Temporal and Spatial Variations of Phytoplankton Community Structure in Lake Erhai,a Chinese Plateau Lake,with Reference to Environmental Factors

Russian Journal of Ecology - Temporal and spatial variations of phytoplankton community in Lake Erhai were investigated from May 2010 to April 2011. A total of 124 species belonging to 8 phyla and...     

Status of air pollution in Beijing

A study has been made on elements organic constituents, TSP, SO2,NO2 of atmospheric pollutants in Beijing. 17 elements, and some PAHs, e. g. B(a)P, B(b, j, k)P, and B(g, h, i)P, in airborne particles by X-ray fluorescence spectroscopy and HPLC, GC/MS, have been determined respectively. It has been shown that the elements Pb, Zn, S and Cu were more enriched in fine particles and different valence states of sulfur at various sites. It was found that the concentrations of S6+ and S2-were more than 85% and less than 15% of the total sulfur respectively. Concentrations of major PAHs and sulfur-containing compounds increased in winter and in urban area. High values for Pb and Zn in city, Fe and Mn at industrial area and Cu, Al rural sites were obtained respectively. This implies the functions of different elemental sources of various sites. Thus, elements can be from distingushed anthropogenic and natural sources.The main contribution of SO2 was found of to have same seasonal variation as the anthropogenic el     

Characterizing sources of nitrate leaching from an irrigated dairy farm in Merced County, California

Dairy farms comprise a complex landscape of groundwater pollution sources. The objective of our work is to develop a method to quantify nitrate leaching to shallow groundwater from different management units at dairy farms. Total nitrate loads are determined by the sequential calibration of a sub-regional scale and a farm-scale three-dimensional groundwater flow and transport model using observations at different spatial scales. These observations include local measurements of groundwater heads and nitrate concentrations in an extensive monitoring well network, providing data at a scale of a few meters and measurements of discharge rates and nitrate concentrations in a tile-drain network, providing data integrated across multiple farms. The various measurement scales are different from the spatial scales of the calibration parameters, which are the recharge and nitrogen leaching rates from individual management units. The calibration procedure offers a conceptual framework for using field measurements at different spatial scales to estimate recharge N concentrations at the management unit scale. It provides a map of spatially varying dairy farming impact on groundwater nitrogen. The method is applied to a dairy farm located in a relatively vulnerable hydrogeologic region in California. Potential sources within the dairy farm are divided into three categories, representing different manure management units: animal exercise yards and feeding areas (corrals), liquid manure holding ponds, and manure irrigated forage fields. Estimated average nitrogen leaching is 872 kg/ha/year, 807 kg/ha/year and 486 kg/ha/year for corrals, ponds and fields respectively. Results are applied to evaluate the accuracy of nitrogen mass balances often used by regulatory agencies to assess groundwater impacts. Calibrated leaching rates compare favorably to field and farm scale nitrogen mass balances. These data and interpretations provide a basis for developing improved management strategies.     

Influence of tobacco smoke on carcinogenic PAH composition in indoor PM10 and PM2.5

Because of the mutagenic and/or carcinogenic properties, Polycyclic Aromatic Hydrocarbons (PAH), have a direct impact on human population. Consequently, there is a widespread interest in analysing and evaluating the exposure to PAH in different indoor environments, influenced by different emission sources. The information on indoor PAH is still limited, mainly in terms of PAH distribution in indoor particles of different sizes; thus, this study evaluated the influence of tobacco smoke on PM₁₀ and PM_2.5 characteristics, namely on their PAH compositions, with further aim to understand the negative impact of tobacco smoke on human health. Samples were collected at one site influenced by tobacco smoke and at one reference (non-smoking) site using low-volume samplers; the analyses of 17 PAH were performed by Microwave Assisted Extraction combined with Liquid Chromatography (MAE–LC). At the site influenced by tobacco smoke PM concentrations were higher 650% for PM₁₀, and 720% for PM_2.5. When influenced by smoking, 4 ring PAH (fluoranthene, pyrene, and chrysene) were the most abundant PAH, with concentrations 4600–21 000% and 5100–20 800% higher than at the reference site for PM₁₀ and PM_2.5, respectively, accounting for 49% of total PAH (Σ_PAH). Higher molecular weight PAH (5–6 rings) reached concentrations 300–1300% and 140–1700% higher for PM₁₀ and PM_2.5, respectively, at the site influenced by tobacco smoke. Considering 9 carcinogenic PAH this increase was 780% and 760% in PM₁₀ and PM_2.5, respectively, indicating the strong potential risk for human health. As different composition profiles of PAH in indoor PM were obtained for reference and smoking sites, those 9 carcinogens represented at the reference site 84% and 86% of Σ_PAH in PM₁₀ and PM_2.5, respectively, and at the smoking site 56% and 55% of Σ_PAH in PM₁₀ and PM_2.5, respectively. All PAH (including the carcinogenic ones) were mainly present in fine particles, which corresponds to a strong risk for cardiopulmonary disease and lung cancer; thus, these conclusions are relevant for the development of strategies to protect public health.     

Isoprene emissions and climate

Biogenic volatile organic compounds (BVOCs) play an important role in atmospheric chemistry and the carbon cycle. Isoprene is quantitatively the most important of the non-methane BVOCs (NMBVOCs), with an annual emission of about 400–600 TgC; about 90% of this is emitted by terrestrial plants. Incorporating a mechanistic treatment of isoprene emissions within land-surface schemes has recently become a focus for the modelling community, the aim being to quantify the potential magnitude of associated climate feedbacks. However, these efforts are hampered by major uncertainties about why plants emit isoprene and the relative importance of different environmental controls on isoprene emission. The availability and reliability of observations of isoprene fluxes from different types of vegetation is limited, and this also imposes constraints on model development. Nevertheless, progress is being made towards the development of mechanistic models of isoprene emission which, in conjunction with atmospheric chemistry models, will ultimately allow improved quantification of the feedbacks between the terrestrial biosphere and climate under past and future climate states.     

A 50 MW concentrating solar power plant for Jordan

The potential of concentrating solar power plant (CSPP) technology in Jordan is assessed and the next steps for development of the first CSPP in the country are presented. For this purpose, a prototype of a 50 MW CSPP for electricity generation in Jordan is proposed and analysis of its economic feasibility has been performed. Moreover, a calculation model – using the concept design of the proposed CSPP, and the solar irradiation data – was developed to estimate the energy yield of the plant. Based on the analyzed solar irradiation data, it was found that Jordan has an outstanding potential for CSPP, especially in the southern locations of the country such as Quweira. At the same time Jordan's energy master plan is seeking for independent energy supply and for an increasing share of renewable energies. Furthermore, Jordan's demand curve over a day closely matches the electricity production of the proposed plant. Combination of these factors creates a very favorable situation. Therefore, establishment of the proposed 50 MW CSPP is highly recommended not only in Jordan, but also in many other countries, which have similar political and economical conditions such as those countries located in the Middle East and North Africa (MENA) region.     

Operational decisions in response to a performance-based regulation to reduce organic waste impacts near Atlantic salmon farms in British Columbia,Canada

Nutrient enrichment of the seafloor (benthos) has been a primary subject of investigation since the beginning of commercial salmon farming. Waste feed and feces passing through the containment nets can create zones of organic enrichment to the benthos in the vicinity of the pen cages. Early studies of salmon farming in British Columbia Canada (500–1200 metric ton production farms) showed that these effects varied greatly and were reduced where conditions of adequate water depth and strong tidal currents were present. More recent studies of farms producing in excess of 2000 tons of fish have documented measurable organic benthic impacts.The implementation of a performance-based waste regulation in British Columbia in 2002 has caused operational changes to achieve and maintain compliance. This paper describes field monitoring data for four representative farm operations including the waste impact levels prior to the implementation of regulatory standards and the effect of adaptive management actions taken to reduce organic enrichment such as modified feed delivery, relatively small position changes to the cages or reducing site production to achieve continuing compliance.Monitoring over several full production cycles at selected farms indicated that sediment impacts at maximum production levels have decreased while maintaining, and in some cases increasing overall production of salmon.     

Cleaner tanning practices for tannery pollution abatement: Role of enzymes in eco-friendly vegetable tanning

Concern about pollution related problems in the global scenario are persuading all the processing industries to adopt cleaner manufacturing practices. Thus, the leather industry is also under pressure to look for effective alternative tanning materials for chromium. Natural products like vegetable tannins are regaining importance. However, there are limitations in the use of vegetable tanning materials because of its high organic load in the effluent, which are difficult to degrade leading to high chemical oxygen demand (COD). Moreover, conventional vegetable tanning process requires partial pickling that involves the use of sodium chloride, to suppress osmotic swelling. This results in very high amount of total dissolved solid (TDS) content in wastewaters. In this investigation, an attempt has been made to design an eco-friendly vegetable tanning process combining pickle-free tanning and application of proteolytic enzymes to improve the exhaustion of vegetable tannins. Such an approach has resulted in more than 95% tannin exhaustion in the case of the experimental process, an increase of 10% compared with the conventional vegetable tanning process. The tanned leathers showed slight improvement in hydrothermal stability. Physical and tactile evaluation of experimental leathers has been better than conventionally tanned leathers. Surface colour values illustrated negligible variation in colour and shade between control and experimental leathers. The resultant leather showed opened up, split compact fibre structure that has been well coated, indicating that the enzyme assisted tanning process did not bring about any major change or destruction on the fibre structure of the leathers. The optimized system has been field tested in a commercial tannery. The results showed that the enzyme assisted tanning process is efficient in terms of improved quality of leather and also led to reduction in total solids (TS), chlorides and COD loads. The enzyme assisted tanning system presented appears to be a viable option for combating pollution arising from the conventional vegetable tanning system.     

A matter of approach: the retort's potential to reduce mercury consumption within small-scale gold mining settlements in Tanzania

The mercury-based gold extraction processes prevalent within small-scale mining are both efficient and harmful. While ensuring relatively high levels of gold recovery, they cause environmental and health problems for people living within mining settlements. This mercury consumption can be minimized by using a simple mercury recycling device known as a retort. While mining legislation in Tanzania dictates the use of retorts for gold recovery, virtually no miners use them, indicating the inadequacy of previous introduction attempts. During action research, retorts were introduced in two mining settlements through a thorough and participatory approach. Twenty miners were given retorts and their attitudes and receptiveness to them were studied. Of the recipients, 18 used the retorts over a period of five months, recycling 10 kilos of mercury. Less mercury was spilled into the environment and miners saved money normally spent on purchasing mercury. The findings have implications for the strategies of development interventions targeting mercury-instigated problems within small-scale gold mining.