The residues, distribution, and partition of organochlorine pesticides in the water, suspended solids, and sediments from a large Chinese lake (Lake Chaohu) during the high water level period

The levels of organochlorine pesticides (OCPs) in the water, suspended solids, and sediments from Lake Chaohu during the high water level period were measured by a solid-phase extraction gas chromatograph–electron capture detector. The spatial distributions of the three phases and the water/suspended solids and sediment/water partition coefficients were analyzed. The results showed the following: (1) The mean contents of OCPs in the water, suspended solids, and sediments were 132.4?±?432.1 ng/L, 188.1?±?286.7 ng/g dry weight (dw), and 13.7?±?9.8 ng/g dw, respectively. The dominant OCP components were isodrin (85.1 %) for the water, DDTs (64.4 %) for the suspended solids, and both isodrin (48.5 %) and DDTs (31.8 %) for the sediments. (2) β-HCH was the primary isomer of HCHs in the water and sediments, and the proportions were 61.7 and 41.3 %; γ-HCH was the primary isomer in the suspended solids, accounting for 49.3 %; p,p′-DDT was the dominant content of DDTs in the water and suspended solids, whereas p,p′-DDD was the main metabolite of DDTs in the sediments. (3) The concentrations of contaminants in the water from the western lake were greater than those from the eastern lake, but the concentrations in the suspended solids from the western lake were less than those from the eastern lake. (4) There was no significant correlation between the water–suspended solids partition coefficient K _d and the n-octanol–water partition coefficient K _ow, and between the sediment–water organic-C weighted sorption coefficients K _oc and K _ow.     

Spatial and temporal trend of Chinese manure nutrient pollution and assimilation capacity of cropland and grassland

Dynamics of livestock and poultry manure nutrient was analyzed at a provincial scale from 2002 to 2008. The nutrient capacity of 18 kinds of croplands and grasslands to assimilate nutrients was assessed in the same temporal–spatial scale. Manure nitrogen (N) had increased from 5.111 to 6.228 million tons (MT), while manure phosphorus (P) increased from 1.382 to 1.607 MT. Manure N and P share similar spatial patterns of yields, but proportion of specialized livestock husbandry and contribution of leading livestock categories (swine, cattle, cow, sheep, layer chicken, broiler chicken) were different. The nutrients generated from dominant seven provinces took more than about half of total manure N in China. After subtracting the chemical fertilizers, there were some manure nutrient capacities in western part of China. Risk analysis of manure nutrient pollution overload in eastern and southern parts of China was serious, which should restrict livestock's developments. Amount of chemical fertilizers applied should be reduced to make room for manure nutrients. For the sake of greenhouse effects, the emission of methane (CH₄) and nitrous oxide (NO _x ) emissions in China is serious for the global change, thus merits further statistics and studies. The spatial and temporal pattern of Chinese manure nutrient pollution from livestock and the assimilation capacity of cropland and grassland can provide useful information for policy development on Chinese soil environment and livestock.     

Synthesis of hybrid carbon nanotubes using Brassica juncea L. application to photodegradation of bisphenol A

Hyperaccumulators contain tubular cellulose and heavy metals, which can be used as the sources of carbon and metals to synthesize nanomaterials. In this paper, carbon nanotubes (CNTs), Cu_0.05Zn_0.95O nanoparticles, and CNTs/Cu_0.05Zn_0.95O nanocomposites were synthesized using Brassica juncea L. plants, and the ultraviolet (UV)-light-driven photocatalytic degradations of bisphenol A (BPA) using them as photocatalysts were studied. It was found that the outer diameter of CNTs was around 50 nm and there were a few defects in the crystal lattice. The synthesized Cu_0.05Zn_0.95O nanocomposites had a diameter of around 40 nm. Cu_0.05Zn_0.95O nanocomposites have grown on the surface of the CNTs and the outer diameter of them was around 100 nm. The synthesized hybrid carbon nanotubes using B. juncea could enhance the efficiency of photocatalytic degradation on BPA. The complete equilibration time of adsorption/desorption of BPA onto the surface of CNTs, Cu_0.05Zn_0.95O nanoparticles, and CNTs/Cu_0.05Zn_0.95O nanocomposites was within 30, 20, and 30 min, and approximately 14.9, 8.7, and 17.4 % BPA was adsorbed by them, respectively. The combination of UV light irradiation (90 min) with CNTs, Cu_0.05Zn_0.95O nanoparticles, and CNTs/Cu_0.05Zn_0.95O nanocomposites could lead to 48.3, 75.7, and 92.6 % decomposition yields of BPA, respectively. These findings constitute a new insight for synthesizing nanocatalyst by reusing hyperaccumulators.     

Adsorption behavior of light green anionic dye using cationic surfactant-modified wheat straw in batch and column mode

An agricultural by-product, natural wheat straw (NWS), was soaked in 1 % cationic surfactant (hexadecylpyridinium bromide, CPB) solution for 24 h (at 293 K), and modified wheat straw (MWS) was obtained. Analysis of FTIR, XFR, and nitrogen element showed that CPB was adsorbed onto surface of NWS. Then, MWS was used as adsorbent for the removal of light green dye (LG, anionic dye) from aqueous solution. The experiment was performed in batch and column mode at room temperature (293 K). Sodium chloride (up to 0.1 mol/L) existed in solution was not favor of LG dye adsorption. The equilibrium data were better described by Langmuir isotherm, and adsorption capacity of q _m from Langmuir model was 70.01?±?3.39 mg/g. In fixed-bed column adsorption mode, the effects of initial LG concentration (30, 50, 70 mg/L) and flow rate (6.5, 9.0, 14.5 mL/min) on adsorption were presented. Thomas and modified dose–response models were used to predict the breakthrough curves using nonlinear analysis method, and both models can fit the breakthrough curves. Theoretical and experimental breakthrough curves were drawn and compared. The results implied that MWS can be used as adsorbent material to remove LG from aqueous solution.     

Contamination status of dioxins in sediment cores from the Three Gorges Dam area, China

In order to screen dioxin pollution in sediment of Three Gorges Dam (TGD) area, three sediment cores were obtained from two sites in 2010~2011; each core was divided into different samples with every 10 cm depth. Sediment dating determined by radiometry (¹³⁷Cs, ²¹⁰Pb) and concentrations of dioxins were analyzed by high-resolution gas chromatography/mass spectrometry. The results indicated: Sediment dating showed no significant difference among all the samples from the same core and the two locations (ANOVA, p?>?0.05). The total amount of polychlorinated dibenzo-p-dioxins (PCDD)/Fs in all sample ranged from 30.7 to 371 pg/g dry weight (d.w.), with the mean value of 66.2 pg/g d.w. PCDDs occupied 60.33~85.22 % of dioxins in each sample, and PCDFs contributed to a very small extend. There was no significant difference in the dioxin concentration between 2010 and 2011 and in the two locations (t test, p?>?0.05), but the vertical distribution of dioxins showed significant different in different depths. Toxic equivalent (TEQ) (WHO 2005, Humans) of samples ranged from 0.15 to 1.60 pg/g d.w.; the mean was 0.41 pg/g d.w. No significant difference was found in TEQ between 2010 and 2011(t test, p?>?0.05). It could be concluded that the distribution of dioxins showed the spatial heterogeneous which resulted from the strong mixing and sediment deposition characteristics. Dioxin concentration in sediment cores was low with very low environmental risk potential. Dioxins at the two sites had the same origin, and exogenous input was the main source. It is the first report on the dioxins concentrations in sediment cores in the TGD area.     

Occurrence and distribution of heavy metals and tetracyclines in agricultural soils after typical land use change in east China

Land use in east China tends to change from paddy rice to vegetables or other high-value cash crops, resulting in high input rates of organic manures and increased risk of contamination with both heavy metals (HMs) and antibiotics. This investigation was conducted to determine the accumulation, distribution and risks of HMs and tetracyclines (TCs) in surface soils and profiles receiving different amounts of farmyard manure. Soil samples collected from suburbs of Hangzhou city, Zhejiang province were introduced to represent three types of land use change from paddy rice to asparagus production, vineyards and field mustard cultivation, and divided into two portions, one of which was air-dried and sieved through 2-, 0.3- and 0.149-mm nylon mesh for determination of pH and heavy metals. The other portion was frozen at ?20 °C, freeze-dried and sieved through a 0.3-mm nylon mesh for tetracyline determination. HM and TC concentrations in surface soils of 14-year-old mustard fields were the highest with total Cu, Zn, Cd and ∑TCs of 50.5, 196, 1.03 mg?kg^?1 and 22.9 μg?kg^?1, respectively, on average. The total Cu sequence was field mustard?>?vineyards?>?asparagus when duration of land use change was considered; oxytetracycline (OTC) and doxycycline were dominant in soils used for asparagus production; OTC was dominant in vineyards and chlortetracycline (CTC) was dominant in mustard soils. There were positive pollution relationships among Cu, Zn and ∑TCs, especially between Cu and Zn or Cu and ∑TCs. Repeated and excessive application of manures from intensive farming systems may produce combined contamination with HMs and TCs which were found in the top 20 cm of the arable soil profiles and also extended to 20–40 cm depth. Increasing manure application rate and cultivation time led to continuing increases in residue concentrations and movement down the soil profile.     

An integrated approach to model the biomagnification of organic pollutants in aquatic food webs of the Yangtze Three Gorges Reservoir ecosystem using adapted pollution scenarios

The impounding of the Three Gorges Reservoir (TGR) at the Yangtze River caused large flooding of urban, industrial, and agricultural areas, and profound land use changes took place. Consequently, substantial amounts of organic and inorganic pollutants were released into the reservoir. Additionally, contaminants and nutrients are entering the reservoir by drift, drainage, and runoff from adjacent agricultural areas as well as from sewage of industry, aquacultures, and households. The main aim of the presented research project is a deeper understanding of the processes that determines the bioaccumulation and biomagnification of organic pollutants, i.e., mainly pesticides, in aquatic food webs under the newly developing conditions of the TGR. The project is part of the Yangtze-Hydro environmental program, financed by the German Ministry of Education and Science. In order to test combinations of environmental factors like nutrients and pollution, we use an integrated modeling approach to study the potential accumulation and biomagnification. We describe the integrative modeling approach and the consecutive adaption of the AQUATOX model, used as modeling framework for ecological risk assessment. As a starting point, pre-calibrated simulations were adapted to Yangtze-specific conditions (regionalization). Two exemplary food webs were developed by a thorough review of the pertinent literature. The first typical for the flowing conditions of the original Yangtze River and the Daning River near the city of Wushan, and the second for the stagnant reservoir characteristics of the aforementioned region that is marked by an intermediate between lake and large river communities of aquatic organisms. In close cooperation with German and Chinese partners of the Yangtze-Hydro Research Association, other site-specific parameters were estimated. The MINIBAT project contributed to the calibration of physicochemical and bathymetric parameters, and the TRANSMIC project delivered hydrodynamic models for water volume and flow velocity conditions. The research questions were firstly focused on the definition of scenarios that could depict representative situations regarding food webs, pollution, and flow conditions in the TGR. The food webs and the abiotic site conditions in the main study area near the city of Wushan that determine the environmental preconditions for the organisms were defined. In our conceptual approach, we used the pesticide propanil as a model substance.     

Volatile organic compounds in the unsaturated zone from radioactive wastes

Volatile organic compounds (VOCs) are often comingled with low-level radioactive wastes (LLRW), but little is known about subsurface VOC emanations from LLRW landfills. The current study systematically quantified VOCs associated with LLRW over an 11-yr period at the USGS Amargosa Desert Research Site (ADRS) in southwestern Nevada. Unsaturated-zone gas samples of VOCs were collected by adsorption on resin cartridges and analyzed by thermal desorption and GC/MS. Sixty of 87 VOC method analytes were detected in the 110-m-thick unsaturated zone surrounding a LLRW disposal facility. Chlorofluorocarbons (CFCs) were detected in 100% of samples collected. Chlorofluorocarbons are powerful greenhouse gases, deplete stratospheric ozone, and are likely released from LLRW facilities worldwide. Soil-gas samples collected from a depth of 24 m and a horizontal distance 100 m south of the nearest waste-disposal trench contained >60,000 ppbv total VOCs, including >37,000 ppbv CFCs. Extensive sampling in the shallow unsaturated zone (0-2 m deep) identified areas where total VOC concentrations exceeded 5000 ppbv at the 1.5-m depth. Volatile organic compound concentrations exceeded background levels up to 300 m from the facility. Maximum vertical diffusive fluxes of total VOCs were estimated to be 1 g m yr. Volatile organic compound distributions were similar but not identical to those previously determined for tritium and elemental mercury. To our knowledge, this study is the first to characterize the unsaturated zone distribution of VOCs emanating from a LLRW landfill. Our results may help explain anomalous transport of radionuclides at the ADRS and elsewhere.     

Optimal control of soybean aphid in the presence of natural enemies and the implied value of their ecosystem services

By suppressing pest populations, natural enemies provide an important ecosystem service that maintains the stability of agricultural ecosystems systems and potentially mitigates producers' pest control costs. Integrating natural control services into decisions about pesticide-based control has the potential to significantly improve the economic efficiency of pesticide use, with socially desirable outcomes. Two gaps have hindered the incorporation of natural enemies into pest management decision rules: (1) insufficient knowledge of pest and predator population dynamics and (2) lack of a decision framework for the economic tradeoffs among pest control options. Using a new intra-seasonal, dynamic bioeconomic optimization model, this study assesses how predation by natural enemies contributes to profit-maximizing pest management strategies. The model is applied to the management of the invasive soybean aphid, the most significant serious insect threat to soybean production in North America. The resulting lower bound estimate of the value of natural pest control ecosystem services was estimated at $84 million for the states of Illinois, Indiana, Iowa, Michigan and Minnesota in 2005.     

Preliminary Strategic Environmental Assessment of the Great Western Development Strategy: Safeguarding Ecological Security for a New Western China

The Great Western Development Strategy (GWDS) is a long term national campaign aimed at boosting development of the western area of China and narrowing the economic gap between the western and the eastern parts of China. The Strategic Environmental Assessment (SEA) procedure was employed to assess the environmental challenges brought about by the western development plans. These plans include five key developmental domains (KDDs): water resource exploitation and use, land utilization, energy generation, tourism development, and ecological restoration and conservation. A combination of methods involving matrix assessment, incorporation of expert judgment and trend analysis was employed to analyze and predict the environmental impacts upon eight selected environmental indicators: water resource availability, soil erosion, soil salinization, forest destruction, land desertification, biological diversity, water quality and air quality. Based on the overall results of the assessment, countermeasures for environmental challenges that emerged were raised as key recommendations to ensure ecological security during the implementation of the GWDS. This paper is intended to introduce a consensus-based process for evaluating the complex, long term pressures on the ecological security of large areas, such as western China, that focuses on the use of combined methods applied at the strategic level.