Phytoextraction of lead-contaminated soil using vetivergrass (<Emphasis Type="Italic">Vetiveria zizanioides</Emphasis> L.), cogongrass (<Emphasis Type="Italic">Imperata cylindrica</Emphasis> L.) and carabaograss (<Emphasis Type="Italic">Paspalum conjugatum</Emphasis> L.)

Background, Aims and Scope The global problem concerning contamination of the environment as a consequence of human activities is increasing. Most of the environmental contaminants are chemical by-products and heavy metals such as lead (Pb). Lead released into the environment makes its way into the air, soil and water. Lead contributes to a variety of health effects such as decline in mental, cognitive and physical health of the individual. An alternative way of reducing Pb concentration from the soil is through phytoremediation. Phytoremediation is an alternative method that uses plants to clean up a contaminated area. The objectives of this study were: (1) to determine the survival rate and vegetative characteristics of three grass species such as vetivergrass, cogongrass and carabaograss grown in soils with different Pb levels; and (2) to determine and compare the ability of the three grass species as potential phytoremediators in terms of Pb accumulation by plants. Methods The three test plants: vetivergrass (Vetiveria zizanioides L.); cogongrass (Imperata cylindrica L.); and carabaograss (Paspalum conjugatum L.) were grown in individual plastic bags containing soils with 75 mg kg⁻¹ (37.5 kg ha⁻¹) and 150 mg kg⁻¹ (75 kg ha⁻¹) of Pb, respectively. The Pb contents of the test plants and the soil were analyzed before and after experimental treatments using an atomic absorption spectrophotometer. This study was laid out following a 3 × 2 factorial experiment in a completely randomized design. Results On the vegetative characteristics of the test plants, vetivergrass registered the highest whole plant dry matter weight (33.85–39.39 Mg ha⁻¹). Carabaograss had the lowest herbage mass production of 4.12 Mg ha⁻¹ and 5.72 Mg ha⁻¹ from soils added with 75 and 150 mg Pb kg⁻¹, respectively. Vetivergrass also had the highest percent plant survival which meant it best tolerated the Pb contamination in soils. Vetivergrass registered the highest rate of Pb absorption (10.16 ± 2.81 mg kg⁻¹). This was followed by cogongrass (2.34 ± 0.52 mg kg⁻¹) and carabaograss with a mean Pb level of 0.49 ± 0.56 mg kg⁻¹. Levels of Pb among the three grasses (shoots + roots) did not vary significantly with the amount of Pb added (75 and 150 mg kg⁻¹) to the soil. Discussion Vetivergrass yielded the highest biomass; it also has the greatest amount of Pb absorbed (roots + shoots). This can be attributed to the highly extensive root system of vetivergrass with the presence of an enormous amount of root hairs. Extensive root system denotes more contact to nutrients in soils, therefore more likelihood of nutrient absorption and Pb uptake. The efficiency of plants as phytoremediators could be correlated with the plants’ total biomass. This implies that the higher the biomass, the greater the Pb uptake. Plants characteristically exhibit remarkable capacity to absorb what they need and exclude what they do not need. Some plants utilize exclusion mechanisms, where there is a reduced uptake by the roots or a restricted transport of the metals from root to shoots. Combination of high metal accumulation and high biomass production results in the most metal removal from the soil. Conclusions The present study indicated that vetivergrass possessed many beneficial characteristics to uptake Pb from contaminated soil. It was the most tolerant and could grow in soil contaminated with high Pb concentration. Cogongrass and carabaograss are also potential phytoremediators since they can absorb small amount of Pb in soils, although cogongrass is more tolerant to Pb-contaminated soil compared with carabaograss. The important implication of our findings is that vetivergrass can be used for phytoextraction on sites contaminated with high levels of heavy metals; particularly Pb. Recommendations and Perspectives High levels of Pb in localized areas are still a concern especially in urban areas with high levels of traffic, near Pb smelters, battery plants, or industrial facilities that burn fuel ending up in water and soils. The grasses used in the study, and particularly vetivergrass, can be used to phytoremediate urban soil with various contaminations by planting these grasses in lawns and public parks. ESS-Submission Editor: Dr. Willie Peijnenburg (wjgm.peijnenburg@rivm.nl)     

锅炉煤炭燃烧过程NOx释放规律及累积转化率影响因素

选用某电厂的实际用煤及焦炭,模拟燃煤电厂的煤炭燃烧过程,在不同温度、助燃气体流量、煤粉粒径和氧含量等多种条件下分别进行实验,得出不同燃烧条件下NOx的释放规律。实验表明,相同条件下,挥发分越大,氮的转化率也相对越大;煤的粒径越小,氮的转化效率越低;随着助燃气体流量的增加,燃料N转化为NOx的总转化效率增加;氧含量增加缩短了反应时间,但燃料N总效率变化不大。     

小麦在与水杨酸诱导的应答过程中PGIP的积累

以ＳＷ８９－２５８９小麦品系为材料,利用自制的小麦抗ＰＧＩＰ血清和ｄｏｔ－ｉｍｍｕｎｏｂｉｎｄｉｎｇ ａｓｓａｙ,并结合ＰＧＩＰ粗提液对ｅｎｄｏ－ＰＧ的抑制实验,研究了小麦内源多聚半乳糖醛酸酶抑制蛋白（ＰＧＩＰ）水平与水杨酸之间的应答关系。发现用水杨酸处理过的ＰＧＩＰ粗提液在ＮＣ膜上的显色斑点颜色均较Ｈ２Ｏ处理的ＰＧＩＰ粗提液深,而且对ｅｎ－ｄｏ－ＰＧ的抑制程度也高于未用水杨酸处理的ＰＧＩＰ粗提液     

硒对汞在稀有鲫体内积累动力学影响

通过增加饲料中亚硒酸钠的含量，研究了硒对氯化汞在稀有鲫体内积累动力学的影响，探讨了硒对汞富集的影响机制，并给出了两种硒浓度下汞的积累方程。结果表明，饲料中０．２ｍｇ／ｋｇ的硒对鱼体汞富集无明显影响，２．０ｍｇ／ｋｇ的硒使鱼体汞富集增加。并且高硒饲料降低了鱼对汞的排除常数，使鱼体总汞的稳态含量增大。     

北京市凉凤灌区土壤重金属的积累及其变化趋势

其含量的几何平均值(0.147mg·kg-1)为北京市土壤Hg背景值(0.0576mg·kg-1)的2.5倍.除Cd、Ni外,其它5种重金属都存在不同程度的积累现象(超过基线值),Hg的超标率(超过基线值)高达34.5%;Pb、Cu次之,超标率分别为8.86%、8.33%;Zn、Cr、As污染相对较轻一些,超标率为2.41%、1.20%、1.19%;没有发现Cd、Ni污染问题.与20世纪70年代中期的调查结果比较发现,经过近30年后,该地区的土壤Hg、Pb、Cu、As含量分别增加了11.4%、40%、26%、9.0%.结果表明,污水灌溉是导致土壤重金属积累的重要原因之一,Hg、Pb是该灌区土壤中需要优先控制的重金属.     

松弛涡旋累积法获取细颗粒物湍流通量的实验研究

利用2018年12月27日-2019年1月8日山东省平原县大气环境实验站观测资料,基于近地面层各物理量湍流输送特征的相似性,以温度（T）作为代理变量,采用松弛涡旋累积法（The Relaxed Eddy Accumulation,REA）计算了重霾天气过程细颗粒物湍流通量,并给出了可信度验证.结果表明：实验观测期间,温度（T）、水汽（H₂O）、二氧化碳（CO₂）等不同物理量的REA法获取的湍流通量的经验系数b分别为b_T=0.56、b_H2O=0.56、b_CO2=0.56.经验系数b的中位数随归一化采样阈值H_REA的增大而逐渐减小;b值的离散性随H_REA的变化存在一个极小值;考虑到温度b值的离散性最小,建议选取温度作为代理变量.REA法计算的细颗粒物湍流通量结果与细颗粒物湍流通量测量装置的结果具有较好的一致性,说明采用代理变量的REA法适用于细颗粒物湍流通量的获取.     

丁香蓼对Cu富集效应的研究

通过盆栽实验研究不同浓度的Cu胁迫对丁香蓼响应和富集效应的影响,结果表明,随着Cu的浓度增加,丁香蓼的株高和生物量降低,长势减弱,但在低浓度(ω(Cu)为125 mg/kg)时降低不明显,与对照组差异性不显著,高浓度与对照组差异性显著。根茎叶中Cu含量随着添加的Cu浓度增加而增加,Cu的含量和富集系数都表现为根叶茎,对Cu的积累量表现为根、茎叶,丁香蓼不是Cu的超富集植物,但对Cu具有较好富集作用和忍耐能力。     

嫩江—齐齐哈尔江段几种蚌类重金属残毒水平

通过对嫩江几种蚌类不同部位重金属残毒分析，得了３种蚌类中背角无齿蚌的富集能力最强，不同部位中，足对总汞的富集能力强，外套膜对镉的富集能力最强，而鳃对铅，铜，锌富集能力最强。     

Comparative growth response of two varieties of <Emphasis Type="Italic">Vigna radiata</Emphasis> L. (var. PDM 54 and var. NM 1) grown on different tannery sludge applications: effects of treated wastewater and ground water used for irrigation

This study evaluates the possibility of using contaminated soil by treated tannery wastewater and the use of tannery sludge in agriculture. The plants of Vigna radiata var. PDM 54 grown on contaminated soil and irrigated with ground water have not shown the translocation of toxic metal (Cr) in the upper part. The biomass of the plant increased when irrigated with treated tannery wastewater compared to ground water, whereas no significant change was observed in chlorophyll and protein contents. In both the varieties (var. PDM 54 and var. NM 1) of V. radiata grown on tannery sludge amendments, the growth parameters exhibited a pronounced positive growth response up to 35% tannery sludge amendments compared with the plants grown on garden soil. Despite the Cr accumulation at lower amendments, no toxicity symptoms were observed in both the varieties of the plants. Higher amendments affected various growth parameters, NR activity, and carbohydrate content of the plants. The results suggest that the plants of V. radiata (var. PDM 54) may be grown on contaminated soil or lower sludge amendments and irrigated with ground water. No translocation of toxic metal Cr was found in the seeds of the plants grown in up to 25% tannery sludge. However, periodical monitoring is required before the consumption of seeds. Overall, the results showed that plant growth patterns were influenced to some extent by the level of soil contamination and the water used for irrigation.     

Arsenic accumulation by ferns: a field survey in southern China

The objective of this study reported here was to characterize arsenic (As) accumulation by Pteris ferns by comparing 3 of the ferns of this genus with each other as well as with four non-Pteris ferns growing on seven sites in southern China with different As levels. A total of 112 samples, including 78 Pteris vittata, 13 P. cretica, 3 P. multifida and 18 ferns from other non-Pteris genera, with the soils in which they grew were collected for As and other elemental analyses. P. vittata was found to be the most dominant species and the most efficient As-accumulator, whereas P. multifida was the lowest As-accumulator among the Pteris ferns, with 4.54–3599, 28.7–757 and 11.2–341 mg kg^–1 As recorded in the fronds of P. vittata, P. cretica and P. multifida, respectively. Arsenic concentrations in non-Pteris ferns were generally much lower than those in Pteris ferns, with 0.81–1.32, 3.59, 10.7, 6.17–24.3 mg kg^–1 in the fronds of Blechumum orientale, Dicranopteris dichotoma, Pteridium aquilinum and Cyclosorus acuminatus, respectively. For P. vittata, the As bioaccumulation factor (ratio of As in fronds to that in soils) changed, whereas the As translocation factor (ratio of As in fronds to that in roots) remained unchanged among the different sites. The concentrations of Fe were very high in all of the collected fern sample, with the exception of B.␣orientale, with 207–6865, 637–3369, 375–1856, 1876, 493-6865 and 492 mg kg^–1 in the fronds of P. vittata, P. cretica, P. multifida, C. acuminatus, P. aquilinum and D. dichotoma, respectively. The association between Fe accumulation and As accumulation and tolerance in these ferns indicates the unique role of Fe in As-hyperaccumulation.