Bacterial Diversity and Community Structure in High Arsenic Aquifers in Hetao Plain of Inner Mongolia,China

The bacterial diversity and community structure of high arsenic (As) aquifers was investigated using an integrated approach adopting both geochemistry and molecular biology (polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene clone library analyses). Nine borehole sediments and one groundwater sample from the living place of a villager (affected by arseniasis) and 12 sediments from a control borehole in Hetao Plain were investigated. The As concentrations ranged from 33.6 to 77.6 mg/kg in high As borehole sediments and 1.5 to 5.8 mg/kg in those samples from the control. The As concentration in the groundwater was 744.8 μg/L. Ratios between As(III) and total As in high As sediments increased gradually with depth and ranged from 0.02 to 0.34. Similarly, the Fe(II)/total Fe presented the same increasing trend with depth. The correlation between TOC contents and total As was positive. High concentrations of total As, S, Fe and TOC were found in clay and low in sand samples. Phylogenetic analysis showed significantly different bacterial communities among high As sediments, control sediments and the high As groundwater. Both DGGE and 16S rRNA gene clone library results showed that the high As sediments were dominated by Thiobacillus, Pseudomonas, Brevundimonas, and Hydrogenophaga, with Thiobacillus being distinctly dominant (63.5%). Whereas the low As sediments were dominated by some other genera including Psychrobacter, Massilia and Desulfotalea. The bacterial populations in the high As groundwater mainly included Pseudomonas, Acinetobacter and Aquabacterium. These results improve our understanding of the bacterial diversity in high As aquifers in Hetao Plain and suggest how specific bacterial populations help mediate the mobilization of As into high As groundwaters.     

Assessments of quaternary ammonium compounds (QAC) for in-water treatment of mussel fouling in vessel internals and sea chests using an experimental seawater pipework system

The primary in-water emergency treatment method for mussel fouling of internal seawater systems of Royal Australian Navy vessels is to flush with a 1% detergent solution containing quaternary ammonium compounds (QAC). Parameters for application of this treatment are based on previous research; however, much of the research has been conducted at small-scales under controlled laboratory conditions. This study examined the efficacy of QAC solutions for treating mussel biofouling under realistic field conditions using experimental seawater piping systems. The efficacy of QAC solutions was highly dependent on the size of mussels present. Chemical treatments comprising 1, 2 and 5% v v^–1 QAC solution were effective at killing large (50–92 mm) mussels in the pipework and sea chest of the system following 24 h exposure. In contrast, small mussels (10–30 mm) appeared resilient to the majority of treatment regimes. Differences in water temperature, DO and pH during dosing had no discernible impact on treatment efficacy.     

Metal(loid)-Contaminated Soils as a Source of Culturable Heterotrophic Aerobic Bacteria for Remediation Applications

Heavy metal–contaminated soils are a serious environmental problem. Herein, the culturable heterotrophic bacterial community present on two metal(loid)-contaminated sites in the Northern Portugal was investigated. The bacterial counts ranged from 5.96 to 7.69 and 7.04 to 7.51 (log CFU g^?1 soil) in Sites 1 and 3, respectively. The bacterial population was predominantly composed of Firmicutes, Proteobacteria, and Actinobacteria on both sites. The most represented genera in Site 1 were Bacillus (41%) and Pseudomonas (27%), whereas Arthrobacter (21%) and Pseudomonas (13%) were the most represented genera in Site 3. Several bacterial isolates showed tolerance to high concentrations of metal(loid)s, suggesting that both contaminated sites are a valuable source of metal(loid)-tolerant bacteria, which may be further used in bioremediation and/or phytoremediation processes.     

Cooperation of Three Denitrifying Bacteria in Nitrate Removal of Acidic Nitrate- and Uranium-Contaminated Groundwater

In uranium-contaminated aquifers co-contaminated with nitrate, denitrifiers play a critical role in bioremediation. Six strains of denitrifying bacteria belonging to Rhizobium, Pseudomonas, and Castellaniella were isolated from the Oak Ridge Integrated Field Research Challenge Site (OR-IFRC), where biostimulation of acidic (pH 3.5–6.5), nitrate-contaminated (up to 140 mM) groundwater occurred. Three isolates were characterized in regards to nitrite tolerance, denitrification kinetic parameters, and growth on different denitrification intermediates. Kinetic and growth experiments showed that Pseudomonas str. GN33#1 reduced NO^? ₃ most rapidly (V_max = 15.8 μmol e^?·min^?1·mg protein^?1) and had the fastest generation time (gt) on NO^? ₃ (2.6 h). Castellaniella str. 4.5A2 was the most low pH and NO^? ₂ tolerant and grew rapidly on NO^? ₂ (gt = 4.0 h). Rhizobium str. GN32#2 was also tolerant of low pH values and reduced NO^? ₂ rapidly (V_max = 10.6 μmol e^?·min^?1·mg protein^?1) but was far less NO^? ₂ tolerant than Castellaniella str. 4.5A2. Growth of and denitrification by these three strains incubated together and individually were measured in OR-IFRC groundwater at pHs 5 and 7 to determine whether they cooperate or compete during denitrification. Mixed assemblages reduced NO^? ₃ more rapidly and more completely than any individual isolate over the course of the experiment. The results described in this article demonstrate 1) that this synthetic assemblage comprised of three physiologically distinct denitrifying bacterial isolates cooperate to achieve more complete levels of denitrification and 2) the importance of pH- and nitrite-tolerant bacteria such as Castellaniella str. 4.5A2 in minimizing NO^? ₂ accumulation in high-NO^? ₃ groundwater during bioremediation. Supplemental materials are available for this article. Go to the publisher's online edition of Geomicrobiology Journal to view the free supplemental files.     

Bacterial Communities Predominant in the Degradation of 13C-Labeled Pyrene in Red Soil

The bacterial community composition using a consortium (CON) with or without methyl-β-cyclodextrin (MCD), used to bioremediate the pyrene-contaminated soil was evaluated through stable-isotope probing (SIP). Microcosms were artificially contaminated with ¹³C pyrene at 15 ppm, and bacterial community composition was determined over a 14-day period. After 14 days, only 29.1% of pyrene was degraded in control, while 90.6% of pyrene was degraded by the bacterial community with MCD, showing the best bioremediation rate of all treatments. After 14 days, PAH degraders became dominated by Proteobacteria. Sphingomonas and Pseudomonas were the predominant genera in all treatments, and Pseudomonas was the main degrader from the bacterial community. The bacterial community was little affected by MCD. The results indicated that the combination of the bacterial community with MCD can be used to bioremediate PAHs polluted soil.     

Antimicrobial and antifouling efficacy of urinary catheters impregnated with a combination of macrolide and fluoroquinolone antibiotics against Pseudomonas aeruginosa

The incidence of catheter associated urinary tract infections (CAUTIs) is increasing worldwide. This study was designed to modify a biomaterial by impregnating a silicone urinary catheter with combination of a macrolide, azithromycin (AZM) and a fluoroquinolone, ciprofloxacin (CIP). Drug release profiles showed slow yet continuous release of antibiotics from catheters for one month. In vitro efficacy testing showed that group B catheters [3% (w v^?1) CIP + 6% (w v^?1) AZM] outperformed group A catheters [2% (w v^?1) CIP + 5% (w v^?1) AZM] by (1) showing larger zones of inhibition (>31 mm) compared to group A (<28 mm) for up to 30 days against Pseudomonas aeruginosa PAO1; (2) killing adhered bacteria in 24 h compared to 24–48 h in group A; (3) showing longer antimicrobial durability for four weeks; and (4) exhibiting a stable real-time shelf life of one year, suggesting that these catheters can be explored in clinical settings, especially in long-term CAUTI.     

Antibacterial and antilarval activity of deep-sea bacteria from sediments of the West Pacific Ocean

Abstract

Deep-sea microorganisms are a new source of bioactive compounds. In this study, crude ethyl acetate extracts of 176 strains of deep-sea bacteria, isolated from sediments of the West Pacific Ocean, were screened for their antibacterial activity against four test bacterial strains isolated from marine biofilms. Of these, 28 deep-sea bacterial strains exhibited antibacterial activity against one or more of the bacteria tested. Active deep-sea bacterial strains belonged mainly to the genera of Pseudomonas, Psychrobacter and Halomonas. Additionally, antilarval activity of 56 deep-sea bacterial strains was screened using Balanus amphitrite larvae. Seven bacterial strains produced metabolites that had strong inhibitive effects on larval settlement. None of these metabolites showed significant toxicity. The crude extract of one deep-sea Streptomyces strain could completely inhibit larval settlement at a concentration of 25 μg ml^?1.     

Intrinsic bioremediability of an aromatic hydrocarbon-polluted groundwater: diversity of bacterial population and toluene monoxygenase genes

The functional and phylogenetic biodiversity of bacterial communities in a benzene, toluene, ethylbenzene and xylene (BTEX)-polluted groundwater was analysed. To evaluate the feasibility of using an air sparging treatment to enhance bacterial degradative capabilities, the presence of degrading microorganisms was monitored. The amplification of gene fragments corresponding to toluene monooxygenase (tmo), catechol 1,2-dioxygenase, catechol 2,3-dioxygenase and toluene dioxygenase genes in DNA extracted directly from the groundwater samples was associated with the presence of indigenous degrading bacteria. Five months of air injection reduced species diversity in the cultivable community (as calculated by the Shannon-Weaver index), while little change was noted in the degree of biodiversity in the total bacterial community, as characterised by denaturing gradient gel electrophoresis (DGGE) analysis. BTEX-degrading strains belonged to the genera Pseudomonas, Microbacterium, Azoarcus, Mycobacterium and Bradyrhizobium. The degrading capacities of three strains in batch liquid cultures were also studied. In some of these microorganisms different pathways for toluene degradation seemed to operate simultaneously. Pseudomonas strains of the P24 operational taxonomic unit, able to grow only on catechol and not on BTEX, were the most abundant, and were present in the groundwater community at all stages of treatment, as evidenced both by cultivation approaches and by DGGE profiles. The presence of different tmo-like genes in phylogenetically distant strains of Pseudomonas, Mycobacterium and Bradyrhizobium suggested recent horizontal gene transfer in the groundwater.     

Microbial Diversity in High Arsenic Groundwater in Hetao Basin of Inner Mongolia,China

The microbial diversity and community structure in twenty-one groundwater samples from high arsenic shallow aquifers of Hetao Basin, Inner Mongolia, China was investigated with an integrated approach including polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE) and 16S rRNA gene phylogenetic analyses. A total of 25 bacterial and 32 archaeal DGGE bands were exercised for sequencing. Phylogenetic analyses showed that the bacterial DGGE bands were dominated by Proteobacteria, and the archaeal bands were dominated by Thaumarchaeota and Euryarchaeota. Based on arsenic concentrations, three samples (corresponding to low, medium, and high level of arsenic, respectively) were selected for construction of 16S rRNA gene clone libraries. A total of 912 (468 and 444 for bacteria and archaea, respectively) 16S rRNA gene clone sequences were obtained and subjected to phylogenetic analyses. The results showed that bacterial communities of these samples were dominated by Acinetobacter, Pseudomonas, Massilia, Dietzia, Planococcus, Brevundimonas, Aquabacterium and Geobacter, and archaeal communities by Nitrosophaera, Thermoprotei and Methanosaeta. The relative abundance of major groups varied as a function of changes in groundwater geochemistry. Acinetobacter, Brevundimonas, Geobacter, Thermoprotei and Methanosaeta dominated in high arsenic samples with high concentrations of methane and Fe(II), and low concentrations of SO^2? ₄ and NO^? ₃, while Pseudomonas and Nitrosophaera were abundant in low arsenic groundwater. These results imply that microbes play an important role in arsenic mobilization in the shallow aquifers of Hetao Basin, Inner Mongolia.     

Multistep approach to control microbial fouling of historic building materials by aerial phototrophs

The scientific multistep approach described herein is a result of two years of research into a control method against microbial fouling and biodeterioration of historic building materials by phototrophs. A series of tests were conducted to select the best antifouling agent for eliminating ‘green’ coatings and protecting surfaces against biofouling. Of the seven active compounds, two with the best penetration abilities were subjected to a photosynthetic activity inhibition test using confocal microscopy. Of the two, a quaternary ammonium salt (QAC) – didecyldimethylammonium chloride (DDAC) – was found to be the most effective. Ten biocides containing QACs at different concentrations were then tested against ‘green’ coatings on wood, brick and plaster, with the best four being selected for further research in model conditions. As a result, biocides containing >14% (v v^–1) DDAC were found to be successful antifouling agents for protecting historical materials against biodeterioration by phototrophs.     

Evaluation of fungal and bacterial bioagents against Rhizoctonia solani on Solanum melongena (L.)

Three fungal and one bacterial bioagents were tested for efficacy against Rhizoctonia solani under in vivo and in vitro conditions. Organisms including native isolates of Trichoderma virens 7109, Paecilomyces lilacinus 7115, Aspergillus niger and Pseudomonas strain were investigated in different combinations to get effective antagonists. T. virens 7109 and A. niger significantly reduced the growth of R. solani under laboratory and field conditions, respectively. Fungal combination had stimulatory effect on total fungal population and was recorded the highest (25.04 × 10⁴ cfu/g soil) in T. virens 7109 + P. lilacinus 7115 combination. Soil treatments with individual bioagents have shown uniformity in disease suppression when compared to combinations. Treatment with combination of bioagents yielded higher fruit harvest when compared to that with single bioagent.     

Vertical and Horizontal Distribution of Bacterial Communities in Alluvial Groundwater of the Nakdong River Bank

As a collaborative effort to characterize a pilot test site for managed aquifer recharge (MAR), vertical and horizontal distributions of microbial communities in the river bank subsurface were investigated to assess the ecological effects after the operation of the MAR using the river water adjacent to the site. Along with a geochemical analysis, barcoded pyrosequencing was performed using the genomic DNAs extracted from the subsurface groundwater/sediment samples retrieved from three multilevel wells among the installed cluster of 14 boreholes. A total of 9 samples from 3 depths (10, 15–25, and 33 m below the ground surface) of each borehole showed higher bacterial abundance and diversity in the shallow (10 m) depths than in the deep (33 m) groundwater. In addition, there was a slight separation of the microbial communities between the depths based on the nonmetric multidimensional scaling analysis of the Yue and Clayton distance and the distance-weighted UniFrac analysis. The phylum Proteobacteria was dominant in all the samples at the sequence abundance of 64.0–97.8% with the total operational taxonomic units of 3375 at the species level, while among the total 288 genera, the genus Pseudomonas and an unclassified genus from Betaproteobacteria were the most abundant across the samples. The community separation between the shallow and the deep groundwater seemed to be correlated with depth differences, supported by differences in the dissolved oxygen (DO) concentration and oxidation-reduction potential (ORP). In the study site, unusually high values of electrical conductivity (EC) were found in the deep groundwater, but those values were unlikely to contribute to the community separation between the shallow and deep groundwater, unlike the DO and ORP values, which were found to influence the community differences.     

Microbial degradation of formaldehyde in white mineral dispersions preserved with formaldehyde-releasing biocides

Two different formaldehyde-degrading microorganisms, Pseudomonas putida and Methylobacterium extorquens, were isolated from calcium carbonate slurry containing the formaldehyde-releasing biocide (ethylenedioxy) dimethanol. Their relative formaldehyde biodegradation and formic acid production kinetics were studied in broth and in calcium carbonate slurry for each microorganism individually, as well as in mixed cultures. Furthermore, the minimal inhibition concentration (MIC) was determined. The results indicated that in slurry, M. extorquens is more tolerant of formaldehyde than P. putida. In slurry, microbial-induced oxidation of formaldehyde caused a temporary accumulation of formic acid, which is presumed to be responsible for pH drop and destabilisation of the calcium carbonate slurry suspension systems. In addition, the residual formaldehyde concentration was observed to drive dominance and recovery of individual formaldehyde-resistant microorganisms in the slurry. Overall, this investigation indicated that biodegradation of formaldehyde in calcium carbonate slurry is brought about by alternating dominance of bacterial genera of mixed formaldehyde-resistant microbial populations.     

Coupling of bioaugmentation and phytoremediation to improve PCBs removal from a transformer oil-contaminated soil

This study was carried out to assess the dissipation of 17 selected polychlorinated biphenyl (PCB_i) congeners in a transformer oil-contaminated soil using bioaugmentation with 2 PCB-degrading bacterial strains, i.e., Pseudomonas spp. S5 and Alcaligenes faecalis, assisted or not by the maize (Zea mays L.) plantation. After 5 and 10 weeks of treatment, the remaining concentrations of the target PCB_i congeners in the soil were extracted and measured using GC-MS. Results showed that the bacterial augmentation treatments with Pseudomonas spp. S5 and A. faecalis led to 21.4% and 20.4% reduction in the total concentration of the target PCBs (ΣPCB_i), respectively, compared to non-bioaugmented unplanted control soil. The ΣPCB_i decreased by 35.8% in the non-bioaugmented planted soil compared with the control. The greatest degradation of the PCB congeners was observed over a 10-week period in the soil inoculated with Pseudomonas spp. S5 and cultivated with maize. Under this treatment, the ΣPCB_i decreased from 357 to 119 ng g^?1 (66.7% lower) and from 1091 to 520 ng g^?1 (52.3% lower). Overall, the results suggested that the combined application of phytoremediation and bioaugmentation was an effective technique to remove PCBs and remediate transformer oil-contaminated soils.     

Isolation,Identification and Efficacy of Inorganic Phosphate-Solubilizing Bacteria from Oxbow Lakes of West Bengal,India

Microbial mobilization of sediment calcium-bound P constitutes an important process of P cycling in aquatic environments. The present study was conducted to identify the bacterial community responsible for inorganic phosphate solubilization in tropical oxbow lakes. Fifty eight phosphate-solubilizing bacteria were isolated from bottom soil, water, and fish gut and examined for solubilization of tricalcium phosphate. Results revealed aquatic PSB to be low-to-moderately capable in P solubilization (mean: 33.5 mg P L^?1; range: 6.3–68.8 mg P L^?1), and bacteria from wetland sediment and water were more effective than those from fish gut. The PSB were identified to belong to diverse genera, viz. Bacillus, Brevibacillus, Enterobacter, Agrobacterium, Pseudomonas, Acinetobacter, Microbacterium, Curtobacterium, Stenotrophomonas and Novosphingobium. The findings help in understanding the microbial role in inorganic P solubilization and identifying important P solubilizers in freshwater environments.     

Pseudomonas prosekii sp. nov., a Novel Psychrotrophic Bacterium from Antarctica

During Czech expeditions at James Ross Island, Antarctica, in the years 2007–2009, the bacterial diversity of the genus Pseudomonas was studied. Twelve fluorescent Pseudomonas strains were isolated from various samples and were subjected to a detailed taxonomic study. A polyphasic approach included genotypic and phenotypic analyses. The genotypic analysis involved sequencing of rrs, rpoB and rpoD genes, DNA–DNA hybridization (DDH) studies as well as manual ribotyping using HindIII endonuclease. The phenotypic characterization included conventional tests as well as biotyping using the Biolog system, protein profiling by SDS-PAGE, and MALDI-TOF MS analysis. Our taxonomic study revealed that all isolates belonged to the same Pseudomonas species with psychrotrophic growth not exceeding 37 °C. The cultures showed a unique position among the phylogenetically related pseudomonads. DDH experiment between the proposed type strain of the antarctic isolates and the closest neighbour P. arsenicoxydans CCM 8423^T showed only 40.9–50.1 % similarity, thus confirming that the characterized strains do not belong to the P. arsenicoxydans species. According to the results obtained we propose the name P. prosekii sp. nov. for this novel Pseudomonas taxon with type strain AN/28/1^T (=CCM 7990^T and LMG 26867^T).     

Sorption of Glyphosate on Soil Components: The Roles of Metal Oxides and Organic Materials

Predicting the behavior, fate, and transport potential of a herbicide in any soil involves understanding the sorption characteristics. The sorption characteristics of glyphosate (GPS) on soil and their main components were investigated, indicating that the mineral phase is more important than the organic carbon in adsorption of GPS. Sorption isotherms were determined from each component using the batch equilibrium method at various concentrations (5, 10, 15, 20, 25, and 30 mg L^?1) and sorption affinity of GPS was approximated by the Freundlich equation. The sorption strength K _f [mg kg^?1 (L mg^?1)^?n] across the various components ranged from 2.1–134.9 while the organic carbon-normalized Freundlich sorption capacity values, K _foc, ranged from 1.28–3.53 mg kg^?1-OC/(mg L^?1)ⁿ. Infrared Fourier transform spectroscopy (FTIR) of the components showed significant structural differences. The results suggest that the presence of the oxides and hydroxides iron, in particular in soil solutions, enhanced GPS adsorption. They also suggest that reduction in OC% due to various treatments may enhance the remobilization of GPS into the aqueous phase (i.e., groundwater), though at different rates. Comparatively, contribution of surface area to the adsorption of GPS on the various components proved more significant than contents of organic carbon.     

Biomarker assessment of organic matter sources and degradation in Canadian High Arctic littoral sediments

This paper presents an uncomplicated approach to improve estimates of groundwater nutrient load to a marine embayment. A two-dimensional chemical profile of shallow groundwater was analysed in a sandy beach in three seasons (early summer, late summer and mid winter) and an adjusted estimate of groundwater nutrient discharge was derived that accounts for a complex biogeochemical environment and non-conservative behaviour of nutrients in the pre-discharge beach groundwater. The study was conducted at Cockburn Sound, Western Australia, where there has been significant groundwater contamination and associated marine ecological degradation. Losses in nitrogen and increases in phosphorus were observed along the discharge pathway beyond that expected from mixing with marine water, and the changes were attributed to chemically and biologically mediated reactions. A slow groundwater velocity (0.14–0.18 m day^?1), high organic carbon (TOC = 0.35–4.9 mmol l^?1, DOC = 0.28–4.6 mmol l^?1) and low to sub-oxic conditions (DO = 0.4–24% saturation) were deemed suitable for chemically and biologically mediated reactions to occur and subsequently alter regional estimates of groundwater nutrient concentration. Accounting for this environment, groundwater loads were calculated that were 1–2 orders of magnitude less than previous regional-based estimates: 0.4–13 kg NO _x ^?  day^?1, 0.2–24 kg NH₄ ⁺ day^?1 and 0.004–0.8 kg FRP day^?1. This paper applies knowledge of recent research and presents scope to marine managers or modellers to account for groundwater inputs to the marine environment.     

Human health risk assessment of arsenic in groundwater aquifers of Lahore,Pakistan

The present study was conducted to estimate As concentration in groundwater and resulting human health risk in terms of chronic daily intake, hazard quotient (HQ), hazard index (HI), and carcinogenic risk (CR) both for oral and dermal exposure to As. Groundwater samples (n = 100) were collected from ten different towns of Lahore District (Pakistan). Arsenic concentration ranged from 2 to 111 µg L^?1 in groundwater samples of the study area, which was significantly greater than the safe limit of As (10 µg L^?1) in drinking water set by the World Health Organization. Health risk assessment of As showed that HQ (0.1–11) for oral exposure and HI (0.1–11) values also exceeded the typical toxic risk index value of 1. 9.75 × E-05–4.59 × E-03 and 5.89 × E-07–2.77 × E-05 for oral and dermal As exposure, respectively. Both CR and cancer index (CIs) values were higher than United States Environmental Protection Agency limit (10^?6), suggesting that people are at high risk of As-induced carcinogenicity from oral and dermal exposure to As in drinking water. It was concluded that As contamination of groundwater causes carcinogenic and noncarcinogenic health effects to the people; therefore, urgent management and remedial actions are required to protect people from As poisoning.     

Environmental Fate of Two Organophosphorus Insecticides in Soil Microcosms under Mediterranean Conditions and Their Effect on Soil Microbial Communities

Assessing dissipation is an integral part of determining pesticide risk. The adsorption and dissipation characteristics of two model insecticides, chlorpyrifos (CHP) and dimethoate (DMT), in a Mediterranean soil were investigated in order to evaluate soil microbial toxicity and to study their soil bioavailability for the purpose of managing pesticide residue with potential bioremediation of contaminated soil. The aim of this study was also to define novel methods for assessing the ecotoxicity of CHP and DMT on microorganisms in the soil. Koc values ranged between 33420–91601 cm³/g and 129–184 cm³/g for CHP and DMT, respectively, indicating that the former is characterized by a strong adsorption affinity, whereas, the latter has a weaker one. In the dissipation study, the half-life (T_1/2) of CHP in top soil was 11.55days; whereas, when dissipation was studied in the same soil sterilized, the half-life was 13.86 days, showing a relatively important abiotic degradation effect. For DMT, however, T_1/2 was 17.32 days and 13.86 days in sterilized soil and non-sterilized soil, respectively, illustrating partial biotic degradation. In terms of leaching behavior, the groundwater ubiquity scores calculated for CHP and DMT were 0.85 and 1.95, respectively, indicating that CHP is a non-leacher, while DMT can be considered a transition insecticide.