. typhimurium and E. coli O157:H7 were introduced. The cumulative amount of released in situ colloids increased linearly with the irrigation rates (R² = 0.986–0.996) and transport of the bacteria was enhanced after colloid mobilization. Interactions of the bacteria with the sediments and the air‐water interface were characterized: these played an important role in controlling S. typhimurium and E. coli O157:H7 retention in soil.     

香薷植物修复铜污染土壤的研究进展

土壤铜污染有自然来源和人为来源。铜污染土壤中有机质、Fe／Al氧化物对铜的专性吸附，是影响土壤中铜生物有效性的主要因素。近年来，我国原生植物修复材料如海州香薷、鸭跖草、酸模、紫花香薷在国内铜污染土壤的研究中得到广泛应用。其中．采用海州香薷开展铜污染土壤植物修复机理和修复技术的研究，已从实验室水培、盆栽试验的生长反应特性、耐及解铜毒的生理生化反应，进展到室外大田修复的示范工程及技术推广阶段。紫花香薷在重金属复合污染土壤上，也有修复前景。开展植物修复材料的产后处置研究，综合利用和深加工，增大植物修复材料价值，对加强植物修复工程的示范和推广步伐，有重要意义。     

Investigating the uptake and acquisition of potentially toxic elements in plants and health risks associated with the addition of fresh biowaste amendments to industrially contaminated soil

Soil contamination by potentially toxic elements (PTEs), due to rapid industrialization and urbanization, is a serious environmental concern that has been threatening both the sustainability of various agroecosystems and human health. Efforts to investigate the bioavailability, transfer, and accumulation of PTEs in the soil–plant system and their possible health consequences have almost exclusively focused in the past studies. However, there is limited evidence for increased human exposure to PTEs through dietary intake of food crop grown on contaminated soil influenced by fresh biowaste amendments (FBAs). Here, we show that FBAs addition to soil markedly (p  ≤ .01) intensified human exposure to PTEs through impacts on solubility, uptake, and bioaccumulation compared with the control. In general, the risk assessment performed indicated that the hazard index values for FBAs treatments were notably higher than that of control; however, these were shown to be less than the legal limit (<1). In addition, the lifetime risks of developing carcinogenicity from exposure to PTEs were far above the maximum regulatory limits (1.00E‐06), indicating that remarkable (p  ≤ .01) amount of PTEs was transferred to food with the addition of FBAs. Conclusively, these results suggest that the use of FBAs to contaminated soil aggravates health risks of PTEs through wheat consumption. Further studies, which incorporate the in vitro gastrointestinal bioaccessibility, should be conducted to heighten our understanding about PTEs exposure and the risks associated with FBAs addition to contaminated soil.     

不同物料蚓粪对土壤酸度和Cu、Pb化学形态的影响

以两种常见的有机废弃物牛粪和稻秆为原料,利用Eisenia foetida生产蚓粪,采用室内培养试验,研究了蚓粪在重金属污染的酸性土壤中对有机碳含量和形态、土壤酸度及Cu、Pb形态的影响。结果表明:在2.5%~10%的蚓粪用量下,土壤总有机碳含量增加了25%~83%,除牛粪蚓粪组的可溶性有机碳显著高于稻秆蚓粪外(P0.05),其余形态两种蚓粪间土壤有机碳含量无显著差异。蚓粪使土壤pH(H2O)值提升0.38~1.13个单位,同时交换性氢和铝的含量分别降低41%~77%和57%~94%,显著降低了土壤酸度,且较对照高出0.35~4倍;牛粪蚓粪仅在10%用量下降低土壤酸度的效果高出稻秆蚓粪22%。蚓粪使土壤中水溶-交换态Cu和Pb含量分别降低22%~70%和29%~70%,使有机结合态Cu和Pb含量分别提高19%~56%和10%~40%,表明蚓粪可以显著降低土壤中Cu和Pb的活性。蚓粪降低土壤Cu、Pb活性的效果分别较对照物料高出0.58~9.6倍和0.16~3.4倍。稻秆蚓粪降低土壤Cu、Pb活性的效果分别比牛粪蚓粪高出11%~61%和1%~32%。综上所述,蚓粪降低土壤酸度和Cu、Pb活性的效果优于对照,牛粪蚓粪降低土壤酸度的效果较好,稻秆蚓粪降低土壤Cu、Pb活性的效果更佳。在降低土壤酸度和Cu、Pb活性方面,蚓粪中的总有机碳、微生物量碳、胡敏酸碳和富里酸碳均具有重要作用,并且蚓粪中有机碳的作用效率高于对照中等量的有机碳。     

Contamination of soils and groundwater with new organic micropollutants: A review

The input of organic micro- and nanopollutants to the environment has grown in recent years. This vast class of substances is referred to as emerging micropollutants, and includes organic chemicals of industrial, agricultural, and municipal provenance. There are three main sources of emerging pollutants coming to the environment, i.e., (1) upon soil fertilization with sewage and sewage sludge; (2) soil irrigation with reclaimed wastewater and (3) due to filtration from municipal landfills of solid wastes. These pollutants contaminate soil, affect its inhabitants; they are also consumed by plants and penetrate to the groundwater. The pharmaceuticals most strongly affect the biota (microorganisms, earthworms, etc.). The response of microorganisms in the contaminated soil is controlled not only by the composition and the number of emerging pollutants but also by the geochemical environment.     

土壤苯污染引起的饮用地下水健康风险评价

由于污染场地所引起的生态环境、食品安全和人体健康问题,污染场地的环境风险评价受到广泛关注。以某水源地油和苯等有机污染调查为依据,利用多介质暴露评价模型(MMSOILS模型),以苯为评价的目标污染物,分析烯烃厂不同分区的土壤苯污染对A地区造成的饮用地下水健康风险。结果表明,研究区4个分区中,裂解装置区的苯污染物释放是A地区地下水污染的主要来源,产生的饮水健康风险值为9.82×10-5,占总风险值的98.8%;而其他三个分区的影响较小;不同分区苯污染对A地区产生的饮水健康总风险值为9.94×10-5,大于美国环境保护署人体健康风险建议值10-6,对人体健康已经产生影响;裂解装置区的土壤苯污染作为饮水健康风险的主要来源,当其浓度值降低至1.32mgkg-1时,才能使其造成的饮水健康风险降低为10-6。