Biotechnological approach of greywater treatment and reuse for landscape irrigation in small communities

A level of water quality intended for human consumption does not seem necessary for domestic uses such as irrigation of green spaces. Alternative water supplies like the use of greywater (GW) can thus be considered. However, GW contains pathogenic microorganisms and organic compounds which can cause environmental and health risks. As the risks related to recycling are unknown, GW treatment is necessary before reusing. To describe the risks related to GW reuses, the scientific approach performed in this study was to characterize domestic GW in order to select an appropriate treatment. The biotechnology chosen is a Horizontal sub-surface flow constructed wetland reactor. In order to minimize health risks, an optimization step based on UV disinfection was performed. The treatment performances were then determined. The treated GW produced in this study reached the threshold values expected by the Moroccan regulation for irrigation of green spaces with treated wastewater. Indeed, the COD and the TSS obtained in treated GW without disinfection are respectively 16.6 mg O₂ L^?1 and 0.40 mg L^?1. The horizontal sub-surface flow constructed wetland (HSSF CW) reactor has been used to treat 1.2 m³/d of GW for 100 days. Three lawn plots have been irrigated respectively with raw GW, treated GW and tap water as a reference. Contrary to the lawn plot irrigated with raw GW, the risk analysis performed in this study has shown no significant difference between the law plots irrigated with treated GW combined with UV disinfection and the one irrigated with tap water. Overall, UV disinfection treated GW produced from the HSSF CW reactor developed in this experiment is thought to be an effective and feasible alternative for agricultural reuse.     

Short-term changes in soil nutrients during wetland creation

This study examined changes in pH and extractable nutrients in soilsfollowing wetland creation. Sample plots were established in two areas: (1) an old-field with parts that were flooded during wetland creation, and (2) a native wetland in a floodplain of the Ohio River called Green Bottom Swamp. Soils were sampled before inundation and eight months afterwards. Compared to old-field soils in the pre-inundation period, swamp soils exhibited: (1) higher acidity, (2) lower NO3 and higher NH4 concentrations, (3) higher extractable P, Fe, and Mn, and (4) lower Ca, Mg, and Zn concentrations. Eight months after inundation, the old-field soil redox decreased from +210 mV in the old field –290 mV, and extractable NO3 and Ca decreased and extractable NH4 and Fe increased, but pH and extractable P, Mn, Mg, and Zn changed either slightly or not at all. These results suggest that eight months is an insufficient period of time for a complete change. Other results suggest that the response of nitrogen during the wetland creation processes may be extremely rapid.     

Temporal changes in soil properties and physiological characteristics of Atriplex species and Medicago arborea grown in different soil types under saline irrigation

Plant and Soil - Salinity stress tolerance is a complex polygenic trait composed of numerous sub-traits that operate at very different timescales. This work elucidates the time-dependence and...     

Soil pH changes associated with lupin and wheat plant materials incorporated in a red–brown earth soil

Both alkalization and acidification of soil occurred when shoot and root materials from lupin and wheat were incubated in a red–brown earth soil, but with three different starting pH values, during a 70-day period. The response of soil pH change to the addition of organic matter depended on the type of plant materials and starting pH. The net effect of addition of lupin and wheat shoots to acid soils (pH<5) caused soil pH to increase, the addition of lupin roots to soils caused soil pH to decrease slightly, whilst with a higher pH soil (6.5) the wheat straw and lupin shoots raised pH and pH was unchanged for soil with addition of lupin roots. The ash alkalinity of plant materials and the mineralization of organic N are major reasons for the soil pH increase, and the nitrification of mineralized N results in soil pH to decrease. Whilst the data given here would suggest the likelihood of soil acidification occurring, particularly on poorly buffered soil given the inevitable influence of legume root materials, the overall directions of soil pH change in a cropping system that is legume-based will be very much influenced by the balance of many factors associated with the soil and plant system.     

变饱和带条件下污水灌溉对土壤氮素运移和冬小麦生长的影响

为了研究地下水浅埋区污水灌溉对土壤环境及作物生长的影响,设置地下水埋深(2、3m和4m)和灌水水量(900m3·hm-2和1200m3·hm-2)2个因素,对冬小麦全生育期土壤氮素和冬小麦生长发育指标进行试验,试验在地中渗透仪中进行.结果显示:灌水后,不同处理土壤中硝态氮含量均显著增加,灌水水平越高,土壤中硝态氮含量增加越多;灌水后,灌水水平B1(900 m3·hm-2)不同潜水埋深地下水硝态氮分别增加34.67%、24.94%、20.88%;灌水水平B2(1200 m3·hm-2)不同潜水埋深地下水硝态氮分别增加58.42%、38.98%、27.21%.潜水埋深越浅,地下水中硝态氮的浓度增加越大,这也就表明由于淋溶和硝化作用产生的硝态氮造成浅层地下水污染的风险越大.污水灌溉对冬小麦的生长发育指标和产量有促进作用;相同灌水水平(B1 和B2),地下水埋深影响冬小麦生长发育指标的大小顺序为:2m＞3m＞4m.     

Seasonal changes in inorganic and organic phosphorus in the soil of a riparian forest

This study addresses the temporal distribution of forms of phosphorus in the soil of a temporarily flooded riparian forest of the valley of the river Garonne (Southwest of France). A sequential extraction for forms of phosphorus of increasing chemical stability was used. During the study period (13 months), the forest was flooded a few days during March and May. In winter, resin-Pi concentration was high (26 g g^–1) in comparison to spring values (<9 g g^–1). NaHCO₃-Po, NaHCO₃-Pi or NaOH-Pi concentrations increased during winter (up to 74, 124 and 78 g g^–1 respectively) and decreased significantly during spring (32, 44 and 32 g g^–1 respectively). This pattern was attributed to simultaneous mineralization and plant uptake during the growing season and to the flood events (erosional processes and P-release). During summer and fall, resin-Pi concentration increased significantly (up to 26 g g^–1 in October). NaHCO₃-Po concentrations remained low during spring and summer (<33 g g^–1), and increased significantly in fall (>45 g g^–1 NaHCO₃-Pi or NaOH-Pi increased in late spring or summer (90 g g^–1 and 68 g g^–1 respectively). Increasing concentrations of the labile forms during late spring or summer were ascribed to the warm temperature and soil dryness that limited plant growth. HCl-Pi increased regularly after the floods (174 g g^–1 before the flood events to 254 g g^–1 after the floods). Residual P presented a similar pattern i.e. 214 g g^–1 and 279 g g^–1 respectively before and after the flood events. This pattern was attributed to a progressive incorporation of flood deposits to the soil.     

Spatial changes of arbuscular mycorrhizal fungi in peach and their correlation with soil properties

Arbuscular mycorrhizal (AM) fungi have beneficial effects on host plants, but their growth is influenced by various factors. This study was carried out to analyze the variation of AM fungi in soils and roots of peach (Prunus persica L. var. Golden Honey 3, a yellow-flesh variety) trees in different soil layers (0–40 cm) and their correlation with soil properties. The peach tree could be colonized by indigenous AM fungi (2.2–8.7 spores/g soil and 1.63–3.57 cm hyphal length/g soil), achieving 79.50–93.55% of root AM fungal colonization degree. The mycorrhizal growth, root sugars, soil three glomalins, NH₄⁺-N, NO₃⁻-N, available P and K, and soil organic matter (SOM) had spatial heterogeneity. Soil spores, but not soil hyphae contributed to soil glomalin, and soil glomalin also contributed to SOM. There was a significant correlation of soil hyphae with spore density, soil NO₃⁻-N, and SOM. Root mycorrhiza was positively correlated with spore density, NH₄⁺-N, NO₃⁻-N, and easily extractable glomalin-related soil protein. Notably, spore density positively correlated with NO₃⁻-N, available K, SOM, and root fructose and glucose, while negatively correlated with available P and root sucrose. These findings concluded that mycorrhiza of peach showed spatial distribution, and soil properties mainly affected/altered based on the soil spore density.     

Potential for detecting changes in soil organic carbon concentrations resulting from climate change

The interaction between soil organic carbon pools and climate change is an important determinant of future atmospheric CO₂ concentrations. Much effort has so far been allocated to manipulative process studies and predictive modelling exercises. Here, we examine the potential for directly detecting predicted changes through repeated soil sampling. Two contrasting benchmark plots were selected in the steppe at the Russian–Mongolian border, where soil organic carbon losses are predicted to be around 10% over the first 50 years of climate change. In both plots, 50 samples were taken to 20 and 30 cm depths. The estimated time intervals before re‐sampling by the same method that were likely to prove significant soil organic carbon losses (α=0.05; statistical power=0.90) were 43 and 26 years.     

Potential role of soil properties in the spread of CWD in western Canada

Chronic wasting disease (CWD) is a horizontally transmissible prion disease of free ranging deer, elk and moose. Recent experimental transmission studies indicate caribou are also susceptible to the disease. CWD is present in southeast Alberta and southern Saskatchewan. This CWD-endemic region is expanding, threatening Manitoba and areas of northern Alberta and Saskatchewan, home to caribou. Soil can serve as a stable reservoir for infectious prion proteins; prions bound to soil particles remain infectious in the soils for many years. Soils of western Canada are very diverse and the ability of CWD prions to bind different soils and the impact of this interaction on infectivity is not known. In general, clay-rich soils may bind prions avidly and enhance their infectivity comparable to pure clay mineral montmorillonite. Organic components of soils are also diverse and not well characterized, yet can impact prion-soil interaction. Other important contributing factors include soil pH, composition of soil solution and amount of metals (metal oxides). In this review, properties of soils of the CWD-endemic region in western Canada with its surrounding terrestrial environment are described and used to predict bioavailability and, thus, potential spread of CWD. The major soils in the CWD-endemic region of Alberta and Saskatchewan are Chernozems, present in 60% of the total area; they are generally similar in texture, clay mineralogy and soil organic matter content, and can be characterized as clay loamy, montmorillonite (smectite) soils with 6–10% organic carbon. The greatest risk of CWD spread in western Canada relates to clay loamy, montmorillonite soils with humus horizon. Such soils are predominant in the southern region of Alberta, Saskatchewan and Manitoba, but are less common in northern regions of the provinces where quartz-illite sandy soils with low amount of humus prevail.     

衡阳紫色土丘陵坡地植被恢复阶段土壤特性的演变

采用空间代替时间序列方法,对衡阳紫色土丘陵坡地不同恢复阶段的土壤理化性质、土壤微生物数量、土壤微生物学性质和主要酶活性特征以及它们之间的相互关系进行研究。结果表明:不同恢复阶段土壤理化特征存在明显差异,从狗尾草群落阶段(Ⅰ)、紫薇-狗尾草群落阶段(Ⅱ)、牡荆+剌槐群落阶段(Ⅲ)到枫香+苦楝-牡荆群落阶段(Ⅳ),0—40cm土壤含水量、容重、非毛管孔隙度、孔隙比、大于0.25mm水稳性团聚体含量、有机碳(SOC)、全氮(TN)、碱解氮(AN)与速效磷(AP)显著增加,土壤容重显著减小,土壤pH值逐渐减小,土壤全磷(TP)、全钾(TK)与速效钾(AK)其差异变化不大,土壤理化特征的差异引起土壤微生物数量、微生物学性质与土壤酶活性的变化;不同恢复阶段土壤微生物总数显著增加,其中细菌数量显著增加,而真菌与放线菌数量显著减少;不同恢复阶段土壤基础呼吸(SBR)、土壤微生物量碳(SMBC)、土壤微生物量氮(SMBN)、土壤微生物量磷(SMBP)、土壤微生物熵(Cmic/Corg)显著增加,而代谢熵或呼吸熵(qCO2)显著减小,碳氮比(C/N)逐渐减小;不同恢复阶段均显著地增加了脲酶(URE)、蔗糖酶(INV)与磷酸酶(APE)的活性;土壤理化性状、土壤微生物数量、土壤微生物学性质与土壤酶活性之间存在密切的相关性。     

Spectroscopic properties of bulk and dichromate oxidation resistant soil organic matter from an anthroposequence in a Mediterranean environment

The shallow soils of Pianosa—a small calcareous island in the Mediterranean Sea, facing Tuscany, central Italy—developed under the same pedogenic factors with the exception of vegetation and, in the last two centuries, human impact. Originally, they were covered by “macchia,” a tangled mix of bushy species, or, in a few more fertile sites, by Quercus ilex L. Currently there are six land uses on the island: (1) pristine macchia, (2) groves of Olea europaea L. totally reinvaded by macchia, (3) degraded residual thickets of Q. ilex, (4) cropland, (5) recently abandoned pastures, and (6) stands of Pinus halepensis Mill. The related soils were analysed by solid-state cross polarisation/magic angle spinning ¹³C-nuclear magnetic resonance (NMR) to compare the spectroscopic properties of their organic pool. The prevalence of O-alkyl C over other C forms is evident in all cases, while there is large variability with respect to the alkyl C to aromatic C ratio between both the different soils, and the horizons of a same soil. On the whole, the results show that on Pianosa Island, human impact has profoundly altered not only the amount but also the quality of soil organic matter (SOM). The SOM residual of the dichromate oxidation in the Walkley–Black method—a widely used method to measure soil organic C—was also analysed by NMR. It comprised almost exclusively alkyl C and aromatic C, as a result of the removal of carbonyl and O-alkyl C. Most of the aromatic C seems to belong to charcoal.     

Changes in microbial and soil properties following amendment with treated and untreated olive mill wastewater

We investigated the effect of untreated and biologically treated olive mill wastewater (OMW) spreading on the soil characteristics and the microbial communities. The water holding capacity, the salinity and the content of total organic carbon, humus, total nitrogen, phosphate and potassium increased when the spread amounts of the treated or untreated OMW increased. The OMW treated soil exhibited significantly higher respiration compared to the control soil. However, the C-CO2/C(tot) ratio decreased from 1.7 in the control soil to 0.5 in the soil amended with 100 m3 ha(-1) of untreated OMW. However, it slightly decreased to 1.15 in the soil amended with 400 m3 ha(-1) of treated OMW. The treated OMW increased the total mesophylic number while the number of fungi and nitrifiers decreased. Actinomycetes and spore-forming bacteria were neither sensitive to treated nor to untreated OMW. The total coliforms increased with higher doses of treated and untreated OMW. A toxic effect of the untreated OMW appeared from 100 m3 ha(-1). This toxicity was more significant with 200 m3 ha(-1), where microflora of total mesophilic, yeasts and moulds, actinomycetes, and nitrifiers were seriously inhibited except for total coliforms and spore-forming bacteria.     

Development of laser induced breakdown spectroscopy technique to study irrigation water quality impact on nutrients and toxic elements distribution in cultivated soil

This study is focused mainly on impact of irrigation water quality in cultivated soil on distribution of essentials nutrients (Al, Mg, Ca, Fe, S, Si, Na, P, and K) and relatively toxic metals (As, Ba, Cr, Cu, Ti, Sn, Mn, Ni, and Zn) using an elegant Laser induced breakdown spectroscopy (LIBS) technique. A pulsed Nd:YAG laser operating at 1064 nm in conjunction with suitable detector was applied to record soil emission spectra. The abundance of these elements were evaluated via standard calibration curve Laser Induced Breakdown Spectroscopy (CC-LIBS) and calibration free Laser Induced Breakdown Spectroscopy (CF-LIBS) approaches. Quantitative analyses were accomplished under conjecture of local thermodynamic equilibrium (L.T.E) and optically thin plasma. The average electron temperatures were estimated by Boltzmann plot method for cultivated soil samples in 7800 to 9300 K range. The electron number density was ~ 1.11 × 1017 cm − 3 to 1.60 × 1017 cm − 3. Prior to application on soil samples, the experimental setup was optimized at the following parameters: pulsed energy = 60 mJpulse-1, sample to lens distance of 9.0 cm, and the gate delay of 3.5 μs. It is noteworthy that nutritional elements content of cultivated soils were found strongly dependent upon the irrigation water quality. The cultivated soil from industrial area was found rich of toxins while the cultivated land using tube well water contains toxins in least amount. Our LIBS findings were also validated by comparing its results with contents measured using a standard inductively coupled plasma optical emission spectroscopy (ICP-OES) method and both were found in excellent agreement. The present study could be highly beneficial for agricultural applications and for farmers to produce safe food products and higher crops yield.     

Succession-driven changes in soil respiration following fire in black spruce stands of interior Alaska

Boreal forests are highly susceptible to wildfire, and post-fire changes in soil temperature and moisture have the potential to transform large areas of the landscape from a net sink to a net source of carbon (C). Understanding the ecological controls that regulate these disturbance effects is critical to developing models of ecosystem response to changes in fire frequency and severity. This paper combines laboratory and field measurements along a chronosequence of burned black spruce stands into regression analyses and models that assess relationships between moss succession, soil microclimate, decomposition, and C source-sink dynamics. Results indicate that post-fire changes in temperature and substrate quality increased decomposition in humic materials by a factor of 3.0 to 4.0 in the first 7 years after fire. Bryophyte species exhibited a distinct successional pattern in the first five decades after fire that corresponded to decreased soil temperature and increased C accumulation in organic soils. Potential rates of C exchange in mosses were greatest in early successional species and declined as the stand matured. Residual sources of CO₂ (those not attributed to moss respiration or humic decomposition) increased as a function of stand age, reflecting increased contributions from roots as the stand recovered from disturbance. Together, the field measurements, laboratory experiments, and models provide strong evidence that interactions between moss and plant succession, soil temperature, and soil moisture largely regulate C source-sink dynamics from black spruce systems in the first century following fire disturbance.     

Concentration and composition of dissolved organic carbon in streams in relation to catchment soil properties

Two adjacent catchments in the Otway Ranges of Victoria, Australia (Redwater and Clearwater) produce water with markedly different concentrations of dissolved organic carbon (DOC) during summer. Water from Redwater Creek had a DOC concentration of 32 mg L^–1, while water from Clearwater Creek had a DOC concentration of 3.8 mg L^–1. Examination of the catchments revealed that while climate, topography, vegetation and land use were similar, the soils were different. The objective of this study was to examine the relationship between the concentration and chemical composition of DOC in stream waters and the nature of soils in the two catchments. Soil mapping determined that clayey soils formed on Cretaceous sediments (Cretaceous soils) occurred throughout both catchments, but that Redwater Catchment also contained a large area (39%) of sandy soils formed on Tertiary sediments (Tertiary soils). The concentration of DOC in forest floor leachate was high in both the Tertiary and Cretaceous areas; however, the concentration of DOC in water draining areas dominated by Tertiary soils was greater than that in water draining areas dominated by Cretaceous soils. Laboratory experiments showed that the Cretaceous soils had higher adsorption capacities for forest floor leachate DOC than the Tertiary soils. The difference in DOC concentrations of the streams was therefore attributed to the difference in adsorption capacity of catchment soils for DOC. Adsorption capacities of the soils were found to be a function of their clay contents and specific surface areas.Solid-state³C nuclear magnetic resonance spectroscopy and pyrolysis-mass spectrometry were used to determine the chemical structure of DOC found in streams and forest floor leachate samples and that remaining in solution after interaction with soil. Chemistry of DOC in forest floor leachate was similar before and after interaction with soil, indicating no preferential adsorption of a particular type of carbon. Thus, differences between the chemical structure of stream DOC and forest floor leachate DOC could be attributed to microbial modifications during its movement through soils and into the streams, rather than losses by adsorption.     

石油污灌土壤污染物的残留与生态毒理

土壤样品采自沈阳东部石油污水灌渠的上、中、下游。进行了污染物 (Cd、矿物油 )含量分析和生态毒性试验。重金属采用原子吸收分光光度仪测定 ,矿物油采用紫外分光光度计测定。生态毒性试验分别参照国际标准组织 (ISO)和OECD指南 ,进行了植物毒性试验和蚯蚓毒性试验。植物试验以小麦种子发芽根伸长抑制率为试验终点 ,试验周期 5 0h ,蚯蚓毒性试验以蚯蚓死亡率和体重增长抑制率为试验终点 ,试验周期 2 8d。结果表明 ,所有土壤均有矿物油积累 ,含量为 6 6 2 2～ 1391 14mg·kg-1,重金属Cd略高于土壤背景值 ,含量为 0 0 6～ 0 37mg·kg-1。然而 ,土壤对高等植物表现有不同程度的生长刺激效应 ,对蚯蚓有急性致死及慢性亚致死效应。种子发芽根伸长抑制率为 - 2 8 6 1%～ - 5 4 6 5 % ,蚯蚓 2 8d死亡率最大值为 10 %。蚯蚓 14d和 2 8d体重增长抑制率分别为 - 5 13%～ - 2 8 0 5 %和 - 31 78%～ 8 0 8%。研究表明 ,长期石油污水灌溉土壤中矿物油的低积累和较明显的生态毒性。     

Analysis of estuarine soil gradients in salt marshes of the southwestern Netherlands with special reference to the Scheldt estuary

Macro- and microgradients in salt-marsh soils of the Scheldt estuary have been studied. The soil parameters used are clay, carbonate, organic matter, pH, nitrogen, potassium and phosphate. The hypothesis that estuarine soil gradients can be reflections of similar aquatic gradients is affirmed for two gradients. Soil gradients of upstream increasing organic matter and phosphate contents have been found, relating significantly to corresponding aquatic gradients caused by river pollution. In the same direction gradients of decreasing nitrogen and potassium contents occur. A macrogradient in carbonate content was not found. Some microgradients in clay and carbonate contents are described, and relevant mutual relationships between the soil parameters are characterized. Communication nr. 149 of the Delta Institute for Hydrobiological Research, Yerseke, The Netherlands     

Relationships between soil microbial properties and aboveground stand characteristics of conifer forests in Oregon

Eight forest sites representing a large range of climate, vegetation, and productivity were sampled in a transect across Oregon to study the relationships between aboveground stand characteristics and soil microbial properties. These sites had a range in leaf area index of 0.6 to 16 m² m^–2 and net primary productivity of 0.3 to 14 Mg ha^–1 yr^–1.Measurements of soil and forest floor inorganic N concentrations and in situ net N mineralization, nitrification, denitrification, and soil respiration were made monthly for one year. Microbial biomass C and anaerobic N mineralization, an index of N availability, were also measured. Annual mean concentrations of NH ₄ ⁺ ranged from 37 to 96 mg N kg^–1 in the forest floor and from 1.7 to 10.7 mg N kg^–1 in the mineral soil. Concentrations of NO ₃ ^– were low ( < 1 mg N kg^–1) at all sites. Net N mineralization and nitrification, as measured by the buried bag technique, were low on most sites and denitrification was not detected at any site. Available N varied from 17 to 101 mg N kg^–1, microbial biomass C ranged from 190 to 1230 mg Ckg^–1, and soil respiration rates varied from 1.3 to 49 mg C kg^–1 day^–1 across these sites. Seasonal peaks in NH ₄ ⁺ concentrations and soil respiration rates were usually observed in the spring and fall.The soils data were positively correlated with several aboveground variables, including leaf area index and net primary productivity, and the near infrared-to-red reflectance ratio obtained from the airborne simulator of the Thematic Mapper satellite. The data suggest that close relationships between aboveground productivity and soil microbial processes exist in forests approaching semi-equilibrium conditions.Abbreviations IR infrared - LAI leaf area index - k _c proportion of microbial biomass C mineralized to CO₂ - NPP net primary productivity - TM Thematic Mapper