Contamination Of Terrestrial Environments Research Articles

Characterization of microplastics in soil, leachate and groundwater at a municipal landfill in Rayong Province, Thailand

Recent years have witnessed a dramatic increase in global plastic production, leading to heightened concerns over microplastics (MPs) contamination as a significant environmental challenge. MP particles are ubiquitously distributed across both continental and marine ecosystems. Given the paucity of research on MPs in Thailand, particularly regarding MPs contamination in terrestrial environments, this study focused on investigating the distribution and characteristics of MPs in a landfill area. We collected 15 soil samples, 2 leachate samples, and 7 groundwater samples from both inside and outside a municipal landfill situated in the urbanized coastal region of Rayong Province. Our findings revealed variability in MPs concentration across different sample types. In soil, the MP count ranged from 240 to 26,100 pieces per kg of dry soil, 58.71 % of all sample sizes are lower than 0.5 mm. Similarly, the size found in the leachate sample, and the average MP in the leachate samples was 139 pieces per liter of MPs. The groundwater samples showed a fluctuation in MPs count from 18 to 94 pieces per liter, and the size of MPs ranged mostly from 0.5 to 1 mm. The predominant forms of MPs identified were sheets, followed by fragments, fibers, and granules. According to μ-FTIR analysis, the majority of the MPs were composed of polyethylene and polypropylene, commonly used in plastic packaging and ropes. The observed high concentrations and extensive distribution of MP contamination underscore the urgency for further studies and effective management strategies to mitigate the adverse impacts of this pollution on various organisms and ecosystems.

BLOOD LEAD CONCENTRATION ANALYSIS BETWEEN REHABILITATION FACILITY AND PERI-URBAN ENVIRONMENT VIRGINIA OPOSSUMS (DIDELPHIS VIRGINIANA) OF ILLINOIS.

The Virginia opossum (Didelphis virginiana) is the only marsupial in North America with a natural range north of Mexico. Its range is widespread throughout the United States, including Illinois. Virginia opossums are opportunistic omnivores that will eat a variety of fruits, grains, insects, and even carrion. They are a ground-foraging species, with frequent soil contact allowing for potential exposure to heavy metal contaminants in terrestrial environments. They are also opportunists that thrive in human-altered ecosystems, including peri-urban environments. Lead is a naturally occurring element and highly toxic metal that is abundant in the soil, primarily due to anthropogenic factors such as fossil fuel use, paint, industrial production waste, and battery recycling. Furthermore, carrion and offal piles containing lead bullet fragments remaining from hunting result in environmental contamination of this heavy metal. Few studies exist on lead exposure in the Virginia opossum. This pilot study evaluates the blood lead burden of 16 free-ranging Virginia opossums presented to a wildlife rehabilitation facility, compared with 16 wild-caught Virginia opossums trapped in grassland, maintained forest, or mixed ecotones. In other species, lead toxicosis has been associated with cognitive dysfunction that may increase the likelihood of trauma or injury in a free-ranging setting. In addition, a high incidence of Virginia opossums presenting for wildlife rehabilitation do so as result of human-animal conflict. Therefore, it was anticipated that individuals presenting for wildlife rehabilitation would have significantly higher blood lead concentrations than their free-roaming counterparts. In this study, every Virginia opossum had measurable blood lead concentrations and the average blood lead concentration of the rehabilitated group was 2.7 times higher than that measured in wild-caught Virginia opossums. These results suggest that Virginia opossums are exposed and susceptible to lead toxicosis due to their diet and foraging behaviors, making them more prone to subsequent injury and presentation to wildlife rehabilitation centers.

Assessing risks from fuel contamination in Antarctica: Dynamics of diesel ageing in soil and toxicity to an endemic nematode

Fuel spills are a major source of contamination in terrestrial environments in Antarctica. Little is known of the effects of hydrocarbon contaminants in fuels on Antarctic terrestrial biota, and how these change as fuel ages within soil. In this study we investigate the sensitivity of juveniles of the endemic Antarctic nematode Plectus murrayi to diesel-spiked soil. Toxicity tests were conducted on soil elutriates, and changes in concentrations of hydrocarbons, polar compounds and PAHs were assessed as the spiked soil was artificially aged at 3 °C over a 45-week period, representing multiple summer seasons of fuel degradation. Nematodes were most sensitive to elutriates made from freshly spiked soils (LC50 419 μg/L TPH and 156 μg/L TPH-SG), with a subsequent decline in toxicity observed in the first 6 weeks of laboratory ageing (LC50 2945 μg/L TPH and 694 μg/L TPH-SG). Effects were still evident up to 45 weeks (lowest observed effect concentration 2123 μg/L TPH) despite hydrocarbons being depleted from soils with ageing (84 % loss) and elutriates becoming dominated by polar metabolites (95 % polar). Nematode sensitivity throughout the ageing period showed evidence of a relationship between LC50 and the proportions of the lighter carbon range fraction of TPH in elutriates, the F2 fraction (C10–14). This study is the first to estimate the sensitivity of Antarctic terrestrial fauna to diesel and provides novel data on the dynamics of fuel chemistry under Antarctic conditions and how this influences toxicity. Findings contribute to predicting ecological risk at existing diesel fuel spill sites in Antarctica, to the derivation of site-specific remediation targets, and to environmental guidelines to assess ecosystem health.

Effects of microplastics on the terrestrial environment: A critical review

Microplastics are emerging contaminants and there has been growing concern regarding their impacts on aquatic and terrestrial environments. This review provides a comprehensive overview of the current knowledge regarding the sources, occurrences, fates, and risks associated with microplastic contamination in terrestrial environments. This contamination occurs via multiple sources, including primary microplastics (including synthetic materials) and secondary microplastics (derived from the breakdown of larger plastic particles). Microplastic contamination can have both beneficial and detrimental effects on soil properties. Additionally, microplastics have been shown to interact with a wide array of contaminants, including pesticides, persistent organic pollutants, heavy metals, and antibiotics, and may act as a vector for contaminant transfer in terrestrial environments. Microplastics and their associated chemicals can be transferred through food webs and may accumulate across multiple trophic levels, resulting in potential detrimental health effects for humans and other organisms. Although several studies have focused on the occurrence and impacts of microplastic contamination in marine environments, their sources, fate, transport, and effects in terrestrial environments are less studied and not well understood. Therefore, further research focusing on the fate, transport, and impacts of microplastics in relation to soil properties, polymer composition and forms, and land-use types is needed. The development of standardized and harmonized methods for analyzing microplastics in soil-plant ecosystems is essential. Future work should also consider the many interactions of microplastics with soil quality and ecotoxicological impacts on biota in the context of global environmental change.

Petroleum-contaminated soil extent recorded by δ<sup>15</sup>N and δ<sup>13</sup>C of plants and soils

Petroleum contamination in terrestrial environments caused by industrial activities is a significant problem that has received considerable attention. Carbon and nitrogen isotopic compositions (δ<sup>13</sup>C and δ<sup>15</sup>N) effectively describe the behavior of plants and soils under petroleum contamination stress. To better understand plant and soil responses to petroleum-contaminated soil, δ<sup>13</sup>C and δ<sup>15</sup>N values of the plants (<i>Trifolium repens</i>, Leguminosae with C<sub>3</sub> photosynthesis pathway, and <i>Agropyron cristatum</i> with C<sub>4</sub> photosynthesis pathway) and the soil samples under one-month exposure to different extents of petroleum contamination were measured. The results showed that petroleum contamination in the soil induced the soil δ<sup>15</sup>N values to increase and δ<sup>13</sup>C values to decrease; from 1.9‰ to 3.2‰ and from −23.6‰ to −26.8‰, respectively. However, the δ<sup>13</sup>C values of <i>Agropyron cristatum</i> decreased from −29.8‰ to −31.6‰, and the δ<sup>13</sup>C values of<i> Trifolium repens</i> remained relatively stable from −12.6‰ to −13.1‰, indicating that they have different coping strategies under petroleum-contaminated soil conditions. Moreover, the δ<sup>15</sup>N values of <i>Trifolium repens</i> decreased from 5.6‰ to 0.8‰ near the air δ<sup>15</sup>N values under petroleum-contaminated soil, which implies that their nitrogen fixation system works to reduce soil petroleum stress. The δ<sup>13</sup>C and δ<sup>15</sup>N values of <i>Agropyron cristatum</i> and <i>Trifolium repens</i> reflect changes in the metabolic system when they confront stressful environments. Therefore, stable isotopic compositions are useful proxies for monitoring petroleum-contaminated soil and evaluating the response of plants to petroleum contamination stress.

Fungal-Mineral Interactions Modulating Intrinsic Peroxidase-like Activity of Iron Nanoparticles: Implications for the Biogeochemical Cycles of Nutrient Elements and Attenuation of Contaminants.

Fungal-mediated extracellular reactive oxygen species (ROS) are essential for biogeochemical cycles of carbon, nitrogen, and contaminants in terrestrial environments. These ROS levels may be modulated by iron nanoparticles that possess intrinsic peroxidase (POD)-like activity (nanozymes). However, it remains largely undescribed how fungi modulate the POD-like activity of the iron nanoparticles with various crystallinities and crystal facets. Using well-controlled fungal-mineral cultivation experiments, here, we showed that fungi possessed a robust defect engineering strategy to modulate the POD-like activity of the attached iron minerals by decreasing the catalytic activity of poorly ordered ferrihydrite but enhancing that of well-crystallized hematite. The dynamics of POD-like activity were found to reside in molecular trade-offs between lattice oxygen and oxygen vacancies in the iron nanoparticles, which may be located in a cytoprotective fungal exoskeleton. Together, our findings unveil coupled POD-like activity and oxygen redox dynamics during fungal-mineral interactions, which increase the understanding of the catalytic mechanisms of POD-like nanozymes and microbial-mediated biogeochemical cycles of nutrient elements as well as the attenuation of contaminants in terrestrial environments.

Polystyrene microplastics impact the occurrence of antibiotic resistance genes in earthworms by size-dependent toxic effects

Microplastics (MPs) and antibiotic resistance genes (ARGs) are two classes of emerging and prevalent contaminants in terrestrial environments. To date, effects of MPs on the occurrence of ARGs in terrestrial invertebrates remain uncertain. Here we exposed earthworms to a soil amended with polystyrene MPs at two environmentally relevant concentrations to elucidate the occurrence and mechanisms of ARGs in earthworms impacted by MPs with different sizes. Nano-size and 10 mg/kg of 100 µm MPs slightly affected the occurrence of ARGs in earthworms. Highest abundance of ARGs was found in the presence of 10 mg/kg of 10 µm MPs, whereas 100 mg/kg of 10 µm MPs significantly changed the profile of ARGs. Metagenomics sequencing and toxicity tests indicated that MPs caused toxicity and influenced the abundance of microbial community in earthworms, resulting in the changes of ARGs. Results of proteomics and metabolomics demonstrated that 100 mg/kg of 10 µm MPs changed the microenvironment of earthworm gut, built a new homeostatic process, and thus increased the abundance of key bacterial that carried a variety of ARGs. This study highlights the size-dependent toxic effects of MPs and their impacts on the transfer of ARGs in terrestrial environments.

Molecular behavior assessment on initial stages of oil spill in terrestrial environments.

The contamination of terrestrial environments by oil spills creates biological risks to humans and affects the ecosystem's health. The studies that aim to evaluate the toxicity and changes in the environments are a field of potential interest to the scientific community. The objective of this study was to evaluate the changes in the chemical composition of crude oil fractions after the simulation of a spill in soil and sand, with emphasis on an immediate temporal investigation. Samples of intermediate (°API = 27.0) and heavy (°API = 20.9) oils from Sergipe-Alagoas basin were used. The evaporation process in the soil was highlighted; while the GC-FID chromatographic profiles demonstrated (1) the disappearance from n-C12 until n-C14 compounds, besides a decrease of more than 50% in n-C15 and n-C16 n-alkanes and (2) no changes in n-C17/Pr and n-C18/Ph ratios for both oils. Analysis of resins fraction performed by Orbitrap-MS has shown changes in the mass spectra profile and compound distribution during the soil and sand exposure process, with N1, O1, and O2 species showing changes in the relative abundance in ESI(+) mode, and O2, N1, and O1 for ESI(-). Changes in polar compounds of oil will depend on the extent of the time of interaction with soil and sand, taking into account intrinsic aspects, such as the nature of the soil and components in it as the organic matter.

Agricultural plastic mulching as a source of microplastics in the terrestrial environment

Plastic mulching is suspected to be a significant source of microplastics in terrestrial environments owing to its intensive application and improper disposal. However, there has been a comparative lack of studies examining this hypothesis. In this study, the occurrence of macroplastics in agricultural soils was investigated by analysing 384 soil samples collected from 19 provinces across China. Additionally, the abundance of microplastics was investigated in potential hotspots that have carried out plastic mulching for over 30 years. Macroplastic concentrations in the soil samples ranged from 0.1 to 324.5 kg/ha, with an average of 83.6 kg/ha; the concentrations were higher in western China than in eastern China. A highly significant linear correlation (R2 = 0.61) was found between the consumption of mulching film and the plastic residue in soils, indicating plastic film mulching may be a major source of macroplastics. The abundances of microplastic particles increased over time in the locations where plastic mulching was continuously employed, with concentrations of 80.3 ± 49.3, 308 ± 138.1, and 1075.6 ± 346.8 pieces/kg soil in fields with 5, 15, and 24 y of continuous mulching, respectively. Fourier transform infrared analyses revealed that the composition of the microplastics matched that of the mulching films, suggesting the microplastic particles originated from the mulching films. These findings confirm that plastic mulching is an important source of macroplastic and microplastic contamination in terrestrial environments. Further studies to investigate the microplastic hazards in soils are thus necessary.

Heavy metal bioaccumulation in honey bee matrix, an indicator to assess the contamination level in terrestrial environments

The most significant risk factor for organisms living in an environment contaminated by heavy metals is the metal bioavailability. Therefore, an efficient ecotoxicological approach to metal contamination is the measure of bioaccumulation level in target organisms. In this work, we characterized the heavy metal bioaccumulation in honey bees, Apis mellifera ligustica, collected at 35 sites from Umbria (Central Italy). The comparison of our data with selected Italian investigations revealed metal bioaccumulation in honey bee matrix of the same order of magnitude, with Cd showing a higher variability. To generalize the results, we developed a Honeybee Contamination Index (HCI) based on metal bioaccumulation in honey bees. An application of the HCI to the present dataset revealed cases of low (sixteen sites), intermediate (eighteen sites), and high (one site) metal contaminations. The comparison of HCI values from the Umbrian dataset with values calculated for other Italian and European metadata showed that most of the Umbrian sites fell in the portion of low and intermediate contamination conditions. HCI represented a reliable tool that provided a piece of concise information on metal contamination in terrestrial environments. Parallel to this effort, we have determined, the metal concentrations in the airborne particulate matter (PM10) at three regional background-monitoring stations in Umbria. These stations are representative of the average air quality of the areas of the investigated apiaries. A comparative analysis of metal enrichment factors in PM10, and honey bees suggested that the contamination in the bees was related to the PM10 values only to a minor extent. On the other side, a clear enrichment of metals such as Cd, Mn, Zn, and Cu in the honey bees appeared to depend on very local conditions and was probably related to the use of pesticides and fertilizers, and the resuspension of the locally contaminated soils and agriculture residues.

Effects of Selenium on Mercury Bioaccumulation in a Terrestrial food Chain from an Abandoned Mercury Mining Region.

Few reports of the relationship exist between mercury (Hg) and selenium (Se) from locations of severe Hg contamination in terrestrial environments. Here, we report the concentrations of Hg and Se as well as Se:Hg molar ratios in biotic samples collected from a region with a long history of Hg mining. Nitrogen isotopes (δ15N) were analyzed to confirm the trophic levels. Results showed that bird feathers at the top trophic level exhibited the highest Hg concentrations, while the lowest concentrations were found in herbivorous insects, demonstrating a significant biomagnification across the food chain. In contrast, herbivorous insects of different types (generalists vs. specialized rice pests) exhibited both the highest and the lowest concentrations of Se, indicating a lack of biomagnification. Indeed, Se was correlated positively with Hg when Se:Hg ratios were greater than one, suggesting Se:Hg molar ratios can be a controlling influence on Hg in terrestrial organisms.

IMPACTO DE LA MINERÍA DEL ORO ASOCIADO CON LA CONTAMINACIÓN POR MERCURIO EN SUELO SUPERFICIAL DE SAN MARTÍN DE LOBA, SUR DE BOLÍVAR (COLOMBIA)

Human activities have increased mercury (Hg) contamination of terrestrial environments, especially gold mining areas. The aim of this study was to evaluate total Hg concentrations (T-Hg) in surface soil samples of San Martin de Loba, south of Bol i var (Colombia), to determine their Hg contamination level. For that purpose, 202 surface soil samples were collected. T-Hg levels were measured by electrothermal atomization and atomic absorption spectroscopy. The T-Hg surface soil concentrations ranged between 0.002 and 23.83 μg/g, with a median value of 3.40 ± 0.36 μg/g, which is slightly higher than the international Hg soil levels. The geoaccumulation index (I geo ) for soils reached values greater than 5, indicating extreme pollution (Class 6) in 17 % of samples, while 70 % was Class 5 (strongly to extremely polluted). This study also provides a risk map to evaluate potential negative repercussions. In conclusion, the municipality of San Martin de Loba can be considered as a strongly polluted area with high Hg content. Technology used to extract gold through amalgamation processes causes a high degree of Hg pollution around this gold mining area. Therefore, alternative extraction methods should be considered to reduce Hg levels that can be released into the environment and affect human health.

Plastic Bag Derived-Microplastics as a Vector for Metal Exposure in Terrestrial Invertebrates.

Microplastics are widespread contaminants in terrestrial environments but comparatively little is known about interactions between microplastics and common terrestrial contaminants such as zinc (Zn). In adsorption experiments fragmented HDPE bags c. one mm2 in size showed similar sorption characteristics to soil. However, when present in combination with soil, concentrations of adsorbed Zn on a per mass basis were over an order of magnitude lower on microplastics. Desorption of the Zn was minimal from both microplastics and soil in synthetic soil solution (0.01 M CaCl2), but in synthetic earthworm guts desorption was higher from microplastics (40-60%) than soil (2-15%), suggesting microplastics could increase Zn bioavailability. Individual Lumbricus terrestris earthworms exposed for 28 days in mesocosms of 260 g moist soil containing 0.35 wt % of Zn-bearing microplastic (236-4505 mg kg-1) ingested the microplastics, but there was no evidence of Zn accumulation, mortality, or weight change. Digestion of the earthworms showed that they did not retain microplastics in their gut. These findings indicate that microplastics could act as vectors to increase metal exposure in earthworms, but that the associated risk is unlikely to be significant for essential metals such as Zn that are well regulated by metabolic processes.

Modelling functional resilience of microbial ecosystems: Analysis of governing processes

Functional stability of microbial ecosystems subjected to disturbances is essential for maintaining microbial ecosystem services such as the biodegradation of organic contaminants in terrestrial environments. Functional responses to disturbances are thus an important aspect which is, however, not well understood yet. Here, we present a microbial simulation model to investigate key processes for the recovery of biodegradation. We simulated single disturbances with different spatiotemporal characteristics and monitored subsequent recovery of the biodegradation dynamics. After less intense disturbance events local regrowth governs biodegradation recovery. After highly intense disturbance events the disturbance pattern's spatial configuration is decisive and processes governing local functional recovery vary depending on habitat location with respect to the spatial disturbance pattern. Local regrowth may be unimportant when bacterial dispersal from undisturbed habitats is high. Hence, our results suggest that spatial dynamics are crucial for the robust delivery of the ecosystem service biodegradation under disturbances in terrestrial environments.

Metal accumulation in wild-caught opossum

The Virginia opossum (Didelphis virginiana) is widespread in the USA, ranging south through Latin America. The ecology of opossums is such that they are in frequent contact with soils, suggesting that they may function as a valuable bioindicator for chemical contamination in terrestrial environments. Surprisingly, there have been virtually no toxicology studies on opossums. Here, we provide the first analysis of metal contaminants in opossum liver tissues. Liver samples were obtained from 471 opossums, collected from 2003 to 2006, at four sites in North Florida and South Georgia, USA, and concentrations of copper, lead, nickel, selenium, and zinc were measured. We found little evidence of age differences in the concentration of any of the metals. However, there were at least some significant differences between years, males and females, and between sites for each metal, although the pattern of these differences was not always consistent across metals. Concentrations of metals in liver tissue were positively correlated with one another, primarily of each metal (except Pb) with zinc. Reference levels of metal contaminants are not available for opossums, but concentrations of Cu, Ni, Pb, and Zn in our samples were for the most part significantly higher than those reported from liver tissues of nine-banded armadillos (Dasypus novemcinctus) collected at the same sites and in the same years. Data from other small mammals studied elsewhere further indicate that metal concentrations in opossums were high, but at this time, it is not possible to determine if these elevated levels generated toxicity. The substantial temporal and spatial variation we found in metal concentrations suggests that determination of baseline levels for opossums may not be straightforward. Nonetheless, this is the first study quantifying metal accumulation in the livers of Didelphis virginiana and, as such, provides an important starting point for future research.

Salmon migration patterns revealed the temporal and spatial fluctuations of the radiocesium levels in terrestrial and ocean environments.

The disabling of the Fukushima Daiichi Nuclear Power Plant (F1NPP) resulted in the release of radionuclides, including 134Cs and 137Cs, into the air and the ocean. The unpredicted nuclear accident is of global concern for human health and the ecosystem. Although investigations of radionuclides in environments were performed shortly after the accident started, the temporal and spatial impacts and fluctuations on the releasing radionuclides to natural environment remain unclear. I focused on salmon, which migrate from inland to the open ocean globally, to reveal the three-year (May 2011 to February 2014) fluctuations and accumulations of 134Cs and 137Cs from terrestrial to open ocean environments after the F1NPP accident. The 134Cs and 137Cs concentrations in six salmonids exhibited lower temporal variations for three years after the F1NPP accident, suggesting that these radionuclides are widely distributed and these radionuclides remain in the natural environment globally with less convergence. The accumulation patterns were significantly different among the different salmon species. Fluvial (freshwater residence) type salmons exhibited significantly higher accumulation in 134Cs (25.3–40.2 Bq kg−1 in mean) and 137Cs (41.4–51.7 Bq kg−1 in mean) than did the anadromous (sea-run) type salmons (0.64–8.03 Bq kg−1 in mean 134Cs and 0.42–10.2 Bq kg−1 in mean 137Cs) suggesting widespread contamination in terrestrial environments versus the coastal and open ocean environments. Salmonids are the most highly migratory animals and are characterised by their strong tendency to return home to their natal site for reproduction. Salmonids have a potential to be a good indicator as an effective monitoring animal.

DNA damage and biochemical toxicity of antibiotics in soil on the earthworm Eisenia fetida

DNA damage and changes in enzyme activities were used as biomarkers to evaluate the genotoxicity and oxidative stress of tetracycline and chlortetracycline on the earthworm Eisenia fetida. The results showed that both antibiotics induced significant genotoxicity on earthworms in a dose-dependent manner (p<0.01) with chlortetracycline having a stronger effect than tetracycline in the short term. The tests on the activities of superoxide dismutase (SOD) and catalase (CAT) enzymes further indicated biochemical stresses induced by the antibiotics. An N-shaped activity pattern was noted with the enzyme activities being stimulated first, then inhibited, and stimulated again with increasing concentration. The induced activity of SOD or CAT could scavenge oxygen free radicals and protect the organisms against oxidative stress by alleviating the corresponding DNA damage. Compared to enzyme activities, DNA damage as a biomarker was more sensitive and is thus more suitable for detecting low concentration exposure and diagnosing the genotoxicity of contaminants in terrestrial environment.

Toxicological Considerations of Contaminants in the Terrestrial Environment for Ecological Risk Assessment

ABSTRACT The terrestrial environment acts as a “sink” for contaminants that have been purposely or accidentally released into the environment. Science and policy that support protective measures for terrestrial ecosystems have run behind those of aquatic toxicology and water quality concerns. As a result ecological risk assessment (ERA) involving terrestrial environments tends to be conducted at a simplistic level, relying on numeric targets (soil quality criteria) as a basis for decision-making. However, soil criteria for ecological receptors are somewhat deficient in terms of the numbers available and the data that supports these numbers. Direct toxicity assessments (DTA) for terrestrial environments, such as those used for water quality evaluations, can provide additional useful information about the toxicity and bioavailability of mixtures of contaminants present in soils. This article outlines the approaches used for assessing the toxicity of soil contaminants in terrestrial environments and critiques their advantages and pitfalls.

Phytotoxicity to and uptake of enrofloxacin in crop plants

Phytotoxicity of enrofloxacin on crop plants Cucumis sativus, Lactuca sativa, Phaseolus vulgaris and Raphanus sativus was determined in a laboratory model: the effect of 50, 100 and 5000 μg l −1 were evaluated after 30 days exposure by measuring post-germinative growth of primary root, hypocotyl, cotyledons and leaves. Concentrations between 50 and 5000 μg l −1 induced both toxic effect and hormesis in plants, by significantly modifying both length of primary root, hypocotyl, cotyledons and the number/length of leaves. A toxic effect is induced by high concentration (5000 μg l −1), while hormesis occurs at low concentrations (50 and 100 μg l −1). A continuum between toxic effect and hormesis is found in the four plant species. Both toxic effect and hormesis can be related to an efficient plant drug uptake, in the order of μg g −1. Plants are able to metabolize enrofloxacin into ciprofloxacin, as also happens in animals; Cucumis, Lactuca and Phaseolus biologically convert about one quarter of stored enrofloxacin. The ecological implication of enrofloxacin contamination in terrestrial environments is discussed.

Hydrocarbon degradation in soils and methods for soil biotreatment.

The cleanup of soils and groundwater contaminated with hydrocarbons is of particular importance in minimizing the environmental impact of petroleum and petroleum products and in preventing contamination of potable water supplies. Consequently, there is a growing industry involved in the treatment of contaminated topsoils, subsoils, and groundwater. The biotreatment methodologies employed for decontamination are designed to enhance in situ degradation by the supply of oxygen, inorganic nutrients, and/or microbial inocula to the contaminated zone. This review considers the fate and effects of hydrocarbon contaminants in terrestrial environments, with particular reference to the factors that limit biodegradation rates. The potential efficiencies, advantages, and disadvantages of biotreatment techniques are discussed and the future research directions necessary for process development are considered.