Xiaoli Bi

Coastal Projects in China: From Reclamation to Restoration

C reclamation has expanded land resources and living spaces and contributed significantly to the economic growth and urbanization process in Netherlands, Japan, South Korea, and China. From the 1950s to the 1990s, China witnessed three important phases of coastal reclamation, mainly for agriculture, salt production, and mariculture, respectively. At that time, over 30% of tidal land was reclaimed. After the 1990s, a new circle of coastal reclamation started to meet the needs of rapid urban expansion at various city levels. According to an official report from China Oceanic Information Network in 2010, the authorized area of reclaimed land was 13 598.74 ha, accounting for 7.03% of the nation’s sea-use area that year (State Oceanic Administration People’s Republic of China, 2011, Figure.1). Particularly, current flourishing reclamation projects at national level, such as Tianjin new coastal district, Caofeidian Industrial Zone in Tangshan City of Hebei Province and the Yellow River Delta High-efficiency Economic Zone in Dongying City of Shandong Province, are expected to push forward the rural−urban transformation greatly for both regional and national development, making the Bohai Bay a new hotspot for coastal reclamation in the coming decades, after East and South China. Compared with reclamation activities before the 1990s, today’s projects are not only to enclose the tidal flats but also to fill in the wetland/coastal water bodies using civil materials. The reclaimed land has been constructed into harbor, seawall, industrial complex, urban district, which will permanently change the geomorphology of the coastal line and the physical processes of the coastal system, exerting even higher impacts on coastal environment and ecosystem. For instance, certain natural interactions, such as the hydrodynamics and sediment processes, between land and sea have been seriously interrupted, leading to shortening of salinity gradient and increase of water eutrophication and pollution, which ultimately results in algae bloom, biodiversity decline and even seawater intrusion. Now, reclamation has increasingly emerged as a hot issue in coastal zones of China. However, several gaps remain in the environmental monitoring after reclamation. Here, we aim at improving the efficiency of long-term and multiple-scale systems for monitoring and managing potential effects of reclamation projects. First, environmental monitoring should be focused on hydro-morphology, eutrophication and pollution as well as organisms in the changing water and sediment systems. The cases from the Northland can provide us with insights into environmental monitoring, such as selection of typical environmental indicators for both abiotic and biotic systems influenced by reclaimed activities. The dominant factors on the coastal environment are variable because of the variety of reclamation activities. For instance, reclamation activities in the Yellow River Delta were carried out mainly for oil industry, so more attention should be paid to the monitoring and assessment of the effects of oil pollution on seawater and sediments. Second, based on the common sample site investigation, spatial pattern of environmental changes should be identified to understand coastal ecosystem responses to the environmental changes at a large scale. Modern geospatial technologies, such as remote sensing and geographic information systems can provide alternative approaches. Time series remotely sensed images can be an ideal data source for retrieving the spatiotemporal information on water quality and soil conditions after reclamation, thus help reveal the underlying mechanism for environmental evolution after reclamation. Finally, reclamation confines the natural area to a narrowed stretch of beach, which has been exacerbated by the sea-level rise induced by global climate change. However, the effects of sea-level rise have been underestimated in most reclamation projects in China. Therefore, we should adopt an integrated study to understand the trend of coastal develop-

Soil Security Is Alarming in China's Main Grain Producing Areas

F production and security is an important thing for China. However, the extensive agriculture practices with high input of chemical materials in the past also brought serious threats to the ecosystem and public health. Since Guangzhou Food and Drug Administration reported on May 16, 2013 that the content of cadmium (Cd) in 44.44% of sampled rice and rice production was above national standards, this event of “Cd toxicity in rice” has caused widespread public concern and anxiety, and China’s food security derived from contaminated soils has been highlighted. In fact, prior to this, more serious problems in today’s China soils were probably overlooked. 76% of Chinese grain was from its main producing areas, such as Henan, which produced 9.7% of national grain in only 6.5% of the country’s arable land. Thus, the soil health of main grain producing areas is a key to food supply to China, even to the international market. Especially, the toxic rice reported was mainly from Hunan and Jiangxi, two of China’s main grain producing areas. In this sense, the safety assessment of China’s food production arising from unhealthy soil environment of main grain producing areas is urgent. High production in China’s main grain producing areas was obtained at a great cost of resources such as fertilizers, pesticides, and agriculture-used films. Figure 1 showed the consumption of fertilizers, pesticides, and agriculture-used films from 1978 to 2008 in Henan. Obviously, this consumption was extremely large, and was increasing markedly with time. Overuse of chemical fertilizers, especially N fertilizers, contributed substantially to the soil acidification of those main grain producing areas. Further, intensive chemical fertilizers combination with agriculture-used films resulted in the accumulation of salinity in facility culturing soils, among which the secondary salinization of soils became the predominant problem. Additionally, the mass remains of used agriculture films especially conventional polyethylene mulches in surface soils would cause serious “white pollution” due to their nondegradability. These changes strongly affected soil quality and its productivity. Above all, soils of the main grain producing areas were probably contaminated by longterm excessive use of fertilizers, pesticides, and agriculture-used films, which could threaten national food security. Therefore, it is time for us to pay utmost attention to checking the soil health of China’s main grain producing areas. Ensuring the soil security of China’s main grain producing areas is of crucial importance for a safe food supply. After the alarming overdevelopment for more than 30 years, it is time for us to improve soil quality and maintain soil health in those areas. First, a comprehensive soil environment survey should be conducted to develop a detailed background information of the national soil environment. The good news is Central People’s Government has authorized this survey in early 2013. Second, decreasing input of chemicals and improving resource use efficiency will ensure soil quality. For example, the consumption of fertilizers (pure nutrients) in Henan in 2008 reached 835.4 kg/ha (Figure 1), far above average of the world (116.6 kg/ha). These inputs of chemical materials could be greatly reduced without a decrease in crop productivity. Third, regulating agriculture systems maybe be necessary in those degraded arable lands such as long-term vegetable and fruit planting bases (for example, Shouguang and Yantai, respectively), where serious salinization and acidification occurred, respectively. A simple and feasible strategy is using intercrop and/or rotation among vegetable, fruit, and grain. Fourth, contaminated arable lands must be remediated. After remediation by application of existing technologies, and assessment of the security of the whole soil−plant system, food crops could be allowed to be planted in these arable lands. In order to produce more and safer food, establishing a sustainable agriculture system in China’s main grain producing areas is necessary and urgent. Under increasing population pressure and environmental strain, Chinese soil scientists are facing many unprecedented challenges such as how to maintain and improve soil productivity, thereby avoiding soil contamination or degradation.

Seasonal changes in soil TN and SOC in a seawall-reclaimed marsh in the Yellow River Delta, China

Coastal salt marsh has been globally fragmented by man-made coastal seawalls. However, the dynamic changes in community structure and abiotic environments in these regenerated marsh after seawall reclamation are largely unknown. We analyzed the seasonal changes of soil nutrient pools and the direction effects on them. The results showed that soil total nitrogen (TN) has decreased but soil organic carbon (SOC) has increased from May to September. Direction has influenced the patterns and seasonal changes in soil TN and SOC. The potential influencing factors have been largely contributed to soil salinity reduction, vegetation growth, microorganism activities with different seasonal characteristics. Researches on seasonal dynamic of marsh regeneration after seawall reclamation can provide us helpful information to understand mechanism of marsh restoration and design coastal marsh restoration projects.

Estimating soil salinity in different landscapes of the Yellow River Delta through Landsat OLI/TIRS and ETM plus Data

Soil salinization has increasingly become a serious issue in coastal zone due to global climate changes and human disturbances. Assessment of soil salinity, especially at the landscape scale, is critical to coastal management and restoration. Two data from OLI/TIRS and ETM+ sensors of Landsat satellite were used to compare their ability to invert the spatial pattern of soil salinity in both farmland and salt marsh landscapes in the Yellow River Delta, China, respectively. The results showed that the in situ electrical conductivity (ECa) of soil, representing soil salinity, were closely related with spectral parameters and salinity indices calculated by the remote sensing data. The results of multiple regression models have showed that nearly all the spectral parameters and salinity indices calculated by OLI/TRIS data were more sensitive to soil salinity than those by ETM+ data. Therefore, the models based on OLI/TIRS data are superior to those on ETM+ data in estimating the spatial pattern of soil salinity in farmland and salt marsh landscapes. Our results were very helpful to evaluate the levels of soil salinization in the Yellow River Delta.

Trends in Moisture Index, Farmland Area, and Their Combined Effects on Grain Production in Northern China

China policies and Grain-for-Green Project have led to changes in farmland area and grain production. Climate change was also occurring during this period. To analyze the effects of land use and climate change on grain production, the area of farmland in northern China during 1988-2008 was determined from remote sensing images, a moisture index (MI) was calculated from daily meteorological data obtained from weather stations, and unit grain production was obtained from statistical yearbooks. Using statistical and spatial analyses, we determined that MI decreased across most of the study area during this period. This decrease in humidity caused humid zones to decrease and semiarid areas to increase. Combined effects of decreased humid area and conversion of farmland resulted in a decrease in agricultural land in humid areas and an increase in semiarid and arid areas. Increases in unit grain production, machine power, and irrigated farmland area led grain production to increase from 122,799,081 to 188,532,597 ton in humid areas, from 28,875,900 to 115,976,814 in semiarid areas, and from 7,622,100 to 15,490,026 in arid areas, respectively. Increased unit grain production and farmland resulted in increased importance of semiarid areas for grain production.

Nuclear power plants in China’s coastal zone: risk and safety

Nuclear power plants are used as an option to meet the demands for electricity due to the low emission of CO2 and other contaminants. The accident at the Fukushima nuclear power plant in 2011 has forced the Chinese government to adjust its original plans for nuclear power. The construction of inland nuclear power plants was stopped, and construction is currently only permitted in coastal zones. However, one obstacle of those plants is that the elevation of those plants is notably low, ranging from 2 to 9 meters and a number of the nuclear power plants are located in or near geological fault zones. In addition, the population density is very high in the coastal zones of China. To reduce those risks of nuclear power plants, central government should close the nuclear power plants within the fault zones, evaluate the combined effects of storm surges, inland floods and tidal waves on nuclear power plants and build closed dams around nuclear power plants to prevent damage from storm surges and tidal waves. The areas without fault zones and with low elevation should be considered to be possible sites for future nuclear power plants if the elevation can be increased using soil or civil materials.

Using local knowledge to map crop types and other land use/cover types with a limited number of TM images in Shandong Peninsula, China

Information on the crop types is necessary for the studies on global food security and other environmental problems. Fields of crop types are distinguished by images for special periods of planting, growing and harvesting from other LULC types. Series of Landsat satellites can provide high quality images during those special periods. With the local knowledge of crop calendar, we calculated Normalized Difference Vegetation Index during the special periods to identify crop and other LULC types. The resultant TM-derived crop and other LULC type map were evaluated using check points and land registration data from government. The accuracy assessment proved that our area estimates of crop and other LULC types were at high level. The results of this study indicated that our algorithm could be applied at large spatial extents to map crop and other LULC types with limited images.