The toxicity of naphthalene to a freshwater microalga,Chlorella pyrenoidosa,and the subsequent recovery of algae from the damage were investigated under two nutrient conditions,either enriched with nitrogen (N) and phosphorus (P),or starved of N and P.Results showed that C.pyrenoidosa was more sensitive to naphthalene under N,P-enriched condition,and the inhibitory rate generally increased at first and then decreased gradually with the evaporation of naphthalene under both nutrient conditions.Enriched N,P reduced the inhibitory rate at initial naphthalene concentration of 5 and 10 mg/L,but enhanced it at 100 mg/L,at which more severe ultrastructure damages were found than those under N,P-starved condition.Observed damages included partly or totally disappearance of nucleolus,nuclear,and plasma membranes.According to the chlorophyll content and cell density measurements,C.pyrenoidosa could recover from naphthalene damage with initial concentrations 50 mg/L in 7 days under both nutrient conditions,while they could not recover if the initial concentration of naphthalene was at 100 mg/L.Under the N,P-starved condition,the inability of C.pyrenoidosa to recover from the naphthalene damage was consistent with the results of high inhibitory rate,low value of specific growth rate (SGR,0.05 day 1),and the severe destruction of cell structure.However,under the N,P-enriched conditions,the observed lower inhibitory rate,higher value of SGR (0.55 day 1),and the intact cell structure of most cells suggested that algae could potentially recover from the naphthalene damage.
The indoor total volatile organic compound (TVOC) concentrations and their relationship to potential influencing factors were evaluated. Samples (n = 2302) were collected from 2007 to 2009 both in old structures and new construction in the city of Hangzhou from bedrooms, sitting rooms and studies that had been decorated within the previous year. The average TVOC concentration in all the newly decorated rooms was 0.65±0.69 mg/m 3 . 35.8% of samples exceeded the China standard. Over the past 3 years, the TVOC concentration decreased and then increased (P < 0.05). The percentage of samples exceeding the China standard in the three rooms decreased in the following order: sitting room>study>bedroom. The characteristics of the TVOC source were a key factor influencing the TVOC concentration. In addition, the TVOC concentration was also (P < 0.05) related to the temperature, humidity, time from the end of decoration to sampling (DR), and the amount of time windows and doors were closed before sampling (DC). The temperature and humidity were less important than the DR and DC. A model to relate the TVOC concentration to the five factors (temperature, humidity, source, DR, and DC) was established based on 288 samples (R 2 = 0.83). The model illustrated that the time for the TVOC concentration to meet the China standard was different for the various rooms, and when the other factors were fixed, the impact of DC (t 1 ) on the TVOC concentration could be quantified as (((t 1 +1)/2) 0.212 1)×100%.
LIU Jian LeiBAI GeCHEN JieZHU LiZhongGUO WeiQiangSHEN XueYou
The pollution status and characteristics of PAEs(phthalate esters) were investigated in indoor air of offices, and PAEs of both gas-phase and particulate-phase were detected in all the samples. The concentration(sum of the gas phase and the particulate phase) was4748.24 ng/m3, ranging between 3070.09 and 6700.14 ng/m3. Diethyl phthalate, dibutyl phthalate, and di(2-ethylhexyl) phthalate were the most abundant compounds, together accounting for 70% of the ∑ 6PAEs. Dividing the particulate-phase PAEs into four size ranges(< 2.5, 2.5–5, 5–10, > 10 μm), the result indicated that PAEs in PM2.5were the most abundant,with the proportion of 72.64%. In addition, the PAE concentration in PM2.5correlated significantly with the total particulate-phase PAEs(R2= 0.85). Thus, the amount of PAEs in PM2.5can be estimated from the total amount of particulate-phase PAEs using this proportion. In a comparison between the offices and a newly decorated study room, it was found that pollution characteristics were similar between these two places. Thus, it is implied that the PAE concentration decreased by 50% 2 yr after decorating.
Min SongChenchen ChiMin GuoXueqing WangLingxiao ChengXueyou Shen
Air pollution surveys of formaldehyde(HCHO) were conducted in 2324 rooms decorated within one year in 2007-2009 in Hangzhou,China.The mean HCHO concentration(C HCHO) was 0.107 ± 0.095 mg/m 3,and 38.9% of samples exceeded the Chinese National Standard GB 50325-2010.Over the past 3 years,the C HCHO decreased with time(p < 0.05).Relationships of potential factors to indoor C HCHO were also evaluated.C HCHO was related to temperature(T),relative humidity(RH),time duration of the windows and doors being closed before sampling(DC),time duration from the end of decoration to sampling(DR) and source characteristics(d).A model to relate indoor C HCHO to these five factors(T,RH,DC,DR,d) was established based on 298 samples(R 2 = 0.87).Various factors contributed to C HCHO in the following order:T,43.7%;d,31.0%;DC,10.2%;DR,8.0%;RH,7.0%;specifically,meteorological conditions(i.e.,RH plus T) accounted for 50.7%.The coefficient of T and RH,R TH,was proposed to describe their combined influence on HCHO emission,which also had a linear relationship(R 2 = 0.9387) with HCHO release in a simulation chamber test.In addition,experiments confirm that it is a synergistic action as T and RH accelerate the release of HCHO,and that is a significant factor influencing indoor HCHO pollution.These achievements could lead to reference values of measures for the efficient reduction of indoor HCHO pollution.
Min GuoXiaoqiang PeiFeifei MoJianlei LiuXueyou Shen
