A simulation analysis of the migration and transformation of pollutants contained in landfill leachate

A dynamic composite model for a soil-water system that can be used to simulate the movement of leachate from a landfill. The composite model includes nine sub-models that trace water movement and the migration and transformation of five pollutants(organic N, NH - 4, NO - 3, NO - 2, and Cl -) in saturated and unsaturated soil. The model to simulate the movement of leachate from a landfill in Laogang Town, Shanghai City was used. In this application, the values for the model parameters were obtained by performing a laboratory simulation experiment of water movement and pollutant migration and transformation in soil columns. Soil and leachate obtained from the landfill site and its vicinity were used in the laboratory experiments. The model was then used to simulate leachate movement and pollutant activity during the ten-year period when the landfill was in operation and in the twenty-year period following its closure. The simulation results revealed that the leachate migrated into the groundwater at the rate of 90—100 meters per year. This model can be applied in the design of future landfills in China for the purpose of assessing and forecasting leachate plumes.

Geological environment impact analysis of a landfill by the Yangtze River

In order to assess the geological environment impact of a city landfill by the Yangtze River, soils from different depths in the dumpsite were sampled and analyzed. It was found that pollutants content at the site was distinctly higher than that in nearby environments. The content of heavy metals, such as Cd, Hg, As, Pb and Cu, reduces as depth increases; the content of elements F, Cl and N is the contrary. Pollutants migration driven by underground water flow was analyzed, considering the hydro-geological conditions of the site. It is believed that, due to leaching after rainfall infiltration, pollutants in the garbage layer migrates deeper, the cohesive soil in the underlying surface prevents them from spreading to the deeper aquifer; additionally, the high pressure tolerance of the deep groundwater is a key factor in preventing pollutants from entering the aquifer. Furthermore, human control has reduced the annual fluctuation range of water level in nearby rivers, weakening the hydrodynamic relations with phreatic water, and thus reducing the spreading of pollutants to nearby surface waters.

Protecting wild yak (Bos mutus) species and preventing its hybrid in China

China has made efforts to protect wild yak （Bos mutus） species and prevent the hybrids between wild yak and domestic yak （Bos grunniens） species.At present,wild yak population of a reasonable estimate would be over 70,000.Due to conservation efforts in environmental protection and ecological construction such as the Wildlife Protection and Nature Reserve Construction Project,the ＂Grain-for-Green＂ Project and the Natural Forest Resources Protection Project,the number of wild yaks is increasing.In general,Tibetan Plateau＇s ecosystem is getting better and its environmental quality shows a gradual improving trend.Tibetan Plateau is one of the world＇s cleanest regions called as the ＂Third Pole＂.In order to preserve the genetic pool of wild yaks,local pastoralists and polices drive off the wild male yaks from the domestic yak herds by making noise （banging washbasins,pots,etc.） or driving cars.Local government also incentivizes the culling of domestic yaks found in wild herds.For the sake of the biological and genetic features of this wild species,and the pastoralist way of life,wild yaks should continuously be protected to keep their genetic integrity.We appeal plans to investigate the gene pollution of wild yaks in some important distribution regions of this species.In the face of hybridizing with domestic yaks,proper guidance is urgently needed to address genetic pollution and protect the genetic integrity of wild yaks.

Impact of drilling waste pollution on land cover in a high subarctic forest-tundra zone

Global climate changes can lead to the destruction of the permafrost zone and contribute to the active transfer of pollutants to natural waters.This can be especially pronounced in the areas of oil and gas production in the Arctic.This study aimed to define the landscape components(i.e.,groundwater,soil water,soil,and indicator plant species)of chemical pollution with metals,oil hydrocarbons,and polycyclic aromatic hydrocarbons,from the discharge of drill cuttings.Studies at two sites in the forest-tundra zone of Western Siberia(Russia)were carried out within two years of pollution.Pollutant migration was found in peaty-gley heavy loamy soils and iron-illuvial clayey podburs,but lateral migration of different pollutants did not exceed 200 m.Additionally,radial migration was practically absent owing to the high buffering capacity of the soil organic horizon and the upward flow of matter in the seasonal melt layer.The main indicators of drilling waste pollution were high concentrations of Sr,Ba,petroleum hydrocarbons,and Cl^(-)ions.At the waste disposal sites,the concentration of Ba and Sr in the soil water were 1150 and 1410μg L^(-1),respectively;in groundwater,they reached 721 and 2360μg L^(-1),respectively.In the soil,Ba and Sr accumulated in the peaty horizon(798 and 706 mg kg^(-1),respectively).The concentration of Cl^(-)ions in the soil water at the site of waste discharge was 1912 mg L^(-1),and at a distance of 200 m,it decreased to 77.4 mg L^(-1).The Cl^(-)concentration in the groundwater was lower,and at a distance of 200 m,it was 38.9 mg L^(-1).The highest concentration of petroleum hydrocarbons in the surface layer was found in the peaty-gley soils(up to 2400 mg kg^(-1)).In glandular-illuvial podburs,it was 420 mg kg^(-1).In horizons BH and BC,it was close to the background values(27 and 33 mg kg^(-1),respectively).Alkalinization of soils and water under the influence of drill cuttings led to the death of oligotrophic and acidophilic vegetation at a distance of up to 50 m,and to the restructuring of the species and spatial structure of plant communities up to 100 m.