再生水不同灌水水平对土壤酶活性及耐热大肠菌群分布的影响

为了探讨再生水不同灌水水平对土壤酶活性和环境污染指示菌耐热大肠菌群分布的影响,采用室内土柱灌水实验,研究再生水、自来水不同灌水水平对土壤酶活性和耐热大肠菌群分布的影响.结果表明:(1)在土壤酶活性方面,相同灌水水平下,与自来水处理相比,再生水灌溉处理提高了土壤脲酶和蔗糖酶活性;再生水不同灌水水平对比分析表明,充分灌水处理显著提高了土壤蔗糖酶活性和深层土壤过氧化氢酶活性.(2)在土壤耐热大肠菌群分布方面,相同灌水水平下,与自来水灌溉处理相比,再生水灌溉显著提高了土壤耐热大肠菌群数量;再生水不同灌水水平对比分析表明,充分灌水处理显著增加了土壤耐热大肠菌群数量;4个处理的表层土壤耐热大肠菌群数量均显著高于深层,且随着灌溉时间的推移,0~60 cm各土层的土壤耐热大肠菌群数量存在降低趋势.(3)通过对土壤耐热大肠菌群数量与土壤酶活性的相关性分析表明,土壤耐热大肠菌群数量与土壤脲酶和蔗糖酶活性呈极显著正相关,与土壤过氧化氢酶活性呈显著正相关.因此,再生水灌溉促进了土壤C、N循环转化酶的活性,合理控制再生水灌水水平可以有效阻控土壤耐热大肠菌群的数量.     

华北稻田灌溉水多级表面流强化人工湿地工程系统设计研究

以河北曹妃甸水稻田为研究对象,分析测定灌溉水样中SS、COD和氨氮的含量并依据有关国家标准确定其污染程度。根据当地农业生产条件、工程地质与农田环境特点及不同治理方案的经济技术可行性,选用由工程保障和植物生态系统构成的多级表面流强化人工湿地系统修复灌溉水有机污染,并对其修复效果进行量化评价。结果表明:研究区内稻田灌溉水SS、COD、NH3-N 3种污染物的浓度削减率依次为76.17%、60.02%、55.08%,出水达到农田灌溉水质标准和地表水Ⅴ类水质要求。人工湿地系统的建立不仅改善灌溉水水质,保证农产品质量,还有效恢复了湿地的生态功能,实现环境与经济效益的统一。     

Temporal and spatial changes of microbial community in an industrial effluent receiving area in Hangzhou Bay

Anthropogenic activities usually contaminate water environments, and have led to the eutrophication of many estuaries and shifts in microbial communities. In this study, the temporal and spatial changes of the microbial community in an industrial effluent receiving area in Hangzhou Bay were investigated by 454 pyrosequencing. The bacterial community showed higher richness and biodiversity than the archaeal community in all sediments. Proteobacteria dominated in the bacterial communities of all the samples; Marine_Group_Ⅰ and Methanomicrobia were the two dominant archaeal classes in the effluent receiving area. PCoA and AMOVA revealed strong seasonal but minor spatial changes in both bacterial and archaeal communities in the sediments. The seasonal changes of the bacterial community were less significant than those of the archaeal community, which mainly consisted of fluctuations in abundance of a large proportion of longstanding species rather than the appearance and disappearance of major archaeal species. Temperature was found to positively correlate with the dominant bacteria, Betaproteobacteria, and negatively correlate with the dominant archaea,Marine_Group_Ⅰ; and might be the primary driving force for the seasonal variation of the microbial community.     

An advanced anaerobic biofilter with effluent recirculation for phenol removal and methane production in treatment of coal gasification wastewater

An advanced anaerobic biofilter (AF) was introduced for the treatment of coal gasification wastewater (CGW), and effluent recirculation was adopted to enhance phenol removal and methane production. The results indicated that AF was reliable in treating diluted CGW, while its efficiency and stability were seriously reduced when directly treating raw CGW. However, its performance could be greatly enhanced by effluent recirculation. Under optimal effluent recirculation of 0.5 to the influent, concentrations of chemical oxygen demand (COD) and total phenol in the effluent could reach as low as 234.0 and 14.2 mg/L, respectively. Also, the rate of methane production reached 169.0 mL CH₄/L/day. Though CGW seemed to restrain the growth of anaerobic microorganisms, especially methanogens, the inhibition was temporary and reversible, and anaerobic bacteria presented strong tolerance. The activities of methanogens cultivated in CGW could quickly recover on feeding with glucose wastewater (GW). However, the adaptability of anaerobic bacteria to the CGW was very poor and the activity of methanogens could not be improved by long-term domestication. By analysis using the Haldane model, it was further confirmed that high effluent recirculation could result in high activity for hydrolytic bacteria and substrate affinity for toxic matters, but only suitable effluent recirculation could result in high methanogenic activity.     

Do plants’ emissions respond to ambient environmental quality? Evidence from the clean water act

In this paper we show that plants respond to downstream ambient water quality after controlling for permitted levels of pollution. We find if past water quality declines by one percent, plants reduce current pollution by 0.35 percent. The magnitude of this coefficient is comparable to the coefficient on permitted discharge levels i.e. regulatory stringency itself. Results are consistent with two mechanisms. First, a decline in water quality may lead to more stringent permits that would raise the cost of abatement of a plant significantly. Second, the plant is likely to be subject to increased public pressure in response to poor water quality. Indeed, as expected, the impact of water quality becomes stronger in locations with higher median household income, higher percent carpooling to work, or lower percent of manufacturing employment but surprisingly with lower median age of residents, lower percent with bachelor׳s degree or higher percent of families with children.     

Leachate characteristics,dry matter yield of Urochloa decumbens and properties of two contrasting soils irrigated with sludgewater in columns

Increasing demands on freshwater and challenges in disposal of wastewaters encourage their use for irrigation. The study evaluated the effects of irrigation of signal grass (Urochloa decumbens) with sludgewater on leaching, uptake and retention of a range of elements in two contrasting soils in columns. The grass was grown on a sandy loam and a clay soil packed in plastic columns and irrigated for 119 days with either undiluted, diluted sludgewater or tap water. The sludgewater had a pH of 6.9 and high aluminum (Al), manganese (Mn), iron (Fe), and boron (B). Analyses were conducted on leachates, above-ground plant biomass (two harvests), and soils at the end of the experiment. Sludgewater treatments increased grass biomass yield and uptake of nitrogen (N), phosphorus (P), potassium (K), and magnesium (Mg) in both soils with a greater nutrient uptake from the clay than the sandy loam. The application of sludgewater increased Mn and reduced P (sandy loam only) in the leachate with no effects on Al, Fe, or B. Uptake of Al, Fe, and B was increased by sludgewater application. Even when diluted, the sludgewater increased extractable Mn, particularly in the clay soil. The findings showed that irrigation of the soils with sludgewater increased Mn and B concentrations and uptake by signal grass, with no negative effects on biomass production. Leaching and accumulation in the soils of toxic elements were minimal in the short term. Sludgewater can therefore be used to grow signal grass in both soils although these effects need to be evaluated under field conditions.     

Mitigating the effects of climate change on the nests of sea turtles with artificial irrigation

For sea turtles, like many oviparous species, increasing temperatures during development threaten to increase embryonic mortality, alter offspring quality, and potentially create suboptimal primary sex ratios. Various methods are being implemented to mitigate the effects of climate change on reproductive success, but these methods, such as breeding programs, translocations, and shading, are often invasive and expensive. Irrigation is an alternative strategy for cooling nests that, depending on location, can be implemented relatively quickly and cheaply. However, multiple factors, including ambient conditions, nest substrate, and species characteristics, can influence irrigation success. Additionally, irrigation can vary in duration, frequency, and the volume of water applied to nests, which influences the cooling achieved and embryonic survival. Thus, it is critical to understand how to maximize cooling and manage risks before implementing irrigation as a nest-cooling strategy. We reviewed the literature on nest irrigation to examine whether artificial irrigation is feasible as a population management tool. Key factors that affected cooling were the volume of water applied and the frequency of applications. Embryonic responses varied with species, ambient conditions, and the timing of irrigation during development. Nest inundation was the key risk to a successful irrigation regime. Future irrigation regimes must identify clear targets, either primary or adult sex ratios, that maximize population viability. Monitoring population responses and adjusting the irrigation regime in response to population characteristics will be critical. Most studies reported on the manipulation of only one or two variables, further research is required to understand how altering multiple factors in an irrigation regime influences the cooling achieved and embryonic responses.     

基于野外实测光谱的污灌区土壤重金属污染快速监测

利用光谱反射率反演土壤重金属含量相比传统实验室化学分析方法具有简单高效、成本低、非侵入性等优点。但光谱采集主要局限于实验室内,大大降低了监测的时效性。采集了龙口市污水灌溉区内的32个土壤样本,对9种重金属(Cr、Mn、Fe、Ni、Cu、Zn、As、Cd、Pb)进行了测定,并对土壤光谱进行了野外实测,同时对实测光谱进行光谱变换,提取了去除包络线(CR)、光谱倒数对数(lg(1/R))、一阶微分(RD1)、二阶微分(RD2)4种光谱指标,采用偏最小二乘回归方法(PLSR)建模。结果表明,污水灌溉区内存在严重的土壤重金属污染现象,As、Ni、Cd等重金属富集情况显著,与Fe、Mn呈显著相关的6种元素为Ni、Mn、As、Pb、Zn、Cr,相应的最优建模光谱指标分别为一阶微分(RD1)、二阶微分(RD2)、反射率(R)、反射率(R)、二阶微分(RD2)、去除包络线(CR),验证精度r分别为0.935 3、0.781 4、0.699 6、0.745 8、0.690 1、0.569 6。研究表明,利用野外实测光谱可以提高土壤重金属监测的时效性,预估土壤重金属含量具有一定的可行性,但针对不同的重金属应使用不同的光谱指标建模来达到最优效果。     

造纸废水灌溉对湿地土壤重金属累积影响及趋势评价

探讨造纸废水灌溉下芦苇湿地土壤重金属累积规律,对有效利用造纸废水,防控湿地重金属污染具有重要意义.本研究以双台河口芦苇湿地土壤为研究对象,分析不同浓度造纸废水(CODCr浓度分别为:300 mg·L-1、175 mg·L-1、50 mg·L-1)灌溉下湿地土壤重金属含量的累积规律,基于重金属残留模型对土壤重金属累积量进行预测和评估.试验结果表明:1废水灌溉使土壤重金属含量显著增加,与废水浓度显著相关,芦苇生长对土壤中As、Ni、Cu含量影响较大而对Pb、Cd含量影响较小.2不同重金属在各土层垂直分布规律存在差异:As、Pb在中间层(20~40 cm)含量最高,Cd、Cu垂直分布较为均衡,Ni主要集中在土壤表层(0~20 cm),中下层(20~60 cm)含量迅速降低.3基于重金属残留模型对土壤重金属累积量进行预测和评估,以300 mg·L-1浓度废水灌溉,重金属都出现不同程度的累积,其中10 a后Cd的累积量超过我国《土壤环境质量标准》一级标准,50 a后Pb的累积量接近一级标准.以175 mg·L-1浓度废水灌溉,各重金属均出现累积,但增长幅度较300 mg·L-1低,50 a后Cd累积量未超过一级标准.以50 mg·L-1废水灌溉时,Pb、Ni、Cu出现土壤轻度积累,50 a后未超过一级标准.     

Rice: Reducing arsenic content by controlling water irrigation

<正>Arsenic has long been recognized as a poison.Arsenic in water supplies that are used for both drinking and crop irrigation can expose many people chronically to elevated levels of arsenic.The main health concern for chronic exposure to arsenic is the development of cancer.Although the World Health Organization(WHO)recommends that total arsenic in drinking water should be under 10μg/L(or 10 ppb),(WHO,2011),some regions