Water environment

About: Water environment is a research topic. Over the lifetime, 13384 publications have been published within this topic receiving 125138 citations.

Water-DNA interactions as studied by X-ray and neutron fibre diffraction.

Abstract: X-ray fibre-diffraction studies indicate a high degree of stereochemical specificity in interactions between water and the DNA double helix. Evidence for this comes from data that show that the molecular conformations assumed by DNA in fibres are highly reproducible and that the hydration-driven transitions between these conformations are fully reversible. These conformational transitions are induced by varying the relative humidity of the fibre environment and hence its water content. Further evidence for stereochemical specificity comes from the observed dependence of the conformation assumed on the ionic content of the fibre and the nucleotide sequence of the DNA. For some transitions, information on stereochemical pathways has come from real-time X-ray fibre diffraction using synchrotron radiation; information on the location of water with respect to the double helix for a number of DNA conformations has come from neutron fibre diffraction. This structural information from fibre-diffraction studies of DNA is complemented by information from X-ray single-crystal studies of oligonucleotides. If the biochemical processes involving DNA have evolved to exploit the structural features observed in DNA fibres and oligonucleotide single crystals, the challenges in developing alternatives to a water environment can be expected to be very severe.

Occurrence of phenols in leachates from municipal solid waste landfill sites in Japan

Abstract: The concentrations of 41 phenols in leachates from 38 municipal solid waste (MSW) landfill sites in Japan were measured. The main phenols detected in leachates were phenol, three cresols, 4-tert-butylphenol, 4-tertoctylphenol, 4-nonylphenol, bisphenol A, and some chlorophenols. The concentration levels of phenols were affected by the pH values of the leachates and the different types of landfill waste. The origins of phenol and p-cresol were considered to be incineration residues, and the major origin of 4-tert-butylphenol, bisphenol A, and 2,4,6-trichlorophenol was considered to be solidified fly ash. In contrast, the major origins of 4-tert-octylphenol and 4-nonylphenol were considered to be incombustibles. The discharge of leachates to the environment around MSW landfill sites without water treatment facilities can cause environmental pollution by phenols. In particular, the disposal of incineration residues including solidified fly ash and the codisposal of solidified fly ash and incombustibles might raise the possibility of environmental pollution. Moreover, the discharge of leachates at pH values of 9.8 or more could pollute the water environment with phenol. However, phenol, 4-nonylphenol, and bisphenol A can be removed to below the con centration levels that impact the environment around landfill sites by a series of conventional water treatment processes.

Impact of small municipal solid waste landfill on groundwater quality

Abstract: The aim of this paper is to analyse changes in the physicochemical elements in groundwater in the vicinity of a small municipal solid waste landfill site located within the territory of the European Union on the basis of 7-year hydrochemical research. Samples of groundwater and leachate near the examined landfill were collected four times a year during two periods, between 2008 and 2012 during the use of the landfill and between 2013 and 2014 at the stage of its closure. The research results were analysed on the basis of general physicochemical properties: pH; total organic carbon (TOC); electrical conductivity (EC); inorganic elements: Cr, Zn, Cd, Cu, Pb, Hg; and one organic element—polycyclic aromatic hydrocarbon (PAH). The analysis was carried out in accordance with the EU and national legislation requirements regarding landfill monitoring. The assessment of the groundwater and analysis indicators of the leachate pollution allowed interpretation of the impact of the municipal solid waste landfill on the state of the water environment in the immediate vicinity. The results show that the increased values of Cd, EC, and TOC turned out to be the determinants of the negative impact of leachate on the groundwater quality below the landfill. The integrated water threat model determined the potential negative impact of a landfill site. The extent depended on local environmental conditions and the self-cleaning process. Deterioration of the chemical status in the quality of the groundwater within the landfill area was a consequence of the lack of efficiency of the existing drainage system, which may result from the 19-year period of its use. The applied correlation relationship between physicochemical elements between leachate and groundwater with a time shift due to the extended time of migration of contaminants or mass transfer in waterlogged ground can be an important tool to identify the threat of groundwater pollution in the area of landfill sites.

Historical distribution and partitioning of phosphorus in sediments in an agricultural watershed in the Yangtze-Huaihe region, China.

Abstract: Agricultural intensification developed rapidly in East China since the 1980s, which caused most of the lakes in these areas to become eutrophic at almost the same time. Less is known about the relationship between agricultural intensification and watershed water quality, as well as historical nutrients dynamics and lake eutrophication processes. The study area, a typical agricultural watershed with high-yield grain production characterized by multipond systems in China's Yangtze-Huaihe region, was selected to evaluate the effects of agricultural intensification on P sediment retention using 137Cs dated sediment cores. Experimental results showed that P kept increasing in the multipond sediments during the past decades, which could be attributed almost entirely to agricultural intensification. An inflection point appeared in the 1980s, before which TP showed no or only a slight increase (200 mg x kg(-1)). Thereafter, it increased dramatically (about 400 mg x kg(-1) by the year 2004) due to the extensive application of phosphate fertilizers. The chemical reactive fraction, KCl-extracted phosphorus (KCI-P), accounted for only 0.3% or less of TP. However, NaOH-extracted inorganic P (NaOH-Pi), accounting for 13-46%, was the main factor causing TP to increase due to long-term P fertilization, whereas CaCO3-bound phosphorus (Ca-P), together with residual phosphorus (Res-P) stayed at a relatively stable level. The increasing TP contents indicated that there was a potential to overwhelm the sorption capacity of multipond systems causing continuous water quality deterioration in the watershed and downstream waters. It is implied that P export resulting from agricultural intensification and water deterioration should be taken into account during the formation of watershed management strategies for the water environment.