It's the water pumped into the tanks for ballast and then pumped out again that pollutes the seas, says John.
1	It	it	PRON	PERS-SG	_	2	expl	_	SpaceAfter=No
2	's	be	VERB	PRES	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	0	root	_	_
3	the	the	DET	DEF	Definite=Def|PronType=Art	4	det	_	_
4	water	water	NOUN	SG-NOM	Number=Sing	2	nsubj	_	_
5	pumped	pump	VERB	PASS	Tense=Past|VerbForm=Part|Voice=Pass	4	acl	_	_
6	into	into	ADP	_	_	8	case	_	_
7	the	the	DET	DEF	Definite=Def|PronType=Art	8	det	_	_
8	tanks	tank	NOUN	PL-NOM	Number=Plur	5	obl	_	_
9	for	for	ADP	_	_	10	case	_	_
10	ballast	ballast	NOUN	SG-NOM	Number=Sing	5	obl	_	_
11	and	and	CCONJ	_	_	13	cc	_	_
12	then	then	ADV	_	PronType=Dem	13	advmod	_	_
13	pumped	pump	VERB	PASS	Tense=Past|VerbForm=Part|Voice=Pass	5	conj	_	_
14	out	out	ADV	_	_	13	advmod	_	_
15	again	again	ADV	_	_	13	advmod	_	_
16	that	that	PRON	REL	PronType=Rel	17	nsubj	_	_
17	pollutes	pollute	VERB	PRES	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	4	acl	_	_
18	the	the	DET	DEF	Definite=Def|PronType=Art	19	det	_	_
19	seas	sea	NOUN	PL-NOM	Case=Nom	17	obj	_	SpaceAfter=No
20	,	,	PUNCT	Comma	_	21	punct	_	_
21	says	say	VERB	PRES	Mood=Ind|Number=Sing|Person=3|Tense=Pres|VerbForm=Fin	2	parataxis	_	_
22	John	John	PROPN	SG-NOM	Number=Sing	21	nsubj	_	SpaceAfter=No
23	.	.	PUNCT	Period	_	21	punct	_	_
