Cadmium (Cd) is ubiquitous in the human environment and has toxic effect on soil microbial biomass or its activity, including microbial biomass carbon (C(mic)), dehydrogenase activity (DHA) and basal respiration (BR), etc., C(mic), DHA, BR were used as bioindicators of the toxic effect of Cd in soil. This study was conducted to determine the effects of Cd on soil microbial biomass and its activity in a paddy soil. The inhibition of microbial biomass and its activity by different Cd concentrations was described by the kinetic model (M1) and the sigmoid dose-response model (M2) in order to calculate three ecological doses of Cd: ED(50), ED(10) and ED(5). Results showed that M2 was better fit than M1 for describing the ecological toxicity dose effect of cadmium on soil microbial biomass and its activity in a paddy soil. M2 for ED values (mg/kg soil) of C(mic), DHA, BR best fitted the measured paddy soil bioindicators. M2 showed that all ED values (mg/kg) increased in turn with increased incubation time. ED(50), ED(10) and ED(5) of C(mic) with M2 were increased in turn from 403.2, 141.1, 100.4 to 1000.7, 230.9, 144.8, respectively, after 10 d to 60 d of incubation. ED(50), ED(10) and ED(5) of DHA with M2 increased in turn from 67.6, 6.2, 1.5 to 101.1, 50.9, 41.0, respectively, after 10 d to 60 d of incubation. ED(50), ED(10) and ED(5) of BR with M2 increased in turn from 149.7, 6.5, 1.8 to 156.5, 50.8, 35.5, respectively, after 10 d to 60 d of incubation. So the ecological dose increased in turn with increased incubation time for M2 showed that toxicity of cadmium to soil microbial biomass and its activity was decreased with increased incubation time.
Biomass ; Cadmium ; toxicity ; Soil ; Soil Microbiology ; Soil Pollutants ; toxicity ; Time Factors

Polycyclic aromatic hydrocarbons (PAHs) are a class of persistent pollutants that are widely distributed in the environment. Due to their stable structure and poor degradability, PAHs exhibit carcinogenic, teratogenic, and mutagenic toxicity to the ecological environment and organisms, thus increasing attentions have been paid to their removals and remediation. Green, safe and economical technologies are widely used in the bioremediation of PAHs-contaminated soil. This article summarizes the present status of PAHs pollution in soil of China from the aspects of origin, migration, fate, and pollution level. Meanwhile, the types of microorganisms and plants capable of degrading PAHs, as well as the underlying mechanisms, are summarized. The features of three major bioremediation technologies, i.e., microbial remediation, phytoremediation, and joint remediation, are compared. Analysis of the interaction mechanisms between plants and microorganisms, selection and cultivation of stress-resistant strains and plants, as well as safety and efficacy evaluation of practical applications, are expected to become future directions in this field.
Biodegradation, Environmental ; Polycyclic Aromatic Hydrocarbons/toxicity* ; Soil ; Soil Microbiology ; Soil Pollutants

To screen the available tomato pollution-safe cultivar varieties and reduce the potential food safety risks in Cd-polluted areas, the differences of Cd accumulation in different tomato (Solanum lycopersicum) varieties in southern China were studied by soil culture and hydroponic experiments. Firstly, the high and low accumulation varieties were selected from 25 tomato varieties under 2.94 mg/kg Cd stress by soil culture test, and then the responses of high and low accumulation tomato varieties to Cd stress were determined by hydroponic experiments. The results of soil culture test show that under 2.94 mg/kg Cd stress, there were significant differences in plant height, total biomass and yield among 25 tomato cultivars, and the Cd contents of fruits of all 25 tomato cultivars exceeded the highest limit value (0.05 mg/kg) of CAC (Codex alimentarius commission). Through cluster analysis, 7, 4 and 14 varieties accumulating relatively high, medium, and low concentrations of Cd in the fruits were screened, among which the highest, the lowest, and the average Cd contents in the fruits were 3.06 mg/kg DW, 1.47 mg/kg DW, and 2.21 mg/kg DW, respectively. The results of hydroponic experiment show that under the same concentration of Cd stress, Qiantangxuri F1, a high Cd accumulating variety, absorbed Cd faster, accumulated more Cd, used shorter oxidative stress response time and had stronger tolerance to Cd than Zhefen 3053, a low Cd accumulating variety. The typical high and low Cd accumulating varieties can provide a reference for agricultural production in heavy metal polluted areas and the development of molecular-assisted breeding methods of PSC. At present, cultivating low Cd accumulating PSC varieties and dynamic monitoring of Cd contents in tomato fruits are feasible methods in medium and light Cd-polluted areas.
Antioxidants ; Cadmium/toxicity* ; China ; Lycopersicon esculentum ; Plant Breeding ; Plant Roots/chemistry* ; Soil Pollutants/toxicity*

OBJECTIVETo investigate the relationship between copper speciation and microbial features (microbial communities and copper tolerance level) in order to determine the adverse effect of different forms of Cu on microorganisms.

METHODSTessier's sequential extraction procedure was used to qualify the different Cu forms (exchangeable, carbonate bound, Fe/Mn oxide bound, residue and organic matter bound), and the copper tolerance level (expressed as IC50, influence concentration) was measured by the plate-count method.

RESULTSBy simple correlation analysis, the IC50 was positively correlated with the concentration of exchangeable Cu (R2 = 0.8204), while weakly correlated with other forms of Cu.

CONCLUSIONThe bacterial community tolerance increases in the copper-contaminated soil while sensitive bacteria decrease in the copper-contaminated soils. The exchangeable Cu exerts high toxicity to microbial communities.

Bacteria ; drug effects ; isolation & purification ; China ; Copper ; analysis ; chemistry ; toxicity ; Environmental Monitoring ; Fungi ; drug effects ; isolation & purification ; Hydrogen-Ion Concentration ; Soil Microbiology ; Soil Pollutants ; chemistry ; toxicity

AIMTo explore the effect of exposure to commercial Parathion (Pc) on the reproductive parameters (sperm and cocoon production and genotoxicity on male germ cells), the survival, the body weight and the gross anatomical changes in Eisenia foetida.

METHODSThree doses of Pc (1478, 739 and 444 mg/kg of soil) and three time intervals of exposure (5, 15 and 30 days) were used.

RESULTSAll treated animals were affected. An acute genotoxic effect, revealed by DNA fragmentation (comet assay), was seen by 5 days. Alterations in reproductive parameters were conspicuous in regard to the number of sperm, cocoons and worms born, and the histological observation of the gonads and seminal receptacles. In addition, the body weight and survival rate were decreased. Neuromuscular function was also affected.

CONCLUSIONEarthworms are suitable bioindicators of chemical contamination of the soil, their advantage being their easy and economical handling.

Animals ; Behavior, Animal ; drug effects ; Insecticides ; toxicity ; Male ; Oligochaeta ; drug effects ; Parathion ; toxicity ; Reproduction ; drug effects ; Soil Pollutants ; toxicity ; Survival Rate

Air Pollutants ; analysis ; Animals ; Child ; Esters ; toxicity ; Humans ; Liver ; drug effects ; Phthalic Acids ; analysis ; metabolism ; toxicity ; Reproduction ; drug effects ; Soil Pollutants ; analysis ; Thyroid Gland ; drug effects ; Water Pollutants, Chemical ; analysis

OBJECTIVETo study the accumulation and translocation of cadmium in the soil and Artemisia annua, and observe its effects on growth of A. annua and artemisinin content.

METHODA. annua were cultivated in pots with Cd concentration at 0.5, 1.5, 4.5 mg x kg(-1) level, respectively.

RESULT AND CONCLUSIONThe growth of A. annua was inhibited at all the Cd levels characterized by the decreases of biomass and agronomic parameters; Most of Cd was accumulated in the roots of A. annua, and the ratios of Cd concentrations in roots and aerial part were 1.8:1 and 2.3:1 at 1.5, 4.5 mg x kg(-1) Cd level, respectively. Artemisinin content increased significant at 0.5 mg x kg(-1) Cd level, but there were no significant changes comparing with control group other Cd levels.

Artemisia annua ; chemistry ; drug effects ; growth & development ; metabolism ; Artemisinins ; analysis ; metabolism ; Cadmium ; analysis ; metabolism ; toxicity ; Plant Extracts ; analysis ; metabolism ; Soil Pollutants ; analysis ; metabolism ; toxicity

OBJECTIVEPrevious work has showed that excess iron accumulation is harmful to reproduction and even promotes death; however, whether the multiple biological toxicity of iron (Fe) exposure could be transferred to progeny remains unknown. The present study used Caenorhabditis elegans to analyze the multiple toxicities of iron exposure and their possible transferable properties.

METHODSThree concentrations of iron sulfate solution (2.5 micromol/L, 75 micromol/L, and 200 micromol/L) were used. The endpoints of lifespan, body size, generation time, brood size, head thrash and body bend frequencies, and chemotaxis plasticity were selected to investigate Fe toxicity and its effect on progeny in Caenorhabditis elegans.

RESULTSThe Fe toxicity could cause multiple biological defects in a dose-dependent manner by affecting different endpoints in nematodes. Most of the multiple biological defects and behavior toxicities could be transferred from Fe-exposed Caenorhabditis elegans to their progeny. Compared to the parents, no recovery phenotypes were observed for some of the defects in the progeny, such as body bend frequency and life span. We further summarized the defects caused by Fe exposure into 2 groups according to their transferable properties.

CONCLUSIONOur results suggest that Fe exposure could cause multiple biological defects, and most of these severe defects could be transferred from Fe exposed nematodes to their progeny.

Animals ; Behavior, Animal ; drug effects ; physiology ; Body Size ; Caenorhabditis elegans ; drug effects ; genetics ; physiology ; Dose-Response Relationship, Drug ; Iron ; toxicity ; Iron Compounds ; toxicity ; Life Expectancy ; Phenotype ; Reproduction ; Soil Pollutants ; toxicity ; Sulfates ; toxicity

Heavy metals, such as cadmium, copper, lead, chromium and mercury, are important environmental pollutants, particularly in areas with high anthropogenic pressure. Their presence in the atmosphere, soil and water, even in traces can cause serious problems to all organisms, and heavy metal bioaccumulation in the food chain especially can be highly dangerous to human health. Heavy metals enter the human body mainly through two routes namely: inhalation and ingestion, ingestion being the main route of exposure to these elements in human population. Heavy metals intake by human populations through food chain has been reported in many countries. Soil threshold for heavy metal toxicity is an important factor affecting soil environmental capacity of heavy metal and determines heavy metal cumulative loading limits. For soil-plant system, heavy metal toxicity threshold is the highest permissible content in the soil (total or bioavailable concentration) that does not pose any phytotoxic effects or heavy metals in the edible parts of the crops does not exceed food hygiene standards. Factors affecting the thresholds of dietary toxicity of heavy metal in soil-crop system include: soil type which includes soil pH, organic matter content, clay mineral and other soil chemical and biochemical properties; and crop species or cultivars regulated by genetic basis for heavy metal transport and accumulation in plants. In addition, the interactions of soil-plant root-microbes play important roles in regulating heavy metal movement from soil to the edible parts of crops. Agronomic practices such as fertilizer and water managements as well as crop rotation system can affect bioavailability and crop accumulation of heavy metals, thus influencing the thresholds for assessing dietary toxicity of heavy metals in the food chain. This paper reviews the phytotoxic effects and bioaccumulation of heavy metals in vegetables and food crops and assesses soil heavy metal thresholds for potential dietary toxicity.
Biological Availability ; Biological Transport, Active ; Food Contamination ; analysis ; prevention & control ; Humans ; Metals, Heavy ; analysis ; pharmacokinetics ; toxicity ; Plants, Edible ; drug effects ; growth & development ; metabolism ; toxicity ; Soil Pollutants ; analysis ; pharmacokinetics ; toxicity ; Vegetables ; drug effects ; growth & development ; metabolism ; toxicity

OBJECTIVEOur objective is to build a model that explains the association between the exposure to trace elements in the soil and the risk of neural tube defects.

METHODSWe built a function with different parameters to describe the effects of trace elements on neural tube defects. The association between neural tube defects and trace element levels was transformed into an optimization problem using the maximum likelihood method.

RESULTSTin, lead, nickel, iron, copper, and aluminum had typical layered effects (dosage effects) on the prevalence of neural tube defects. Arsenic, selenium, zinc, strontium, and vanadium had no effect, and molybdenum had one threshold value that affected the prevalence of birth defects.

CONCLUSIONAs an exploratory research work, our model can be used to determine the direction of the effect of the trace element content of cultivated soil on the risk of neural tube defects, which shows the clues by the dosage effect of their toxicological characteristics. Based on our findings, future biogeochemical research should focus on the direct effects of trace elements on human health.

China ; epidemiology ; Dose-Response Relationship, Drug ; Environmental Exposure ; Female ; Humans ; Metals ; chemistry ; toxicity ; Models, Biological ; Neural Tube Defects ; chemically induced ; epidemiology ; Pregnancy ; Prevalence ; Soil Pollutants ; chemistry ; toxicity ; Trace Elements ; chemistry ; toxicity