Human uptake of persistent chemicals from contaminated soil: PCDD/Fs and PCBs

Trace amounts of polychlorinated dibenzo-p-dioxins/furans (PCDD/Fs) and polychlorinated biphenyls (PCBs) are ubiquitous in the environment. Because of industrial activity, other human activities, and accidents, higher concentrations of these chemicals may be present in soil, in residential and recreational areas. Human uptake of these chemicals from such soils has been assumed by regulators, and people contacting such soils may be concerned about potential adverse health effects. Accordingly, clean up levels have been set by state and federal agencies. Whether and to what extent humans actually take up these chemicals from soil is the focus of this review. Since humans are also exposed to PCDD/Fs and PCBs in food and air, their concentrations in these media are presented. We find that their presence in soils is unlikely to increase human body burdens.     

Ecology and Population Biology of Aflatoxigenic Fungi in Soil

Soil serves as a reservoir for Aspergillus flavus and A. parasiticus, fungi that produce carcinogenic aflatoxins in agricultural commodities. Populations in soil are genetically diverse and individual genotypes show a clustered distribution pattern within fields. Surveys over large geographic regions suggest that climate and crop composition influence species density and aflatoxin‐producing potential. Aflatoxigenic fungi reside in soil as conidia, sclerotia and hyphae, which act as primary inocula for directly infecting peanuts or for infecting aerial crops (corn, cottonseed, tree nuts) through wind and insect dispersal. Infected crops periodically replenish soil populations during drought years.     

利用石墨炉原子吸收分光光度法测定土壤中铬的含量

目的：建立土壤中铬含量的石墨炉原子吸收分光光度测定法.方法：试样经酸消解后,注入原子吸收分光光度计石墨炉中,电热原子化后吸收357.9 nm共振线,在一定浓度范围其吸收值与铬含量成正比,与标准系列比较定量.结果：线性范围为0～20ng/mL,回收率为98％～102％,检出限为0.26ng/mL,相对标准偏差RSD为4.6％.结论：该试验方法具有操作简单,技术条件便于掌握,消解彻底,结果重复性好等优点,可用作土壤中铬含量的测定.     

土壤因子对新疆阿魏挥发油成分的初步研究

目的：研究中药新疆阿魏挥发油成分与其土壤因子的关系。方法：在4个不同样地采集阿魏树脂和土壤样品,通过资料查阅和实地调查,考察产地的生态环境。用气相色谱和GC-MS联用方法分析了药材中的化学成分。结果：4个样地挥发油含量均大于10%,符合国家药典规定。挥发油中成分和相对含量也近乎一致。结论：新疆伊宁县白石墩是新疆阿魏的道地产区。其生长地土壤中有机质（17.4-22.6g/kg）、氮（30.3-46.7mg/kg）、磷（5.5-8.5mg/kg）、钾（182.773mg/kg）养分含量较少,pH值（7.91-8.16）偏碱性,总盐含量（1.0-2.6g/kg）相对较高。     

Effects of long-term fertilization on the diversity of bacterial mercuric reductase gene in a Chinese upland soil

Soil mercury (Hg) pollution has received considerable attention due to its neurotoxin effects and its potential risk to food safety. The microbial transformation of Hg plays a key role in reducing Hg toxicity by the mercuric reductase (MerA) conferred by genes arranged in the mer operon. This study investigated the effects of long‐term fertilization on the diversity of bacterial mercuric reductase gene (merA), which specify the reduction of ionic Hg²⁺ to the volatile elemental form Hg⁰, in an agricultural soil with relatively high Hg content. The soil samples were collected from different treatments, including control without fertilizer (CK), fertilizer nitrogen (N), combined fertilizers (NPK) of N, phosphorus (P) and potassium (K), and NPK plus organic manure (NPK + OM). The merA gene diversity patterns were analyzed based on the merA clone libraries and sequencing measurements. Results showed that the merA gene diversity was influenced by soil variables depending on the fertilization practices. In particular, NH₄⁺ and NO₃^– contents had strong effect on the merA gene diversity pattern both in the N and NPK treatments, whereas the merA gene diversity pattern in NPK + OM treatment was distinctly influenced by the contents of organic matter, available P and K. These results suggested that long‐term fertilization had significant influences on merA gene diversity, which could be helpful to understand the Hg reduction process and potentially serve microbial remediation of Hg contaminated soil. (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Comparative study on production,purification of penicillin by Penicillium chrysogenum isolated from soil and citrus samples

Objective

To explore various unexplored locations where Penicillium spp. would be available and study the production of penicillin from the isolated Penicillium spp. in different media with altered carbohydrate source.

Methods

The collected soil samples were screened for the isolation of Penicillium chrysogenum (P. chrysogenum) by soil dilution plate. The isolated Penicillium species were further grown in different production media with changes in the carbohydrate source. The extracted penicillin from various isolates was analyzed by HPLC for the efficacy of the product. Further the products were screened with various bacterial species including methicillin resistant Staphylococcus aureus (MRSA). And the work was extended to find the possible action on MRSA, along with characterization using other pathogens.

Results

From the various soil and citrus samples used for analysis, only the soil sample from Government General Hospital of Bangalore, India, and Sanjay Gandhi Hospital, Bangalore, India, showed some potential growth of the desired fungi P. chrysogenum. Different production media showed varied range of growth of Penicillium. Optimum production of penicillin was obtained in maltose which proved maximum zone of inhibition during assay. Characterization of penicillin on pathogens, like wild Escherichia coli strain, Klebsiella spp., and MRSA, gave quite interesting results such as no activity on the later strain as it is resistant. HPLC data provided the analytical and confirmation details of the penicillin produced. Accordingly, the penicillin produced from the soil sample of Government General Hospital had the high milli absorbance unit of 441.5 mAu compared with that of the penicillin produced from Sanjay Gandhi Hospital sample, 85.52 mAu. Therefore, there was a considerable change in quantity of the penicillin produced from both the samples.

Conclusions

The Penicillium spp. could be possibly rich in hospital contaminants and its environments. This research focuses on various unexplored sources of medical ailments, and also shows that the growth of penicillin is high in maltose rich media that could possibly enhance the growth.     

Moderate and high endemicity of schistosomiasis is a predictor of the endemicity of soil-transmitted helminthiasis: a systematic review

The authors conducted a systematic literature review with the following aims: to investigate how frequently soil-transmitted helminthiasis (STH) infections are endemic where schistosomiasis is present; and to assess the correlation between the risk level of schistosomiasis and that of STH. Among 155 sites on which data were collected and analyzed, schistosomiasis was present in 130, all of which were also co-endemic for STH, whereas 25 sites were endemic only for STH. Ninety percent (117 out of 130) of the areas eligible for preventive chemotherapy (PC) against schistosomiasis are also eligible for PC against STH. This fact provides managers of control programmes with the operationally important indication that use of available information on endemicity of schistosomiasis is a valid tool to predict the presence of STH in the same geographical area and to estimate the need of PC for STH. The implementation of this tool is expected to save financial and human resources and help accelerate the scale-up of PC throughout the world.     

Bromoxynil residues and dissipation rates in maize crops and soil

A residue analytical method for the determination of bromoxynil in soil and maize was developed using high performance liquid chromatography with diode-array detector (HPLC-DAD) and high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS). The residual level and dissipation rate of bromoxynil in the soil and maize crops were determined using the established method. The mean half-life of bromoxynil in soil was 4.12 days with a dissipation rate of 91.25% over 21 days. The mean half-life in maize seedling was 1.14 days with a dissipation rate of 97.79% over 7 days. The final residues of bromoxynil were undetectable in maize grain, maize stem and soil at the harvest time, suggesting that residual levels of bromoxynil in maize plants are safe to humans and animals as well as to the environment.     

Residues and dissipation dynamics of molluscicide metaldehyde in cabbage and soil

The dissipation of metaldehyde on cabbage and in soil was studied and half-life (DT₅₀) was estimated in a field study carried out at three different locations. Metaldehyde was sprayed on cabbage at 937.5 and 1406.25 g a.i.ha⁻¹ for residue study and 1875 g a.i.ha⁻¹ for dissipation study in cabbage and soil. Samples of cabbage and soil for dissipation experiment were collected at 0, 1, 2, 3, 5, 7, 14 and 21 days after treatment. For residue studies, cabbage and soil samples were sampled at 5, 7 and 10 days after treatment. Quantification of residues was done by LC-MS/MS. The DT₅₀ of metaldehyde in cabbage and soil were 0.48-1.61 days and 0.75-1.02 days, respectively, when applied at 2 times of the recommended high dosage. Residues of metaldehyde in cabbage were all below the maximum residue levels of 1.0 mg kg⁻¹ at both recommended high dosage and 1.5 times the recommended high dosage.     

Mercury contamination in the riparian zones along the East Fork Poplar Creek at Oak Ridge

Oak Ridge (Tennessee, USA) has a history of mercury (Hg) contamination in its aquatic and soil environment associated with past nuclear-weapons production activities at its Department of Energy (DOE) sites. Three different riparian zones along the Lower East Fork Poplar Creek were investigated in order to study Hg distribution and transformation in surface soils. The surface soil samples collected from these areas showed higher total Hg on an average (129.08 mg/kg) and higher total organic carbon (5.50%) in the upstream soils compared to the other two downstream locations that contained only 31.78 and 19.98 mg/kg total Hg and 2.88% and 1.65% of TOC on average, respectively. Further, methyl Hg concentrations were also comparatively higher in case of the upstream soils (30.10 μg/kg) than that of the downstream sites (5.69 and 4.05 μg/kg). The study showed a plume-like dispersion of Hg in the terrestrial environment along the creek, with decreasing Hg concentrations with distance from the Hg source zone. Also, the transformation of Hg in the soils was found to have been influenced by the soil TOC contents.