To systematically explore the spatial-temporal distribution and main controlling factors of dissolved oxygen（DO） in deep lakes,we take Lake Xiannv,a large subtropical reservoir in south China,as the research object.By collecting the historical data of DO at four state-controlled points in Lake Xiannv from 2008 to 2021 to analyze its interannual changes.We also conducted intensive monthly monitoring of Lake Xiannv from May 2014 to April 2015 and from January 2018 to December 2018,which were hefore and after the water pollution accident in 2016.The factors influencing DO in Lake Xiannv were quantitatively analyzed by the structural equation model（SEM）.Results showed that from 2008 to 2021,the DO concentration of Lake Xiannv first decreased and then increased,with a range of 5.1-18.7 mg/L,and the seasonal means were spring＞winter＞autumn＞summer.Before the water pollution accident,the DO concentration in the central area and the outlet of Lake Wulong was higher and water temperature,chlorophyll-a and turbidity were the main driving factors for the change of DO.After the accident,the DO concentration in Lake Qianyang and the bays of Lake Wulong was higher and chlorophyll-a and water nutrition were the main driving factors for the change of DO.There are common changes between pH and DO.The vertical monitoring results of the deepest point（Jiangkou） showed that the vertical changes of water temperature and DO in Lake Xiannv were summer＞autumn＞spring＞winter.We found that there were low DO（DO＜5 mg/L） zones below 5 m of the lake in summer and autumn,thermocline and metalimnetic oxygen minimum（MOM） were observed in summer.In general,the water pollution accident broke the nutrient balance of Lake Xiannv,and the large increase in nutrient concentration led to an increase of phytoplankton,which was the main reason for the increase in DO concentration on the surface of Lake Xiannv,and the changing of deep-water DO concentration is closely related to water temperature and water depth.

微生物燃料电池(MFCs)能够在降解有机物的同时将化学能转化为电能,近年来其独特的能源环境效应在降解藻类生物质方面引起广泛关注.然而,成分复杂的藻类细胞壁会阻碍藻类生物质在微生物燃料电池中的降解.为了提高微生物燃料电池降解藻类生物质的效能,通常需要对藻类生物质进行预处理,破坏藻类细胞壁使生物基质释放,并将难降解的大分子有机物分解为易降解的小分子有机物.综述了目前应用于微生物燃料电池降解藻类生物质的预处理方法,包括机械法、加热法、微波法和超声波法等物理预处理法,酸、碱、氧化等化学预处理法,酶或微生物细胞(细菌或真菌)作催化剂的生物预处理法,以及上述多种预处理方法耦合的联合预处理法.评估了这些预处理方法的能耗和经济性,并对藻类生物质预处理过程与降解过程耦合的集成化或紧凑型微生物燃料电池系统进行介绍,以期为今后微生物燃料电池系统与其他藻类生物质预处理方法的结合研究提供一定参考和依据.

江西赣州地区分布着全球稀有的离子吸附型稀土矿,其开采工艺主要为原地浸矿,提取过程中主要使用硫酸铵,长期的原位浸提对当地的土壤环境造成的污染风险亟待评估.本研究以定南县原地浸矿工艺的典型离子吸附型稀土尾矿为研究对象,开展了矿区不同土层氮污染现状研究,设置了不同高程的采矿区(山顶、山腰、山脚)及附近未受浸矿干扰的山体对应深度的土柱进行对比研究,运用描述性统计、均值分析、Pearson相关性和主成分分析等方法,探索了定南原地浸矿的离子型稀土尾矿氨氮含量赋存现状,分析了定南该类稀土尾矿深层土壤氮化物污染特征.结果 表明:顶子脑稀土矿山土壤Kj-N、NH4+-N和NO3-N含量平均值分别为339.26 mg/kg、156.29 mg/kg和27.63 mg/kg,下茶坑稀土矿山土壤Kj-N、NH4+-N和NO3--N含量平均值分别为226.42 mg/kg、100.46 mg/kg和18.20 mg/kg,两个对照区土壤Kj-N、NH4+-N和NO3-N含量平均值为157.69 mg/kg、2.55 mg/kg和2.74 mg/kg;稀土矿山开采后山体深层土壤(4 m～12 m)中氨氮污染严重(顶子脑:744 mg/kg,下茶坑:374mg/kg);顶子脑稀土矿山的山顶氮化物污染程度比山腰和山脚污染程度高(P＜0.05),下茶坑稀土矿山山顶、山腰和山脚受氮化物污染程度近似(P＞0.05);两座矿山山顶处凯氏氮与铵态氮含量之间存在显著的正相关性(P＜0.0l),山腰和山脚处铵态氮与硝态氮含量显著正相关性(P＜0.01),两座矿山的铵态氮与土层深度之间存在显著的正相关性(P＜0.01);稀土矿山中氮化物的存在形式主要是铵态氮,且铵态氮是稀土矿区判别污染的主要影响因素.

为探究“稀土王国”江西省赣南地区离子型稀土矿对周边水体环境的影响,以离子型稀土矿分布密集区定南县濂江月子河流域和龙迳河龙头流域为研究对象,综合分析研究区特征污染物p(NH4+-N)空间分布特征,采用相关性分析和主成分分析揭示其主要污染来源及影响因素.结果表明:①离子型稀土矿停产整顿半年后,濂江月子河流域和龙迳河龙头流域p(NH4+-N)超过1.00和2.00 mg/L的采样点分别达72％和68％;pH范围为2.95～ 7.66,平均值分别为6.23和5.53,水体总体上偏酸性;p(TN)、ρ(NH4+-N)、EC与ρ(NO3-N)变异系数较大,均介于0.80～ 1.50之间.②相关性分析结果显示,p(NH4+-N)与p(TN)、EC均呈极显著正相关(P＜0.01);p(NH4+-N)与pH呈显著负相关(P＜0.05).③流经稀土尾矿区的水体中ρ(NH4+-N)随距离增加呈现明显的空间梯度分布特征,即距稀土矿区边界200 m处水体中p(NH4+-N)最高(12.20～ 200.00 mg/L),其次为1.15 km内(3.69～ 11.80 mg/L)及3.5 km以上水体(0.80～1.51 mg/L),矿区周边未受到采矿活动影响的水体中p(NH4+-N)最低(0.03～0.15 mg/L).④PCA结果表明,2条河流的主要环境影响因子为p(TN)、p(NH4+-N)、pH和EC,主要受到周边稀土矿山尾矿的强烈影响.研究显示,离子型稀土矿原位浸矿开采停产半年后,重点小流域水体中p(NH4+-N)高概率超标的现状仍然存在,受稀土开采活动影响较大.建议进一步开展重点小流域NH4+-N剩余“库容”精算和矿山周边地表水定期监测.

为了保护大部分水生生物,维护水生生态系统结构和功能的完整性以及生物的多样性,推导硫化物水质基准并以此为依据制定水质标准已成为迫切需要.参照国际通用的相关技术指南,从美国环境保护署(USEPA)的ECOTOX毒性数据库和中国知网中收集了相应的硫化物对水生生物的毒性数据.结合我国水生生物区系特点,筛选出广泛存在于我国水体中的水生生物毒性数据.采用美国规范方法SSR法对毒性数据进行了分析,得到的硫化物急性和慢性基准分别为1.46、1.10μg·L-1,且用荷兰物种敏感度分布(SSD)法和评价因子法进行了比较,SSD法与SSR法所得结果在同一数量级,评价因子法相对保守.

以某工业园为例,采用排放因子法估算2010-2016年园区冶炼企业大气重金属的年平均排放量,从污染物种类、时间变化2个方面分析了冶炼企业大气重金属的排放特征,并揭示了其与周边土壤污染的相关性.结果表明:2010-2016年间,冶炼企业大气砷、铅、镉共累积排放649.29 kg,年均增长达44.60％.大气降尘造成土壤中砷、铅、镉年增加值分别占土壤标准值的1.01％、1.02％和3.77％,以此推算,大气降尘造成土壤镉、砷、铅超标的累积时间分别为16 a、31 a、60 a以上;大气砷和铅之间有显著正相关性,土壤中砷-铅、镉-铅、镉-砷之间均具有显著正相关性,说明它们的同源性很高.

为探究叶面喷施肥料是否可有效缓解重金属对水稻的毒害作用,以湘晚籼17和五优369基因型水稻品种为材料,通过盆栽试验法测定复合叶面肥对土壤不同浓度Cd胁迫下水稻幼苗的生长情况和地上、地下部Cd积累效应.结果表明:喷施自制复合叶面肥不仅能促进2种水稻幼苗株高和干重的增长,且能有效地抑制水稻地上部Cd积累,对湘晚籼17的抑制效果优于五优369.这说明多养分复合叶面肥对水稻Cd积累的调控效果可能与水稻自身品种差异和土壤Cd的浓度有关.

Despite growing concern about the potential adverse effects of elevated antimony concentrations in soil,hardly any toxicity data are available for terrestrial invertebrates.To explore the toxicity of antimony to soil invertebrates and compare toxicity differences among different types of soil,the acute and chronic toxicity of antimony to Folsomia candida were assessed in three typical soils (i.e.,Hailun isohumosol,Qiyang ferrosol and Beijing primosol) using mortality,avoidance and reproduction as evaluation endpoints.The 2-day EC50 (i.e.,concentration causing 50％ toxic effect) values expressed in measured total antimony concentrations for the avoidance of F.candida were 298,＞400 (i.e.,avoidance rate did not reach 50％ at the highest concentration) and 132 mg/kg,respectively.The 7-day LC50 (i.e.,median lethal concentration) values for the mortality of F.candida were 3352,4007 and 2105 mg/kg,respectively.The 28-day LC50 values for the mortality of F.candida were 2271,1865 and 703 mg/kg,respectively.The 28-day EC50 values for the reproduction of F.candida were 1799,1323 and 307 mg/kg,respectively.The results showed that avoidance was a more sensitive endpoint than reproduction and mortality,and the toxic effect of antimony on F.candida significantly varied with soil types.The toxicity of antimony in Beijing primosol was maximally nearly six times higher than that of in Hailun isohumosol and Qiyang ferrosol,indicating the distinct impact of soil physicochemical properties on the toxic effect of antimony.But the differences of LC50 or EC50 values expressed in water-extracted antimony concentrations among the three soils decreased,indicating that the water-extracted antimony consisted with the toxicity of antimony obviously and could explain the toxicity variations among the three soils.The study can provide the basis for establishing a prediction model of antimony toxicity as well as formulating the quality standard value of antimony in soil.