Heavy metal pollution in China: Origin, pattern and control

Goal, Scope and Background. Heavy metal is among one of the pollutants, which cause severe threats to humans and the environment in China. The aim of the present review is to make information on the source of heavy metal pollution, distribution of heavy metals in the environment, and measures of pollution control accessible internationally, which are mostly published in Chinese. Methods. Information from scientific journals, university journals and governmental releases are compiled focusing mainly on Cd, Cu, Pb and Zn. Partly Al, As, Cr, Fe, Hg, Mn and Ni are included also in part as well. Results and Discussion. In soil, the average contents of Cd, Cu, Pb and Zn are 0.097, 22.6, 26.0 and 74.2 mg/kg, respectively. In the water of. the Yangtze River Basin, the concentrations of Cd, Cu, Pb and Zn are 0.080, 7.91, 15.7 and 18.7 pg/L, respectively. In reference to human activities, the heavy metal pollution comes from three sources: industrial emission, wastewater and solid waste. The environment such as soil, water and air were polluted by heavy metals in some cases. The contents of Cd, Cu, Pb and Zn even reach 3.16, 99.3, 84.1 and 147 mg/kg, respectively, in the soils of a wastewater irrigation zone. These contaminants pollute drinking water and food, and threaten human health. Some diseases resulting from pollution of geological and environmental origin, were observed with long-term and non-reversible effects. Conclusions. In China, the geological background level of heavy metal is low, but with the activity of humans, soil, water, air, and plants are polluted by heavy metals in some cases and even affect human health through the food chain. Recommendations and Outlook. To remediate and improve environmental quality is a long strategy for the polluted area to keep humans and animals healthy. Phytoremediation would be an effective technique to remediate the heavy metal pollutions.

Effect of desert soil algae on the stabilization of fine sands

Four filamentous cyanobacteria, Microcoleus vaginatus, Phormidium tenue, Scytonema javanicum (Kutz.) and Nostoc sp., and a single-celled green alga, Desmococcus olivaceus, all isolated from Shapotou (Ningxia Hui Autonomous Region of China), were batch cultured and inoculated onto unconsolidated sand in greenhouse and field experiments. Their ability to reduce wind erosion in sands was quantified by using a wind tunnel laboratory. The major factors related to cohesion of algal crusts, such as biomass, species, species combinations, bioactivity, niche, growth phase of algae, moisture, thickness of the crusts, dust accretion (including dust content and manner of dust added) and other cryptogams (lichens, fungi and mosses) were studied. The best of the five species were M. vaginatus and P. tenue, while the best mix was a blend of 80% M. vaginatus and 5% each of P. tenue, S. javanicum, Nostoc sp. and D. olivaceus. The threshold friction velocity was significantly increased by the presence of all of the cyanobacterial species, while the threshold impact velocity was notably increased only by the filamentous species. Thick crusts were less easily eroded than thin crusts, while biomass was more effective than thickness. Dust was incorporated best into Microcoleus crust when added in small amounts over time, and appeared to increase growth of the cyanobacterium as well as strengthen the cohesion of the crust. Microbial crust cohesion was mainly attributed to algal aggregation, while lichens, fungi and mosses affected more the soil structure and physico-chemical properties.

A column method for determination of soil organic partition coefficients of eight pesticides

A column method was developed to conveniently and reliably determine the soil organic partition coefficients (K-oc) of three insecticides (methiocarb, azinphos-methyl, fenthion), four fungicides (triadimenol, fuberidazole, tebuconazole, pencycuron), and one herbicide (atrazine), in which real soil acted as a stationary phase and the water solution of pesticide as an eluent. The processes of sorption equilibrium were directly shown through a breakthrough curve(BTC). The log K-oc values are 1.69, 1.95, 2.25, 2.55, 2.69, 2.67, 3.10, and 3.33 for atrazine, triadimenol, methiocarb, fuberidazole, azinphos-methyl, tebuconazole, fenthion and pencycuron, respectively.

INFLUENCE OF LINEAR ALKYLBENZENE SULFONATE (LAS) AS ORGANIC COSOLVENT ON LEACHING BEHAVIOR OF PCDD/FS FROM FLY-ASH AND SOIL

The leaching of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) was measured in soil and standard fly ash column eluted with pure water and linear alkylbenzene sulfonate (LAS)- water. The data obtained were used to evaluate the leachability of PCDD/Fs from waste dump like incineration residual slag and fly ash deposition. The leaching rate was shown to be increased significantly by using LAS water. The leachate contents of PCDD/Fs were above their known water solubility. Concentration of PCDD/Fs in the leachates as well as the relative leaching (calculated on the fly ash content) increased with increasing chlorinating degree and decreasing water solubility. LAS above the critical micelle concentration (CMC) probably enhances PCDD/Fs solubility.

施肥措施对黄土旱塬区小麦产量和土壤有机碳积累的影响

利用中国科学院长武农田生态试验站的长期田间试验(1984年2~007年),研究了小麦产量,耕层有机碳变化,评价了土壤管理和气候因素对土壤有机碳(Soil organic C,SOC)变化的影响。研究涉及6个处理:休闲地(F);不施肥(CK);有机肥(M);氮肥(N);氮、磷肥(NP)和氮、磷、有机肥(NPM)处理。结果表明,施肥可以显著提高作物产量和SOC积累,CK、M、N、NP、NPM处理平均产量依次为1.5、2.6、2.0、3.3、4.0 t/hm2,2007年F、CK、M、N、NP、NPM处理0—20 cm土层SOC积累量依次为-1.09、0.76、8.59、1.02、3.42和9.5 t/hm2。作物产量与SOC含量呈显著的正相关关系(r=0.80),有机碳输入量与SOC含量相关性更好(r=0.97),外源有机碳的输入也是提高SOC的重要措施。施肥措施对作物固碳和SOC影响存在显著(P<0.05)差异。土壤固碳速率(Y)与SOC输入量(X)符合线性方程Y=0.231X-0.0813(r=0.98)。施肥可以提高黄土高原半干旱地区土壤生产力和SOC的积累,且无机肥和有机肥配施效果最佳。

施肥对黄土旱塬区黑垆土土壤肥力及硝态氮累积的影响

本文以长期定位试验为依托,研究了黄土高原旱塬区黑垆土大田对比试验和长期定位施肥对土壤肥力及硝态氮累积和淋溶的影响。结果表明:长期施用有机肥能够明显增加土壤养分,氮磷和有机肥配施效果显著;和1984年土壤养分状况相比,大田对比试验土壤有机质增加了27.1%,全氮和全磷提高了84.2%和34.8%,有效氮、有效磷和速效钾增加了46.9%、540.0%和10.2%,养分水平与长期定位试验中氮磷配施相近。长期定位试验中氮磷配施或与有机肥配施能够有效地减少土壤剖面中硝酸盐的累积和淋溶,氮肥单施硝态氮累积量最大,为1006.4kg/hm2,大田对比试验土壤硝态氮总累积量较长期定位试验中施用氮肥处理的总累积量少。

长期连续种植苜蓿草地地上部分生物量与土壤水分的空间差异性

基于苜蓿长期连续种植定位试验,研究了不同施肥与采样位置差异对苜蓿草地地上部分生物量和土壤水分的影响。苜蓿长期连续种植19年后,施肥对苜蓿地上部分生物量的影响不显著;试验样地内呈由外及内植株高度逐渐下降、地上部分生物量积累逐渐减小的"生物漏斗"现象,距样地中心位置不同引起的差异远远超过施肥处理引起的差异。中下层土壤水分也呈类似的漏斗状分布。相关分析表明,苜蓿地上部分生物量与1 m以下土壤水分含量呈显著相关,表明在长期连续种植条件下下层土壤水分状况是决定苜蓿草地生长状况的主要因素。