Establishing environmental background values of selected trace elements and environmental quality assessment of fi negrained sediments in the Jiaozhou Bay catchment,China

With the development of economy,the impact of human activities on ecological environment is increasing,and environmental protection work is important.Trace elements(Co,Ni,Cu,Pb,Zn,Cd,Cr,and Sc)in surface fi ne-grained sediment samples from the Jiaozhou Bay catchment were selected to evaluate their 2015 environmental background values and the environmental quality.Using statistical analysis,the environmental background values(ranges)of Sc,Co,Ni,Cu,Pb,Zn,Cd,and Cr were calculated,being 13.1(10.8-15.4),12.4(8.6-16.2),32.0(22.9-41.2),29.6(13.5-64.9),24.1(13.0-44.6),77.6(38.5-156.5),0.07(0.02-0.20),and 82.5(66.5-104.0)mg/kg,respectively.The enrichment factor,contamination factor,and pollution load index were used to evaluate the pollution status of the Jiaozhou Bay catchment.The environmental background values of most elements are higher than those of the upper continental crust and lower than those of global shale.At present,the pollution in the eastern Jiaozhou Bay is much higher than that in the western part.The results shall be helpful for future management for trace element pollution monitoring in the Jiaozhou Bay catchment.

Application of sewage sludge and intermittent aeration strategy to the bioremediation of DDT- and HCH-contaminated soil

Adding organic amendments to stimulate the biodegradation of pesticides is a subject of ongoing interest. The effect of sewage sludge on the bioremediation of dichlorodiphenyltrichloroethane(DDT) and hexachlorocyclohexane(HCH) contaminated soil was investigated in bench scale experiments,and intermittent aeration strategy was also used in this study to form an anaerobic–aerobic cycle. Bioremediation of DDT and HCH was enhanced with the addition of sewage sludge and the intermittent aeration. The removal rates of HCH and DDT were raised by 16.8%–80.8% in 10 days. Sewage sludge increased the organic carbon content from 6.2 to218 g/kg,and it could also introduce efficient degradation microbes to soil,including Pseudomonas sp.,Bacillus sp. and Sphingomonas sp. The unaerated phase enhanced the anaerobic dechlorination of DDT and HCH,and anaerobic removal rates of β-HCH,o,p′-DDT and p,p′-DDT accounted for more than 50% of the total removal rates,but the content of α-HCH declined more in the aerobic phase.

Reaction mechanism of arsenic capture by a calcium-based sorbent during the combustion of arsenic-contaminated biomass: A pilot-scale experience

Large quantities of contaminated biomass due to phytoremediation were disposed through combustion in low-income rural regions of China.This process provided a solution to reduce waste volume and disposal cost.Pilot-scale combustion trials were conducted for in site disposal at phytoremediation sites.The reaction mechanism of arsenic capture during pilot-scale combustion should be determined to control the arsenic emission in flue gas.This study investigated three Pteris vittata L.biomass with a disposal capacity of 600 kg/d and different arsenic concentrations from three sites in China.The arsenic concentration in flue gas was greater than that of the national standard in the trial with no emission control,and the arsenic concentration in biomass was 486 mg/kg.CaO addition notably reduced arsenic emission in flue gas,and absorption was efficient when CaO was mixed with biomass at 10% of the total weight.For the trial with 10% CaO addition,arsenic recovery from ash reached 76%,which is an ~8-fold increase compared with the control.Synchrotron radiation analysis confirmed that calcium arsenate is the dominant reaction product.

Identifying factors that influence soil heavy metals by using categorical regression analysis:A case study in Beijing,China

Identifying the factors that influence the heavy metal contents of soil could reveal the sources of soil heavy metal pollution.In this study,a categorical regression was used to identify the factors that influence soil heavy metals.First,environmental factors were associated with soil heavy metal data,and then,the degree of influence of different factors on the soil heavy metal contents in Beijing was analyzed using a categorical regression.The results showed that the soil parent material,soil type,land use type,and industrial activity were the main influencing factors,which suggested that these four factors were important sources of soil heavy metals in Beijing.In addition,population density had a certain influence on the soil Pb and Zn contents.The distribution of soil As,Cd,Pb,and Zn was markedly influenced by interactions,such as traffic activity and land use type,industrial activity and population density.The spatial distribution of soil heavy metal hotspots corresponded well with the influencing factors,such as industrial activity,population density,and soil parent material.In this study,the main factors affecting soil heavy metals were identified,and the degree of their influence was ranked.A categorical regression represents a suitable method for identifying the factors that influence soil heavy metal contents and could be used to study the genetic process of regional soil heavy metal pollution.

Review on remediation technologies for arseniccontaminated soil

Arsenic(As)is a top human carcinogen widely distributed in the environment.As-contaminated soil exists worldwide and poses a threat on human health through water/food consumption,inhalation,or skin contact.More than 200 million people are exposed to excessive As concentration through direct or indirect exposure to contaminated soil.Therefore,affordable and efficient technologies that control risks caused by excess As in soil must be developed.The presently available methods can be classified as chemical,physical,and biological.Combined utilization of multiple technologies is also common to improve remediation efficiency.This review presents the research progress on different remediation technologies for As-contaminated soil.For chemical methods,common soil washing or immobilization agents were summarized.Physical technologies were mainly discussed from the field scale.Phytoextraction,the most widely used technology for As-contaminated soil in China,was the main focus for bioremediation.Method development for evaluating soil remediation efficiency was also summarized.Further research directions were proposed based on literature analysis.

Concentration and speciation of arsenic in an insect feeding on the leaves of Pteris vittata

The development of an effective and green bioinsecticide is a research hotspot.This study demonstrated the possibility of using an arsenic(As)hyperaccumulator as a bioinsecticide.When the As concentration in the Pteris vittata fronds exceeded 138 mg kg^(–1),the larva of the hawk moth(Theretra clotho)displayed apparent preference to lower-As-concentration P.vittata fronds.The As concentration in the larva body was as high as 850 mg kg^(–1).Such high concentration of As in the larva body might have been the case that T.clotho lacks a process to exclude As.The larval frass showed an As concentration of only 1%–4%of that in the larva body.The predominant As species in the larva body and frass was As(III)-SH.The percentage of As(III)-SH was slightly higher in the frass than that in the larval body.Chelation with thiols may be a universal detoxification mechanism for As in both plants and insects.In general,the adoption of P.vittata as a bioinsecticide should be feasible.However,the exact processes to achieve this goal still need further study.The mechanism of different animals to detoxify As is another interesting research topic.