Reconstruction of atmospheric concentrations and deposition of uranium and decay products released from the former uranium mill at Uravan, Colorado

Radionuclide concentrations in air from uranium milling emissions were estimated for the town of Uravan, Colorado, USA and the surrounding area for a 49-yr period of mill operations beginning in 1936 and ending in 1984. Milling processes with the potential to emit radionuclides to the air included crushing and grinding of ores; conveyance of ore; ore roasting, drying, and packaging of the product (U(3)O(8)); and fugitive dust releases from ore piles, tailings' piles, and roads. The town of Uravan is located in a narrow canyon formed by the San Miguel River in western Colorado. Atmospheric transport modeling required a complex terrain model. Because historical meteorological data necessary for a complex terrain model were lacking, meteorological instruments were installed, and relevant data were collected for 1 yr. Monthly average dispersion and deposition factors were calculated using the complex terrain model, CALPUFF. Radionuclide concentrations in air and deposition on ground were calculated by multiplying the estimated source-specific release rate by the dispersion or deposition factor. Time-dependent resuspension was also included in the model. Predicted concentrations in air and soil were compared to measurements from continuous air samplers from 1979 to 1986 and to soil profile sampling performed in 2006. The geometric mean predicted-to-observed ratio for annual average air concentrations was 1.25 with a geometric standard deviation of 1.8. Predicted-to-observed ratios for uranium concentrations in undisturbed soil ranged from 0.67 to 1.22. Average air concentrations from 1936 to 1984 in housing blocks ranged from about 2.5 to 6 mBq m(-3) for (238)U and 1.5 to 3.5 mBq m(-3) for (230)Th, (226)Ra, and (210)Pb.     

Exploring trends, sources, and causes of environmental funding: a study of Florida counties

Florida is one of the largest spenders on the environment in the U.S. Employing a database from Florida counties, this study examines two distinct environmental funding areas in government: funding to protect the environment, and funding to develop the environment. These two types of funding serve different purposes, support different activities and operations, and draw from different revenue sources. The results show that environmental funding in government is a response to the environmental pressure generated by economic activities and population growth. Counties with a higher level of manufacturing and farming activity spend more to protect the environment, while counties with higher population densities spend more to develop the environment. Moreover, counties with more funding for public safety and economic development activities spend less on the environment, indicating that environmental funding is influenced by the political processes in public budgeting in which diversified interests compete for resources. These results show that environmental spending in government is the result of combined forces arising from environmental pressure and budgetary politics.     

Long-term phosphorus fertility in wastewater-irrigated cropland

Land treatment of municipal wastewater effluent is a proven method for augmenting freshwater resources and avoiding direct nutrient discharges to surface waters. We assessed changes in soil test phosphorus (P) of the Ap horizon of cropped fields continuously irrigated for 26 yr with secondary effluent from the Penn State University wastewater treatment plant. For annual P additions averaging 97 kg P ha(-1), Mehlich-3 P (M3P) response in the 0- to 20-cm surface soil (initially < 20 mg kg(-1)) was represented by two lines. For the first 12 yr of irrigation, soil test P increased, with 14.5 kg P ha(-1) needed to increase M3P by 1 mg P kg(-1). After the initial buildup, M3P maintained a quasi-steady-state value of approximately 110 mg kg(-1). Over time, the surface soil equilibrium P concentration at zero sorption increased markedly (from < 1 to 5.5 mg P L(-1)), and extractable aluminum (Al) decreased significantly (P < 0.001). Speciation modeling using Visual MINTEQ suggests complexation of Al by dissolved organic carbon at site pH conditions. Loss of Al from the surface layer lowered its P-sorbing capacity, causing added effluent-P to move into the subsoil. Results suggest that current management practices can continue for many years without exceeding the surface soil M3P environmental threshold (200 mg kg(-1)) used in state P-based nutrient policies.     

Real-time quantification of mcrA, pmoA for methanogen, methanotroph estimations during composting

Composting is the controlled biological decomposition of organic matter by microorganisms during predominantly aerobic conditions. It is being increasingly adopted due to its benefits in nutrient recycling, soil reclamation, and urban land use. However, it poses an environmental concern related to its contribution to greenhouse gas production. During composting, activities of methanogenic and methanotrophic communities influence the net methane (CH4) release into the atmosphere. Using quantitative polymerase chain reaction (qPCR), this study was aimed at assessing the changes in the methyl-coenzyme M reductase (mcrA) and particulate methane monooxygenase (pmoA) copy numbers for estimation of methanogenic and methanotrophic communities, respectively. Open-windrow composting of beef cattle (Bos Taurus L.) manure with temperatures reaching > 55 degrees C was effective indegrading commensal Escherichia coli within the first week. Quantification of community DNA revealed significant differences in mcrA and pmoA copy numbers between top and middle sections. Consistent mcrA copy numbers (7.07 to 8.69 log copy number g(-1)) were detected throughout the 15-wk composting period. However, pmoA copy number varied significantly over time, with higher values during Week 0 and 1 (6.31 and 5.41 log copy number g(-1), respectively) and the lowest at Week 11 (1.6 log copy number g(-1)). Net surface CH4 emissions over the 15-wk period were correlated with higher mcrA copy number. Higher net ratio of mrA: pmoA copy numbers was observed when surface CH4 flux was high. Our results indicate that mcrA and pmoA copy numbers vary during composting and that methanogen and methanotroph populations need to be examined in conjunction with net CH4 emissions from open-windrow composting of cattle feedlot manure.     

Removal of polycyclic aromatic hydrocarbons from aqueous solution on soybean stalk-based carbon

Soybean [ (L.) Merr.] stalk-based carbons were prepared by phosphoric acid activation at different carbonization temperatures. Characteristics of the prepared carbon, including specific surface area, iodine number, and amount of methylene blue sorption, were determined. Experiments on phenanthrene, naphthalene, and acenaphthene, as representatives of polycyclic aromatic hydrocarbons (PAHs), removal from aqueous solution by the prepared carbon were conducted at different levels of carbon addition. The results indicated that the specific surface area, iodine number, and amount of methylene blue sorption increased with an increase of carbonization temperature. The maximum values were observed at 700°C and were 287.63 m g, 508.99 mg g, and 90.14 mg g, respectively. The removal efficiencies of phenanthrene, naphthalene, and acenaphthene tended to increase with increasing carbon amounts and carbonization temperature. The optimal removal performance was obtained under the experimental conditions of carbon concentrations of 0.04 g 32 mL and carbonization temperature of 700°C, and the removal efficiencies of phenanthrene, naphthalene, and acenaphthene were 99.89, 100, and 95.64%, respectively. The performance of the prepared carbon was superior to that of commercial activated carbon. Additionally, for the same carbon concentrations, the removal efficiency of PAHs on prepared carbons followed the order: phenanthrene > naphthalene > acenaphthene. Results obtained from this work provide some insight into the reuse of an agricultural residue, and also provide a new application for the treatment of PAHs in contaminated water utilizing activated carbon prepared from agricultural residues.     

Impacts of pollution controls on air quality in Beijing during the 2008 Olympic Games

Air pollution has become one of the main environmental concerns in China since the 1980s due to China's rapid economic growth and resultant pollution. However, it is difficult to directly evaluate the anthropogenic contribution to air pollution in China. The 2008 Olympic Games in Beijing provided a unique opportunity for testing the contribution of anthropogenic pollution because of the clean-up controls on air quality in Beijing enforced over the period of the Games. In this case study, we monitored the concentrations of major air pollutants before, during, and after the Olympics at a suburban site in Beijing. Atmospheric concentrations of PM10, PM2.5, NH3, NO2, SO2, and the particulate ions NH4+, NO3-, SO4(2-) Ca2+, Mg2+, and K+ all decreased during the Olympic period because of strict emission controls, compared with the same period from 2005 to 2007. For example, the average PM10 concentration (61 microg m(-3)) during the Olympics was only 37% of that (166 microg m(-3)) in the same month (August) from 2005 to 2007. However, just 1 mo and 1 yr after the Games had ended, mean concentrations of these pollutants had increased significantly again. This rapid "recovery' of air pollutant concentrations after the Olympics suggests that China needs to implement long-lasting decreases in its air pollution in Beijing and other major cities.     

Relationships between net primary productivity and stand age for several forest types and their influence on China's carbon balance

Affected by natural and anthropogenic disturbances such as forest fires, insect-induced mortality and harvesting, forest stand age plays an important role in determining the distribution of carbon pools and fluxes in a variety of forest ecosystems. An improved understanding of the relationship between net primary productivity (NPP) and stand age (i.e., age-related increase and decline in forest productivity) is essential for the simulation and prediction of the global carbon cycle at annual, decadal, centurial, or even longer temporal scales. In this paper, we developed functions describing the relationship between national mean NPP and stand age using stand age information derived from forest inventory data and NPP simulated by the BEPS (Boreal Ecosystem Productivity Simulator) model in 2001. Due to differences in ecobiophysical characteristics of different forest types, NPP-age equations were developed for five typical forest ecosystems in China (deciduous needleleaf forest (DNF), evergreen needleleaf forest in tropic and subtropical zones (ENF-S), deciduous broadleaf forest (DBF), evergreen broadleaf forest (EBF), and mixed broadleaf forest (MBF)). For DNF, ENF-S, EBF, and MBF, changes in NPP with age were well fitted with a common non-linear function, with R(2) values equal to 0.90, 0.75, 0.66, and 0.67, respectively. In contrast, a second order polynomial was best suitable for simulating the change of NPP for DBF, with an R(2) value of 0.79. The timing and magnitude of the maximum NPP varied with forest types. DNF, EBF, and MBF reached the peak NPP at the age of 54, 40, and 32 years, respectively, while the NPP of ENF-S maximizes at the age of 13 years. The highest NPP of DBF appeared at 122 years. NPP was generally lower in older stands with the exception of DBF, and this particular finding runs counter to the paradigm of age-related decline in forest growth. Evaluation based on measurements of NPP and stand age at the plot-level demonstrates the reliability and applicability of the fitted NPP-age relationships. These relationships were used to replace the normalized NPP-age relationship used in the original InTEC (Integrated Terrestrial Ecosystem Carbon) model, to improve the accuracy of estimated carbon balance for China's forest ecosystems. With the revised NPP-age relationship, the InTEC model simulated a larger carbon source from 1950-1980 and a larger carbon sink from 1985-2001 for China's forests than the original InTEC model did because of the modification to the age-related carbon dynamics in forests. This finding confirms the importance of considering the dynamics of NPP related to forest age in estimating regional and global terrestrial carbon budgets.     

Application of China’s National Forest Continuous Inventory Database

The maintenance of a timely, reliable and accurate spatial database on current forest ecosystem conditions and changes is essential to characterize and assess forest resources and support sustainable forest management. Information for such a database can be obtained only through a continuous forest inventory. The National Forest Continuous Inventory (NFCI) is the first level of China’s three-tiered inventory system. The NFCI is administered by the State Forestry Administration; data are acquired by five inventory institutions around the country. Several important components of the database include land type, forest classification and ageclass/ age-group. The NFCI database in China is constructed based on 5-year inventory periods, resulting in some of the data not being timely when reports are issued. To address this problem, a forest growth simulation model has been developed to update the database for years between the periodic inventories. In order to aid in forest plan design and management, a three-dimensional virtual reality system of forest landscapes for selected units in the database (compartment or sub-compartment) has also been developed based on Virtual Reality Modeling Language. In addition, a transparent internet publishing system for a spatial database based on open source WebGIS (UMN Map Server) has been designed and utilized to enhance public understanding and encourage free participation of interested parties in the development, implementation, and planning of sustainable forest management.     

Factors Influencing Farmers’ Willingness to Participate in the Conversion of Cultivated Land to Wetland Program in Sanjiang National Nature Reserve,China

Sanjiang National Nature Reserve (NNR) is a state-owned natural wetland in China that has suffered severe degradation due to cultivation and wetland reclamation by farmers. As a consequence, the conversion of cultivated land to wetlands (CCW) was proposed by the government of Heilongjiang province and the United Nations Development Programme/Global Environment Facility (UNDP/GEF) project team in 2007. We suggest that voluntary participation in the CCW could be an important tool for accomplishing the integrated objectives of wetland conservation and local development. The purpose of this study was to examine the main factors that influence farmers’ willingness to participate in the CCW through a field investigation and a questionnaire. Based on the data from our questionnaire, which provided an effective sample of 310 households in 11 villages, the influencing factors of farmers’ willingness to participate were analyzed through binary logistic regression analyses. It was concluded that age, education, the amount of cultivated land, geographical location, and the perceived benefits and risks were important factors for participation. Furthermore, suggestions for improving the wetland compensation system and providing alternative livelihoods are proposed to strengthen participation.     

Ligand-assisted degradation of carbon tetrachloride by microscale zero-valent iron

Degradation of carbon tetrachloride (CT) by microscale zero-valent iron (ZVI) was investigated in batch systems with or without organic ligands (ethylenediaminetetraacetic acid (EDTA), citric acid, tartaric acid, malic acid and oxalic acid) at pHs from 3.5 to 7.5. The results demonstrated that at 25°C, the dechlorination of CT by microscale ZVI is slow in the absence of organic ligands, with a pseudo-first-order rate constant of 0.0217 h(-1) at pH 3.5 and being further dropped to 0.0052 h(-1) at pH 7.5. However, addition of organic ligands significantly enhanced the rates and the extents of CT removal, as indicated by the rate constant increases of 39, 31, 32, 28 and 18 times in the presence of EDTA, citric acid, tartaric acid, malic acid and oxalic acid, respectively, at pH 3.5 and 25°C. The effect of EDTA was most significant; the dechlorination of CT at an initial concentration of 20 mg l(-1) increased from 16.3% (no ligands) to 89.1% (with EDTA) at the end of 8h reaction. The enhanced CT degradation in the presence of organic ligands was primarily attributed to the elimination of a surface passivation layer of Fe(III) (hydr)oxides on the microscale ZVI through chelating of organic ligands with Fe(III), which maintained the exposure of active sites on ZVI surface to CT.