Impact of coal gangue on the level of main trace elements in the shallow groundwater of a mine reclamation area

Coal gangue is the most used filling material during reclamation of areas suffering subsidence from min- ing. Main trace element levels (F, As, Hg, and Pb) in shallow groundwater in the reclamation area may be affected by leaching from the gangue. This can has an impact on the application of the water for agricul- tural irrigation or use as drinking water. Therefore, it is of great significance to understand the effect coal gangue has on the shallow groundwater of a reclaimed area. We studied the effect of coal gangue on fluo- rine, arsenic, mercury, and lead levels in the shallow groundwater of a reclamation area by testing the water and the coal gangue. One well near the reclamation area was used as a control well and element levels in water from this well and from the soil next to the well were also measured. The results show that the levels of these elements are increasing in the reclamation area over time. The increase in fluorine, arsenic, mercury, and lead in monitor wells varies from 7.42% to 8.26%, from 7.13% to 7.90%, from 4.85% to 6.48%, and from 4.69% to 6.42%, respectively. Fluorine and arsenic levels are lower in monitor wells than in the control water. The other elements are found in greater concentration than in the control. The Nemerow index also indicates that the shallow groundwater in the reclamation area I is moderately affected by the back-filling coal gangue, while the shallow groundwater in the reclamation area II and III are slightly affected by the back-filling coal gangue. This shallow groundwater could be used for agri- cultural irrigation or for drinking.

Ecological Planning of Spartina alterniflora Invaded Tideland Based on Mechanical Mowing and Hydraulic Reclamation: A Case Study of Xihu Port in Xiangshan County

Spartina alterniflora is a major invasive plant in the coastal tideland of China that has serious negative impact on local economy and ecology.This paper took Hugang New Town in Xiangshan County,Zhejiang Province for example,concluded the method of controlling S.alterniflora by integrating mechanical mowing and hydraulic reclamation in view of the threatening expansion of this species and serious land shortage in the local area.Moreover,it explored the ecological planning method of reclamation area based on this method.In view of the ecological sensitivity of the reclamation area,urban ecological planning concept was introduced into both processes of the development:penetrative reclamation and urban planning.The reclamation project has to meet such requirements as site selection,scope,water surface ratio etc.,the planning ensures the ecological sustainability in functional orientation,spatial structure,green space system and development intensity.

Spatio-temporal dynamics of vegetation in Jungar Banner of China during 2000–2017

It is known that the exploitation of opencast coal mines has seriously damaged the environments in the semi-arid areas.Vegetation status can reliably reflect the ecological degeneration and restoration in the opencast mining areas in the semi-arid areas.Long-time series MODIS NDVI data are widely used to simulate the vegetation cover to reflect the disturbance and restoration of local ecosystems.In this study, both qualitative(linear regression method and coefficient of variation(CoV)) and quantitative(spatial buffer analysis, and change amplitude and the rate of change in the average NDVI) analyses were conducted to analyze the spatio-temporal dynamics of vegetation during 2000–2017 in Jungar Banner of Inner Mongolia Autonomous Region, China, at the large(Jungar Banner and three mine groups) and small(three types of functional areas: opencast coal mining excavation areas, reclamation areas and natural areas) scales.The results show that the rates of change in the average NDVI in the reclamation areas(20%–60%) and opencast coal mining excavation areas(10%–20%) were considerably higher than that in the natural areas(<7%).The vegetation in the reclamation areas experienced a trend of increase(3–5 a after reclamation)-decrease(the sixth year of reclamation)-stability.The vegetation in Jungar Banner has a spatial heterogeneity under the influences of mining and reclamation activities.The ratio of vegetation improvement area to vegetation degradation area in the west, southwest and east mine groups during 2000–2017 was 8:1, 20:1 and 33:1, respectively.The regions with the high CoV of NDVI above 0.45 were mainly distributed around the opencast coal mining excavation areas, and the regions with the CoV of NDVI above 0.25 were mostly located in areas with low(28.8%) and medium-low(10.2%) vegetation cover.The average disturbance distances of mining activities on vegetation in the three mine groups(west, southwest and east) were 800, 800 and 1000 m, respectively.The greater the scale of mining, the farther the disturbance distances of mining activities on vegetation.We conclude that vegetation reclamation will certainly compensate for the negative impacts of opencast coal mining activities on vegetation.Sufficient attention should be paid to the proportional allocation of plant species(herbs and shrubs) in the reclamation areas, and the restored vegetation in these areas needs to be protected for more than 6 a.Then, as the repair time increased, the vegetation condition of the reclamation areas would exceed that of the natural areas.

Carbon footprint of crop production in Heilongjiang land reclamation area,China

In the context of global warming,agriculture,as the second-largest source of greenhouse gas emissions after industry,had attracted widespread attention from all walks of life to reduce agricultural emissions.The carbon footprint of the planting production system of the Heilongjiang Land Reclamation Area(HLRA),an important commodity grain base in China,was evaluated and analyzed in this paper.On this basis,this paper sought feasible strategies to reduce carbon emissions from two aspects:agronomic practices and cropping structure adjustment,which were particularly crucial to promote the low-carbon and sustainable development of agriculture in HLRA.Therefore,using the accounting methods in IPCC and Low Carbon Development and Guidelines for the Preparation of Provincial Greenhouse Gas Inventories compiled by the Chinese government,relevant data were collected from 2000 to 2017 in HLRA and accounted for the carbon emissions of the planting production system in four aspects:carbon emissions from agricultural inputs,N_(2)O emissions from managed soils,CH_(4) emissions from rice cultivation and straw burning emissions.Then carbon uptake consisted of seeds and straws.Finally,with farmers'incomes were set as the objective function and carbon emissions per unit of gross production value was set as the constraint,this paper simulated and optimized the cropping structure in HLRA.The results showed that there was a“stable-growing-declining”trend in the total carbon emissions and carbon uptake of the planting production system in HLRA,with total carbon emissions of 2.84×10^(10) kg and total carbon uptake of 7.49×10^(10) kg in 2017.In the past 18 years,carbon emissions per unit area and carbon emissions per unit of gross production had both shown a decreasing trend.To achieve further efficiency gains and emission reductions in the planting production system,it was recommended that the local governments strengthen the comprehensive use of straw resources,optimize irrigation and fertilization techniques,and adjust the cropping structure,i.e.,increase the planting area of maize and soybeans and reduce the planting area of rice,and increase subsidies to protect the economic returns of planters.

Community structure of benthic macroinvertebrates in reclaimed and natural tidal flats of the Yangtze River estuary

Previous studies have found differences between communities of benthic macroinvertebrates living in constructed tidal flats compared with natural ones.We analyzed the distributional characteristics of benthic macroinvertebrates in a blowing sand reclamation area(Area A),a dike-building silting area(Area B),an out-ofsiltation area(Area C),and a natural tidal flat(Area D)in order to characterize the community structure and diversity of benthic macroinvertebrates in a human-disturbed estuarine tidal-flat wetland.A total of 32 benthic macroinvertebrate species were identified(Area A=7;Area B=12;Area C=10;Area D=27).The diversity index was variable where:Area B<Area C<Area A<Area D.A higher average annual abundance of benthic macroinvertebrates was found at Area B(840.43±569.23)ind/m^(2) than in Area D(203.00±5.85)ind/m^(2),Area A(42.87±10.21)ind/m^(2),and Area C(17.64±1.50)ind/m^(2).The biomass in Area C(3.18±0.39)g/m^(2) was lower than in the other areas.One-Way ANOVAs detected significant differences(P<0.05)in the abundance and biomass within Area B among seasons;however,there were no significant seasonal differences(P>0.05)in the abundance and biomass of Areas A,C,and D.An abundance/biomass curve showed that the habitat in Areas A,B,and C could be categorized as moderately disturbed,whereas Area D was categorized as undisturbed.The results of cluster analysis suggested distinct assemblages in the four sampling areas.Reclamation raised the altitude of tidal flats,weakening the tidal power and changing the physical and chemical parameters of the water,leading to a change in the community structure of benthic macroinvertebrates.