Tracing the Movement of Irrigated Effluent into an Alluvial Gravel Aquifer

Three microbial tracers – Escherichia coli J6-2, a somatic coliphage (ØESR1) and endospores of Bacillus subtilis var. niger NCIB 8649 tracer strain JHI – were added to effluent flood irrigated onto border dyke strips at a sewage treatment plant near Christchurch, New Zealand. All three tracers, and three effluent indicators – faecal coliforms, F-RNA phages, and chloride – were recovered in a bore, approximately 100 m downstream. A simple spatial model was applied to the breakthrough curves (BTCs) in the bore, using a series of hypothetical “entry points” in the strips. This analysis indicated effluent transport velocities through the 16.8 m deep vadose zone of between 15.7 and 39.2 m hr^{? 1}. The shapes of the BTCs for the microorganisms and chloride were very different, suggesting that they reached the groundwater table via two pathways: – both underwent rapid transport to the groundwater though macropores, but chloride also underwent far slower (matrix) transport though micropores. The BTC shapes also suggested transport velocities in the vadose zone of E. coli J6-2 > B. subtilis JH1 endospores > phage ØESR1, which is consistent with the theory of pore size exclusion, based on particle size. Reductions in microbial concentrations were ≈100 times greater than for chloride, and occurred rapidly, suggesting that up to 99% of the microorganisms underwent early exclusion from macropore flow and were removed during matrix flow. Nevertheless, the results show that substantial numbers of bacteria and viruses will still reach the groundwater through macropores beneath effluent irrigation schemes located on alluvial gravel formations.     

Impact of Fertilizer Application and Agricultural Crops on the Quality of Groundwater in the Alluvial Aquifer,Northern France

In France, the quality of water resources with respect to nitrates deteriorated between the beginning of 1970s and 2000s. A stabilization of the situation and of the improvements has been observed punctually since the 2000s. Despite the application of the Nitrates Directive in France (91/676/CEE), the overall situation remains degraded, with numerous increases in nitrate concentrations in the underground waters. In the North of France, an alluvial groundwater’s nitrate concentration exceeds the drinking water limit fixed at 50 mg/l, in the sectors of Catillon-sur-Sambre and Rejet-de-Beaulieu. In order to quantify and model the impact of agricultural nitrogen on groundwater, an approach based on an integrated model has been established using three specific codes for each lithological horizon: Agriflux (for the root zone), VS2DT (for the unsaturated zone), and ModFlow-MT3D (for the saturated zone). The results illustrate the sensitivity of quality to agricultural crops used. Based on scenarios over 20 years, the predictions show a link between nitrate concentrations in the groundwater and agricultural crops as well as fertilization. Improving quality with a concentration of nitrate less than 50 mg/l requires a reasoned management accompanied by rotations of crops and transformations into grasslands and for sensitive areas the use of the culture producing the least nitrogen flow such as beets. The integrated model constitutes an efficient tool for predicting the evolution of the groundwater quality, especially in sensitive areas like the valleys with a rapid nitrate transfer to the aquifer. The model makes it possible to correctly evaluate the concentrations of nitrates reaching the groundwater with a monitoring of the concentration evolution in each lithological horizon, thus constituting a good tool for the management of agricultural pollution.     

Aquifer Vulnerability Zoning, an Indicator of Atmospheric Pollutants Input? Vanadium in the Salamanca Aquifer, Mexico

Aquifer vulnerability assessments can be incorporated in groundwater contamination studies. Atmospheric pollutants as vanadium, V, can reach aquifers after soil deposition if the system is vulnerable. Vanadium concentrations were detected in soil and groundwater in Salamanca Mexico. V origin is related mainly to particulate emissions from a thermoelectric plant that is using fuel oil number 6 with high V content. To determine the V origin in groundwater, a soil and groundwater monitoring was carried out. A SINTACS vulnerability zoning was done. Vanadium in soil, emissions and groundwater is well correlated. The V input is associated to aquifer vulnerable zones.     

古人类活动对土壤发育的影响——以河南仰韶村文化遗址为例

选择在河南仰韶村文化遗址内,分别选取一个受到古人类活动干扰的土壤剖面(简称文化剖面)和没有受到古人类活动干扰的土壤剖面(简称自然剖面),通过分析和比较两个剖面中炭屑、各种氧化物含量和土壤发育指标数值,研究古人类活动对土壤发育的影响。研究结果显示,在古人类用火形成的灰烬层中,炭屑含量达到最大值2.38×105粒g-1,约为自然剖面最高值的12.35倍,这使得Si O2、Al2O3、Fe2O3、K2O、Mg O和Na2O含量相对减少,均达到最小值,而Ca O、Mn O含量达到最大值,表明古人类用火产生大量含Ca和Mn物质;而在古人类居住形成的文化层中,除Si O2几乎无变化外,其余物质均出现最大值或达到波峰,表明古人类居住活动有利于各种氧化物的富集。文化剖面发育指标数值总体高于自然剖面,在文化剖面内,文化层和灰烬层的上覆和下伏自然土层中各种元素物质含量基本相同,表明古人类活动阻碍了各种元素物质向下迁移和聚集,使下伏自然土层保持在一个相对封闭的环境中,由此推测古人类活动基本阻碍了土壤发育进程。     

气候变化和人类活动的水文水资源效应研究进展

水文过程的变化及其影响机制具有复杂性。一方面,气候变化和人类活动影响水文水资源;另一方面,水文水资源又会对这种影响做出响应,这种双向性和不确定性使得这一领域的研究比较复杂且发展较为缓慢。当前国内该方面研究仍处于探索阶段。系统总结了当前国内外气候变化和人类活动的水文水资源效应研究在理论、观点、方法与实践等方面取得的最新进展,指出了该领域研究的薄弱环节,并展望了未来主要的研究方向。国内外关于气候变化或者人类活动单一影响因素对水文水资源影响的研究较多,将二者结合并定量化区分的研究并不多见。加强定量化研究,明确各因素的影响比重,对深化该领域的研究有深远意义。     

总离子强度缓冲剂对含氟溶液测定的影响

对总离子强度缓冲剂对含氟溶液测定的影响进行了研究,结果表明:加入TISAB时测定的吸附平衡液浓度比未加入时高,且初始浓度的越大其差值越大,说明未加入TISAB时并未能测出吸附平衡液中的总氟,而是有一部分未被测出。未被测出的浓度是紫色土>红壤>黄壤、石灰土,低浓度条件下石灰土大于黄壤,而较高浓度条件下黄壤大于石灰土。加入TISAB与不加入TISAB时吸附量相差很大,加入情况下吸附量要小。在氟的吸附试验中,应加入离子强度缓冲剂(TISAB),以测定出平衡液中的总氟。     

贵州省岩溶山区生态环境脆弱性及人为活动的影响——以息烽县为例

根据对息烽县生态环境现状及人为活动的实际调查结果,分析了贵州省岩溶山区生态环境变化的主要特征以及人为活动的特点,探讨了该区生态环境脆弱性与人为活动的关系．     

Nitrogen Mineralization as Influenced by Different Organic Manures in an Inceptisol in the Foothill Himalayas

Nitrogen-use efficiency can be enhanced through an understanding of the nitrogen (N) mineralization behavior of organic sources. An incubation study was conducted to assess the impact of organic manures on N mineralization. The manures, farmyard manure (FYM), Leucaena leucocephala, and poultry manure, were applied to the soil alone or along with urea. There was a rapid increase in the amount of mineral N released with a peak appearing either at 14 days (+urea treatments) or 21 days (manure only) of aerobic incubation. Thereafter the net N mineralized decreased gradually and levelled off beyond day 56. Overall the cumulative net N mineralized after 98 days of incubation was in the order urea > Leucaena + urea > poultry manure + urea _> FYM + urea > Leucaena > poultry manure > FYM > zero N. The potentially mineralizable N (N₀) was lower in treatments where urea was not applied.     

长三角地区有机农药污染地下水的微生物群落分析

选择长江三角洲地区一处长期受到有机农药污染的浅层含水层,采集水样,采用不依赖于培养的16SrDNA序列分析方法,对该污染地下水中的微生物群落特征进行了分析和鉴定。结果表明,这种分析方法完全可行,该有机污染含水层具有较好的微生物多样性,且可能有一种未经鉴定的新菌种。     

Multi-Block Data Modeling for Characterization of Soil Contamination: A Case Study

Multi-block (heavy metals, pesticides, physico-chemical parameters) data set pertaining to the soils of alluvium region in Indo-Gangetic plains was analyzed using principal component analysis (PCA) and multiple factor analysis (MFA) methods to delineate the contaminated sites and to identify the possible contamination sources in the study region. In normal PCA, the first three factors were dominated mainly by heavy metals, pesticides and physico-chemical variables, respectively, thus identifying samples/sites contaminated with these. The MFA results, due to its unique weighting scheme of variables of different blocks extracted, to more realistic information about the spatial distribution of samples and relationships among the variables. MFA minimized the influence of variables of one single block on the first few components, allowing variables of all blocks equally to share the common MFA space. This resulted in delineating the sites/regions contaminated with variables (Al, Co, Cu, Mn, Ni, Pb, V, Na, SO₄, aldrin, lindane, HCB, HCH, DDT, and endosulfan) of all the blocks, rather than by particular block variables as in case of normal PCA, where, the variables of single block dominate the first factors, suppressing other block variables. MFA which can be considered as a method for standardization of the multi-block variables was successfully applied to the three block data set of soils.     

Selected Soil Enzyme Activities,Soil Microbial Biomass Carbon,and Root Yield as Influenced by Organic Production Systems in Sweet Potato

A field experiment was conducted on Typic Rhedustalfs to determine the effects of various organic production systems. Results revealed that the soil microbial biomass carbon (SMBC) content was greatest with the application of 100% N through farmyard manure. The ratio index value of biofertilizer along with 50% N through any one of the organic sources were greater than 100% N through green leaf manure?/?vermicompost, integrated use of manure and fertilizer (conventional production system), and control (traditional system of production). Soil enzymes varied with the production systems. The urease, phosphatase, and β-glucosidase activities were more with greater nitrogen, phosphorus, and organic-matter treatments, respectively. The SMBC, soil enzymes, and microbial activity were very responsive to organic production systems, but their levels and activities were not reflected in sweet potato root yield.     

作物生长对土壤N_2O排放影响的研究进展

N2O是一种重要的温室效应气体,不仅具有很强的温室效应,而且参与大气对流层和平流层的许多光化学反应,因而在全球变化的研究中受到广泛关注。综述了作物生长对土壤N2O排放影响的研究状况,为认识植物生长与土壤N2O排放的关系,调控和减缓土壤N2O排放提供依据。作物生长下的土壤N2O排放受植物类型、生长阶段、生长状况和人为管理等方面影响,植物通过引入光合产物到土壤,吸收利用土壤养分和水分改变土壤环境而影响土壤N2O排放,适当的人为管理措施可以调控和减轻土壤N2O排放。     

淮河流域人为活动造成新的水土流失及其防治对策

淮河流域因解决粮柴短缺问题造成新的水土流失面积约3880万亩,占全流域山丘区总流失面积的44%,其中滥垦山地300万亩,坡耕地1000万亩,坡式梯田500万亩,田间隙地、林粮间作地400万亩,滥樵滥伐林地1680万亩,所导致的土壤侵蚀量达1.2亿t,占总侵蚀量的52%。该文在分析上述问题的基础上,提出了对现有林草植被和水土资源的保护,引进节能技术,选择优良品种,大搞水土保持,狠抓坡耕地治理,营造薪炭林,以及开展以小流域为单元的综合治理,解决流域内因粮柴短缺问题造成的水土流失。     

Changes in Chemical Structure and Biological Activity of L-DOPA as Influenced by an Andosol and Its Components

Velvetbean ( Mucuna pruriens ) has been reported to release 3-(3',4'-dihydroxyphenyl)-L-alanine (L-DOPA) as an allelochemical that inhibits the growth of other plants, although the inhibitory activity depends on the soil type and it is extremely reduced in Andosols. To clarify the effects of Andosols and their components on the chemical structure and plant-growth-inhibitory activity of L-DOPA, an L-DOPA solution was reacted with an Andosol and its components (weathered pumice and purified allophane), and the resultant solution was subjected to ¹H nuclear magnetic resonance and ultraviolet-visible spectral analyses, and plant-growth-inhibitory activity tests. When the L-DOPA solution was added to the soil components, the concentration of L-DOPA in the solution decreased by adsorption and transformation (polymerization) reactions. The adsorption mechanism included a ligand exchange reaction. The rate of L-DOPA transformation was faster at higher pH values. The soil components displayed a catalytic activity and accelerated the transformation of L-DOPA. Similar transformation occurred when light was irradiated. At pH values higher than 4.0, the transformed products from L-DOPA consisted of humic substances-like heterogeneous components, whereas specific components with low molecular weight were included when L-DOPA was transformed at a pH value of 9.7 or higher. The plant-growth-inhibitory activity of L-DOPA was extremely weakened when L-DOPA was adsorbed on or transformed (polymerized) by soil components. Therefore, in soils with high abilities of adsorption and transformation of L-DOPA such as in Andosols, it was likely that the L-DOPA concentration in the soil solution decreased quickly by adsorption and transformation reactions and the allelopathic activity of L-DOPA was lost.     

Soil Properties as Influenced by Incorporation of Crop Residues

Chemical transformation,nutrient release and changes in the energy content of decomposing rape,sunflower and soybean residues confined in buried fiberglass bage were assessed in a laboratory study during a 340-day incubation period.The organic C decreased by about 70% while total N,after initial decay,remained almost constant for each type of residue.The NH4^ -N was progressively oxidized and,consequently,the NO3^-N increased.The C/N ratio narrowed with loss of C.Hemicellulose,cellulose and lignin decreased with different trends for each crop residue.The energy content,was reduced to about 25% in rape,30% in sunflower and 20% in soybean residues.Total P,K,Ca and Mg contents decreased for each type of residue The results suggest that the three residues could imporve the nutrient pool of the soil.     

Inhibition Kinetics of Ammonia Oxidation Influenced by Silver Nanoparticles

Silver nanoparticles (AgNPs) have significantly increased in production and use for anti-microbial propose. This agent, after used, is released into sewerage system resulting in possibility to inactivate non-targeted microorganisms in wastewater treatment plants. In this study, the inhibitory effect of AgNPs on ammonia oxidation was investigated using respirometric assay. The initial concentrations of AgNPs and ammonia ranged 0.25?C10.00 and 14?C280?mg/L, respectively. Half saturation constant (K _s) for ammonia oxidation was found to be 15.9?mg?N/L. Under the presence of AgNPs, the maximum oxygen uptake rate and K _s declined. The effect of AgNPs was proved to follow an uncompetitive-like inhibition kinetic type with the inhibition coefficients (K _i) of 5.5?mg/L. Increasing AgNPs from 0.25 to 10.00?mg/L inhibited 4 to 50?% of ammonia-oxidizing activities at the initial ammonia concentrations from 14 to 280?mg/L. Based on transmission electron microscopic observation, AgNPs could damage the microbial cells. All findings indicated that AgNPs substantially reduced ammonia-oxidizing microorganisms and their activities. Thus, special attention should be made to manage discharge of AgNPs into the environment.     

pH Influenced by the elemental composition of nutrient solutions

Nutrient solutions can be considered as aqueous solutions of inorganic ions. The pH of a nutrient solution is a property that is inherent to its composition. If another pH is aimed at, this can only be reached by changing the elemental composition. The pH of an aqueous solution is determined by the initial concentration of acids and bases. In the case of nutrient solutions, this is dihydrogen phosphate (H₂PO₄ ^‐), bicarbonate (HCO₃ ^‐) and/or ammonium (NH₄ ⁺). In this study, formulas are derived to calculate the pH of a nutrient solution as a function of the concentration of H₂PO₄ ^‐, NH₄ ⁺, and/or HCO₃ ^‐. The pH of a nutrient solution affects the dissociation, complexation, and precipitation reactions occurring in nutrient solutions. These chemical reactions significantly impact elemental speciation and bioavailability, and therefore, have to be taken into account in hydroponic plant nutritional research. The term “speciation”; indicates the distribution of elements among their various chemical and physical forms like: free ions, soluble complexes, chelates, ion pairs, solid and gaseous phases, and different oxidation states, all of which influences their reactivity, mobility and bioavailability. A good knowledge of the chemical reactions occurring in nutrient solutions is the first prerequisite in hydroponic plant nutritional research. The pH of a nutrient solution is determined by its initial concentration of H₂PO₄ ^‐, NH₄ ⁺, and HCO₃ ^‐.     

黄土高原中部地区土壤侵蚀人为影响因素的分析

黄土高原中部地区是典型的农业区，开荒扩种在本区表现突出，由于人为不合理的社会经济活动的影响，水土流失成为制约本区经济发展的突出问题。本文通过典型调查和总体分析相结合，对影响土壤侵蚀的人为因素进行了评价。认为土地利用结构不合理，人口的失控增长，森林植被的破坏以及工业化进程中对水土保持工作不十分重视等是人为加速土壤侵蚀的几个主要方面。     

三江平原人类活动的水文效应

分析了三江平原人类活动对地表径流过程、土壤水、地下水以及地表水质的影响。对人类活动水文影响的尺度和趋势进行了预测分析,指出人类活动水文影响的时空尺度将日益扩大,径流过程人为化、区域水系网状化、湿地景观破碎化及地表水质恶化等问题将越来越严峻。