Cadmium concentration and distribution in corn (Zea mays L.) grown on a calcareous soil for three years after three annual sludge applications.

The disposal of digested sewage sludge on crop-producing land appeals to municipalities as an option but may pose a hazard to human and animal health if the plant material contains elevated levels of some heavy metals. This paper reports the levels of cadmium in corn grain and stover for six years -- three years with sludge applied annually and for three years after sludge applications were terminated. The cadmium concentration in corn grain from the sixth year was similar to values found in corn grown on non-sludged plots. In corn stover from treated plots the cadmium concentration was greater than from untreated plots. Our study indicated that phytotoxic levels of cadmium did not exist even though elevated levels occurred in the corn stover.     

Determination of T‐2 toxin in grain and grain products by HPLC and TLC

Abstract

The purpose of this study was to investigate the T‐2 toxin contaminated grain and grain products consumed especially by Turkish population. The T‐2 toxin was detected using the high performance liquid chromatography (HPLC) with UV detector at 208 nm and the identify of T‐2 was further confirmed by thin layer chromatography (TLC). The recovery was 91 ±4.24% for corn flour fortified with the known amount of T‐2 toxin (1 ppm). The detection limits of T‐2 toxin for the HPLC and the TLC were 25 ng and 50 ng, respectively. A total of 30 commercially available grain and grain product samples were analyzed. Two corn flour samples were found to contain detectable levels of T‐2 toxin at a level of 1.60 ppm and 4.08 ppm.     

Sorption of atrazine and metolachlor by earthworm surface castings and soil

Abstract

Atrazine and metolachlor were more strongly retained on earthworm (Lumbricus terrestris L.) castings than on soil, suggesting that earthworm castings at the surface or at depth can reduce herbicide movement in soil. Herbicide sorption by castings was related to the food source available to the earthworms. Both atrazine and metolachlor sorption increased with increasing organic carbon (C) content in castings, and Freundlich constants (K_f values) generally decreased in the order: soybean‐fed > corn‐fed > not‐fed‐earthworm‐castings. The amount of atrazine or metolachlor sorbed per unit organic carbon (K_oc values) was significantly greater for corn‐castings compared with other castings, or soil, suggesting that the composition of organic matter in castings is also an important factor in determining the retention of herbicides in soils. Herbicide desorption was dependent on both the initial herbicide concentration, and the type of absorbent. At small equilibrium herbicide concentrations, atrazine desorption was significantly greater from soil than from any of the three casting treatments. At large equilibrium herbicide concentrations, however, the greater organic C content in castings had no significant effect on atrazine desorption, relative to soil. For metolachlor, regardless of the equilibrium herbicide concentration, desorption from soybean‐ and corn‐castings treatments was always less than desorption from soil and not‐fed earthworm castings treatments. The results of this study indicate that, under field conditions, the extent of herbicide retention on earthworm castings will tend to be related to crop and crop residue management practices.     

Effect of chronic exposure to cadmium on hepatic drug metabolism

Abstract

In an attempt to examine the chronic effect of low levels of cadmium on hepatic drug‐metabolizing enzyme system, an experiment was carried out in which growing male rats were given 0, 5, 10, and 2 0 ppm of cadmium in drinking water for a period of 8 weeks. An ip administration of a hypnotic dose of pentobarbital to the cadmium‐treated and the control rats 2 4 hr following the termination of the experiment exhibited that there was no significant difference in the drug metabolism in control and any of the treated groups. Next, liver microsomes were isolated from animals in all groups to study their ability to metabolize drugs in vitro. The results indicated that the activity of benzphetamine N‐demethylase and aniline hydroxylase, and the concentration of microsomal cytochrome P‐450 were almost identical in the control and treated groups. On the other hand, a single ip dose of cadmium (2 mg/kg) caused significant decrease in the in vivo and in vitro microsomal drug metabolism. These results suggest that although a single ip dose of cadmium (2 mg/kg) causes significant inhibition of drug metabolism, chronic exposure to cadmium up to 2 0 ppm in drinking water over a period of 8 weeks is unlikely to affect hepatic drug metabolism.     

NaOH预处理对玉米秸秆固态厌氧消化的影响

实验主要研究了NaOH预处理对玉米秸秆厌氧消化产气量和产气效率的影响。采用质量分数分别为1.0%、2.5%、5.0%和7.5%NaOH溶液对玉米秸秆进行24 h浸泡和未浸泡等预处理,测定其厌氧消化过程中各指标的变化。结果表明,经质量分数为5.0%NaOH浸泡24 h后,玉米秸秆木质素降解率最大,为38.67%;厌氧发酵累积产气量为226.75L/kg VS,与未经碱处理实验组相比提高了38.5%。该结果提示,5.0%NaOH溶液浸泡24 h后可使玉米秸秆厌氧消化的产气量和产气效率显著提高。     

Seepage from deep bedded and poultry litter systems

Abstract

The work reported indicates that there could be a potential of ground water pollution by NO₃‐N from turkey facilities built on both sandy and clay soils. At four different depths (30.54, 61.08, 91.62, and 122.16 cm), the NO₃‐N levels for the clay soil were 1572, 497, 66, and 28 ppm, and those for the sandy soil were 293, 425, 324, and 164 ppm, respectively. No significant P increases were observed but there did exist a significant increase of K in the topsoil for both clay and sandy turkey structures. The results show that swine hoop houses with less than three or four years of age may not pose a threat to groundwater pollution due to the leaching of nutrients. The only dairy feedlot sampled in this study, although it has been used for more than 20 years, did not show leaching of NO₃‐N and P. However, it did show a significantly elevated concentration of potassium in the topsoil, as compared to the background sample. More sites should be investigated to verify this.     

Accelerated degradation of carbofuran in standing water from carbofuran‐retreated Azolla plots

Abstract

Carbofuran (2, 3‐dihydro‐2, 2‐dimethyl‐7‐benzofuranyl N‐methylcarbamate) was mixed with standing water from six flooded Azolla (a fern harboring a nitrogen fixing alga, Anabaena azollae) plots that had been regularly treated with carbofuran before. The insecticide completely disappeared in 5 to 10 days when mixed with water from three of the six plots. The enrichment culture, prepared by further additions of carbofuran to the standing water from an Azolla plot, degraded bendiocarb (2, 2‐dimethyl‐l, 3‐benzidioxol‐4‐yl‐N‐methylcarbamate), carbofuran and carbosulfan [2,3‐dihydro‐2,2‐dimethyl‐7‐benzofuranyl (di‐n‐butyl‐aoinosulfenyl) methyl‐carbamate ] in that order. Enrichment culture, upon sterilization by autoclavlng, lost its ability to degrade carbofuran. Evidently, accelerated degradation of carbofuran in standing water from retreated Azolla plots was mediated by microorganisms.     

Effects of pen bedding and feeding high crude protein diets on manure composition and greenhouse gas emissions from a feedlot pen surface

Greenhouse gas (GHG) emissions from concentrated animal feeding operations vary by stage of production and management practices. The objective of this research was to study the effect of two dietary crude protein levels (12 and 16%) fed to beef steers in pens with or without corn stover bedding. Manure characteristics and GHG emissions were measured from feedlot pen surfaces. Sixteen equal-sized feedlot pens (19?×?23 m) were used. Eight were bedded approximately twice a week with corn stover and the remaining eight feedlot pens were not bedded. Angus steers (n = 138) were blocked by live weights (lighter and heavier) with 7 to 10 animals per pen. The trial was a 2?×?2 factorial design with factors of two protein levels and two bedding types (bedding vs. non bedding), with four replicates. The study was conducted from June through September and consisted of four ?28-day periods. Manure from each pen was scrapped once every 28 days and composite manure samples from each pen were collected. Air samples from pen surfaces were sampled in Tedlar bags using a Vac-U-Chamber coupled with a portable wind tunnel and analyzed with a greenhouse gas gas chromatograph within 24 hr of sampling. The manure samples were analyzed for crude protein (CP), total nitrogen (TN), ammonia (NH₃), total volatile fatty acid (TVFA), total carbon (TC), total phosphorus (TP), and potassium (K). The air samples were analyzed for methane (CH₄), carbon dioxide (CO₂), and nitrous oxide (N₂O) concentrations. The concentration of TN was significantly higher (p < 0.05) in manure from pens with cattle fed the high protein diets. The volatile fatty acids (VFAs) such as acetic, propionic, isobutyric, butyric, isovaleric, and valeric acids concentrations were similar across both treatments. There were no significant differences in pen surface GHG emissions across manure management and dietary crude protein levels.

Implications: Livestock manure produces odor and emits GHGs (CO₂, CH₄, and N₂O) at different stages of production and management practices that have significant environmental concerns. Thus, it is important to measure GHG contributions from different sources and develop appropriate mitigation strategies for minimizing GHG contribution from livestock production facilities. Two dietary protein levels (12 and 16%) fed to beef steers in pens with or without corn stover bedding were studied. The results indicated that dietary protein levels and bedding vs. no bedding had very little effect on GHG emissions and manure composition under open feedlot conditions in North Dakota climatic conditions and management practices.     

Microbial dechlorination of 2,4,6‐trichlorophenol in anaerobic sewage sludge

Abstract

The dechlorination of 2,4,6‐trichlorophenol (TCP) in municipal sewage sludge with a chlorophenol (CP)‐adapted consortium was investigated. Results show that dechlorination rates differed according to the source of the sludge samples used in the batch experiments. No significant differences in 2,4,6‐TCP dechlorination were observed following treatment with inoculum at densities ranging from 10% to 50% (V/V), but a significant delay was noted at 5% (V/V) density. Overall, results show that the higher the 2,4,6‐TCP concentration, the slower the dechlorination rate. The addition of acetate, lactate, pyruvate, vitamin B₁₂ or manganese dioxide did not results in a significant change in 2,4,6‐TCP dechlorination. Data collected from a bioreactor experiment revealed that pH 7.0 and a total solid concentration of 10 g/L were optimal for dechlorination. Dechlorination rates decreased significantly at higher agitation speeds. 2,4,6‐TCP dechlorination was enhanced under methanogenic conditions, but it was inhibited under denitrifying and sulfate‐reducing conditions.     

Long‐term mercury accumulation in the presence of cadmium and lead in oseochromis aureus (Steindachner)

Abstract

The effects of cadmium and lead on chronic mercury accumulation were investigated in O. aureus. After 140 days’ exposure the accumulation of mercury in the liver, brain, gill filaments, intestine, caudal muscle, spleen, trunk kidney and eye was analysed. The exposure concentrations were 0.05, 0.10 and 0.20 mg/L for mercury alone. O. aureus was also exposed to mixtures of 0.05 mg/L mercury with lead (0.05 mg/L and 0.50 mg/L or cadmium (0.05 mg/L) and 0.10 mg/L mercury with 0.10 mg/L cadmium. In food fish, a knowledge of toxic metal accumulation patterns is of great importance because of their contribution to the human diet and, as fishmeal, to the diet of agricultural animals. The trunk kidney consistently accumulated higher concentrations of mercury than any of the other tissues investigated.     

Cadmium and copper toxicity in three marine macroalgae: evaluation of the biochemical responses and DNA damage

Marine macroalgae have evolved a different mechanism to maintain physiological concentrations of essential metal ions and non-essential metals. The objective of the present work was to evaluate the antioxidant response and DNA damage of copper and cadmium ions in three halophytes, namely, Acanthophora spicifera, Chaetomorpha antennina, and Ulva reticulata. Accumulation of copper was significantly higher (P?P?U. reticulata > A. spicifera > C. antennina. DNA damage index analysis supported that copper was significantly (P?相似文献   

Reversed association between levels of prostate specific antigen and levels of blood cadmium and urinary cadmium

Prostate cancer associated with cadmium exposure may indicate a link between prostate specific antigen (PSA) and levels of blood cadmium (BCd) and urinary cadmium (UCd). Thus, these associations were investigated. We recruited 295 men, 50 years of age and above from a health check-up program at a health center as subjects of the study. They completed a self-reported questionnaire and provided fasting samples of blood and urine for cadmium assay. The assay was performed using atomic absorption spectrophotometry. Blood samples were also collected for the assays of total cholesterol and high-density lipoprotein measures. The means of BCd and UCd increased with age and the means of all subjects were 1.19 ± 1.04 μg L⁻¹ and 1.37 ± 1.76 μg g⁻¹ creatinine, respectively. The PSA levels were positively associated with the lipid levels, but reversely associated with BCd and UCd levels. The multivariate logistic regression analysis showed that men with PSA ? 4.0 ng mL⁻¹ had an odds ratio (OR) of 0.4 (95% CI = 0.1-0.9) to have BCd > 0.49 μg L⁻¹, and an OR of 0.4 (95% CI = 0.2-1.0) to have UCd > 0.45 μg g⁻¹ creatinine. In conclusion, the PSA levels are reversely associated with BCd and UCd levels.     

Changes in concentration of lead and cadmium in water from three rivers in Derbyshire

River water from three sites in different streams in Derbyshire was sampled during different periods within 1 year to evaluate fluctuations in cadmium and lead concentration. The results indicate that most of the cadmium was in solution, while most of the lead was associated with particles at all sites. Period of sampling appeared to have a greater effect on the concentration of cadmium and lead than flow rate: metal levels were higher in spring than in autumn. Nevertheless, the total lead concentration increased with flow rate, presumably because more particles were then brought into suspension; however, the lead concentration in the filtrate was reduced at higher flow rates, presumably due to dilution in the greater water volume. Dissolved cadmium concentration increased with rising flow rate at relatively low flow rates and was diluted at high flow rates. The data suggest that particles with which most of the lead is associated remain in suspension for a considerable time even when flow rate decreases.     

Anti-oxidative property of crude rice oil extracted from cadmium-contaminated rice

Local residents who habitually consume cadmium-contaminated rice (Oryza sativa L.) can be exposed to cadmium toxicity in Mae Sot District, Tak Province, Thailand. This study aimed to investigate an alternative for utilizing cadmium-contaminated rice without compromising their health with hazard risks. First, cadmium (Cd) concentration in rice grain and crude rice oil was determined (0.203 ± 0.030 and 0.007 ± 0.002 mgCd/kg dry weight, respectively). Then crude rice oil extracted from cadmium-contaminated rice grain was studied for its anti-oxidative property using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical scavenging approach. Next, quantitative analysis of γ-oryzanol in crude rice oil was conducted. Results indicated that the level of cadmium concentration in the rice grain could cause adverse effects on human health. However, the amount of cadmium in the crude rice oil was safe for consumption. In crude rice oil anti-oxidative property, crude rice oil extracted from cadmium-contaminated rice was significantly higher than the control (P < 0.05). The concentration of γ-oryzanol in crude rice oil extracted from cadmium-contaminated rice was significantly higher than that in the control crude rice oil (P < 0.05). This study demonstrates an alternative way to use the rice grown in cadmium-contaminated areas for crude rice oil production for its anti-oxidative properties.     

腐熟污泥对废水中Cd(Ⅱ)与Zn(Ⅱ)的吸附性能研究

利用腐熟污泥作为一种重金属吸附剂,考察其对水中重金属锌和镉的吸附过程.实验数据的拟合采用了Pseudo-first Order-和Pseudo-second Order 2种动力学模型以及Langmuir和Freundlich 2种吸附等温线模型;拟合结果表明,腐熟污泥对锌与镉的吸附过程符合Pseudo-second ...     

Determination of three cresol isomers in sewage sludge by solid-liquid extraction with low temperature purification and gas chromatography-mass spectrometry

Abstract

Cresols are chemical contaminants derivative from phenol which can be found in sewage sludge. However, little attention has been given to monitoring these compounds in environmental matrices in the literature. Thus, the objective of this study was to develop a simple method based on solid-liquid extraction with low temperature purification for determining three cresol isomers in sludge. The quantification of these compounds was performed by gas chromatography coupled to mass spectrometry with a previous derivatization step. After a detailed study, the cresol recovery was higher than 91%, with relative standard deviation lower than 12% and a limit of quantification of 20?μg kg^?1. Linearity was achieved between 10 and 90?μg L^?1 (R² > 0.98) with the standard solutions prepared in matrix extracts due to the trouble caused by the matrix effect. The proposed method was applied with success for monitoring cresols in sewage sludge samples coming from six different wastewater treatment plants. All samples showed contamination by cresols, mainly p-cresol with values between 32.3 and 516.9?μg kg^?1. The majority of the analyzed samples showed a total sum of the isomers higher than the maximum residue limit established by Brazilian legislation (160?μg kg^?1).     

Degradation dynamics,residues and risk assessment of Dufulin enantiomers in corn plants and corn by LC/MS/MS

ABSTRACT

The degradation dynamics and terminal residues of dufulin enantiomers were investigated in two typical corn plants. A convenient and precise chiral method by high-performance liquid chromatography coupled with tandem triple quadrupole mass spectrometry (HPLC/MS/MS) using a Chiralpak IC column was developed and validated for measuring dufulin enantiomers in corn plants and corn. The two enantiomers of dufulin quickly dissipated in the corn plant, and no noticeable stereoselectivity was observed during degradation or in the final residues. After 30% rac-dufulin wettable powder with a 1- to 1.5-fold dose of the recommended value was sprayed two to three times on corn plants, the residue levels of S-(+)-dufulin and R-(-)-dufulin in corn from both sites were lower than or equal to 0.0520 mg kg^–1 on days 7, 14 and 21 after the last application. The dietary risk assessment indicated that dufulin did not exhibit obvious dietary health risks in corn samples when good agricultural practices were implemented. The findings from this study may be used to better understand the chiral profiles of dufulin in the environment and the effect of dufulin residues in corn on health.     

Effect of Solids Concentration on Bacterial Leaching of Heavy Metals from Sewage Sludge

Abstract

Microbial metal leaching from sewage sludge (2-9% w/v) was carried out with the iron-oxidizing bacterium Thiobacillus ferrooxidans. Measurements of pH, oxidation-reduction potential, and concentration of Fe²⁺ indicated that T. ferrooxidans was effective in removing metals from an incubation bath containing less than 5% sludge solids concentration. Specifically, Cu leaching was completely suppressed at a high solids concentration of 9% (w/v). Results indicated that the deactivation of T. ferrooxidans at a high sludge content was mainly due to the presence of inhibiting materials such as organic matter. A mixed culture of sulfur-oxidizing bacteria was obtained by enrichment from anaerobically digested sewage sludge to enhance the efficiency of the microbial leaching process. These bacteria were much more effective in metal leaching than was iron-oxidizing T. ferrooxidans. At 9% (w/v) solids concentration, the leaching efficiencies of Zn and Cu were 78% (2.66 g/kg dry sludge) and 59% (1.36 g/kg dry sludge), respectively. Therefore, when removing heavy metals from the anaerobically digested sewage sludge, the indigenous sulfur-oxidizing bacteria isolated in the current study were more efficient than T. ferrooxidans, especially at high sludge solids concentrations.     

Lead,cadmium and mercury contents and bioaccumulation potential of wild edible saprophytic and ectomycorrhizal mushrooms,Croatia

ABSTRACT

Lead (Pb), cadmium (Cd), and mercury (Hg) contents in ten species of edible mushrooms in Trako??an, Croatia were determined. In addition, the similarity between the studied species was determined by cluster analysis. The caps and stipes of the fruiting bodies were analysed separately. The analyses were carried out by inductively coupled plasma - optical emission spectrometry (ICP-OES). The greatest mean lead concentrations of 1.91 and 1.60 mg kg ^?1 were determined in caps and stipes of Macrolepiota procera. The greatest mean concentrations of cadmium (3.23 and 2.24 mg kg^?1) were determined in caps and stipes of Agaricus campestris and of mercury (2.56 and 2.35 mg kg^?1) in Boletus edulis. In terms of the anatomical parts of the fruiting body (cap-stipe), a considerably greater concentration of the analysed elements was found in the cap for all mushroom species. According to calculated bio-concentration factors, all the examined species were found to be bio-accumulators of Cd and Hg. On the basis of the accumulation of the studied metals, great similarity of mushroom species belonging to the same genus and partial similarity of species of the same ecological affiliation was obtained by cluster analysis.