Effect of various phosphorus levels on the extraction of Cd, the transformation of P, and phosphorus-related gene during the phytoremediation of Cd contaminated soil.

Phytoremediation has emerged as a common technique for remediating Cd pollution in farmland soil. Moreover, phosphorus, an essential element for plants, can alter the pectin content of plant cell walls and facilitate the accumulation of Cd in plant tissues, thereby enhancing phytoremediation efficiency. Therefore, pot experiments were conducted in order to investigate the effect of phosphorus levels on Cd extraction, phosphorus transformation and phosphorus-related genes during phytoremediation. The results revealed that an optimal application of suitable phosphate fertilizers elevated the soil's pH and electrical conductivity (EC), facilitated the conversion of soil from insoluble phosphorus into available forms, augmented the release of pertinent enzyme activity, and induced the expression of phosphorus cycling-related genes. These enhancements in soil conditions significantly promoted the growth of ryegrass. When applying phosphorus at a rate of 600 mg/kg, ryegrass exhibited plant height, dry weight, and chlorophyll relative content that were 1.27, 1.26, and 1.18 times higher than those in the control group (P0), while the Cd content was 1.12 times greater than that of P0. The potentially toxic elements decline ratio and bioconcentration factor were 42.86% and 1.17 times higher than those of P0, respectively. Consequently, ryegrass demonstrated the highest Cd removal efficiency under these conditions. Results from redundancy analysis (RDA) revealed a significant correlation among pH, total phosphorus, heavy metal content, phosphorus forms, soil enzyme activity, and phosphorus-related genes. In conclusion, this study suggests applying an optimal amount of suitable phosphate fertilizers can enhance restoration efficiency, leading to a reduction in soil Cd content and ultimately improving the safety of crop production in farmlands.

Status and environmental management of soil mercury pollution in China: A review.

The harm from mercury pollution to human health and the environment has long been known. In recent years, the combination of industrial activities and long-term atmospheric transport has resulted in a sustained increase in mercury concentrations in soils. However, soil remediation and mercury-contaminated soil management in China are still in its infancy, and there is ample space for the development of related research. We systematically reviewed several pertinent topics and found that soil mercury pollution around mines and industrial soil in China is the most serious. The highest mercury content is found in the soil around the Tongren mercury mine in Guizhou Province and the thermometer factories. The average content of soil mercury is similar to that of atmospheric mercury emission in China. Mercury content in soil gradually decreases from the southeast to the northwest. In order to repair the mercury-contaminated soil, solidification and stabilization technology have been developed in China and applied in the engineering of restoration. In the future, we will study more effective stabilizer materials and select plants highly rich in mercury, to develop low-cost and high-repair-rate remediation technology. China has also developed a series of policies, regulations, and regulatory documents to manage mercury pollution, such as the Agricultural Land Standard and the Construction Land Standard. Compared with other countries, the screening values for soil mercury in China are relatively low. China has also established control standards for methylmercury in soils of residential and industrial land. In addition, China has issued emission standards and control notices related to the mercury industry. However, there are still shortcomings in soil remediation technology and environmental management systems for mercury pollution in China. In the future, China will formulate standards according to local conditions and improve the responsibility mechanism, financial mechanism, and level of public participation.

Soil contamination in China: Current priorities, defining background levels and standards for heavy metals.

The Chinese Government is working to establish an effective framework in managing soil contamination. Heavy metal contamination is key to the discussion about soil quality, health and remediation in China. Soil heavy metal contamination in China is briefly reviewed and the concepts of background values and standards discussed. The importance of contaminated land and its management for China food security and urbanization are discussed. Priorities for China's next steps in developing an effective research and management regime are presented. We propose that critically important to the science-based risk assessment of contaminants in soils is the incorporation of speciation and bioavailability into the measurement and evaluation criteria. Consideration of soil biology/ecological endpoints will be necessary to protect ecosystem health. National and regional/local scenarios of land use type/usage will address residential/urban re-use of industrial land as well as varying agricultural scenarios.

Syntheses, Structures, and Characteristics of Three Metal Complexes Constructed Using Hexacarboxylic Acid.

In this study, three new 3D coordination polymers (CPs), {[Cd3(L)(H2O)6]·H2O}n (1), {[Cu1.5(L)0.5(bimb)1.5]·5H2O·DMF}n (2), and {[Mn1.5(H3L)(bibp)0.5(H2O)2]·3H2O}n (3) (bimb= 1,3-bis(imidazol-1-yl)benzene, bibp= 1,4-bis((4-imidazol-1-yl)benzyl)piperazine), were prepared under solvothermal or hydrothermal conditions based on a hexadentate ligand (1,3,5-triazine-2,4,6-triamine hexa-acetic acid (H6L)). Structural elucidations were carried out by IR spectra along with single-crystal X-ray diffraction analysis, while thermogravimetric analysis (TGA) (dynamic and isothermal) and XRD techniques were used for property evaluations of the polymers. Furthermore, the fluorescence properties and detection of the Fe3+ ions in 1 were tested at room temperature, and the electrochemical behavior of 2 is also stated in this article.

Postnatal separation prevents the development of prenatal stress-induced anxiety in association with changes in oestrogen receptor and oxytocin immunoreactivity in female mandarin vole (Microtus mandarinus) offspring.

Oestrogen has both anxiogenic and anxiolytic effects because of variation in opposing action on alpha (ERα) and beta (ERß) estrogen receptors in the medial preoptic area (mPOA), bed nucleus of the stria terminalis (BNST) and medial amygdala (MeA). Oxytocin (OT) reverses some of the anxiogenic effects of oestrogen in the hypothalamic paraventricular nucleus (PVN) and supraoptic nucleus (SON). Because anxiety disorders are twice as common in women as in men, and oestrogen and OT are more important in females, we examined interactions between prenatal restraint stress (GS) and postnatal early short-term maternal separation (MS) and female mandarin vole behaviour, estrogen receptors and OT. The results show that adult female offspring from GS/noMS mothers showed increased anxiety in open-field and elevated plus-maze tests and had lower serum 17-beta-oestradiol (E2 ) levels than female offspring from GS/MS, noGS/MS and noGS/noMS mothers. GS/noMS females had more immunoreactive neurons for ERα in several brain regions and less ERß- and OT-immunoreactive neurons in brain areas compared to GS/MS, noGS/MS and noGS/noMS offspring. Interestingly, noGS/MS and GS/MS offspring were similar to noGS/noMS offspring in that they did not develop anxiety as adults. We propose that MS alters the serum concentration of E2 and that the ERß/ERα ratio and OT level in the brain may be responsible for the decrease in anxiety-like behaviour in adult female offspring initially exposed to anxiety-inducing conditions via an adverse foetal environment.

Distribution and integrated assessment of lead in an abandoned lead-acid battery site in Southwest China before redevelopment.

Lead-acid battery sites have contributed enormous amounts of lead to the environment, significantly affecting its global biogeochemical cycle and leaving the potential risks to human health. An abandoned lead-acid battery site prepared for redevelopment was selected in order to study the distribution of lead in soils, plants, rhizosphere soils and soil solutions. In total, 197 samples from 77 boreholes were collected and analyzed. Single extractions by acetic acid (HOAc) were conducted to assess the bioavailability and speciation of lead in soils for comparison with the parts of the plants that are aboveground. Health risks for future residential development were evaluated by the integrated exposure uptake biokinetic (IEUBK) model. The results indicated that lead concentrations in 83% of the soil samples exceeded the Chinese Environmental Quality Standard for soil (350 mg/kg for Pb) and mainly occurred at depths between 0 and 1.5 m while accumulating at the surface of demolished construction waste and miscellaneous fill. Lead concentrations in soil solutions and HOAc extraction leachates were linked closely to the contents of aboveground Broussonetia papyrifera and Artemisia annua, two main types of local plants that were found at the site. The probability density of lead in blood (PbB) in excess of 10 µg/dL could overtake the 99% mark in the residential scenario. The findings provided a relatively integrated method to illustrate the onsite investigations and assessment for similar sites before remediation and future development from more comprehensive aspects.

Screening of herbaceous plants for peat-enhanced rehabilitation of contaminated soil with oily sludge.

A batch pot experiment using nine herbaceous species were conducted for peat enhanced rehabilitation of contaminated soil with oily sludge in the initial contents of 0%, 1.3%, 7.4%, and 12.2%, respectively. The results showed that petroleum hydrocarbons removal, plant growth indices and enzyme activities varied depending on plant species and oil contents. Cotton, ryegrass and tall fescue were effective in the rehabilitation of oily sludge contaminated soils. The total petroleum hydrocarbon (TPH) removal ranged from 30.0% to 40.0% after 170 days of treatment. Plant biomass was shown to be the preferred indicator for screening phytoremediation plant because it was closely correlated with TPH removal and enzyme activities. Peat-enhanced plant rehabilitation could be a good strategy for the treatment of oily sludge contaminated saline soils.

Characterization and assessment of contaminated soil and groundwater at an organic chemical plant site in Chongqing, Southwest China.

Contamination from organic chemical plants can cause serious pollution of soil and groundwater ecosystems. To characterize soil contamination and to evaluate the health risk posed by groundwater at a typical organic chemical plant site in Chongqing, China, 91 soil samples and seven groundwater samples were collected. The concentrations of different contaminants and their three-dimensional distribution were determined based on the 3D-krige method. Groundwater chemistry risk index (Chem RI) and cancer risk were calculated based on TRIAD and RBCA models. The chemistry risk indices of groundwater points SW5, SW18, SW22, SW39, SW52, SW80, and SW82 were 0.4209, 0.9972, 0.9324, 0.9990, 0.9991, 1.0000, and 1.0000, respectively, indicating that the groundwater has poor environmental status. By contrast, the reference Yangtse River water sample showed no pollution with a Chem RI of 0.1301. Benzene and 1,2-dichloroethane were the main contaminants in the groundwater and were responsible for the elevated cancer risk. The cumulative health risk of groundwater points (except SW5 and SW18) were all higher than the acceptable baselines of 10(-6), which indicates that the groundwater poses high cancer risk. Action is urgently required to control and remediate the risk for human health and groundwater ecosystems.

Temporal Changes in Microbial Metabolic Characteristics in Field-Scale Biopiles Composed of Aged Oil Sludge.

Disposal of oil sludge, a hazardous waste, is currently a prevalent environmental issue. In this study, two field-scale biopiles were constructed to explore the temporal changes of microbial metabolic characteristics during the biotreatment of aged oil sludge. Bulking agent was mixed thoroughly with oily sludge to form a treated pile. The BIOLOG™ system was used to analyze the community level physiological parameters, including microbial metabolic activity, diversity, and variance. In comparison with the control, the community level physiological parameters of the treated pile were dramatically improved. Microbial metabolic activity of the treated pile was improved by 25.06% calculated from the maximums during the treatment. Microbial diversity index (Shannon index) ranges were improved from 1.64-3.02 (control pile) to 2.34-3.14 (treated pile). The numbers of petroleum-degrading bacteria and the total heterotrophic bacteria were correlated with the environmental temperature, and microbial metabolic characteristics in the treated pile revealed the distinctive carbon resources selection with the addition of cotton stalk. Temporal microbial metabolic characteristics, which have important effect on bioremediation, were revealed in this study.

Fractal geometry of fingering front morphologies of water and NAPL flow in homogeneous porous media: A comparison study.

Fingering front morphologies for water and non-aqueous phase liquids (NAPLs) infiltrating into homogeneous unsaturated porous media were quantitatively described based on the fractal assumption. Correlations of fractal dimensions with physical properties of the fluids were studied. The implications of fractal dimensions for environmental systems are further discussed. Fingering front morphologies had fractal properties, and diesels which with high capillary numbers experienced high fractal dimensions than water. Fractal dimension was suggested as an indicator for dye coverage and infiltration depth, which represent pollution area and depth, respectively. The pollution areas showed positive correlations with fractal dimensions while the infiltration depths showed negative correlations. This information is useful for contaminated soil risk management and important in the effective design of recovery and remediation schemes.